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WindWatch page 08 June 2016
The technical resource for wind profitability
ENGINEERING & DEVELOPMENT
NEW IDEAS TO BOOST PRODUCTION AEP UP 5% MAY BE SCRATCHING THE SURFACE Planning for problems in the BOP PAGE 52
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HERE’S WHAT I THINK
Senior Editor | Windpower Engineering & Development mfroese@wtwhmedia.com
|
Wind industry inspires present and future generations
A
merican author and critic, William Deresiewicz, uses virtual modeling to help boost turbine performance. once said, “The true purpose of education is to GE Renewable Energy gets extra credit for inspiring make minds, not careers.” For those interested younger minds as well. With AWEA as host, GE sponsored in a sector such as, say, wind power (where the the KidWind Challenge, a program that lets students U.S. installed more electric generating capacity than any explore the power of wind by building and testing their other technology last year), education may provide both — own turbines. Teams that excel and make the national a sharp mind and successful career. competition are then ranked based on how many units If you attended AWEA’s WINDPOWER 2016 in New of energy their turbines produce when placed in a wind Orleans this past May, the largest wind-related conference tunnel. This year, 400 middle and high-school teams and exhibition in North America, you may have noted competed at the national challenge in New Orleans. a few things. Yes, the United States is the number one For St Louis, Missouri, team leader and volunteer, country in generating wind energy and delivering it to Lynn Shellenberger, KidWind is a chance to give kids customers. With plans to add 8 GW a year to the grid over something she never got in school. This year two of her the next decade or so means American wind power is also teams made it to the nationals, and most of them were on track to meet and exceed its vision of 10% by 2020. girls. “I graduated high school with a 7th-grade reading Impressive. But all of that hard work doesn’t just level and discovered I had a learning disability. I did happen. What’s perhaps more remarkable is what the wind not do well in science or math or believe I could,” she industry’s offering this generation and the next in terms shared. “But this program engages kids through hands-on of employment. As AWEA CEO Tom Kiernan explained experiences. It inspires them to learn through research and during his opening speech at WINDPOWER: “In 2015, demonstration. Plus, it is an equity program that does not the Department of Labor did a survey about what the discriminate based on gender, race, or income.” fastest growing profession is in this country. They looked Although her teams didn’t place this year, at healthcare and software developers, but no. The fastest Shellenberger said what counts is that her students learn growing profession is wind-turbine technician.” about the future career opportunities available to them. “If “That’s why the theme for this year’s WINDPOWER you live in a city, chances are you’ve never seen a wind 2016 is Generation Wind,” he added. “This is our time.” turbine or know much about one.” She said in the past Seems it is also the time to inspire a future generation. If her teams visited a turbine out in LeRoy, Minnesota where you noticed anything different at this year’s event, it may some of the college-aged kids in the area struggled to have been the number of students on the show floor. find work. Now some are training as wind technicians. I noticed some climbing ENSA’s training tower. “These are good-paying job that are a real possibibility ENSA, an exhibitor at the show, provides work-at-height for any of these students. But it starts with equity and safety training and rigging services — a must for any engagement,” she said. In my opinion, it also starts with wind technician in the field. I saw others experiencing an industry that’s dedicated to growth and education. ACCIONA Energía’s virtual reality program that lets users “We’ve built an American success story that creates make a maintenance “visit” to a wind farm from home. jobs, cuts carbon pollution and costs for consumers,” said Others were checking out GE’s Digital Wind Farm, which Kiernan. For that the wind industry should be proud. W
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2015
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CO NT R I BUTORS
GOON
BERGES
PEDRO BERGES is Sentient Science’s Implementations Manager, a job that entails leading the implementation of commercial projects with Sentient’s Digital Clone platform and working on developing drives system models. He has a Master’s Degree in Robotics from the University of Notre Dame. He is also a New York State certified Professional Engineer.
HAMMETT
HALEY
MICHAEL GOON is an associate in the New York office of Milbank, Tweed, Hadley & McCloy and a member of the firm’s Tax Group. He advises clients on tax matters relating to renewable energy, partnership taxation, and project finance. Goon also represents clients in bond offerings, IPOs, financing transactions, and passive foreign investment company reviews. mgoon@milbank.com
LEE
KARLOV
JAY HALEY has been involved in wind energy since 1983 and is the Principal in Charge of the EAPC Wind Energy team in Grand Forks. He has made hundreds of public presentations on wind energy and has been the wind industry’s primary spokesperson in North Dakota. Haley provides consulting services to wind developers, financial institutions, electric utilities, communities, economic development groups, universities, and Native American tribes.
STEUER
SOELLINGER
MORTIMER
MAAS
BRUCE HAMMETT, an electrical engineer, began his renewable energy career in 1982, during the early days of the California wind energy experience. He provided controls and BoP components for the growing number of wind farms. Since 1986, Hammett has delivered components and expertise to the North American renewable energy industry as President of Wind Energy Commercial Solar (WECS) Electric Supply Inc. WECS supplies a full range of electrical, mechanical, and hydraulic components, as well as BoP services, to support wind turbines and solar systems — from the point of connection of the utility transmission to the point of connection to the energy source. LEAH KARLOV is tax partner at Milbank, Tweed, Hadley & McCloy LLP. She has significant experience in complex financing transactions, including leveraged leases and tax advantaged financings, private placements and syndicated financing transactions. Karlov has served as lead tax counsel on numerous matters representing major financial institutions (as tax equity investors and lenders) and project developers in connection with the financing, construction, acquisition and operation of facilities generating electricity through the use of wind and other renewables. lkarlov@milbank.com TRISTAN LEE is employed in the U.S. Strategic Business Unit of the AES Corporation. He is a veteran Performance Engineer with an extensive background spanning nearly a decade in modern wind-turbine design, operation, and
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Contributors 6-16_Vs3.indd 4
performance improvement for Vestas, GE, and Siemens’ turbines. He is responsible for monitoring site performance, providing diagnostic reports, supporting engineering initiatives, and working with local leaders to evaluate methods and opportunities for enhancing site reliability and sustainability. He studied automation robotics and wind energy technology at Texas State Technical College, and Lee has patents pending related to wind resource assessment and wind-turbine performance optimization. HILMAR MAAS is a Fire Safety Solutions Expert working at the Siemens Building Technologies Division in Zug, Switzerland. He studied Building Technology at Muenster University of Applied Sciences in Germany, and is now a professional in fire-alarm systems and gas fire-extinguishing systems (VdS-certified). Mass is responsible for for largescale industrial projects at Siemens. ALAN MORTIMER (BSc Hons MSc CEng MIMechE) is Director of Innovation at renewable energy consultancy, SgurrEnergy. After graduating from Glasgow University with a degree in Aeronautical Engineering, Alan spent four years at James Howden & Co. in Glasgow before joining ScottishPower, working in its renewables development. Alan spent 25 years there with roles that included Head of Innovation and Head of Wind Development. He developed the strategy for, and then delivered, a wind portfolio including the UK’s largest wind farm, Whitelee. At SgurrEnergy, Alan’s role covers a broad range of renewable technology innovation opportunities including onshore wind performance optimisation, offshore wind cost reduction, wave and tidal technology developments, renewable heat and energy storage. AARON SOELLINGER is Sentient Science’s Program Manager. Leveraging his background in game theory and economics, Soellinger built the DigitalClone for Suppliers product, a software application that gives sellers an ability to use the DigitalClone network to conduct advanced market segmentation and directly interact with customers through a private network. He has his Bachelor of Science in Economics from Purdue University. BRIAN STEUER, Director of Business Development at Voelker Sensors, has over 25 years’ experience as a successful entrepreneur, engineer, inventor, and product development specialist who has founded or co-founded four successful companies throughout his career. He has been granted seven U.S. patents for devices used in automotive safety, electronic test automation, and microprocessor programming He has built and led organizations with proven operational excellence in manufacturing of complex products such as, consumer and commercial electronics, medical equipment, and networking equipment.
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E D I T O R I A L EDITORIAL
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5 Photos courtesy of TGM Wind Services
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www.windpowerengineering.com
JUNE 2016 • vol 8 no3
CONTENTS
D E PA R T M E N T S 02
Editorial: Wind energy inspires present and future generations
31
Software: What might be the financial impact of a new wind farm on your community? The Jedi tells
08
Windwatch: A chilling story of blade abuse,
33
Projects: Advice for first-time wind developers
36
Turbine of the Month: Envision’s E128-3.6 PP 2B
38
Policy: IRS Notice 2016-31: Beginning construction under the PATH Act
What to do with extra towers, Journal bearings in a planetary stage, Ask a wind tech, Wind work around North America
20
Reliability: Improving wind-turbine performance
24
Bolting: New torque tools call for a
28
with PLCs
40
technician’s upgrade
Safety: Fire prevention and protection for wind
56
Equipment world: Electrical conductors, Safety gloves, Wind turbine coupling, AC powered electric wrench, Advanced electrical converter
60
Downwind: Who says only one turbine per tower? Not this OEM
turbines offshore and on
46
Fluids & Filters: Oil monitoring promises accurate real-time
readings
F E AT U R E S
42 How small data from material
science accurately predicts failure rates and more
Decades of experience with bearing and gear materials have let engineers write accurate predictive maintenance software. Now, it provides guidance on the most durable and appropriate replacement components for wind turbines.
xx
A few new ideas for improving wind farm outputs
AEP improvements of 5% and more are possible by taking advantage of improved controls, aerodynamic techniques, a better understanding of local winds, and more.
ON THE COVER
A wind tech from SgurrEnergy adjusts a lidar unit to measure more accurate wind flows.
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52 Planning for crises on the balance-of-plant
When making an O&M plan for a wind site, remember to include more than just the turbines on your list. Without the substation, connection systems, and supporting balanceof-plant (BoP) infrastructure, those turbines and the power generated lose their value. Here’s what you can do to optimize BoP operations at a wind farm.
www.windpowerengineering.com
JUNE 2016
6/9/16 1:17 PM
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Havoygavlen Wind Farm is the northern most wind farm on earth. Weather conditions mean a welldesigned blade maintenance plan is mandatory. 8
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IF IF BLADES BLADES ARE ARE AA KEY KEY TURBINE TURBINE COMPONENT, COMPONENT, WHY WHY NOT NOTTREAT TREATTHEM THEM THAT THATWAY? WAY? Michelle Froese • Senior Editor Windpower Engineering & Development
MANY WOULD ARGUE THAT TURBINE BLADES are a critical part of a wind generator. Blades are the key component for receiving and maximizing wind energy, so proper care would seem essential to optimal production. Ville Karkkolainen, Managing Director at Bladefence, a blade inspection and repair company, agrees but says what actually happens in field tells a different story. “Most of the time I feel like we are a fire department being called after the emergency -- when the blades are already in devastating and sometimes irreparable conditions,” he said during a presentation at the recent Wind O&M Dallas 2016 conference, put on by Wind Energy Update. Karkkolainen claims about 90% of Bladefence’s revenues come from project services, meaning significant damage has already occurred by the time the company is asked to service turbine
blades. “It’s not only a matter of keeping blades alive for 20 years, it’s also a matter of service and performance during a blade’s lifetime,” he said. “A maintenance plan is essential.” It’s no secret turbine blades are damaged by dust, moisture, wind gusts, and lightning strikes. Aerodynamic loads and gravity can also fatigue and damage blades. “Yet there’s very little open data on the subject,” shared Karkkolainen, which is interesting, he said, because we’re in an era of data gathering. “There’s been much discussion on the number of sensors in and on wind turbines, which is true for almost every turbine component — except for the blades.” He gave the example of a gearbox, which can have dozens of sensors that remotely report to a turbine owner or control center, but blades tend to just have one strain sensor. Strain detection is
JUNE 2016
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W I N D W A T C H
Lightning strikes are one of the most abusive natural events that blades face. A lightningprotection system, imperative for blade protection, may also be required by insurance companies.
still one of the most common methods to monitor a blade’s condition. “But these are huge, remote devices with several failure modes. So it is difficult to remotely and reliably evaluate blade conditions from afar, or to make accurate predictions from the collected information.” Of course, it’s possible to visually inspect blades by use of cranes or skylifts but, for most companies, such equipment is too expensive, so it is saved for maintenance and repairs, explained Karkkolainen. “This leads us to the cameras and drones, which are becoming more widely used today. At the end of the day it’s not so much how data is consistently collected, but how the information is analyzed and used afterwards.” According to Karkkolainen, the wind industry still lacks the necessary standards or best practices for ideal blade inspections and for consistent collection and analysis of inspection data. For example, after a blade inspection, a wind-farm owner is typically given files full of information that are often challenging to interpret and review with accuracy. “Understanding the issues or root cause of blade damage can be daunting,” he said. “This is especially true after warranty 10
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when going from the OEM — which often has a consistent method for measuring blades that is not always publicly shared — to an ISP or to self-performing inspections. It can be difficult at this point to develop a consistent and intelligent database to use for future blade planning and maintenance.” Developing standards or a transparent and streamlined method for comparing common blade failures will take time. “Unfortunately, this is not an issue that will be solved overnight,” he said. “Eventually, data compatibility from company to company is something to strive for in the industry.” For this reason, Bladefence has begun collecting blade data over the last few years as part of a database to note and compare consistencies and differences. “Even from a relatively small sample size, it is possible to see trends in root causes and in damage progression in different failure modes and in different turbine types,” said Karkkolainen. “It is possible to track the effects of various environmental factors, such as moisture and freezing temperatures, that can damage blades.” Aside from Bladefence’s own inhouse studies, one study from 3M shows
trends from leading-edge blade damage. The study indicated that the effects of weathering on the output of turbines are much greater than previously thought, and that damage caused by airborne objects (such as sand or rain) can reduce the energy output of a turbine by more than 20% per year. “It’s the only publicly available study I know of so there is certainly a lack of available data,” he said. “I don’t think figures from these studies should be interpreted as definitive facts because each wind farm is different, but there are definitely trends worth looking at.” Karkkolainen presented an example of what can happen when blade damage is ignored. He showed two images, one with a blade that had moderate leadingedge erosion, and another of the same blade a couple years later when the damage was now severe. “It’s worth noting that this took place in under two years,” he said. “Plus, the initial data was there for the customer to act upon. But in this case, they didn’t until it was almost too late. So what began as a manageable condition became a dangerous and nearly irreparable case where the blade could have easily snapped off.” In Karkkolainen’s experience, blade
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W I N D W A T C H
maintenance and repairs often get pushed aside until later usually due to time or budgetary constraints. “The unfortunate part of this scenario is that these issues are often obvious by year seven or eight of a blade’s life. Yet, as was the case with the turbine in this example [it was at year 11], its blades were no longer available from the OEM. So the option became either to repair the blade at a high cost or to completely write-off the entire turbine.” For repair techs, this becomes a difficult position. “How do you tell a wind-farm owner that because of their lack of foresight and proper maintenance, they’ve pushed themselves into a position where now they have to scrap the turbine completely — never mind pointing out the health and safety concerns of such a damaged blade?” Sometimes it’s possible to convince the manufacturer to reproduce a blade, but it is often costly and not necessarily affordable or worth the price. If you think blade maintenance isn’t ignored or often overlooked, think again. His next example showed a photo of a blade on which the damaged leading edge was duct-taped together.
