RT3-5 電能質(zhì)量評估及前景展望ppt課件

1、Power Quality Assessment and Its Outlooks for Further ResearchXiao XiangningNorth China Electric Power University, ChinaSeptember 15, 10:40-11:10CICED2010, Nanjing, 12-16day;development of the power supply system for more intelligent3BackgroundZSmart Grid Research is becoming a focusing issue.Smart

2、Grid in China Can Achieve 10.5 Billion Tons of Carbon Emission Reduction over the Next Decade Strong Smart Gridin China4BackgroundsZAfter analyzing to the adverse impaction of SG, a n e x p e r t o f P Q standardization in USA, prof. McEachern said if the research work not to do on PQ problems same

3、times, smart grid will make power quality worse, not better. ZPower quality control should be regarded as a important part of smart grid .ZBut the benefits of SG are great, so it should c o n t i n u e 5BackgroundsZA power quality disturbance can be defined as a deviation from the ideal (sinusoidal,

4、 constant magnitude) voltage or current. ZBased on the monitored data or simulated data of power system operating parameters, power quality assessment, which is a very important part of power quality research area, is a process of calculating the quality indices and checking whether the values fulfi

5、ll the standard limitation, or whether the power disturbances make equipments miss-function. 6BackgroundsZThe power quality standards should be improved on the basis of further research, though a set of useful standards have been published. The changes of power load constitution, the development of

6、distributed generators, and the integration of large scale new sources, resulted from the construction of Smart Grid, will introduce challenges and opportunities for new sufficient important and interesting research in the domain of power quality. 7Extensive Voltage Sag Characteristics AssessedZVolt

7、age sags are, according to standards, characterized by one magnitude and one duration. Other indices are still in dispute.-IEC 61000-4-30, IEC61000-2-2（12,8), IEC61000-4-11(34)-IEEE std 493, IEEE std 1346 -CIGRE C 4.07-SEMI 47 -EN 50160-NRS 048 but there are many new indices are discussed and studie

8、d in8Extensive Voltage Sag Characteristics AssessedZFrom the view of influenced equipment, manufacturers, as well as power suppliers, should be aware of more characteristics than just magnitude and duration. 9Extensive Voltage Sag Characteristics AssessedZCIGRE/CIRED/UIE Joint Working Group C4.110 V

9、oltage Dip Immunity of Equipment and Installations(2010.04) For characterizing dip immunity of three-phase equipment, voltage-tolerance curves should be given for three general dip types: Type I, Type II and Type III dips.10Power quality economics-sagsZThe economic cost assessment of power quality a

10、nd the profit and loss analysis of power quality investment have contributed to the development of power quality industry and power quality economics.CIGRE JWG C4.107- Economic Framework for Voltage Quality-Propose a standardized method of collecting information, based on the experience of various i

11、nternational studies.-Recommend a methodology of using these data to cost and motivate power quality interventions on the power system or within the customer plant. - Provide indicative costs for specific industry sectors, where possible. -Provide detail the main factors influencing decisions about

12、the investment in increased immunity of equipment.ZVoltage sags are the most concerned voltage quality disturbances and Economics on sags is a critical study because the costs are very significant.11E.g. Cost of downtime is dependent on many factors. Voltage dip pattern with time of the day.varying

13、customer size in annual kWh consumptionvarying season and time of dayvarying business type12Corrected reliability indices based on economicsZBesides sustained interruptions, voltage sags and short-duration interruptions disturb the continuous operation of customers especially, of typical continuous

14、manufacturing plants.SAIDI the average interruption duration of the customers servedSASDI Average sag economic equivalent interruption duration /1min interruption costsiiCASDICS1(,) /isDiiENSASDICASDICSF V TTypeN13Example of a contour chart: HV/MV sites (CP95 value ) Customer Sag Frequency the numbe

15、r of sag events for the customer per yearCSF(Vs=80%,T=100ms,Type=Type III) =35 per yearType IType IIType IIIImmunity Curve14Corrected reliability indices based on economicsZThe definition of corrected reliability comprehensive index ASAI* (RS*) SAIDI and SASDI are coordinate of the economic losses o

16、f customers impacted by sustained interruptions, short-duration interruptions and voltage sags. *(1) 100%8760SAIDISASDIASAI-(1) 100%8760SAIDIASAI -15Voltage sag assessmentThe procedure for obtaining the corrected reliability indicesZMain four factors for assessmentDeal with Time AggregationDeal with

17、 Phase AggregationC a l c u l a t i o n o f Defined indices and check with the specified objectsProcedure16Voltage deviation assessmentZIEC 61000-4-30:2008IEC 61000-4-30 supports power quality measurement methods. The new edition 2008 cancels and replaces the first edition published in 2003. Measure

