Functional Analysis of AMI-SmartGrid

2010 International Conference on Power System Technology

Functional Analysis of Advanced Metering Infrastructure in Smart Grid BAI Xiao-min

ZHU Ning-hui

Meng Jun-xia

Graduate School of China Electric Power Research Institute

Graduate School of China Electric Power Research Institute

CEPRI, Beijing, China

CEPRJ, Beijing, China

bxm@epri.sgcc.com.cn jxmeng@epri.sgcc.com.cn,

zhunh@epri.sgcc.com.cn

Abstract-Today, smart grid has been widely discussed in worldwide. As advanced metering infrastructure is one of main technologies of smart grid, its structure and functions of each component is represented. In terms of basic features of smart

grid, some key capabilities that advanced metering infrastructure should possess are analyzed, and its impacts on power grid networks as well. Combining current research situation of power utility information acquisition system in china, this paper provides reference for building smart grid of user side on the basis of these preliminary analyses.

throughout the whole system, but also provides measurement points and observability in system level. It is always considered to be the fIrst step in smart grid constructionl41. Generally, AMI system consists of smart meters installed in user side, metering data management system located in power company, and communication networks connects theml51• In order to strengthen demand side management, the system extends to user's home area network, as fIgure 1 shows.

Keywords- smart grid; advanced metering infrastructure(AMI); demand

side

management(DSM);

distributed

generation;

functional analysis

I.

INTRODUCTION

As today's power grid just acts as power transportation

equipment from a central power plant to the user, it can't cope with changes about economic development and environmental challenges. Focus on sustainable development of power industry, and high efficient and safe operation of the power grid, applying advanced communication, control and computer technologies to change model of power production, transmission and utilization fundamentally is an inevitable developing trend of power grid. Smart grid is more suitable for multiple energy generation type, more suitable for its customers' choosing independently, more suitable for a two­ way energy flow and information flow between its customers and itself1.l, 21. This flexible, two-way smart interaction put forward higher requirements to electric energy metering. As most advanced structure of energy metering, advanced metering infrastructure(AMI) not only retains functions of automatic meter reading(AMR), but also forms a two-way communication platform based on automatic meter management, and builds a bridge for interaction between customers and the grid friendly. As a key technology of smart grid, AMI has been valued by each national power company, and becomes one of topics in power industry naturally in china.

II.

COMPONENTS AND ITS ROLE IN AMI

AMI integrates meters(including water, gas, etc.), communication networks and software to measure, collect, storage, analyze and use data on electricity consuming as well as system operation[31. From power company's aspect, AMI not only provides communication networks and facilities

CEPRI Academician fund

978-1-4244-5940-7/10/$26.00©2010 IEEE

Figure 1.

AMI composition, structure and data flow diagram

Smart meter, which is a digital instrument based on micro­ controller to achieve energy measurement, monitoring and control capabilities, is an important component of AMI. Smart meter collects detailed real time data on energy consuming, deliver the raw data through two-way communication networks to MDMS. The raw data is analyzed and processed in MDMS in order to achieve a number of complex functions of AMI. As collecting many electrical parameters measurements with time scales, smart meter becomes a system sensor and measuring point distributed all over the grid.

An advanced two-way communication network forms a high speed channel to exchange power flow and information flow between consumer and the grid. This can be realized by a variety of communication media. Two-way communication provides a means of improving energy effIciency and reliability of the grid. It also make user participate system operation actively and friendly, interact between user's resources and the grid deeply and coordinately. On the contrary, these capabilities put forward higher demands to the communication network. Therefore, combining specifIc needs of smart grid, data amount, real time requirement, communication means and so on should be studied.

MDMS is a database system for acquisition, processing and storing measured values of meters, acts as an analytical tools to interact with other information systems. It can manage all meters, transmit data other than tarrif, turn on/off electricity, manage data on fault detection and recover from failure, generate and process worksheet in filed work automatically, show as figure 2. In addition, MDMS can integrate operation system of the grid in order to achieve coordinating system fault management, scheduling system operation, completing load research and forecasting management, etc.

A.

Offer a variety of measurement information

Data collection and storage is a basic function of smart meter. Smart meter can measure many electrical parameters, such as active power, apparent power, power factor, voltage/current RMS etc. In addition, it can provides voltage and current waveform sampling data to realize (remote)power quality monitoring. AMI can read meters at a specified time or any time in terms of orders delivered from upper control center.