“This turbine is owned by one of the largest utilities in the world with more than 1 GW of installed capacity,” he said. “This isn’t about blaming the company, but I show this image to drive home a point. We have a vision in this country of 10% more wind energy by 2020, which is important but we also have to face reality and the state of today’s turbines. If we’re going to have an honest discussion about generating reliable and economical wind energy of the future, let’s start today.” Karkkolainen pointed out that ISPs are subject to stringent quality control and must submit verifying documents that support their work. “Why shouldn’t there be similar standards for each sector in the industry?” he asked. He admitted that the wind industry
presents unique challenges. It is an interesting industry, he said, and one that presents different ideal conditions depending on the sector or device. “For instance, slip rings and bearings tend to work better in humid conditions but blade repair work should be done in far dryer conditions. So one way or the other, you have to prepare for these challenges.” One way to do so is by ensuring devices receive ongoing maintenance. Karkkolainen also believes the industry needs more innovation. “I’ve been here for six years and in some ways little has changed. The message, at least from a materials standpoint, is that we need more courage to try new technologies in the market.”
The leadingedge damage on this blade has been "repaired" with duct tape, certainly not a recommended technique.
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Despite examples of poor blade conditions there are also success stories, even in challenging conditions. Case in point: Havoygavlen Wind Farm, the northern most wind farm on earth, located on the 71st latitude in Norway. “In 2013 when we began as an ISP on the site, they only had five days last year when the temperature was above +15º C, enabling blade repairs with conventional materials — and even so there was always snow on the ground. If this is your weather scope and it’s September, you cannot do anything before June,” he said. “This extreme site underlies the fact that a blade maintenance plan is needed, and should be reviewed or revised year after year.” But as Karkkolainen also pointed out, extreme conditions should not be the only time a well-devised maintenance plan comes into play. “You have to be proactive when it comes to blade maintenance regardless of site location.” Insurance companies are slowly starting to require these plans, too. “One of the harshest conditions blades face is lightning,” he said. “We’ve had several cases in Europe in which an insurance company has threaten to deny a claim if the owner could not present data from a lightning protection system (LPS) The owners had not been careful enough in fulfilling their duty by ensuring blade protection.” In another case, workers found pieces of a turbine half a kilometer away after a thunderstorm. “The insurance company asked how could this happen with a LPS? The root cause analysis showed that it was a combination of a faulty LPS and blocked drain holes at blades tips. This is worth noting because drones or ground-based imagery cannot check drain hold or the condition of the LPS.” There are places in Germany that lawfully require annual inspections of LPS and drain holes in turbine blades because it’s considered a health and safety issue that can cause catastrophic events. “Inspection and blade maintenance should be part of the same process and 12
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The technician's eye view down the length of the blades show leading edge erosion and dirt clearly visible.
not occur separately,” Karkkolainen advised. “Doing so saves time and repair costs at the time of an inspection. And consider the long-term ramifications. By catching leadingedge erosion early, you can save the blade and potentially a whole turbine from going out of service. Now that’s a positive for the industry.” W
WHAT DO YOU THINK?
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JUNE 2016
6/9/16 3:29 PM
Castrol_THE BEST OPTION_WindpowerED.pdf
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THE BEST OPTION IS HAVING ONE CastrolÂŽ is the only lubricant supplier that offers fit for purpose technology options. We utilize multiple product-based solutions that can align with your O&M strategy and deliver continuity within your fleet. Our expert engineering services can provide insights to help you obtain the maximum value from your lubricants and your turbines. Ask us what options Castrol has for you. Castrol.com/windenergy or 1-877-641-1600
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W I N D W A T C H
Towers for turbines, towers for training. Get your towers here! WHAT DO YOU DO WHEN WIND-FARM PLANS GO SOUTH, but the turbines and towers have been ordered? Ouch. This scenario played out not long ago in Oregon when the Federal government axed plans for a 10 turbine wind farm. It was too close to a military base, it said. Chinese OEM SANY was to supply the turbines and towers and the towers arrived first. So now, nine good towers each capable of holding a 2-MW turbine, plus one damaged tower are sitting in the Port of Vancouver, Washington looking for a new home. To see if the 10th tower could be fixed, President of ph-consulting group inc. Peder Hansen was called in to provide an analysis. “It could be repaired but the owners considered the cost prohibitive,” he says. No big problem. Given the current building boom, the others should be easy to sell. Right? Not exactly. “The nine good towers are still at the port because SANY is not selling this type of machines in the U.S. anymore, but wants to get rid of them,” says Hansen. However, there is a practical and a dynamic problem to the sale. The practical problem is that the bolt diameter in the top flange may not fit other turbines, and so would require an extra cost adaptor. And the dynamic problem is one of natural frequency. If the vibrations generated by a different turbine are close to the natural frequency of the tower, it could eventually weaken by fatigue or embrittlement. “A solution would be to alter the speed of the turbine or add mass to the tower. Several people have suggested where to weld on more mass or add concrete ballast. Both fixes are widely viewed as unsatisfactory solutions,” he says. Hansen suggests further that the tower fatigue problem will arise again as U.S. turbines reach their 20 year life. After two
Tower sections are being handled carefully at the Port of Vancouver, Washington.
decades of vibration, they may not be capable of heavier loads from upgraded equipment. In any case, one of the 10 towers will be scrapped or recycled, which brings up a larger problem for the wind industry. “We are talking about 100 to 200 tons of steel in each tower, some of it two-inches thick. Now consider the hundreds of towers under turbines that will soon reach their 20 year service life. If they are to be taken down to make room for taller towers and more productive turbines, the towers will have to be cut apart and hauled away, a job almost as difficult as transporting and erecting such large loads now.” Hansen however, suggest other uses for the good towers. “Schools that train wind technicians might like a tower for its climbing, safety, and rescue classes. Then the dynamics of the tower are unimportant. Another thought was for an adventure company to let people experience the thrill and challenge in climbing and rappelling,. Hansen says he sure there are many other ideas. If you have one, let him know. W
Turbine towers here. Get your towers. The one damaged turbine tower, dropped while unloading, will probably be turned into scrap. The other nine however, are ready for service under a turbine or elsewhere.
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JUNE 2016
6/9/16 1:33 PM
W I N D W A T C H
NREL readies new wind-turbine drivetrain for commercialization
The Romax designed journal bearing performed well during tests in normal operation scenarios, as well as abnormal scenarios such as dithering.
ENGINEERS AT NREL have completed tests on an unusual wind-turbine drivetrain that is the collaboration of several companies. The design sports a single-stage gearbox designed by Romax Technology, a medium-speed permanent-magnet generator, and a power converter developed by DNV Kema with high-efficiency modules developed by Cree (now Wolfspeed). The goal of the project’s first phase, which began in 2011, was to design an advanced drivetrain that could improve reliability and efficiency, reduce the cost of wind energy, and scale to larger power ratings. NREL project lead Jon Keller says the 1.5-MW design can scale to ratings as high as 10 MW. In 2013, the team received follow-on funding to develop the prototype and demonstrate the technology’s commercialization potential. The new gearbox consists of a single planetary stage that uses compliant flex-pins and journal bearings to support the planets, thereby eliminating the lowerreliability, higher-speed stages found in traditional gearboxes. Traditional three-stage, high-speed gearboxes have been plagued with reliability issues caused by large and unpredictable loads imparted to gears and bearings by high wind and turbulence, utility faults acting through the generator, and hard stops. “Our goal was to produce the best power density in the smallest package,” says Romax Technology mechanical JUNE 2016
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engineer Travis Histed. “The journal bearings with positive pressure lubrication allow for reduced planet size and a fourth planet.” The flex pins are used to let the system find a natural load equilibrium. “If one pin is carrying too much load, it sort of flexes out of the way and the others pick up the load. It is a way to improve load sharing over a conventional threeplanet design,” says Histed. “At the end of the test sequence, we added a test to simulate a full year of what’s called dithering, when the rotor is locked and the wind rocks the rotor back and forth. We dithered it quickly at 2 Hz and without oil. The coming teardown will tell how well the bearing held up.” The planetary-stage design has seen a lot of evolution since early days from SRB (Spherical Roller Bearing) to CRB (Cylindrical Roller Bearing) to integral CRB or TRB (Taper Roller Bearing). “The innovative design of the journal bearing is a breakthrough for the industry to improve efficiency and system
windpowerengineering.com
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The unusual gearbox, designed by Romax Technology, sports four planet gears riding on journal bearings and flex pins. The drivetrain is a semi-integrated, mediumspeed, medium-voltage configuration. The single stage design has a 1:5.8 ratio.
In addition, the power converter now has algorithms to compensate the inverter voltage and current levels to reduce torque transients during utility faults. This reduces mechanical loads due to electrical utility faults.
reliability,” added Dr. Zhiwei Zhang, VP Engineering from Romax Technology. “The medium speed co-axial drivetrain is also a developing trend for windturbine technology because it realizes the balance between the complexity of the mechanical drivetrain and generator cost. It also removes the high speed stage which is usually vulnerable to failures such as White Etch Cracks or WECs. The medium-speed drivetrain will demonstrate additional reliability and efficiency advantages over conventional high-speed designs when it is scaled to higher power rates for offshore applications. ”
In terms of reliability, NREL’s Keller estimates a significant increase in gearbox reliability (compared to a conventional three-stage gearbox) because it doesn’t have an intermediate or high-speed stage where most failures occur. “The use of a double-tapered roller main bearing to isolate rotor loads and journal bearings in the planetary stage should also improve reliability,” he says. There are improvements on the electrical side as well. The team is also exploring medium-voltage, wide-bandgap, silicon-carbide power modules. These state-of-the-art power modules
The journal bearing performed so well, as indicated by a low particle count in the oil, the team decided to vibrate the gearbox for 6 hours with the oil flow off. As expected, the metal particle count did rise. The teardown will tell more.
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JUNE 2016
6/9/16 1:36 PM
GET YOUR WORKSITE ON TRACK ---tracks for 4x4 trucks · atvs · utvs · tractors · custom applications---
Brad Foote Gearing manufactured the gearbox with journal bearings provided by Miba.
modules are expected to reduce losses within the power converter, leading to increased efficiency, energy capture, and revenue. “The power converter modules contain siliconcarbide diodes that reduce switching losses. Depending on a point of comparison -- traditional low voltage or medium voltage modules -- there can be a 0.5 to 1.5% gain in module efficiency,” says Keller. “In addition, the power converter now has algorithms to compensate the inverter voltage and current levels to reduce torque transients during utility faults. This reduces mechanical loads due to electrical utility faults,” he says. What’s more, the improved efficiency of the power converter modules results in less heat generation, which is likely to improve module reliability. The design also offers significant reductions in weight. “We find that a medium-speed configuration tends to have about a 20% decrease in weight compared to a three-stage, DFIG configuration and, at 10 MW, about half the weight of a comparable direct-drive configuration,” adds Keller. The team began testing the drivetrain prototype in a 2.5-MW dynamometer with the controllable grid interface at the National Wind Technology Center at NREL last July and finished testing in April. Technology readiness levels have been advanced and combined with a commercialization plan will lead to deployment of the drivetrain technologies. Successful deployment of the more efficient, reliable drivetrain will further reduce the cost of wind energy and ensure that U.S. companies are at the forefront of technical innovation within the global wind-power industry. W
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W I N D W A T C H
Ask a wind tech Wind technician Krista Zappone says her office is unique with a better view than most.
AS PART OF THEIR EVERYDAY JOB, wind technicians often risk their lives climbing turbines to maintain electrical and mechanical equipment. The wind industry owes much of its success to these talented men and women who keep turbines running and wind farms safely online. In this new series, we interview wind technicians to learn about what they do and what advice they’d recommend to others interested in the field. In this second install, we spoke to Krista Zappone, with Senvion USA.
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Tell us about your career choice: where do you work now, and what inspired you to become a wind technician? I work for Senvion USA, a sublet of the German manufacturing company, and am currently stationed at Eva Creek Wind Farm, one of their remote sites just outside Healy Alaska. As I neared graduation from Eastern Washington University in 2012 (with a B.A. in Women and Gender Studies), I decided I wanted to work with my hands and learn how to “do” something. For me that meant something that offers a sense of accomplishment once the job gets done. Today, I help operate and maintain 12, MM92 CCV turbines (24-MW capacity) in the heart of Alaska’s unforgiving interior. Where and how long did you train for your current role? After university, I enrolled in a six-month wind-turbine service technician program at Northwest Renewable Energy Institute (NWREI). I started with Senvion as a temporary staffing agent in Washington State, and was eventually offered a full-time position at Eva Creek. This will be my fourth summer in Alaska.