18、ment Aggregation The 10/12-cycle r.m.s. value shall be used. Underdeviation 200,.200,.200,if then if then rmsms idinrms under idinrmsms idinrms under irmsms iUUUUUUUU-200,200,200,if then if then rmsms idinrms over idinrmsms idinrms over irmsms iUUUUUUUU-150/180 cycle and 10 min aggregation are perfo

19、rmed using the square root of the arithmetic mean of the squared input values.2,1(/ )/100nunderdinrms under idiniUUUnU-2,1(/)/100noverrms over idindiniUUnUU-Overdeviation Underdeviation Overdeviation 17Voltage deviation assessmentZIEC-Assessment Indices suggested the number, or per cent, of values d

20、uring the measurement interval that exceed high or low contractual values might be counted; the worst-case values might be compared to high and/or low contractual values (the measurement interval might be different for this possibility); one or more 95 % (or other percentage) probability weekly valu

21、es, expressed in volts, might be compared to high and/or low contractual values; the number of consecutive values that exceed high and/or low contractual values might be counted. 18Voltage deviation assessmentZEuropean StandardsCENELEC EN 50160:2007 “Voltage characteristics of electricity supplied b

22、y public distribution systems”, 2007CLC/TR 50422 Application Guide to the European Standard EN 50160 on “Voltage Characteristics of Electricity Supplied by Public Distribution Systems”, 2003UNIPEDE Report “Application Guide to the European Standard EN 50160”, 1995UNIPEDE Report “Measurement Guide fo

23、r Voltage Characteristics”, 1995EURELEC “Power Quality in European Electricity Supply Networks” - 2nd edition, 200319Voltage deviation assessmentZA European Standards -Assessment Index during each period of one week, 95 % of the 10 min mean r.m.s. values of the supply voltage shall be within the ran

24、ge of 10 % of nominal voltage for LV and of declared supply voltage for MV . all 10 min mean r.m.s. values of the supply voltage shall be within the range of + 10 % / - 15 % (LV). 11non5%1008NNNN-20Voltage deviation assessmentZGB/T 12325-2008 the basic measurement time interval for supply voltage de

25、viation is a 10-cycle, and each 10-cycle measurement should be close to the next interval without overlapping; the arithmetic mean calculation is used over four optional aggregation intervals: 3s, 1min, 10min and 2h in accordance with local conditions and demands.GB/T 12325 also complements the term

26、 of qualified voltage rate(QVR). 1100%TQVRT21Voltage deviation assessmentZThe problem of two-side assessment with percentiles disturbance level x Compatibility level zLpdff(x)P(xzCP95)Assessed valuezCP95 disturbance level xpdfOverdeviation limitzL+f(x)UnderdeviationlimitzL-1.0(a)(b)how is 5% time/lo

27、cation statistical values picked out form two-side deviations to obtain the 95% compatibility level ?22Voltage deviation assessmentZIEC method the definitions of overdeviation and underdeviation are two independent parameters. Problem: if the CP95 value of voltage overdeviation complies with the lim

28、it level (or contractual agreement), in the 95% time of voltage positive deviation qualified, are all of the voltage r.m.s values qualified or do all of the voltage variations keep in the guarantee range? 23Voltage deviation assessmentZAn engineering method Respectively picking out 5% from the stati

29、stical spaces of underdeviation or overdeviation. Problem When the number of statistical data in one side of deviation is very small, which is always a common sense, one should be careful about the confidence interval . 24Voltage deviation assessmentZAssessment indexQualified rate, a core index, is

30、used as compatibility index between power systems and electric end-users. The worst-case values of deviations and the number of consecutive values that exceed high and/or low limits indicate a warning to system operators and power quality engineers. 25Voltage deviation assessmentZInteraction between

31、 DER (distributed generators / the integration of large scale new sources) and voltage deviation assessment DER impacts the time/spatial distribution of voltage magnitude. 26Voltage deviation assessmentZInteractionThe selection of index impacts the penetration rate of DER To determine how much DER c

32、an be accepted, a suitable performance indicator and an appropriate limit are needed.27OutlooksZIt is necessary to establish a standardized power quality assessment framework, to carry out power quality parameters and economic assessments, improving horizontal and vertical comparability of measured

33、or simulated data, in turns to promote the mitigation of power disturbances.ZWith the changes of load composition, we should research the characteristics of disturbances and the sensitive mechanism of the disturbed equipments, and improve the limitation and immunity standards ; 28OutlooksZWith the development of distributed generators and the integration of large scale new sources, it is significant to study the interaction between distribution network and DG on power quality and its assessment methods. 29Power frequencyFlickerVoltage sagswellUnba