Detailed measurement data provides an accurate basis for power system scheduling, planning and operation. In addition, power company through anti-tamper, delayed investment and intelligent device maintenance, monitors and uses distribution equipments more efficient, and distributes energy to its customers more reliable.

Figure 2.

Main functions of metering data management system

Home area network(HAN) coordinates user's energy management system and portal, connects smart meter and other user's controllable intelligent electric equipments to achieve more efficient load management with the help of price signal(voltage, frequency) or combination signal as incentive automatically. Usually, intelligent nodes in HAN connected by

wireless ZigBee or power line carrier, but it seems the latter approach is more promising.

III.

FUNCTIONAL ANALYSIS OF AMI IN SMART GRID

In order to meet future power grid development, which may involve variable price, improve power quality, increase real power grid utilization coefficient, provide a variety of options for consumer, reduce power consuming and lower loss and so on, functional analysis of AMI is necessary. These capabilities are achieved by virtue of advanced technologies to make AMI play a better role in smart grid.

The development of energy metering system has experienced three phases, which are AMR automatic meter management(AMM), and AMI AMM is a transitional form from AMR to AMI. AMR only permits to deliver information on unique direction, its automatic meter reading makes power staff get rid of heavy manual labor, and greatly improve reading accuracy. However, AMR has little amount of information available, has no or only a simple monitoring capabilities. It can not meet requirements to flexible interaction.

AMI has added complex monitoring functions besides advanced two-way communication capability, and integrated user side controllable resources to complete demand response based on specific incentive signal. For example, smart home 6 should be take into consideration[ 1. ,

.

With the help of smart meter, power company can provide customers with an integrated information and bill. Breakdown of the bill(power consumption of different appliances in one day and one month) displays power consumption information in both cash and kWh format. Customers may reduce electricity costs by adjusting their consumption pattern based on their own historical data. Power company may recommend power saving strategies to its customers, display relevant information(which can be released through broadcast, web, etc.) on in-home display(IHD) to meet customers' requests to improve service level.

B.

Achieve demand side management Demand side management requires electricity users to

respond to incentive pay or price change, to transfer or reduce

load by changing their original consumption mode for shifting 7 peak load[ 1. Power grid changes operation strategy from

traditional model that follows with load changing into load

shift mode, and demand side resources used to balance power generation

and

power

supply

all

the

time.

Demand

management can be realized by direct load control, variable

price and other means to improve utilization efficiency of the

grid, avoid or mitigate investments 8 transmission and distribution grid[ 1.

1)

on

power

plant,

Support flexible price policies

Real time price reflects changes in supply and demand of

electricity, may be used as incentive signal in demand side management. AMI provides users who join into electricity

market with real time(TOU) price information. Electricity

charge will be reduced if the users response to price change by

optimizing their consumption pattern. Supporting variable

price requires smart meter has a precise clock, power company

should issue an unified time signal to calibrate all meters'

clock at a specific time. When users allow power company to

control their electric equipments, smart meters should support

a remote limited load switch on/off service.

2)

Integrate distributed generations in user side

A large number of distributed generations(DGs) will be

connected with medium voltage or low voltage distribution grid in the future. Uni-directional power flow in traditional

distribution grid will be changed absolutely. Power system

must

use

new

protection

schemes,

voltage

control

and

instrument to meet needs to two-way power flow. These

distributed generations include user's small wind power, solar power, energy storage device and PHEVI91. With the help of

AMI, these DGs are integrated into the grid to achieve demand side management by local coordinate controller1101• In addition to meet user's own electricity needs, distributed

generations can support peak load and emergency power as

power company can accurately identifY the alarming meter

and its location, dispatch staff in time without user calling or

the staff inspecting spot periodically.

As an electronic device, smart meter has greater reliability

risk. Any electronic piece in the meter failure will bring many

problems

to

its operation and maintenance, even cause

well as other assistant services. For example, user's distributed

scrapping of the whole meter some time. Therefore, functional

period, which enhances stability, reliability and efficiency of power system[\l]. Therefore, smart meter should have negative

exceed the prescribed index in product life cycle. Besides, in

power flow in smart grid.

reverse power apply, over voltage, over current should have

generation delivers electricity back to the grid at peak load

power accumulation capability for measuring bi-directional A large number of plug-in hybrid electric vehicles(PHEV)

and plug-in electric vehicles(PEV) will cause a great impact

on the existing power grid in the near future. PHEV(PEV) can either act as a distributed generation or a power loadl121• As a

node in HAN, charging behavior of this friend appliance can be monitored through home energy management systeml131•

3)

User's home area network

HAN consists of intelligent thermostat, IHD, intelligent

appliances,

PHEV etc.

gateway(home

gateway

Smart can

be

meter can be used as a configured

separately

to

modules of smart meter should be rational planning in order to facilitate repair and maintenance, and failure rate should not order to prevent damage due to misuse of the meter, such as

protective measures in its hardware and software design.