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What does your average day on the job look like? An average day at Eva Creek varies greatly depending on the time of year. Outside temperatures can range from -40 to +70º F. There are no direct roads from where we live in town, so every morning our three-person team gets on a four-wheeler and rides across a cat track on a rail bridge to where we park our company trucks. Then, we begin a 10-mile journey through the mountains to the O&M building where we discuss and begin the day’s task, which can include routine turbine inspections and maintenance or dealing with some type of breakdown or retrofit. There are many potential hazards to mitigate during any given day, from icing events or heat exhaustion. It is truly a land of extremes, but we always err on the side of caution. In severe storms, when there is concern about getting trapped onsite, our team will stay in and monitor the wind farm from our computers. Our turbines have a lot of icing protocols built into their software. What is your favorite part of being a wind technician, and what do you find most challenging? My favorite part of being a wind technician is the view! Eva Creek has a beautiful view of Mt. Denali when the skies are clear. Only a small percentage of people get to see the planet from this perspective. The job itself is also rewarding. I climb hundreds of feet to the nacelle and fix million-dollar machines — not everyone can say that. Being a part of the wind industry also means taking part in a better, more sustainable future, and I am proud to do my part. What advice would you impart to others interested in joining the wind industry? Go for it! The wind industry has a ton of potential and is still young enough that anyone — men or women of all backgrounds — can get involved and through several different ways. You can enroll in a short program like I did at NWREI, go the traditional route through college, or slowly try to gain relevant work experience. Wind turbines are beautiful machines that maintain a combination of electrical, mechanical, and hydraulic features. You don’t necessarily have to be an expert in each one. You just have to learn how the components all work together.
www.windpowerengineering.com
JUNE 2016
6/9/16 1:39 PM
Wind work around North America American wind power has had a successful start to 2016 with its most productive first quarter for installations since 2012. According to the Q1 report from the American Wind Energy Association, wind added 520 MW of new electric generating capacity to the power grid from January through March. There are now more than 48,800 wind turbines operating in 40 states plus Puerto Rico, and for now the first time, Guam. Plus, more wind power is on the way. Construction starts in the first quarter bring the total to 10,100 MW, with an additional 5,100 MW in advanced stages of development and nearing construction.
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Blattner Energy is celebrating a new milestone: 30,000 MW of wind power installed or under contract across North America, which includes more than 15,900 turbines and more than 900 miles of new transmission lines. This accounts for onethird of all installed wind-power capacity in the U.S. and Canada. This milestone is supported by the wind-power portfolio of Blattner, its sister company, D.H. Blattner & Sons, Inc., and Canadian joint-venture operation, Borea Construction, ULC.
Ongoing plans are underway for the Icebreaker offshore wind project in Lake Erie. Last year, developer LEEDCo announced it would use Mono Bucket foundations for the project, predicting cost savings of 30 to 50% compared with monopile systems. Now the site’s developer plans to adapt existing regional barges in response to vessel supply challenges. The modification of these existing barges could speed transportation and alleviate related expenses and concerns. JUNE 2016
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High winds and new jobs for Ontario
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Tax credits support Colorado wind power
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EDF EN Canada has signed a 20year power purchase agreement with Ontario’s Independent Electricity System Operator for the 60-MW Romney Wind Energy Centre. The project is a partnership between EDF EN Canada and the Aamjiwnaang First Nation. Construction of the 20 turbines will begin in 2018 on more than 10,000 acres of privately owned land in the Municipality of Chatham-Kent and the Town of Lakeshore. Xcel Energy is seeking to build the 600MW Rush Creek Wind Project and a 345kV transmission line in eastern Colorado (built in parts of Arapahoe, Cheyenne, Elbert, Kit Carson, and Lincoln counties). If approved, Vestas would produce the turbines. Xcel Energy says that by using production tax credits, it can reduce capital costs and directly pass these savings along to Colorado consumers — saving residents and businesses more than $400 million on a net present value basis over the 25-year life of the project. windpowerengineering.com
Montanans Charge! for renewables
A new marketing campaign was launched by Montana Renewable Energy Association and Renewable Northwest to expand the use of clean energy in the state. The campaign, called Charge! leaves talk of climate change out of the conversation, and instead focuses on economic reasons to turn to wind power and other renewables. Statistics show that more than half of all electricity generated in Montana is currently exported instead of used in state. (Check out: http://chargemt.org)
Goldwind inks deal for Rattlesnake Wind
Goldwind Americas has signed an agreement to acquire Texas’ 160-MW Rattlesnake Wind Project from Renewable Energy Systems Americas. Once operational, the project will become Goldwind’s largest U.S. wind farm. Located about 125 miles northwest of Austin, Rattlesnake Wind will use 64 Goldwind 2.5-MW Permanent Magnet Direct-Drive wind turbines. The project represents the first phase of an expected 300 MW of wind energy in the area, constructed under a BoP agreement.
Assessing floating offshore wind for the U.S.
The U.S. Bureau of Ocean and Energy Management is collaborating with state and federal agencies in Oregon, Hawaii, and California to assess the impacts and benefits of floating offshore wind projects in the Pacific Outer Continental Shelf. The organization has already received a few unsolicited lease requests, including one from Trident Winds for a floating wind project offshore from Morro Bay, California. Trident Winds could potentially contribute 800 MW of nameplate capacity with about 100 floating foundations.
Empire State Connector to transmit NY wind energy
HVDC transmission developer, Empire State Connector Corp. (ESC) has entered into a Memorandum of Understanding (MOU) with wind developer, Invenergy. Invenergy is developing a portfolio of up to 600 MW of new Upstate New York wind-generation projects that ESC could help deliver to downstate customers. The MOU confirms Invenergy’s commitment to offer competitively priced wind power via the Empire State Connector transmission project — a key step in reaching the proposed Clean Energy Standard of 50% renewables by 2030. WINDPOWER ENGINEERING & DEVELOPMENT
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RE L I ABI L ITY Tr i s t a n L e e Performance Engineer AES Corporation
Improving wind-turbine performance with PLCs
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ost turbines use mechanical anemometers and wind vanes to measure conditions at a wind farm. Data collected, including the wind speed and direction, is then sent to the turbine controllers, which help optimize the blades for maximum wind generation. However, there is often inherent vulnerability within these existing OEM monitoring and control systems, which can lead to higher maintenance costs and poorer turbine power performance. One problem is that the sensors use moving parts. The anemometer uses “cups” for wind speed measurements and the wind vane uses a “vane tail” for measuring vector change, or wind direction. The physical inspection of a large population of such turbine sensors at a Texas wind farm revealed the majority of failures were linked to bearing problems that led to accuracy degradation and shortened instrument life. Increased bearing rolling resistance also affected wind measurement accuracy, and therefore turbine efficiency, because this data is used to optimize turbine performance. Winter did not help this wind farm either. Cold weather had a negative impact on turbine performance, freezing the exposed mechanical components of the sensors and causing another maintenance issue. The wind farm The 296 turbines at AES Corporation’s Buffalo Gap Wind Farm in central Texas were constructed in three phases from 2006 through 2008. The break down: phase one comprises of 67 Vestas V80 1.8-MW turbines, phase two has 155 GE 1.5-MW turbines, and phase three totals 74 Siemens 2.3-MW turbines. The capacity of the wind
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AES Corporation maintains 296 wind turbines at its Buffalo Gap Wind Farm.
farm is 524 MW, currently making it the seventh largest wind farm in the world. It annually generates more than 1,600,000 MWhr (1.6TWhr) of clean, renewable energy. Although quality wind turbines were installed from leading suppliers, these units were not immune to sensor issues. For example, the Siemens turbine suffered the greatest impact during freezing weather. Only a slight amount of moisture coupled with freezing temperatures would cause the anemometer and wind vane to lock up, effectively shutting the BG3 turbines down. The heated GE sensors were slightly more tolerable to winter weather, but experienced a much lower mean time between bearing failures because of the higher operating temperatures of the sensor bearings. Another problem was sensor performance. Research and testing proved that the cup and vane type sensors were not accurate in high turbulence or under steep wind shear conditions. The devices were also not suited for use downwind of the rotor because of the strong rotor wash or air turbulence at the site. A reason for failure Rotor acceleration increases gradually with wind speed during normal operation. However, when the anemometer under-reports wind speed from a partial failure, there is an increase in rotor acceleration indicating that a large amount of wind energy (typically around 10%)
www.windpowerengineering.com
JUNE 2016
6/9/16 1:48 PM
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RELIABILITY
is not being converted into electrical energy. Instead, that energy is absorbed through the main bearing and drivetrain, and dissipated by the rotor motion. The rolling resistance in anemometer bearings typically increases over time until they seize completely. Ideally, when a turbine recognizes abnormal loading from increased rolling resistance, it will fault before a complete seizure. But in many instances, a turbine never recognizes the problem. This partial failure of an anemometer is more destructive than a complete failure because it can destroy a turbine’s drivetrain. To operate safely and efficiently, wind turbines need accurate information on wind conditions. Protecting a turbine makes it vital to record wind data, especially during turbulence. Accurate measurements are not possible when an anemometer’s rotational speed is unable to change at a fast rate, as is the case when operating with faulty bearings. The turbine control system adjusts blade pitch and rotor speed differently depending on the degree of turbulence. It does so to protect the blades and drivetrain from fatigue related to poor use of the blade airfoil. Poor or inaccurate anemometer measurements mean incorrect adjustments and increased fatigue. The need for precise measurement of wind direction is also important. At the Buffalo Gap Wind Farm power output significantly decreased once the turbines exceeded ± 10 degrees of yaw misalignment. Improving the system Research into the anemometers and wind vanes on the Buffalo Gap wind turbines led engineers to use ultrasonic instrumentation or high-frequency sound energy to conduct examinations and make measurements. Ultrasonic instrumentation was determined to be a 22
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An ultrasonic sensor (the round dome) mounted on top of a turbine showed it could measure wind speed and direction more accurately than the OEM’s mechanical anemometer and wind vane, providing vital information to the PLC.
measurement tool that could potentially provide more accurate and reliable indication of wind conditions. Based on this assessment, engineers replaced the wind measurement mechanical sensors with a single ultrasonic sensor (see image, An ultrasonic sensor) and used an IDEC programmable logic controller (PLC) to convert signals from the sensors and gain better control the wind turbines. IDEC is a manufacturer of control, operator interface, and other automation components. The company’s controller proved reliable, user-friendly, and affordable, which was imperative for a site that needed to install a total of 296 of these components. The intent was to convert the signal from the ultrasonic sensor into a usable form for the turbine controllers. Available ultrasonic sensors were unable to provide the specific and varying information required for the different turbine controller types. Therefore, an
IDEC FT1A-PC3 Modbus adapter was installed, which accepts the input from the ultrasonic sensor signal and sends it to an IDEC FT1A-H40RSA PLC via Modbus. The PLC acts as an emulator for the turbines because the research engineers were able to write specific ladder programs based on the make and model of each turbine. This let the PLC emulate the digital-logic-sensor signal required by each turbine’s controller. The engineers were also able to create algorithms to provide non-linear corrections to dynamics, such as the nacelle transfer function and yaw bias. All the IDEC equipment and a 240W power supply fit into a turbine’s nacelle, along with the existing OEM turbine controller. Using LIDAR, a light detection and ranging technology, to validate anticipated performance and the continued application of statistical tools and methods, the team realized it could further improve turbine performance.
www.windpowerengineering.com
JUNE 2016
6/9/16 1:49 PM
RELIABILITY
The new IDEC PLC with power supply and the existing turbine controller, all fit into a wind turbine’s nacelle.
Yaw bias (alignment) and wind speed correction (nacelle transfer function) were discovered to be inherently dynamic and non-linear. Using this data, engineers were able to write algorithms to correct the distorted wind speed and direction data before interpretation by the turbine control system — thereby increasing energy capture and reducing drivetrain fatigue. Data from the PLCs is transmitted to a control center where engineers perform statistical analysis, program the PLCs and turbine controllers, and analyze data to predict failures before they happen. Project crews are in the process of
installing the IDEC PLCs and power supplies into Buffalo Gap Wind Farm’s 155 GE 1.5 SLE turbines and 74 Siemens 2.3-MW turbines. It takes two people four hours to install the control system and ultrasonic instrumentation at the top of the tower. IDEC assisted in the installation and start-up process, provided technical support throughout the development phase, and continues to provide support during the “fine tuning” phase. Initial results in the turbines with PLCs have included increased meteorological accuracy, less operational downtime, and reduced turbine drivetrain fatigue
loading. When compared to neighboring turbines with known good wind vanes at the Buffalo Gap Wind Farm, engineers discovered a 20% reduction in production could result from a GE turbine operating with a partially failed wind vane. The increased turbine efficiency is enough for AES Corporation’s to evaluate integration of the devices into the rest of their U.S. wind turbine fleet. W
Data from the IDEC PLCs is transmitted to AES Corporation’s control center for analysis.
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B O LT I NG
New torque tools call for a technician’s upgrade
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t was not long ago that a wrench was just a wrench. Along came more complex tasks that brought up questions regarding accuracy and safety. Tools changed with hydraulic capability, then electric versions, and more recently the idea of a bolting system entered discussions. A bolting system? “It’s the unique combination of equipment that’s the best for each job,” says HYTORC COO Jason Junkers. “The tool itself, whether it is hydraulic, pneumatic, or electric, is the center of the system. From there we determine the best reaction fixtures, fasteners, lubrication and accessories to make the job as safe and accurate as possible. Hydraulic tools require an appropriately sized pump for the job, and consideration of special limitations such as overhead clearance, or general working space, like the confines of a wind turbine nacelle. So a bolting system is really a combination of things that make it best suited for the specific application it’s being used on.”
Getting OEMs to adopt new ideas can be challenging, but wind-farm owners looking to trim costs are more likely to consider new O&M thinking. One new bolting idea is the washer that increases safety by eliminating external reaction points and prevents bolts from coming loose in the presence of constant vibration.
Things keep changing One safety goal, for example, is to get away from external moving parts, such as reaction arms, the fixture most commonly used to stop the tool from turning during high powered tightening and loosening operations. “Those are the most dangerous part of bolting. It’s where most injuries come from,” says Junkers. A few recent wrenches do not require reaction arms.
To set torque: On the first screen, use the up and down arrows to select the required torque. When reached, a green light turns on and the gun stalls. The battery icon and the “OK” signal a charged battery. Middle screen: Setting an angle to more than zero tells the gun to add this amount of rotation after reaching the required torque. The last screen provides a release angle before removing the tool. The HYTORC Lithium Gun works on 36V and is capable of tightening about 100 bolts on one charge. The tool comes with two batteries.
