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Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Power Quality Assessment and Its Outlooks for Further Research,Xiao,Xiangning,North China Electric Power University, China,September 15, 10:40-11:10,CICED2010, Nanjing, 12-16day;,development of the power supply system for more intelligent,Contents,Backgrounds,Voltage sags assessment,Extensive Voltage Sag Characteristics Assessed,Power Quality Economics,Corrected Reliability Indices based on Economics,Voltage deviation assessment,Reasonable Assessment,Interaction Between DER and Quality Assessment,Outlooks for power quality assessment,Conclusion,Background,Smart Grid Research is,becoming a focusing issue.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Smart Grid in China Can Achieve 10.5 Billion Tons of Carbon Emission Reduction over the Next Decade,Strong Smart Gridin China,Backgrounds,After analyzing to the adverse impaction of SG, an expert of PQ standardization in USA,prof,.,McEachern,said if the research work not to do on PQ problems same times, smart grid will make power quality worse, not better.,Power quality control should be regarded as a important part of smart grid .,But the benefits of SG are great, so it should continue,Backgrounds,A power quality disturbance can be defined as a deviation from the ideal (sinusoidal, constant magnitude) voltage or current.,Based 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 fulfill the standard limitation, or whether the power disturbances make equipments miss-function.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Backgrounds,The 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 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.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Extensive,Voltage,Sag,Characteristics,Assessed,Voltage 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 studied in,Background,Voltage sags,Deviations,Outlooks,Conclusion,Extensive,Voltage,Sag,Characteristics,Assessed,From the view of influenced equipment, manufacturers, as well as power suppliers, should be aware of more characteristics than just magnitude and duration.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Extensive,Voltage,Sag,Characteristics,Assessed,CIGRE/CIRED/UIE Joint Working Group C4.110 Voltage 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.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Power quality economics-sags,The economic cost assessment of power quality and 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 international 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 the investment in increased immunity of equipment.,Voltage sags are the most concerned voltage quality disturbances and Economics on sags is a critical study because the costs are very significant.,Background,Voltage sags,Deviations,Outlooks,Conclusion,E.g. Cost of downtime is dependent on many factors.,Voltage dip pattern with time of the day.,varying customer size in annual kWh consumption,varying season and time of day,varying business type,Corrected reliability indices based on economics,Besides sustained interruptions, voltage sags and short-duration interruptions disturb the continuous operation of customers especially, of typical continuous manufacturing plants.,SAIDI,the average interruption duration of the customers served,SASDI,Average,s,ag economic equivalent interruption,d,uration,Background,Voltage sags,deviations,outlooks,Conclusion,Example of a contour chart:,HV/MV sites (CP95 value ),Customer Sag Frequency the number of sag events for the customer per year,CSF(Vs,=80%,T=100ms,Type=Type III) =35 per year,Type I,Type II,Type III,Immunity Curve,Corrected reliability indices based on economics,The definition of corrected reliability comprehensive index,ASAI,* (RS*),SAIDI,and,SASDI,are coordinate of the economic losses of customers impacted by sustained interruptions, short-duration interruptions and voltage sags.,Background,Voltage sags,deviations,outlooks,Conclusion,Voltage sag assessment,The procedure for obtaining the corrected reliability indices,Main four factors for assessment,Deal with Time Aggregation,Deal with Phase Aggregation,Calculation of Defined indices and check with the specified objects,Procedure,Voltage deviation assessment,IEC 61000-4-30:2008,IEC 61000-4-30 supports power quality measurement methods. The new edition 2008 cancels and replaces the first edition published in 2003.,Measurement,Aggregation,Background,Voltage sags,deviations,outlooks,Conclusion,The 10/12-cycle,r.m.s,. value,shall be used.,Underdeviation,150/180 cycle and 10 min aggregation are performed using the square root of the arithmetic mean of the squared input values.,Overdeviation,Underdeviation,Overdeviation,Voltage deviation assessment,IEC-Assessment Indices suggested, the number, or per cent, of values during 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 values, 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.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Voltage deviation assessment,European Standards,CENELEC EN 50160:2007 “Voltage characteristics of electricity supplied by public distribution systems”, 2007,CLC/TR 50422 Application Guide to the European Standard EN 50160 on “Voltage Characteristics of Electricity Supplied by Public Distribution Systems”, 2003,UNIPEDE Report “Application Guide to the European Standard EN 50160”, 1995,UNIPEDE Report “Measurement Guide for Voltage Characteristics”, 1995,EURELEC “Power Quality in European Electricity Supply Networks” - 2nd edition, 2003,Background,Voltage sags,Deviations,Outlooks,Conclusion,Voltage deviation assessment,A,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 range 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).,Background,Voltage sags,Deviations,Outlooks,Conclusion,Voltage deviation assessment,GB/T 12325-2008,the basic measurement time interval for supply voltage deviation 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 of qualified voltage,rate(,QVR,).,Background,Voltage sags,Deviations,Outlooks,Conclusion,Voltage deviation assessment,The problem of two-side assessment with percentiles,how is 5% time/location statistical values picked out form two-side deviations to obtain the 95% compatibility level ?,Background,Voltage sags,Deviations,Outlooks,Conclusion,Voltage deviation assessment,IEC method,the definitions of,overdeviation,and,underdeviation,are two independent parameters.,Problem:,if the CP95 value of voltage,overdeviation,complies with the limit 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?,Background,Voltage sags,Deviations,Outlooks,Conclusion,Voltage deviation assessment,An engineering method,Respectively picking out 5% from the statistical 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 .,Background,Voltage sags,Deviations,Outlooks,Conclusion,Voltage deviation assessment,Assessment index,Qualified rate, a core index, is 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.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Voltage deviation assessment,Interaction between DER (distributed generators / the integration of large scale new sources) and voltage deviation assessment,DER impacts the time/spatial distribution of voltage magnitude.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Voltage deviation assessment,Interaction,The selection of index impacts the penetration rate of DER,To determine how much DER can be accepted, a suitable performance indicator and an appropriate limit are needed.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Outlooks,It 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 or simulated data, in turns to promote the mitigation of power disturbances.,With 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,;,Background,Voltage sags,Deviations,Outlooks,Conclusion,Outlooks,With 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.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Power frequency,Flicker,Voltage sag,swell,Unbalance,Outlooks,From equipment sensitivity point of view, an equipment may be disturbed by one or more power disturbances at the same time. So it is needed to research the influence of many disturbances at the same time on the equipments. It is likely to generate new disturbance classification and evaluation.,Voltage magnitude,Background,Voltage sags,Deviations,Outlooks,Conclusion,Outlooks,Power quality monitoring assessment functions is possibly as a part of distributed intelligence in future smart distribution network. Data mining will be based on the assessment technique.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Outlooks,With the breakthrough of DC technologies, future power quality comprehensive mitigation system will also include MV DC distribution network. So in a MV DC system, it is necessary to define and assess its power quality.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Configuration of multiple power quality supply system in Sendai, Japan,DC Smart Grid,Conclusion,The inevitable increase in the complexity of the transmission and distribution system will produce challenges and exciting opportunities for research.,Researchers should not feel constrained by standards and they should dare to deviate from them when needed Math H. J.,Bollen,.,Background,Voltage sags,Deviations,Outlooks,Conclusion,Thank you,for your attention!,
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