GUARANTEED EFFICIENCY AND HIGH OPERATIONAL AVAILABILITY WITH CUSTOMISED GENERATOR TECHNOLOGY

No-one purchasing a generator manufactured by Hitzinger, an Austrian industrial engineering company founded over 75 years ago, ever receives an ‘off the peg’ solution. On the contrary, Hitzinger’s engineers design and finetune each machine to the needs of the customer, selecting solutions from a full range of options, tailoring to site and grid conditions, and accommodating all kinds of special requests. It’s a service that pays off. Thousands of successful plant-development projects completed around the world over several decades serve as reference works underlining the outstanding reputation Hitzinger’s generators enjoy. Regardless of how varied site requirements may be, Hitzinger guarantees the best machine for each respective application.

Last summer, in the Swiss town of Beckenried in the canton of Nidwalden, the municipality’s utilities operators celebrated completion of their latest small­scale power plant: ‘Napf’. The project became necessary due to an accident that occurred in 2013, when a slope­mounted pipe to the Napf equalising basin was damaged by a landslide. The opportunity to replace the defective gravity channel with a penstock was seized, and the previously unused 70­metre head was finally exploited for power generation. Moreover, the project envisioned the integration of a second water conduit leading into the power plant to enable the two turbines in the central station to be fed from two different mountain streams. An unusual solution in terms of electromechanical equipment was chosen to achieve this goal. It involved two horizontal­axis Pelton turbines, each with its own independent supply of water, driving a single centrally­located synchronous generator via a rigid shaft. The generator is now driven from both sides at 500 rpm. It was designed by the premium­quality Austrian manufacturer Hitzinger, adapted and optimised to suite the very special circumstances. The Linz­based mechanical engineers faced the challenge posed by the fact that each of the generator shaft ends was mounted directly to its own impeller. Resultantly, all operational safety and efficiency calculations had to be carried out for singleturbine and two­turbine operations, at full and at partial loads. All shaft load cases were analysed via FEM using ‘Ansys’ technical simulation software. The natural bend frequency of the rotor was examined closely, too. Hitzinger used high­grade chromemolybdenum alloyed steel for the shaft, and produced greased bearings that guarantee a minimum service life of 150,000 hours. The machine group uses an air­cooled generator with an output rated at 425 kVA to supply around 1.2 GWh of green electricity per year.

Deployed In Tyrol

Hitzinger supplied considerably larger generators for two Tyrolean power plants that went into operation just a few months ago, Langer Grund and Kelchsau­Zwiesel. Al­ though both power plants are located in the same valley, the essential difference was that the Langer Grund power plant was built completely from scratch, whereas the Kelchsau­Zwiesel power plant was existing infrastructure in need of an overhaul. In the latter case, the two original Pelton turbines, each with an absorption capacity of 700l/s, were replaced by two 4­jet Pelton turbines, each with a nominal flow of 1.4m³/s. The two Pelton turbines were connected to the Kelchsau­Zwiesel power plant. A 3­MVA Hitzinger synchronous generator was coupled with each of the two Pelton turbines, and is among the larger generators in the Upper Austrian manufacturer’s portfolio today – one than now extends to machines with an impressive output of 7.2MVA. The 20­metric­ton machines at the Kelchsau­Zwiesel power plant can achieve overspeed of up to 1080 rpm. The new power plant is now expected to produce around 23 GWh per year, compared to the

16 GWh yielded by the old plant. That’s an increase of more than 50%. A vertical­axis 6­jet Pelton turbine forms the heart of the new Langer Grund power plant, and has been designed to discharge 2.5m³/s from a 126­m gross head. The 2.5­MW turbine is directly coupled with a Hitzinger water­cooled synchronous generator, designed for a nominal output of 3,100 kVA. Since commissioning, the machine group has performed excellently.

Electricity Powers Scotch Whisky Distillery

These standards have also been achieved at a new reference plant in the Scottish Highlands. Deanston is a traditional whisky distillery, located about 80 km northwest of Edinburgh, and has its own hydroelectric power plant. The Upper Austrian company GUGLER Water Turbines GmbH supplied a Kaplan Z turbine to replace two Francis turbines that had reached the end of their working lives. The turbine was adapted to the cubic shape of the machine building with a modern Hitzinger synchronous generator (output rating 390 kVA) mounted directly onto the turbine housing. The Upper Austrians’ proven machine constellation ensures absolutely smooth and reliable operation, as was impressively demonstrated during the first months of operation in the Scottish Highlands. The Linz­based generator specialists can invest the benefits of 75 years of experience, supplying machines designed to operate relatively conservatively, in that they offer considerable reserves and seldom operate at upper performance limits, thus are not at risk from heat build­up. This point is a key to ensuring generators have a long technical service life. Performance efficiency specifications are also stated conservatively. In all the years of its existence, the Linz­based manufacturer is proud to have complied with almost every efficiency specification ever stipulated. Today, Hitzinger generators guarantee features ‘as standard’ that other manufacturers only make available as extras.

WATER-JACKET COOLING

In the Swiss municipality of Blatten in Valais, a powerful synchronous generator was also customised for the Gisentella power plant that started operation last year. The project involved extending the existing plant that uses a head of just under 300m, and a maximum flow volume of 800l/s. The new powerhouse is equipped with a 4­jet synchronous generator. A 4­jet, 2.1­MW vertical­axis Troyer­built Pelton turbine was installed for this purpose, and directly coupled to a Hitzinger synchronous generator – rotating at 1,000 rpm and designed for an output of 2.5MVA. A water­operated cooling circuit around the generator jacket is connected to the heat exchanger in the underwater area of the machine, guaranteeing optimum operating temperatures and ensuring ultra­low­noise emissions when running. The new machine group has been in daily use since May last year.

A Giant Leap In Performance

A steep rise in performance was achieved by modernising the Weissenbach power plant, a power­generation facility that had served a company of Tyrolean cement experts for almost 60 years. A few months ago, the old machine set was removed, and replaced by a solution consisting of a modern Francis spiral turbine and a directly­coupled Hitzinger generator – more specifically, a brushless synchronous generator with roller bearings, designed for a nominal apparent power output of 580 kVA at nominal speed. The operators were very positive after the first regular months of operation. The generator alone achieved an efficiency increase of over 10%. On average now the successfully renovated power plant delivers around 62% more electricity than the previous infrastructure, so it’s no surprise the operators are very pleased with the new machine set.

Special Software Makes The Difference

The performance of these machines is only one of the benefits, as the long­established Linz manufacturer’s machines have always offered significant advantages in terms of technical service life, too. The rule­of­thumb still applies: The cooler a generator remains when operating, the longer its working life will be. For this reason, Hitzinger generators are tailor­made for each respective application, and generously designed in advance with regard to the magnetic cut in order to ensure sufficient reserves. Everything works on the basis of programmes developed over decades by engineers with a vast wealth of hands­on experience. The programmes facilitate computation on a variety of factors and items, such as stability at speed, vibrations and bearings – and help identify the optimum machine for the location in question. In order to maintain the greatest possible control over their own product, Hitzinger still retains a large degree of proprietary control over the manufacturing process, hand­crafting most of the generator in the factory in Linz. Customers choosing a Hitzinger generator can rely on solid mechanical engineering quality, and on the fact that Hitzinger attaches great import­ ance to its after­sales service. Every machine that leaves the factory bears a serial number, allowing its entire configuration to be retrieved. This is invaluable information should repair work be required. At Hitzinger, customer satisfaction continues to be the company’s central guiding principle.

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