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www.windpowerengineering.com
JUNE 2016
6/10/16 10:35 AM
B O LT I N G
And to encourage efficiency, Junkers says his company engineers have developed a kit for most every job in the turbine. The purpose of the kits is to make a job as intuitive as possible. “It reduces the amount of training that’s necessary, so anyone in the nacelle can say, ‘This tool is made for the brake bolts, this one is for blade bolts, and I just have to put it on the wrench and lock it into place,” he adds The electrification of wind-turbine bolting The difference between hydraulic and electric systems is significant enough to warrant a technical upgrade. The transition is more complex than putting down one tool and picking up another. For instance, the right tool depends on a lot of things, the first of which should be whether or not the electric wrench can do the job. The largest sized HYTORC Lithium Gun is capable of about 3,000 ft-lb. “Even when the job calls for 3,000 ft-lb, we recommend at least 30% more capacity — about 3,900 ft-lb, for breakingout or loosening nuts — which would eliminate use of the electric tools. Still, electric versions are becoming more widely used. Most bolting in the wind turbine is within the range of electric tools,” says Junkers.
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One plus for hydraulic tools is that they can, thanks to the custom rig designed by HYTORC engineers, tighten all the bolts on a mainshaft at one time.
Many supply companies offer free or inexpensive safety and operational training when clients purchase new products. “A problem in the wind industry is that these tools are often shared among sites or shipped with kits to the sites, so users may expect one and get the other. However, even when techs are at a wind farm in the middle of nowhere, a call to the local distributor will get a service van to the site for hands-on safety and operational training.” That’s important because the tools look familiar. “Many people use battery or plug-in power drills, so a wind tech might figure that using a new wrench is straightforward. But when dealing with 3,000 ft-lb, and especially when using a reaction arm, there are safety risks. Users must be trained on correct use and in the availability of fixtures that can make the job safer.” Hydraulic tools have their place and advantages, such as higher torques, and they can power multiple tools simultaneously. But the pump can 26
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weight 80 lbs or more, and torque is controlled by setting a pressure limit on the pump. Most benefits of the electric wrenches are related to convenience and portability. Unlike hydraulic tools, the electrics don’t need the heavy pump and that’s a big benefit especially in wind power when technicians must climb towers to the nacelles. “On the electric tool, a green light tells when the selected torque has been reached. Users can also choose the turn-of-nut method, which is simpler with electrics. Both settings are performed in one shot. Pull the trigger and the wrench does the torqueing, followed by the turn of angle,” says Junkers. But how long does the battery last? “The work time on a battery charge is difficult to answer because of many variables, such as tightening or loosening bolts, dry or lubed threads, and high torque or low. But in general, many users can torque around 100 nuts on a single charge. And the tool comes with two batteries.” W
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JUNE 2016
6/9/16 1:59 PM
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6/9/16 8:42 AM
SA F E TY Hilmar Maas Fire Safety Solutions Expert S i e m e n s B u i l d i n g Te c h n o l o g i e s D i v i s i o n
Fire prevention and protection for wind turbines offshore and on
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t is a rare occurrence but one that turbine owners aren’t willing to risk at a wind farm: a fire. The remote location of most wind projects and the sheer height of most turbines mean fire-fighting efforts if needed are too little too late. At 80-plus meters high (and growing), today’s turbines are outside the range of the fire department. When it comes to offshore turbines, which are soon to hit U.S. waters, human intervention in the event of fire is virtually impossible.
Of course, guidelines exist for turbine fire prevention systems. NFPA 850 is the U.S. National Fire Protection Association’s recommended practice for protection of electric generating plants and high-voltage direct current converter stations. It also identifies hazards and protections for wind-power facilities. But these are just recommended practices and not the law (although individual states and counties might have additional bylaws). In Europe, manufacturers must comply with section 1.5.6 of the 2006/42/EC machinery directive, which states: “Machinery must be designed and constructed in such a way as to avoid any risk of fire or overheating posed by the machinery itself or by gases, liquids, dust, vapors, or other substances produced or used by the machinery.”
Thirty wind turbines at Germany’s Riffgat Offshore Wind Farm in the North Sea were the first to have Siemens’ fire detection and extinguishing system, Active Fire Fighting System (AFFS), installed in 2014. So far the system has kept the offshore turbines safe from incident.
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SAFETY
However, even with stringent manufacturing safeguards, a turbine is made of various mechanical and electrical components where failures can occur and potentially lead to fire. Lightning provides yet another source of concern outside the control of manufacturers and wind-farm operators. Once ignited, it is tough to prevent a fire from burning through an entire turbine, especially in the nacelle. Repairs are costly and often the entire generator system, nacelle, or rotor blades need replacing. Risks to wind technicians make fireprevention measures even more critical, especially out at sea where high waves or gusty winds can make rescue efforts next to impossible. That’s why a comprehensive fire-safety plan is important because it is the only way to effectively avoid risk and serious losses.
A fire-detection and extinguishing system is important in wind turbines but ideally more than one device is needed for warranting safety. Also consider the quality of circuit breakers, fuses, and cables used in each turbine to ensure meeting fireprotection standards.
FIRE-PROTECTION PRODUCTS
Graduated protection Should a fire develop, automatic fire alarm and extinguishing systems can minimize damage and reduce downtimes — and should be a must for every turbine regardless of state standards or bylaws. Sensitive smoke and heat detectors, and fire alarms that detect thermal and optical signals, can detect a fire at an early stage and forward the information to a central alarm system that will initiate a complete shutdown. As a measure of protection before a spark ignites, graduated protection concepts offer the highest available level of fire protection. A graduated protection structure means defective system parts in a turbine are selectively disconnected from the grid before potentially causing a surge or risk of fire. For example, a proper arc-fault-detection system for switchgear will detect a fault and immediately open the medium-voltage circuit breaker on the high-voltage side of the transformer. Whether onshore or offshore, proper configuration in a turbine must also account for internal and external risks — from electrical components inside a nacelle and lightning due to an unexpected weather system. For electrical systems: Protection systems, including fuses and circuit breakers, should selectively detect faults and promptly disconnect defective parts of a turbine’s network or individual electrical equipment (such as transformers, cables, and generators). When necessary, protection systems must also ensure immediate and controlled shutdown of a turbine with all-pole disconnection from the grid. If protection devices are triggered, a fault signal should automatically alert personnel at a remote-monitoring center. For lightning strikes: Lightning current and over-voltage surge arresters are used to protect electrical equipment from high currents resulting from direct lightning strikes. Proper protection must take into account each specific turbine type at a wind farm. To guarantee optimal protection when performing an initial risk assessment, it’s necessary to consider the potential paths of a lightning current (for instance, from the JUNE 2016
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A comprehensive fire-protection plan for wind turbines ideally includes more than one safeguard. An extensive portfolio of monitoring and protection devices is more likely to ensure the safe and high availability of a turbine and a wind farm. Products in this portfolio may include: • Circuit breakers. In wind turbines, they have the job of switching and protecting the main circuit, and disconnecting it from the network during maintenance work. In their fire-protection function, circuit breakers prevent fires that are triggered by overload and short-circuit currents, and protect against non-permissible heating of cables from overloading. Open circuit breakers can also provide alarm signals for integration in the communication or network system of a turbine. • Semiconductor protection fuses prevent fires caused by uncontrolled failure of power semiconductors, such as IGBTs. They also protect highquality devices and system components (like thyristors) in converters and soft starters from the impact of a short circuit. • Differential current-monitoring devices reveal undetected ground faults in electrical installation by indicating the presence of differential currents. By sending an immediate signal, these devices enable preventive maintenance before a fault current potentially causes a fire. • Measuring instruments for power monitoring make it possible to measure the quality of the in-feed from a wind turbine and monitor the electrical quantities of the main circuit. This provides early detection of overloads and operational faults, preventing associated damage. • Residual-current devices are important for the safety of maintenance personnel because they protect against dangerous shock currents in the event of direct or indirect contact. These protection devices detect fault currents caused by insulation faults. They initiate the disconnection of the affected circuit and, therefore, also prevent fires. • Busbars. Installing busbars instead of cables in turbines can effectively contribute to fire safety. Unlike cables insulated with PVC, the sheet metal housing of busbars has a considerably lower fire load. Epoxy coatings that are resistant to aging also offer a high degree of surface protection for the conductors. Additional benefits of busbars include the high short-circuit strength of the tap-off units and their thermal loading capacity in the event of lightning strikes.
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SAFETY
A comprehensive fire-safety protection plan is imperative to keep wind turbines generating and wind technicians and site workers safe at all times.
rotor blade via the hub, the nacelle, and tower to the foundation). Offshore protection A graduated protection structure is ideal for onshore and offshore turbines. For the latter, there is also another available level of defense. Siemens Building Technologies Division has created an Active FireFighting System (AFFS) that detects fires in offshore turbines and automatically extinguishes them. This lets project owners avoid the hassle of launching a costly and time-consuming offshore fire-fighting effort. AFFS combines intelligent fire detectors with integrated ASAtechnology or Advanced Signal Analysis (ASA). The sensors in this system record incoming data or signals, which are converted into mathematical components using algorithms and compared to preprogrammed values. By selecting an ASA parameter, the algorithms and fire detector are set to monitor expected local environmental influences. The optimal parameter is then adjusted to observe potential risks or differences in the existing environment and trigger a signal if atypical. A Sinorix fire-extinguishing system is included that uses nitrogen, an inert gas, to fight fires. This extinguishing system operates on the principle of inertization, or oxygen displacement. During a fire, the oxygen content in the area is diluted by nitrogen to create a non-explosive, non-flammable environment. Nitrogen is inexpensive and obtained quickly and easily by removing it from the ambient atmosphere. The fire-detection system monitors pain points and system-relevant components of the wind turbines. If AFFS detects a fire in the nacelle or in the tower caused by a short circuit in a control cabinet, the detector system transmits this data to a turbine’s control unit. If the fire detector is triggered, the system immediately activates the gas30
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extinguishing system to put out the fire, leaving behind no residue. The wind turbine is automatically shutdown by its controller and the system is shutdown under “no-load” conditions. When necessary, operators at an offsite control station can take further steps through remote access. The fire-detection system continuously sends status messages and system data to the control station. Subsequently, the cause of the fire can be identified and the turbine returned to operation in the shortest time possible. To enhance safety, one system is installed in the nacelle and one in the tower base. Both systems are interconnected but operate autonomously in the event of a network outage or power failure. The AFFS systems also have a modular design, which makes replacement quick and easy by the installed supportsystem of the nacelle.
The AFFS system was the first to gain certification by third-party validation organizations, VdS Schadenverhütung GmbH and Germanischer Lloyd, a part of DNV, for the protection of offshore wind turbines. It is the first system to receive recognition by both testing and approval bodies for the combined system of fire detection and extinguishing systems for wind turbine equipment. Although a rare event, it is nearly impossible to extinguish a fire in a wind turbine using conventional fire-fighting methods, and especially in offshore waters. Complete fire prevention will always rank top in the industry, and should be top of mind for offshore wind developers now working on projects in U.S. waters. As a back-up defense system, Advanced Signal Analysis and an AFFS system is a worthy safeguard against serious turbine damage and repair costs. W
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OCTOBER 2015
6/9/16 2:02 PM
S OFTWA R E
What might be the financial impact of a new wind farm on your community? The Jedi tells
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ith interest in the wind industry growing nationwide, localities in which the farms are considered would probably like to know their financial impact. You could hire an accountant for a few guesstimates, but the Energy Department’s National Renewable Energy Laboratory might have better answer and sooner thanks to JEDI. It is the Jobs and Economic Development Impact model, and in particular, the Land-based Wind Model. (The joke at Federal labs is that no project starts without first defining a clever acronym). The good news is that the program, actually an Excel spreadsheet, is free and here: www.tinyurl.com/ nrel-jedi. You will see right away that NREL has been busy. It offers at no cost about 18 programs under the Jedi umbrella, all in Excel, and with user notes for five of the more complex programs. Models are also available for projects that deal with biofuels, solar, natural gas, and even coal projects. Two other wind energy models address distributed wind and offshore projects. While this is mostly a program-only site, users can pose questions to JEDISupport@nrel.gov.
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We’ll focus on the land based, wind-farm model. After you accept the restrictions, the model downloads along with some default values and figures for a demo wind farm. However, your Excel will probably require that you allow the operation of macros. For Windows users: Pick the Windows symbol, upper left in Excel, Excel options, Trust Center, Trust Center Setting, and then Enable all macros. The model takes only a few inputs such as the number of turbines, wind farm nameplate rating, its cost, and location. We invented a 100-MW wind farm for Ohio with 50 turbines, and the model provided a wide range of values. For instance, the model says that 60 jobs will be created for Construction and interconnection labor, 149 more from Induced impacts, and others for a total impact of 479 jobs. What may be of equal interest to the community around the site, the model predicts a Local revenue and supply chain impact of $400,000 and local spending could reach $666,209.