D. Data security issues Data

security

is

mainly

to

prohibit

non-authorized

operations. In one hand, measurement data as well as working

parameters should not be changed as a result of illegal operation

or

interference(electromagnetic

interference,

electrostatic, etc.) in any case. On the other hand, data

encryption should be done in public networks to prevent

disclosure, even be modified of important data to reduce

improve reliability of the meter), see figure 3. Users control

security risks and avoid significant economic losses. Data

out home. For example, a housewife can use her mobile phone

Software measures include data backup, different level access

their smart appliances remotely through HAN when they are to control smart appliances in home, configure home security

system,

adjust

intelligent

thermostat

or

edit

a

home

entertainment program. Power company displays variable

price and electricity utilization information on IHD, uses home

energy

management

algorithm to

coordinate

controllable

resources in user side to optimize user's energy utilization.

security rights

measures

both

management.

involve

Hardware

switch, sealed buttons, etc.

£,

software

measures

and

hardware.

include

built-in

measure

values,

A variety of remote service capabilities MOMS

manages

meters

and

their

including adds/deletes meters, modifies or sets parameters of

meters, and remote updates software of meters. Therefore,

smart meter can be applied in broader context because of this

\\irclcss communicati

A/

/¥ () n

kind of flexible design. Remote calibration feature allows the

grid

other meters

PV

......

smart meter

Zig8ee or

staff easily correcting measure values to improve measure accuracy of meters in the control centerl141• AMI enables

wind smart thermostat

'" , PLC' " ..

remote software and hardware fault diagnosis, and returns

diagnostic results back to MOMS, locates fault and response Home area network

:

HAN

tHD

energy slOrage

t=

.. -

F.

...... smart appliances

PI-IEV/PEV

Figure 3.

In the

utilization

short

rate,

user's home area network and its gateway

term,

reduces

AMI

costs

can

of

increase

system

electricity

quickly.

asset

supply

by

producing peak load shifting capacity through changing user's

load pattern. In the long run, AMI can reduce system peak demand or local peak demand, and reduce investments for electricity demand growth.

C. A variety of event alarms and protection functions Smart meter issues a variety of alarm signals, including

meter malfunction alarm, power-down alarm, theft/tamper

alarm etc., and sent alarm information to MOMS for further analysis. With the help of GPRS or other intelligent systems,

Business expand and value-added services

User energy management system is integrated into home automation systems, which makes customer has a better electricity service. Meanwhile, communication networks of AMI can be fully utilizedl151• With further development of two­ way communication facilities, customer will enjoy home automation and a variety of value-added services that has nothing to do with electricity supply as well, such as home shopping, home banking, security system(home security, alarm

for the elder and the weaker), multimedia applications etc.

IV.

CONCLUSION

With smart grid technical support, interaction between power grid and user resources will be operated deeply and widely through AMI. Earnings come from lowering peak power demand, enhancing the grid reliability, improving asset utilization coefficient, continuously reducing energy consume costs, environment protection and something like this will be

achieved. Standards and nonns in smart electricity utilization field is necessary, which can realize interoperability between different manufactures. All parts of power system(generation, transmission, distribution, utilization and power company) should be coordinate developed and jointly promoted, because coordinate control and optimal operation of the whole system is far greater than simple overlay of each components.

Cooperation between power industry and others is necessary, and electric car is a good example. In order to popularize PHEV in smart grid, cooperation of car manufactures and power industry is required. Thus, electric vehicles can be recharged easily in many places, and process of charging is supervised to avoid adverse impact on the grid. Cooperation of appliance manufactures and power industry is contributed to realize home automation, as well as demand side management through smart meter operating user's controllable loads. Some infonnation of the grid and tariff should be visible to make system operation and resources allocation link with user's choices effectively.

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