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SOFTWARE
There are well over 100 calculated quantities in several categories. For instance, construction costs break into Equipment and Balance of Plant along with a local share. None of the equipment (turbines, blades, towers) will be locally sourced (it’s in Ohio) although most of the Construction material (concrete, rebar, roads) and Electrical will come from local firms. That answers the question in the headline but the model does not stop there. The Wind farm - Project summary data, in an accompanying table, details other items such as a Total installed project cost of $206 million and local spending of $45.8 million. So how accurate are the figures? “There have been a few periods in which we evaluated the outputs of the model and executed some recalibrations,” says NREL software developer for JEDI and energy analyst Eric Lantz. “Most of our work focused on the onsite portion of job creation. That part is relatively easily tracked, the number of construction workers onsite and the number of people that service the facility once in operation. Calibrations have been informed by looking at data from across a large but not comprehensive sample of projects,” he says. 32
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For other portions of the jobs reported, such as indirect and supply chain induced, Lantz says his team has done work to determine the share of goods and services provided to the plant by local vendors. “It should come as no surprise that we found those figures vary widely across projects. The default functions for these parameters are intended to be representative and grounded in observed trends we saw, but users should adjust those numbers for their specific project of interest because the results are relatively sensitive to where you manufacture and procure the equipment and services that go in to the project,” he adds. NREL also provides some assistance in using the Jedi model more effectively in a video here: tinyrul.com/jedi-demo W
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JUNE 2016
6/9/16 2:12 PM
PROJ ECT S Jay Haley P. E . , P r i n c i p a l i n C h a r g e o f W i n d E n e r g y EAPC
Advice for first-time wind developers
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ith the latest renewal of the Production Tax Credit, the windpower industry will likely see an influx of new developers as it has in the past. Many first-time wind developers come from another business or energy development sector, so are already familiar with the project development process from their industry. They may also understand the various phases and nuisances involved with moving a project forward. However, wind development comes with its own unique and often subtle development challenges that can easily make or break a project. A full understanding of those subtle industry differences
can save time, costs, and avoids potential pitfalls when developing a wind farm. Start off right The typical phases of wind-farm development are: prospecting, land securing, wind resource assessment, interconnection and transmission studies, wind-farm design, permitting, power purchase agreements, financing, procurement, construction, and operations. Wind-farm development is a complex process. As a project progresses through the various stages of development, there are many opportunities for mistakes that can seriously affect the final outcome
Success! North Dakota’s first wind farm is an example of a well-planned project with 41 turbines located near Edgeley and Kulm. (Photo: Joy Powers)
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PROJECTS
and success of a wind farm. Some of the biggest mistakes in wind development begin in the early stages and are difficult to overcome as the project progresses. Poor site selection is all too common with new developers. Sites are ill chosen for the wrong reasons, such as location preferences, or without sufficient due diligence. Typical problems that arise from poor site selection include: • Landowner issues • Less than adequate wind resource • Lack of access to transmission (or no capacity on existing lines) • Lack of an off-taker for the power • Constructability issues, and • Fatal permitting issues. Collect quality data Most investors and banks require a minimum of one year of onsite wind data before either will consider financing a project. Most turbine manufacturers have the same requirement. Depending on the size of the project and the complexity of the terrain, a number of measurement sites are necessary to validate wind flow at the site. A financeable wind measurement campaign includes proper selection of measurement locations and heights, a reliable measurement instrument, and an equipment maintenance plan. Also needed is a high degree of data recovery and thorough documentation. In simple terrain, where a potential site is mostly agricultural with minimal trees, meteorological (met) masts are typically distributed no more than two kilometers away from the nearest turbine once in place. As terrain becomes more complex with steeper slopes and more surface roughness in the form of structures or trees, the two-kilometer rule of thumb no longer applies and it becomes essential to place met masts in locations that accurately capture the wind flow turbines will ultimately face. As wind turbines get taller and blades longer, it is critical to measure wind 34
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speeds at hub height and within the vertical profile of the swept area of the blade. Failure to obtain accurate wind measurements could jeopardize the chances of getting wind turbines certified for a site. Selection of the measurement instrument is also extremely important. Using less expensive, lower quality instruments can result in lower quality data and higher uncertainty in the wind regime. This, in turn, can lead to significantly higher financing costs, many times more than the amount saved on cheaper instrumentation. In cold-weather regions, it is advisable to use some heated instruments on the met tower. This can help avoid data loss from icing conditions. It can also help quantify the amount of icing losses expected in operation by comparing data from an iced anemometer to a heated one. An independent engineer is often asked to verify the wind regime and energy projections prior to financial closing, so the wind measurement campaign must be thoroughly documented and the met towers precisely installed at a potential development site. Installation details such as tower location, mounting heights, boom directions, instrument models, serial numbers, calibration coefficients, and site photographs are all necessary for the independent engineer to perform his or her task accurately. Connect with the utility If you intend to sell power to a local utility once the wind farm is up and running, it is a good idea to open up a dialog early on. It is also important to research the local infrastructure, proposed upgrades to transmission systems and substations, long range plans for large transmission
When building a new wind farm, some of the most challenging issues occur in the early planning and construction stages. New developers should spend time on research and due diligence before committing to their first wind project. (Photo credit: Joy Powers)
projects, and the overall system operations for that region. The late stage of project development is a less than ideal time to learn there are no interested buyers for the output from the wind farm — and this does happen from time to time. The reason? There are several including political changes that affect the market, interconnection or transmission issues preventing access to the market, or unrealistic expectations regarding the anticipated power pricing. It cannot be overstated: proper due diligence in the early stages of a wind project can help avoid costly mistakes and disappointment down the road. Know the opposition Establishing strong local connections and community support is often the best way to anticipate and avoid opposition that may threaten land leases, project permits, and wind-farm financing. It is worth engaging local politicians and government agencies, and befriending financial institutions and major landowners that may have influence in the community. Before doing so, do your research. It first helps to understand local issues and neighborhood concerns. Permitting bodies tend to look more favorably upon projects that have strong local support
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JUNE 2016
6/9/16 2:24 PM
PROJECTS
and participation, so being proactive can successfully impact a new wind project. Partnering with local landowners and municipalities as opposed to “taking over” will benefit everyone in the long run, including your construction crew if the project is approved. It is also beneficial to employ local people and businesses as much as possible during the design, construction, and O&M phases. Learn the laws Permitting is an expensive part of a windpower project, and requirements vary from state to state and from county to county. One missed step can quickly jeopardize or halt a project from moving forward. For example, regulations are often changing with regards to bats, eagles, migratory flyways, and endangered species or regions, so keep up with the latest rules and bylaws. Federal Aviation Administration rules and restrictions can also eliminate a substantial amount of property from a developable area. Also look into possible impacts to aviation, defense, or weather-radar stations that may restrict turbine locations. As a project progresses through the various stages of development there are many opportunities for mistakes or missed information that can affect the final outcome of a project. Some of the biggest mistakes are made in the early stages and are difficult to overcome as the project progresses. If you are planning to enter the wind development business for the first time, it pays to do your homework, seek advice from others with experience, connect with the locals, and develop a solid plan before you get too far into your first wind project. W
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6/10/16 10:42 AM
T UR BI NE OF THE M O NTH
Paul Dvorak Editorial Director Windpower Engineering & Development
Envision Energy 3.6 MW two-blade offshore turbine
Envision two-blade design by the numbers Turbine
IEC Class
3.6 -128 IEC III
Rotor diameter 128m Rated power
Cut in wind speed
Cut out wind speed Rotor speeds
Diameter, swept area
Power density, @rated speed Generator type
3.6 MW 3 m/s 25 m/s 4 to 15 rpm 128m, 12,868 m2 279 W/m2 Direct drive, permanent magnet
Generator rated voltage 730V Generator power (Qty: 2) Tower type
1,800 kW Cylindrical, tapered tubular steel
Hub height 88m
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f the wind industry is to continue its growth, it will have to continue bringing down costs of the hardware and operating expenses, along with improving reliability. The engineers with Denmark’s Envision Energy have ideas along those line that do not include three blades and a gearbox. Who is Envision, you ask? It is a quiet wind turbine OEM with a portfolio packed with about 20 models. And despite their reticence, the company is not afraid to take chances. Consider its Envision 3.6 MW, two blade design. It is unusual enough to deserve recognition as our Turbine of the Month. Most readers are probably unfamiliar with this company but it already has what it calls a Global Digital Energy Center in Houston, a Digital Energy Innovation Lab in Silicon Valley, and more recently, a blade research facility in Boulder, Colo. The firm also has research center in Denmark where a prototype of the two-blade turbine has been flying for nearly four years. (www.project-gc1.com). The company says it took less than two years to get its two bladed, partial-pitch turbine up and generating power. Company aerodynamic
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The cutaway lets Envision reveal a few details of its 3.6 MW direct-drive design.
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TURBINE OF THE MONTH
engineer Kristian Godsk made the comments at a Sandia Blade Workshop. He says the design is the first of its kind and suggests that its features can cut 10% off the capital expenditure for offshore turbines. Inelegantly titled an E128-3.6 PP 2B, the turbine gets most of its advantages from the two-blade design. For instance, having just one fewer blade than a convention three-blade turbine reduces production costs, and that lightens the up-tower mass (15 to 20% less than a threeblade design) which means the tower can weigh less making it easier to transport and erect. Furthermore, the two-blade design allows lifting the blade and nacelle at once, further cutting construction costs. There are operational advantages as well. For instance, the two-blade rotor can be parked in a horizontal position in high wind, such as typhoons, or shear and remarkably, the blade holds itself horizontal. Envision says the design is fit for sites with extreme-force winds. (See the video here: http://tinyurl.com/envision36) Innovation in the rotor includes a 22-m center fixed length called an extender. The outer blade lengths pitch independently of the center section and are the source for the PP or partial-pitch reference. Although the extender has a fixed length, it allows customizing the rotor diameter by fitting it with blade tips that match the full rotor length to a site’s prevailing wind speeds. Hence, low-wind speeds would allow longer tips for a greater swept area, and shorter tips for higher wind speeds. Transformers and converters are mounted in enclosures at the base of the tower, not in the nacelle. In addition, the design sports two converters, each 1.8 MW, making it possible to run on one converter when necessary. The location makes them easier to maintain when offshore. Also interesting is that the main shaft is made of carbon fiber and its flexability damps some of its loads, according to Godsk. He adds that It has been possible to customize the flex and twist in the shaft exactly to operational requirements. This together with the weight distribution (rotor versus generator rigidity) produces a configuration which mechanically ensures good characteristics for low-voltage ride through. In the most violent storm to sweep the site, wind hit 51 m/s, enough to break a cup off the turbine’s anemometer. But the controls positioned the turbine sideways to the high wind so it suffered no damage. The prototype has been “flying” on the Denmark coast since 2012 in winds that average about 10 m/s. W JUNE 2016
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The two blade Envision Energy 3.6 MW turbines also sports two convertors each rated for 1.8 MW. Two blades allow several distinct advantages over conventional designs. For one, the hub and blades can be lifted in one unit which lowers construction costs. And the length of the blade extensions can be customized for particular sites.
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P OL I CY L e a h K a r l o v, Ta x P a r t n e r • M i c h a e l G o o n , Ta x A s s o c i a t e M i l b a n k , Tw e e d , H a d l e y & M c C o y L L P
IRS Notice 2016-31: Beginning construction under the PATH Act
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n December 18, 2015, President Obama signed into law the Protecting Americans from Tax Hikes Act of 2015 (the PATH Act),1 which extended the production tax credit (PTC) under section 45 of the Internal Revenue Code (the Code) for wind facilities that begin construction before January 1, 2020. The PATH Act also extended the PTC for other renewable energy facilities, such as biomass, geothermal, and hydrokinetic.
However, after 2016, the PTC for wind facilities is subject to a phaseout. For example, if construction begins: • In 2017, the PTC will undergo a 20% reduction. • In 2018, the PTC will undergo a 40% reduction. • In 2019, the PTC will undergo a 60% reduction.
The PATH Act extended the PTC for wind facilities when site construction begins before January 1, 2020.
On May 5, 2016, the Internal Revenue Service (IRS) released Notice 2016-31 (Notice),2 clarifying the circumstances under which a taxpayer has officially begun construction under the PATH Act.3 Background On April 15, 2013, the IRS published Notice 2013-29,4 providing guidance on what it means to “begin construction” under the American Taxpayer Relief Act of 2012 (ATRA), the original legislation that introduced the “begun construction” requirement.5 Notice 2013-29 provided two alternative ways to demonstrate that construction had begun before the ATRA deadline of January 1, 2014.6 1. By beginning physical work of a significant nature before January 1, 2014 (the “physical work test”), or 2. By paying or incurring at least 5% of the total cost of the eligible property before January 1, 2014 (the “5% safe harbor”).7 Among other requirements, the physical work test requires that the taxpayer maintain a continuous program of construction after it has begun at a site. The 5% safe harbor requires that the taxpayer maintain continuous efforts to advance toward completion of a project after 5% of the total costs have been paid or incurred for the project. On September 20, 2013, the IRS published Notice 2013-608, which among other things provided a safe harbor in applying the continuous efforts and continuous construction requirements (collectively known as the “continuity safe harbor”).9 More recently, to address the PATH Act’s extension of the PTC, the IRS also released the Notice, which is intended to: 1. Further extend and modify the continuity safe harbor. 2. Provide additional guidance regarding the application of the continuity safe harbor and the physical work test. 3. Clarify the application of the 5% safe harbor to retrofitted renewable energy facilities. Unless otherwise specified, the Notice also maintains that the guidance provided in Notice 2013-29, Notice 2013-60, Notice 2014-4610, and Notice 2015-25 continues to apply.
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POLICY Continuity safe harbor Under the Notice, the continuity safe harbor will be satisfied as long as a taxpayer places a facility in service during a calendar year that is within four calendar years of the year during which construction began on a project.11 For example, if construction of a wind facility begins on January 15, 2016, and the facility is placed in service on or before December 31, 2020, then it will meet the continuity safe harbor. The Notice specifies that a taxpayer may not rely upon the physical work test and 5% safe harbor in alternating calendar years. This means that if a taxpayer performs physical work of a significant nature on a facility in 2015, and then pays or incurs 5% or more of the total cost of that facility in 2016, the continuity safe harbor will apply beginning in 2015 and not in 2016. Moreover, the facility must be placed in service no later than December 31, 2019 to satisfy the continuity safe harbor. It is critical that taxpayers are mindful of the activities conducted at or with respect to a facility (including expenses incurred) because the clock can begin ticking for purposes of the continuity safe harbor, regardless of a taxpayer’s intention. The Notice also revises and expands the non-exclusive list of permitted construction disruptions. Additions include: 1. Interconnection-related delays (e.g., those relating to the completion of construction on a new transmission line or necessary transmission upgrades to resolve grid congestion issues that may be associated with a project’s planned interconnection). 2. Delays in the manufacture of custom components.12 In terms of permissible financing delays, the Notice has removed the qualification that financing delays be less than six months.13 Physical work test In the Notice, the IRS reiterates that the physical work test focuses on the nature of the work performed and not the amount of work or the cost. The Notice maintains that if the work performed is of a significant nature, there is no fixed minimum amount of work or monetary, or percentage threshold, required under the physical work test.14 In the case of wind facilities, excavation for the foundation, setting of anchor bolts into the ground, and pouring of concrete pads of the JUNE 2016
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foundation are some examples of physical work of a significant nature. A facility As is consistent with prior guidance, the Notice defines a “facility” to include all components of property that are functionally interdependent (i.e., the placing in service of each component is dependent upon the placing in service of each of the other components in order to generate electricity).15 Multiple facilities operated as part of a single project are treated as a single facility whether a taxpayer is relying on the physical work test or the 5% safe harbor.16 The determination of whether multiple facilities are operated as a single project, and therefore treated as a single facility, must be made in the calendar year during which the last of the multiple facilities is placed in service.17 Whether a developer is relying upon the physical work test or the 5% safe harbor, multiple facilities that are treated as a single facility for determining whether construction of a facility has begun may be disaggregated and treated as multiple separate facilities for purposes of determining whether a facility satisfies the continuity safe harbor.18 The disaggregated facilities that are placed in service by the continuity safe harbor deadline will be eligible for the continuity safe harbor, and those that are not may satisfy the continuity requirements under a facts and circumstances determination. Retrofitted facilities The Notice provides that a facility comprised in part of used property may qualify as originally placed in service, provided that the fair market value of the used property is not more than 20% of the facility’s total value (known as the 80/20 rule).19 In the case of a single project comprised of multiple facilities, the 80/20 rule is applied to each individual facility. Furthermore, with respect to the 5% safe harbor, only expenditures paid or incurred that relate to new construction are taken into account.20 W
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For further reading 1Pub. L. No. 114-113, Div. Q, 129 Stat. 2242 (2015). 2 Notice 2016-31 (May 5, 2016). 3 The PATH Act also extended the investment tax credit (ITC) for solar energy facilities for construction that begins before January 1, 2022. However, the Notice does not provide guidance for the extension of the ITC for solar energy facilities, but a separate related guidance is expected to follow. 4 Notice 2013-29 (Apr. 15, 2013). 5 Pub. L. No. 112-240, 126 Stat. 2313 (2013). 6 On December 19, 2014, the Tax Increase Prevention Act of 2014 (TIPA) extended by one year to January 1, 2015 — the date by which construction of a qualified facility must begin. Pub. L. No. 113-295, 128 Stat. 4021 (2014). 7 Notice 2013-29, § 3. 8 Notice 2013-60 (Sept. 20, 2013). 9 Under Notice 2013-60, pursuant to ATRA, a taxpayer was deemed to satisfy the continuity safe harbor if a project was placed in service before January 1, 2016. Pursuant to TIPA, the IRS released Notice 2015-25 (Mar. 11, 2015), extending the continuity safe harbor in Notice 2013-60 by one year to projects placed in service before January 1, 2017. 10 On August 8, 2014, the IRS released Notice 2014-46, clarifying and modifying Notices 201329 and 2013-60. 11 Notice 2016-31, § 3. 12 Notice 2016-31, § 4.02(2)(e) and (f). 13 Notice 2016-31, § 4.02(2)(j). 14 Notice 2016-31, § 5.01. 15 Notice 2016-31, § 5.04(1). 16 Notice 2016-31, § 5.04(2). 17 Notice 2016-31, § 5.04(3). 18 Notice 2016-31, § 5.04(4). 19 Notice 2016-31, § 6.01. 20 Notice 2016-31, § 6.02.
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F LU I D S & F I LT E R S
Brian Steuer Director of Business Development Vo e l k e r S e n s o r s I n c .
Oil monitor promises accurate real-time readings
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educing oil maintenance expenses and minimizing equipment downtime is of major interest to operators of wind turbines and industrial equipment. Periodic oil analysis, one way to reduce maintenance, can extend the life of equipment in excess of three times the normal or historic average. In addition, the cost of replacing equipment can be reduced by 50% or more. Opportunities for minimizing equipment failure, reducing the cost of analysis, and automating oil maintenance provide the need for developing an oilcondition sensor that operates in real time. The Oil Sentinel is one such sensor that installs directly into gearboxes or industrial processing equipment to continuously monitor the quality of oil and hydraulic fluids. In addition to offering significant advantages to planned equipment maintenance, the device provides preventive advantages as well. The sensor’s continuous monitoring capability can detect problems before they become catastrophic, such as cooling system failures, leaks, and the use of incompatible fluids. Using proprietary technology, the sensor eliminates the two-step process of sampling and lab analysis, and directly measures four oil parameters important to gearbox maintenance: water contamination, oxidation, temperature, and level. The trip point for water contamination is triggered at levels above 0.06% by volume, depending on the oil’s saturated relative humidity
(SRH). The trip point for oxidation is adjusted according to the composition of the oil and is correlated with the acid number (TAN) measurements at levels as low as 0.2 acid number units. An over-temperature detector compares the oil temperature in the reservoir to the ambient temperature to prevent excessive heat from damaging equipment. In addition, a level indicator ensures proper lubrication by monitoring the oil supply. The device consists of a sensing element, a mechanical interface (that secures to the oil reservoir) and a signal-conditioning unit with an easy-to-read LED that displays the condition of the oil.
Interactions between the charged groups adjust as the oil moves from a nonpolar (clean) condition to a polar (oxidized or water contaminated) condition.
How it works The Oil Sentinel uses a patented technique that employs a polymeric bead matrix (held between two conducting permeable surfaces) containing charged groups that serve as a conducting medium for measuring the oil’s solvent properties. The method operates by correlating a relative change in the electrical properties of the beads with a relative change in the solvent properties of an oil. In other words, the interactions between the charged groups adjust as the oil moves from a nonpolar (clean)
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condition to a polar (oxidized or water contaminated) condition. Water can be detected as droplets, as an emulsion or fully dissolved. Oxidation, which occurs because of thermal decomposition in superheated areas of industrial processing equipment, is measured independently of water. The method does not require external standards, is independent of an oil viscosity and is compatible from 20 to 70°C (as measured in the reservoir). Results The accompanying plots provide a graphical representation of water contamination and oxidation measurements with the new sensor. Results are compared with standard laboratory techniques. The test oil was treated with deionized water as a percent of volume to simulate a contaminated condition. The oil-water emulsion was mixed with a high-speed blender and the percent-water content was confirmed using Karl Fisher titration methods. Results show that above the SRH, the sensor detects the free water and triggers a response. Additional
The graph plots the results of detecting water in an oilwater mixture using the Oil Sentinel sensor.
water provides an incremental change to the signal. The oils plotted in Correlating oxidation were artificially aged at elevated temperatures to simulate oxidized conditions. Data was measured using three industrial oils: general purpose hydraulic oils (HL-32), spindle oils (FC-22) and antiwear hydraulic oils (HM-32). A plot of the data shows a linear correlation between sensor output and AN measurements that demonstrate the independence of viscosity and composition. Benefits Predictive and proactive maintenance of industrial machinery is a proven strategy in extending equipment life and reducing downtime. Current practices involve periodic sampling and analysis by external labs. This service costs from $30 to $50 per sample (depending on the scope of the test) with a typical minimum turnaround time of 48 hours. In most cases, these tests come back negative, indicating an acceptable level of oil quality and introducing additional cost into the maintenance cycle. Disposal fees add further to the service costs. In the end, this form of monitoring provides at best a snapshot at the instant the sample is taken and often does not consider recent changes in the condition of equipment or the number of duty cycles. By contrast, the Oil Sentinel provides a method for continuous, oil-condition monitoring with an easyto- read LED display, or by remote monitoring. This method allows combining the conventional two-step approach of oil monitoring (sampling and analysis) into a single, more efficient step. Optimizing oil monitoring provides an effective means of automating the process and managing service costs, warranty expenses, catastrophic events, disposal fees, and environmental demands. W
The graph illustrates the sensor’s oxidized oil measurements and compares them with the acid number (AN) measurements.
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Sentient Science Computational Tribologist Dr. Elon Terrell (wearing glasses) goes uptower to assess gearbox problems and confirm predictions from company software, DigitalClone.
How small data from
material science
accurately predicts failure rates and more Decades of experience with bearing and gear materials have let engineers write accurate predictive maintenance software. Now, it provides guidance on the most durable and appropriate replacement components for wind turbines. Pedro Berges • MSME PE • Implementations Manager Aaron Soellinger • Product Marketing Program Manager Sentient Science
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ind power set a record breaking 22% increase in annual installations for 2015. There are at least 281,924 wind turbines generating 432,883 MW of power around the globe. In the United States alone, about 48,500 turbines generate 74,471 MW, enough to power about 20 million American homes, according to the Global Wind Energy Council. In addition, Bloomberg projects that 19 more GW of wind will be installed globally by 2021. Governments around the world have seen the benefit of renewable energy and offer incentives to spur more installations. U.S. Congress recently passed a five-year, long-term extension with a phase out of the Production Tax Credit. The PTC lets owners of qualified renewable energy facilities receive tax credits for each kilowatt-hour of electricity generated by the facility over a 10-year period.
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Today, utilities continue to sign some of the lowest cost, longterm Power Purchase Agreements. That means wind-farm owners and operators must look for innovative ways to lower their Levelized Cost of Energy and remain profitable. That includes investing in predictive maintenance and condition-based monitoring systems to mitigate downtime and O&M costs, which are the largest operating expenditures after the initial capital investment for a wind project. Problem with big data All wind turbines use SCADA systems to monitor several operational conditions, such as wind speed and direction, atmosphere pressure, and temperature, and then use the data to analyze the performance and “health” of the turbine. Many also use sensors to detect vibrations that signal a failure. Big data usually refers to the mountains of information generated by monitored
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material science From clean steel to failure This is how a bearing or gear breaks. What exactly initiates nucleation is a matter of some debate in material circles.
machines, such as wind turbines, along with the effort and algorithms that sort through them to find actionable information. This big data approach to predictive maintenance can pose a challenge for operators to manage without the necessary infrastructure and trained personnel. Statistical and machine learning approaches to predicting the health of a turbine using big data can prove effective when the number of false positives and false negatives are consistently low. However, ineffective systems can do more damage than good by causing costly and unnecessary checks, according to most operators. For example, maintenance and service calls are more difficult and expensive in the wind industry than in fossil fuel factories because of the difficulty involved with climbing a 100-m tower to reach the ailing equipment. Once in the nacelle, the technician may have to use a borescope to see inside the gearbox and check for visible cracks. Similar work in offshore wind farms costs significantly more. Another method: Small data A better way uses a proprietary, material-science-based computational testing approach to determine the earliest time to detect gearbox failures, so the operator is alerted to make operational and component level changes that will extend the life of that gearbox. The fusion of material science, operational conditions, and computational testing enables the detection of cracks and other failure initiations in bearings before the traditional machine-learning approaches would have detected the flaws. The root cause of most windturbine mechanical failures is early fatigue crack initiation, which sensors cannot detect until the failure is imminent. However, if action was taken sooner, the failure could have been prevented soon after damage begins. JUNE 2016
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Sentient Science has developed this material-sciencebased, computer-testing method. It is often referred to as the small-data approach. It allows for accurate prognostic health maintenance and, hence, multi-year budgeting. More recently, the material-science approach can differentiate between various bearing suppliers according to expected life and thereby offer life-extension recommendations so assets can achieve optimal life and operational performance in the field. The bearing is the microprocessor of the machine Most wind-turbine gearbox mechanical failures originate from bearing damage. To predict these failures, it’s critical to understand the steps a bearing goes through on its way to failure. Those stages are crack initiation, crack propagation,
Company Implementations Manager Pedro Berges at his workstation where he turns component-failure data into prediction information.
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material science short-crack growth, long-crack growth, and operational failure. Bearing failures may or may not be detectible by sensors and big-data methods. When they are not readily detected and treated, bearing misalignments can cause catastrophic failure of the gearbox. Condition-based monitoring systems only detect the long-crack growth and operational failure, which typically occurs within the last few weeks of the bearing life. In the best circumstances, a site manager barely has enough time to perform predictive maintenance to save the gearbox from primary and secondary failures. The costs accumulated by gearboxes can grow exponentially when denied proper service and maintenance strategies. Aggregate industry statistics show that a wind-turbine gearbox is replaced every five to seven years at a cost of $200,000 to $300,000 for 1.5-MW systems and approximately $750,000 for 2.5-MW gearboxes. That does not include the cost of the crane, labor, and the loss of revenue from downtime. However, when component damage is predicted early enough, up-tower repairs can limit component replacement costs to between $30,000 and $75,000. Such activity can effectively delay gearbox replacement. Life-extension solutions Sentient’s prognostic approach uses material science to analyze and capture the material microstructure and properties of the bearings, gears, and gearbox under the customer’s operating conditions. This “small data” approach tests components on highperformance computers to predict the failure rates from 0 to 30 years. The company’s DigitalClone Live Software as a Service delivers failure rates in a web portal, which operators can use to build multi-year rolling O&M spending forecasts and plan less costly, preventative-maintenance schedules. The material-science method applies its knowledge of friction and the effects that it has on the rotating mechanical systems. The DigitalClone Live software simulates how subcomponents interact with each other within a system, such as a gearbox, and the time it takes for critical components to begin 4 4 WINDPOWER ENGINEERING & DEVELOPMENT
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When O&M crews have a choice between two or more components, especially bearings and gears, the buyOnLife feature provides an evaluation of the components and how they will perform in the client’s turbine.
crack initiation, propagation, and growth. If a forecasted failure can be prevented, the software will suggest a life-extension solution, such as an operational change, a surface treatment, a component change, or use of a lubrication additive to extend the life of the gearbox. For example, scientists recently developed a material-science-based predictive model for a 1.5-MW gearbox and studied the impact that a nano and microparticle based lubricant additive treatment had on the system. It was predicted that with use of the additive, an improvement in the overall bearing life would occur by a factor of 3.3 and overall gear life by a factor of 2.6. Buy this bearing, not that one Another small-data solution provides comparative data regarding gearbox or subcomponent choice from different suppliers. Depending upon the operator’s use case, it’s often more economical to reconfigure an existing gearbox with better components than to exchange the gearbox for a new model. Sentient Science software can recommend component changes based on lifing data of competitive components and the lifing impact on the gearbox system. Lifing refers to data or parameters that govern component life. Those responsible for maintenance can effectively extend the life of existing assets to meet their proposed design life and proformas.
In some cases, a gearbox life can be extended beyond a 20-year life. This feature is called “Buy on Life” so the operator has lifing impact data along with cost data to make purchasing decisions. Our company has been aggregating lifing data and failure rates of gearbox assets across the wind market and launched a new product for suppliers at the American Wind Energy Association WINDPOWER 2016 conference last month. The company’s new DigitalClone Live product means suppliers will have visibility into operator demand by understanding which gearbox models will require uptower component replacement or complete change out over the next 18 months. Operators will also have access to various auction mechanisms to engage the supplier community and find the lowest prices for components with the longest life. In Daniel Yergin’s book, “The Quest,” he writes that the power of reducing friction by just 1% across the major industries can amount to driving as much value in the market as a new source of fuel. Today’s technology helps operators achieve greater than that 1% improvement by extending the life of their existing assets and providing the right data to make better supply chain and inventory decisions. Using this small-data approach, operators will reduce O&M costs, lower energy costs, and improve profitability. W
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New ideas for improving wind-farm outputs AEP improvements of 5% and more are possible by taking advantage of improved controls, aerodynamic techniques, a better understanding of local winds, and more.
Alan Mortimer • Director of Innovation • SgurrEnergy Inc.
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he global wind energy sector has enjoyed dynamic growth over the past decade averaging 10 to 15% annually and last year reached over 430-GW capacity worldwide. By 2020, wind energy may deliver between 8% and 12% of the world’s electricity, a significant contribution. While the global wind sector growth continues at a rapid pace, many wind farms are maturing, resulting in owners and operators scrutinising operational performance more than ever. Considerable attention has been paid to reliability and maintenance optimization in recent years, but the industry is now placing additional focus on performance enhancement. Advances in technology and understanding show that in many cases wind farms have not been optimally designed for the real on-site wind conditions and relevant constraining factors. There is substantial potential for improvement through retrospective measures related to control, aerodynamics, and even the local environment, delivering an opportunity for considerable commercial gain for wind farm owners. Technology advancement Measurement technology is an important contributor to understanding wind energy. Lidar in particular is giving previously unavailable levels of detailed and accurate data on the behavior of the wind in and around wind farms. Lidar data is now showing that many of the assumptions around wind characteristics are incorrect, revealing significant potential to better operate wind farms. A good example of this value being realized is a U.S. wind farm which had suffered highly excessive rates of gearbox failures, with no obvious explanation. On further investigation of the site wind regime, using lidar, it became clear that low-level jets (high speed winds occurring relatively low in the atmosphere) were impinging the upper half of the rotor causing damaging loads to the drive trains.
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Several ideas for improving wind farm outputs
Lidar reveals boundary layer secrets These winds were not previously observed at the site because the traditional met mast that was used only recorded winds up to the hub height of the turbines, missing the higher level jets. The solution was to change the operating regime to avoid running during the most damaging conditions, as characterised by the lidar measurements, thereby avoiding substantial gearbox replacement costs.
The lidar scan of wind through a wind farm site shows how lidar can open our eyes to real wind behavior. It clearly shows a defined boundary layer above the rotors. This is typical of stable atmospheric conditions and is seen to break down as stability reduces, for example, in periods of high solar radiation. This sort of information is invaluable for fully understanding performance drivers and optimizing wind farms accordingly.
Yaw misalignment versus normalized power
The curves indicate the power lost from yaw misalignments. For instance, a 6° misalignment (orange curve) can limit a turbines power output to about 93% of full potential. Poly 8 and 9 refer to different curve fitting polynomials.
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Taking control Other technology advances are letting us improve the control of wind turbines to enhance performance as well as better manage component loadings. Control architecture has improved significantly in recent years and many older wind farms can now benefit from a controller upgrade to meet current standards and also better reflect the information we have on the behaviour of the wind. Many wind farms are simply an aggregation of wind turbines controlled and individually operated, rather than operating as one well-optimized, efficient grid asset. This means there is room for improvement in control of the wind farm itself to control it as effectively as a power station, as if it were a single unit integrated with the grid. Managed properly, there are ways that wind farms can provide support to the grid under certain conditions such as system faults and dips in voltage or frequency. This is particularly important as more and more renewables come onto the system. Advanced wind farm control can also manage constraining factors more optimally, such as situations in which turbines are shut down due to noise limits or shadow flicker effects. Excessive energy is often lost through traditional constraining practices and much of it can be recovered with appropriate control design. Aerodynamic efficiency Wind-turbine design involves certain compromises in relation to aerodynamic efficiency. For example, the optimum aerodynamic blade shape must be altered to allow the blade to carry structural loads, and to manufacture it at reasonable cost. The result is a trade-off in which there are accepted aerodynamic losses. New findings from lidar are uncovering complex wind characteristics, confirming that this trade-off is not optimum and that the aerodynamic losses can be greater than the ideal. Aerodynamic efficiency is also often affected by blade degradation issues, one example being erosion of the leading edge which occurs over time and result in appreciable performance degradation. These losses may not be fully appreciated until the degradation has reached a critical condition requiring major repairs. There is good news: a substantial proportion of these aerodynamic losses can be recovered.
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Adopting aeronautical techniques Blade repair techniques have evolved over the years to the point where the original blade shape can be fully recovered. In addition, the application of vortex generators can be highly effective. Vortex generators are most commonly seen in the aeronautical industry, on aircraft wings, and the same theory applies to wind turbine blades. When the angle of attack of the flow to that wing exceeds a certain level, the aerodynamics suddenly break down and the wing goes into what is called stall. At the point of stall the airflow over the upper surface of the wing breaks away from it and no longer creates the suction effect which creates lift. The effect is the same on a windturbine blade. It uses the same principle so we find the occurrence of stall often more prevalent than expected and it typically occurs at a certain point on the blade. Vortex generators can mitigate this effect by energizing the air, effectively putting a small twist into the air flow close to the surface of the blade which delays the effect of stall so the turbine can efficiently operate at a greater range
of angles of attack, therefore increasing production. However, vortex generators must be carefully applied in exactly the right configuration for the turbine and the site characteristics, so field measurements using lidar have a key role to play. This technique is being effectively applied in wind energy. In the right applications, vortex generators can deliver two to three percent increase in energy yield. Vortex generators are hardware that can be applied to individual turbines. They are small and their application is relatively straightforward. However, their installation must be carried out in a robust manner (as well as optimally positioned) to ensure they can withstand the rough environment for the long term. There have been challenges, but there are now suitable adhesives available to ensure that the overall solution is effective. Into the woods Although only a limited proportion of wind farms are within or close to forestry, there is substantial performance optimization potential for these projects. Experience is confirming that operating
Power curve degradation due to yaw error.
The blue power curve shows how yaw errors of greater than 12.5 degrees degrade power performance, by as much as 20% at some wind speeds. JUNE 2016
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a wind farm within forestry results in complex interactions between the trees and wind turbines, even when these turbines are well above the forest canopy. It is understood that trees slow the wind, but the extent to which they do in practice is turning out to be more significant. Trees absorb energy and make the wind flow more complex, increasing turbulence and increasing the gradient of wind speed above the canopy, which when added to other effects means that the turbines operate less efficiently. With an in-depth understanding of these issues, it is possible to more accurately model and predict true forestry impacts, thereby establishing a true optimum balance between forestry restructuring (and associated costs), and the commercial benefits of energy yield gain and reduced loadings. In fact, the benefits of improved forestry restructuring are wide ranging and include: • Increased wind speeds (due to less roughness) resulting in increased energy yield • Reduced turbulence leading to lower loadings and longer component lifetime • Reduced wind shear leading to better power performance and reduced loadings • Reduced wind veer leading to less yaw error, improved power performance and reduced loadings • Reduced thermal effects particularly excessive vertical flow components typical in forested areas. A case in point SgurrEnergy’s recently completed forestry restructuring assignments have identified performance enhancements in excess of 5% annual energy production (AEP) for the whole wind farm, validated by comprehensive computational fluid dynamics (CFD) modelling and on-site lidar measurements.
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Several ideas for improving wind farm outputs
Additionally, because of the reduced turbulence and wind gradient, the loadings on the turbines are reduced which has a positive impact on maintenance costs and on turbine life. Forestry restructuring solutions typically involve target felling with replanting to modern standards, thereby having a positive benefit for the environment, while, importantly, delivering commercial gain for the wind-farm owner. Total optimization The range of optimization measures continues to expand. Most recently we have developed adaptive noise control which will manage noise constraints much more efficiently than traditional techniques. Using real-time measurements
and control ensures that production is continually maximized while meeting noise limits. It is important to point out that all of the optimization measures considered at any wind farm are scrutinized ahead of commitment to ensure a positive cost to benefit ratio, in accordance with the owner’s requirements. Some optimization measures are low cost low gain, perhaps one to two percent. Others are higher cost and higher gain. The right combination of optimization techniques can deliver between 5% and 12% additional energy yield, making optimization an important commercial consideration for wind farm owners and a significant driver towards cost of energy reduction for the sector. W
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Planning for crisis on the balance-of-plant When making an O&M plan for a wind site, remember to include more than just the turbines on your list. Without the substation, connection systems, and supporting balance-of-plant (BoP) infrastructure, those turbines and the power generated lose their value. Here’s what you can do to optimize BoP operations at a wind farm. Bruce Hammett • President • WECS Electric
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hroughout the life of every wind farm, many challenges arise that will need attention to keep its turbines generating power. What begins with choices concerning turbine size and proper installation leads to decisions on O&M and repairs. Typically, the more proactive and organized a site owner, the better. However, transmission is an element often left off the table during discussions on maximizing power production. Without a grid, generating usable power becomes a pointless exercise. Every wind farm starts with a site design that basically includes two parts: the wind turbines and the balance of plant (BoP). BoP is a term given to the supporting infrastructure of a wind farm that does not include the turbines — such as the substation and connection system.
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There are a lot of components inside a wind turbine and if they break or need repairs, their owner and operators are faced with a downed turbine. BoP is much the same, except that one faulty wire can affect an entire wind farm’s power-generating capacity. So how do wind-farm owners optimize the BoP operations? And what is a reliable O&M strategy for electrical components? First, it is important to define the different segments of the balance of plant. • The substation is part of the electrical generation system that gets power from turbines to the grid, and that includes a number of components working at voltages of 35 kV and below.
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A well-designed substation includes redundancy to avoid or override failures (though not all of today’s wind farms support this feature) and a breaker in the middle that separates its two sides. The high-voltage section is the one that’s connected to the utility. • A collection system is a combination of components but mainly consists of underground cable, which collects energy from each wind turbine. Sometimes the cable spiders out into three or four different directions, and eventually flows back to one breaker. It is connected and interconnected through various types of apparatus, rubber goods, T bodies, and splices — and, with so many parts, good installation is key. The collection system should help minimize losses and voltage drops. • Turbine indicator-connect is a recent BoP addition. At one time as many as 13 turbines were connected through a pad-mounted transformer. Modern technology has brought the 35-kV circuit breaker and tower base, which means the indicator-connect is now part of each turbine and the collection system. • Sub transmission is the underground portion of the BoP that connects to each wind turbine.
Lightning doesn’t only pose a risk to wind turbines and their blades. It is also extremely dangerous and damaging to a collection system, and other components often all the way back to the utility interconnect.
• Overhead transmission includes the above-ground lines. This is either inside the 35-kV grid on substation grounds, or it represents the high-voltage energy that’s going out to the purchasing utility. • Transmission is the lines that take power from a wind site to a location that can be 10 to 1,000 miles away. Beyond turbine health For the most part, wind turbines can withstand wind, rain, snow, lightning, electrical shocks, vibrations, and more. Today’s turbine owners would not expect less. The balance of plant of a wind farm must face these elements, too, and somehow house and maintain electricity safely and securely. Most BoP operations were developed by a utility as an interconnected system of electrical wires, connectors, and protectors. Chances are, the lowest bidder also installed the system. However competent in operation, its design was based on the utility industry and was only theoretical in terms of the wind farm and the various potential turbines at a site. For example, a substation might be designed for a specific wind farm, but a mile or two away it must connect to another substation with completely different technology, or one from another utility. It might also have to work sideJUNE 2016
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When developing an O&M plan for a wind farm, remember to include the substation, collection lines, and overhead transmission lines.
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Planning for crisis
Depending on a wind farm’s location, opening equipment doors could reveal a snake or other critter. Ants and termites can also infest and ruin expensive electrical equipment. Their surprises are potential hazards of the job for a balance-of-plant technician or electrician.
by-side with Siemens and GE turbines. So BoP is essentially placed into a living organism — a wind farm with moving turbines — that can change in an instant depending on the direction of the wind or weather, or even the turbine capacity. To date, the best of educated minds have yet to determine how everything is supposed to fit together within a wind farm and without a hitch. Nature is not always your friend Lightning is just one issue that wind farms have to deal with at the turbine level. It is also extremely dangerous and damaging to a collection system — quite possibly all the way back through to the utility interconnect. Rain is also a concern. Then there are winters that bring all kinds of frost and icing scenarios that can affect BoP operations depending on the location. Weather aside, nature’s creatures and critters also pose a threat. The type of critter will vary by region, but here are some examples: • Termites, ants, mice, and snakes. These hungry pests seem to love a good cable to gnaw on or substation to hide in. Many hours of concern have been taken at various wind sites to get rid of rattlesnakes, only to open a substation door and find one there. 5 4 WINDPOWER ENGINEERING & DEVELOPMENT
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When a breaker trips at a wind farm, it is necessary to go onsite and find the fault. Unfortunately, when it is underground, the area will have to be dug up and then put back together once the issue is resolved.
• Cows and bulls. These guys laze around the field and they look for something to scratch their side or back on. Bulls are certainly not easy to deal with, but they can take out a junction box, ruin a pad-mounted transformer, and destroy a switchyard. If not careful, they can also ruin the day of a technician who is servicing equipment. Safety is paramount, and electricity at a substation is not the only concern. • Texas turkey buzzard (and other birds). These birds have a massive wingspan. For some reason, they are not adverse to flying into live components within a switchyard, hurting themselves and possibly taking out the entire system. • Prey. Eagles have been known to drop their prey, and sometimes in the worst location on power lines. Plan of attack Just like for a wind turbine, owners and operators must prepare for known and unknown circumstances when it comes to operating BoP. A good plan of attack involves planning for potential and unexpected problems — and includes the who, what, when, where, and how. For example, say a rat chewed through a cable at a substation, then a storm hits, and
a transformer blows up. Oil is everywhere. Is there a containment and cleanup strategy in place? As the site owner, do you have in-house capabilities or have you already planned for a subcontractor, and are they available on speed dial? Damage equates to downtime, so know your site, the resources, and have a plan. • Location, location, location. Weather that can damage wind turbines can also damage substation and components in the collection system. Wind farms in the bitter cold of Alaska are going to face different conditions than in sunny, earthquake-prone California. Know your location and its potential environmental risks. • Know your system. Some questions to consider: What do you do when something blows up? Is there a plan in place to fix things? Do you have the paperwork for each part and service agreement? Take vendor relationships seriously, and know who to call and when. It could be a manufacturer, distributor, or an independent service provider, and it might be someone different for each component. Also, prepare for the unexpected by having repair tools and materials, such as cleaners, readily accessible. For example, if you have to redo a splice without proper cleaner, you still won’t have a good splice after the repair.
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• Repair or replace? Imagine replacing a turbine or two in an older fleet. So you have an early GE working next to a brand new Siemens turbine, or vice versa. What’s going on between the turbines in terms of the types of energy (voltage and current) that each of those turbines is generating, and how will it react in the substation and in the collection system? This scenario could easily blow out all of the arrestors within a substation or throughout the entire system. Lead times. Suppose a particular splice needs replacing. Chances are it is not a great problem because in the right place, it’s possible to find hundreds of them on the shelf. But parts such as insulators, major switches, and pad-mounted or current transformers carry lead times. If something unexpected goes down, what is your plan and how much downtime can you afford? Insulators are fairly common equipment. If an ABC insulator goes down, and XYZ version may do exactly the same job, so know your equipment. Operations & maintenance. A common O&M issue in today’s wind farms is poor splicing. A few contractors have done such a poor job of splicing cable that some of the younger wind farms are already requiring splice replacements. Some owners are replacing 300 or 400 splices at a time because they’re aware of the workmanship on the first 40. Even so, the cost of all that downtime is likely going to leave them with something not working on the BoP side. In this case, a plan is needed for more than just the cable repairs. Safety and security. With every upgrade or repair, the person standing behind it has specific training and a mindset. For safety, quality control and minimum training requirements should be in place. Security enters the picture when some wise guy drives by and decides to take a shot at one of your insulators, or your turbine, or your main transformer. Do you have safeguards in place? If you need heavy equipment – a crane or just a ladder JUNE 2016
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– are there safety rules in place? If work is near hazardous voltage, precautions are imperative. Think outside the box. Imagine multiple scenarios that could go wrong, and train to fix each one. Nearby utilities may have assets available that you might buy or borrow in a pinch. Sometimes in the case of a main substation transformer or main circuit breaker, a utility can help fix a transmission line or help get a substation back online. A lot of the equipment put into substations today has capability that can monitor BoP health in real time. Such equipment can provide valuable data, but if a transformer goes offline, a clear line of communication is necessary. Before things go wrong, ensure due diligence and schedule post-operations testing in which a third-party comes in to ensure site quality. Avoid relying solely on the equipment manufacturer or site contractor. An independent, unbiased startup analysis can save costs down the line. Case in point Let’s look at a typical BoP problem: A breaker trips. Thankfully, it didn’t trip out the substation but now you have to go onsite and find the underground fault. You need the proper equipment and someone who knows how to use it. There is no exact science to trenching, so expect to tear the area up. And remember to implement the high-voltage protocol. Safety is critical site-wide because you’re working with electricity. After finding the little splice responsible for the problem, anticipate an 18-inch length of cable to accompany it because they don’t pull very well. You will have to put in a second splice, and another piece of cable. Just make sure it is available. Now, let’s talk costs for a 100-megawatt site. The average cost per megawatt-hour is $45. But the high-voltage technician and his overtime is probably closer to $100/ hour. Also an average wind technician is now going to come off-tower to help out. His labor rate is $35/hour, and $45/hour with overtime.
The energy loss on the feeder in this example is about 18% of the total production. The initial response in terms of wages, the four technicians, the highvoltage tech (assuming 10 hours) is $1,800 for the wind technicians and $2,000 for the high-voltage tech. Then, there’s the evacuation work that includes location and excavation, and putting things back together again. If you don’t have your own digger, estimate about $4,100. You also have to consider the materials and the cost of the splice and extra cable, and the labor involved, so that will likely cost another $1,000 to $1,250. The lost feeder means lost revenue. Over the repair period, 15 to 25% of the site is down (18% was estimated based on the 45 hours). If you have the replacement splice ready, it is still at least $30,000 in lost revenue. But the job is not over because now operation of the turbines must be restored as does the high-voltage connections between them. All of these things add up in terms of time, labor, and lost production. It is also a good idea to find out why the splice failed. Unfortunately, one reason is simply that it is manmade. When you take into account other areas of failure, such as a main circuit breaker in a feeder, that device probably has 75 different key parts — each of them with a big lead time. But, each of those parts is integral to the breaker. So, as site owner, how have you planned for its repair? Balance of plan is often the last consideration at a wind farm. But whatever the BoP O&M plan is, it could save your wind farm from thousands of dollars of lost revenue and from more than just a downed turbine. W
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E Q UIPMEN T All-weather grip-protection work gloves Hi-Line Utility Supply Co. www.hilineco.com Don’t lose another small part or tool because of oily or wet gloves. Power Gripz glove protectors and work gloves offer an adjustable Velcro strap and proprietary grip pads from palm to fingertips to ensure a secure fit and superior dexterity. The all-condition gloves come in Kevlar or Thinsulate for protection against the elements, including arc and heat-penetration protection. Available in Class 1 to 4, Power Gripz exceed ASTM F-696 standards.
Ultra rugged notebook good for work up tower Getac www.getac.com
Maintenance-free replacement couplings Zero-Max, Inc. www.zero-max.com
The B300 ultra-rugged notebook computer delivers maximum performance and comprehensive security for the
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most extreme,
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conditions simulating a 20-year load spectrum of
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continuous operation, Zero-Max couplings easily
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composite material properties withstand all types
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extremes from -40 to +70° C, as well as moisture and chemicals native to the nacelles of wind turbines. 56
WINDPOWER ENGINEERING & DEVELOPMENT
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www.windpowerengineering.com
JUNE 2016
6/9/16 3:19 PM
E Q U I PME N T AC-powered, torque multipliers Norbar Torque Tools www.norbar.com EvoTorque2 is a new generation of AC-powered torque multipliers with unprecedented accuracy, versatility, and ease of operation. This tool is factory calibrated and certified to an accuracy of ±3%, regardless of fluctuating voltages. Operating ranges are from 100 to 4,500 lb-ft (135 to 6,000 N•m) and up to 3,000 readings can be stored in internal memory with time and date stamping. The wrench measures in torque, torque and angle, and torque audit mode for pre-tightened bolts. Lightweight at only 23 lbs (10.4 kg), EvoTorque2 is offered in 110 or 230 Vac versions.
High-capacity conductor CTC Global www.ctcglobal.com ACCC is a low-sag conductor that can increase the capacity of existing transmission lines and mitigate grid congestion. The conductor incorporates conductive aluminum and leverages
Modular fault ride-through system for power converters Ingeteam www.ingeteam.com
aerospace-derived carbon fiber technology, making it twice as strong as steel and 70% lighter. ACCC’s improved conductivity
Ingeteam has developed the grid-compliant Crowbarless
serves to carry more current while reducing line losses by 25 to 40%
system to deal with low-capacity transmission lines (or
or more. What’s more is the composite core will not corrode. It is
weak grids) and fault-ride through events. Crowbarless is
highly resistant to environmental aging and degradation from cyclic
a fault ride-through (FRT) system for power converters,
load fatigue.
which strengthens the grid compliance of doubly fed induction generators. Because of its modular FRT operation, Crowbarless offers improved capabilities and response to voltage sags compared to the active crowbar system conventionally used to protect a power converter from grid voltage transient.
JUNE 2016
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windpowerengineering.com
WINDPOWER ENGINEERING & DEVELOPMENT
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6/9/16 3:20 PM
E Q UIPMEN T Industry’s most energy efficient 24-48 Vdc red obstruction controller Dialight www.dialight.com Dialight has launched the A0/A1 Red Controller System. It has the lowest dc-power consumption in the industry, making it ideal for operating its Vigilant Low (L-810) and Medium (L-864) Intensity red obstruction lights typically for met towers for the wind industry or cellular communication towers where solar and battery or generators are typically used as the power source. Drawing just under three watts, it’s the most efficient of its kind on the market, enabling the use of smaller batteries and panels for a much lower overall system cost compared to competing systems.
Small tool retractors Gear Keeper www.gearkeeper.com/guide Even small items, such as tape measures or screwdrivers, dropped from above present serious safety hazards. A new line of Gear Keeper General Purpose Retractors offers a simple and convenient tethering solution that safely secures small tools. The retractor lets tools extend as needed and automatically retract back to a secure mounting hold when not in use. The retractable devices provide industrial-strength lanyard extensions up to 36” for ample reach when extended, and can be attached to the user by a choice of four mounting options. They also offer a range of three retraction forces and are available with a snap mount, threaded stud mount, aluminum carabiner, or a Velcro strap.
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www.windpowerengineering.com
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AD Abaris .................................................................................. 17 AeroTorque .......................................................................... 7 AMSOIL ............................................................................. IFC AWEA ..................................................................................45 Aztec Bolting ............................................cover/corner,25 Bachmann Electronic Corp. ............................................ 1 Bronto Skylift ....................................................................... 5 CANWEA ............................................................................27 Castrol ................................................................................ 13 Dexmet Corp ......................................................................11 Evonik Oil Additives USA, Inc. .......................................... 3 ExxonMobil ......................................................................IBC Gradient Lens ....................................................................35 Mattracks ............................................................................ 17 Renewable NRG Systems ..............................................BC Ulteig ................................................................................... 51 WoWE .................................................................................50 Zero-Max, Inc. ................................................................... 21
SALES
BLADE MAINTENANCE DESERVES MORE ATTENTION / www.windpowerengineering.com
INDEX
WindWatch page 08 June 2016
The technical resource for wind profitability
ENGINEERING & DEVELOPMENT
NEW IDEAS TO BOOST PRODUCTION AEP UP 5% MAY BE SCRATCHING THE SURFACE Planning for problems in the BOP PAGE 52
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Vestas’ challenges scaling rules with a multi-rotor demonstrator
1
2 1. In cooperation with the Technical University of Denmark, Vestas is installing a concept demonstrator to test the technical feasibility of operating and controlling a multi-rotor turbine. 2. The purpose of the multi-rotor concept is to explore a different approach to lowering cost of energy by challenging turbine scaling rules.
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THE CONCEPT OF A WIND TURBINE with multi-rotor arrays is nothing new. Back in 2009, a company named Greenward Technology designed what it called the “Wind Turbine Quad Array,” which mounted four smaller turbines on arms to capture as much energy as a conventional unit with a 100-m diameter rotor. It seems the model never made it passed the 1-m scale, and the company no longer exists. In 2014, UK company aerotrope worked with GL Garrad Hassan to engineer the support structure and yaw system for the “OWES 5-MW” 16-rotor array (view a 2014 presentation at http://tinyurl.com/vestas4rotors). Times are changing. Global turbine manufacturer, Vestas, is taking the concept to the next level. In cooperation with the Technical University of Denmark, the company is installing a concept prototype to test the technical feasibility of operating a multi-rotor turbine. The prototype is under construction at the Risø test site near Roskilde, Denmark. So why bother with multiple rotors, you may ask? There are several viable reasons but they all come down to cost — and size. Today’s tallest towers reach 150 meters. Some companies plan for greater heights. Taller turbines mean longer, heavier blades and components. With all that weight comes related costs for material, manufacturing, transportation, installation, and maintenance. With its “concept demonstrator,” Vestas is challenging the scaling rules that turbines have to grow in size to increase their energy capacity and production. A multirotor turbine may benefit from reduced structure loading and weight from blades, hub, and the drivetrain compared to conventional turbines. Less weight and smaller-size components also reduces transportation challenges. The smaller unit size may also mean an array produces greater aerodynamic efficiency and more power. Vestas’ multi-rotor demonstrator uses four refurbished V29-225 kW nacelles (which the company produced from 1990 tot 1997), mounted on a support structure that consists of a tower with arms that each yaw individually upwind. Rotor arms are braced with steel tension cables that offer a flexible, lightweight mount that can reduce mass and loads. The prototype’s tip height of 74 m is notably shorter than many of today’s turbines but it meets Risø’s building height restriction (of 75 m). The demonstrator is well instrumented to measure factors such as load, wind speed, power production, and ambient conditions including temperature and humidity. A LiDAR system is also positioned at the top of the support
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structure to measure the wind field in front of the rotors. Throughout the year of test operation, data will undergo ongoing analysis to assess the feasibility of the multi-rotor concept. Vestas is confident in its design but admits the prototype’s future success depends on several factors. Many new load and control features still need developing and testing to assess the technical and commercial feasibility of the multi-rotor array. For example, the rotor is also a concept demonstrator to assess potential challenges and is not for sale. Vestas is investigating three main technical areas during operation of the multi-rotor demonstrator: structural dynamics (testing for unforeseen vibrations in the structure), aerodynamics (because the rotors mount quite close to one another, it’s important to discover how they interact), and loads (how accurately they can be predicted and adjusted over time). “Installing a concept turbine shows that innovation sometimes entails entirely new thinking and approaches. This process of continuous innovation and exploration is extremely important,” said Jorge Magalhaes, Senior Vice President, Vestas Innovation & Concepts, in a recent press statement. “It provides us with essential knowledge that can help us bring down our products’ cost of energy and integrate key technologies to solve customer challenges.” He added: “Ultimately, the goal is to assess if we can build an even more cost-efficient turbine by challenging the scaling rules.” Vestas reveals a bit more in its video here: http://tinyurl.com/scalingrules. W
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T:9”
Keeping wind turbines and their components up and running is your job. Mobil™ has the lubrication solutions to help, with product technology that protects against extreme conditions and maintenance services that help ensure equipment reliability. Learn more at mobilindustrial.com
6/9/16 8:33 AM
T:10.875”
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Up here, there are no small parts.
S:10.375”
© 2016 Exxon Mobil Corporation. All rights reserved. All trademarks used herein are trademarks or registered trademarks of Exxon Mobil Corporation or one of its affiliates unless otherwise noted.
S:8.5”
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Henry Bush
RNRG Senior Test Engineer
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