ELECTRIC DISTRIBUTION SYSTEM RISK ASSESSMENT USING ACTUAL UTILITY RELIABILITY DATA A Thesis Submitted to the College of Graduate Studies and Research in Partial Fulfillment of the Requirements for the Degree of Master of Science in the Department of Electrical Engineering University of Saskatchewan Saskatoon. Saskatchewan, Canada By Zhe Feng © Copyright Zhe Feng, March 2006. All rights reserved. PERMISSION TO USE The author has agreed that the Library, University of Saskatchewan, may make this thesis freely available for inspection. Moreover, the author has agreed that permission for extensive copying of this thesis for scholarly purpose may be granted the professor or professors who supervised the thesis work recorded herein or, in their absence, by the Head of the Department or the Dean of the College in which the thesis work was done. It is understood that due recognition will be given to the author of this thesis and to the University of Saskatchewan in any use of the material in this thesis. Copying or publication or any other use of this thesis for financial gain without approval by the University of Saskatchewan and the author’s written permission is prohibited. Request for permission to copy or to make any other use of the material in this thesis in whole or part should be addressed to: Head of the Department of Electrical Engineering 57 Campus Drive University of Saskatchewan Saskatoon, Saskatchewan Canada S7N 5A9 i ABSTRACT This thesis describes the research conducted on the use of historical performance data in assessing the financial risk for a power distribution utility in a performance based regulation (PBR) regime. The historical utility data used in this research are taken from the Canadian Electrical Association (CEA) annual reports. The individual utility data in these reports are confidential and only provided to the participating utilities. Thirteen utilities that participate in the CEA data reporting activity agreed to provide their individual utility data for the research described in this thesis. These utilities are anonymous and are referred to by numerical designations in accordance with the CEA protocol. This research could not have been conducted without the support of these utilities. The objectives of the research described in this thesis are to examine and analyze the variations in the annual performance indices of the thirteen participating utilities and the aggregated systems including the overall indices and the cause code contributions, and to examine the possible utilization of historic utility reliability indices to create suitable reward/penalty structures in a PBR protocol. The potential financial risk and actual financial payment analyses for these selected utilities are conducted using their historical performance data imposed on a number of possible reward/penalty structures developed in this thesis. An approach to recognize adverse utility performance in the form of Major Outage Years (MOY) is developed and the influence of the MOY performance in PBR decision making is examined. ii ACKNOWLEDGEMENTS The author would like to express her sincere gratitude to her supervisor Dr. Roy Billinton for his invaluable guidance, encouragement and support during the course of this research work and in the preparation of this thesis. It was absolutely a wonderful opportunity and pleasant experience in lifetime working under Dr. Billinton’s supervision. The author would like to express her sincere thanks to the thirteen utilities and Canadian Electrical Association for providing the valuable information in the preparation of this thesis. Their support is thankfully acknowledged. The author would also like to extend her gratitude to her graduate study teachers, Professors S. O. Faried, R. Karki and N.A. Chowdhury for strengthening her knowledge in electrical engineering. The author would like to take this opportunity to acknowledge the constant encouragement and support from her parents, parents in law, and all friends throughout her studies in Canada. Special thanks go to her husband, Zhanyu Shen, for his support, understanding and encouragement. Financial assistance provided by the Natural Science and Engineering Research Council of Canada through a research grant to Dr. Billinton is gratefully acknowledged. iii TABLE OF CONTENTS PERMISSION TO USE………………………………………..…………….………...i ABSTRACT...………………………………………………………………….……...ii ACKNOWLEDGEMENTS…………………………………………………………..iii TABLE OF CONTENTS…………………………………………………………......iv LIST OF FIGURES......................................................................................................vii LIST OF TABLE............................................................................................................x ACRONYMS............................................................................................................xviii 1. INTRODUCTION....................................................................................................1 1.1 Electric Power System..........................................................................................1 1.2 Power System Reliability......................................................................................1 1.3 Power System Functional Zones and Hierarchical Levels...................................3 1.4 Distribution System Reliability............................................................................4 1.5 Performance Based Regulation (PBR)..................................................................6 1.6 Canadian Electricity Association..........................................................................7 1.7 Research Objectives and Outline of the Thesis....................................................8 2 . DISTRIBUTION SYSTEM RELIABILITY......................................................11 2.1 Power Distribution System Introduction............................................................11 2.2 Basic Distribution Systems Configuration..........................................................11 2.3 Distribution System Reliability Indices..............................................................14 2.3.1 Load Point Indices...........................................................................14 2.3.2 System Reliability Indices...............................................................14 2.4 Prediction and Performance Assessment............................................................17 2.5 Analytical and Simulation Methods....................................................................18 2.5.1 Analytical Methods..........................................................................18 2.5.2 An Example Utilizing the Analytical Method.................................20 2.5.3 Simulation Methods.........................................................................22 2.6 Canadian Service Continuity Data......................................................................24 iv 2.7 Summary.............................................................................................................26 3. INTERRUPTION CAUSE ANALYSIS BASED ON ACTUAL DATA.............27 3.1 Introduction.........................................................................................................27 3.2 CEA Interruption Cause Code Definition...........................................................27 3.3 Analysis of Interruption Causes..........................................................................29 3.3.1 Urban utilities: Utility 1-1 to 1-7.....................................................30 3.3.2 Integrated utilities: Utility 2-1 to 2-6...............................................38 3.3.3 Region systems................................................................................44 3.3.4 Canada System.................................................................................48 3.4 Summary.............................................................................................................51 4. RELIABILITY INDEX PROBABILITY DISTRIBUTIONS AND RISK NALYSIS USING R/PS.....................................................................53 4.1 Introduction.........................................................................................................53 4.2 Reliability Index Distributions............................................................................54 4.3 Reward/Penalty Structure...................................................................................56 4.4 Risk Analysis Using a R/PS................................................................................57 4.5 SAIFI and SAIDI distributions based on five year performances......................60 4.6 Utility Risk Assessment......................................................................................64 4.6.1 Introduction to risk assessment........................................................64 4.6.2 Case study of R/PS using different year data bases.........................66 4.7 Analysis of the R/PS for Three Hypothetical Dead Zone Widths......................70 4.7.1 Analysis of Utility 1-3.....................................................................70 4.7.2 Analysis of Utility 2-3.....................................................................73 4.8 Analysis of Different Slopes of R/PS.................................................................75 4.9 Analysis of Different Slopes of R/PS on the Actual Payment............................78 4.10 Summary..............................................................................................................80 5. MAJOR OUTAGE YEAR ANALYSIS................................................................82 5.1 Introduction.........................................................................................................82 5.2 Major Event Day (MED)....................................................................................83 5.3 Classification of Major Outage Years (MOY)....................................................84 v 5.3.1 Analysis of Utility 1-3.....................................................................85 5.3.2 Analysis of Utility 2-3.....................................................................88 5.4 Major Outage Year Analysis for 2004.................................................................91 5.5 Major Outage Year Analysis for 2003.................................................................97 5.6 Summary...........................................................................................................103 6. FINANCIAL RISK ASSESSMENT EXCLUDING MAJOR OUTAGE YEAR AND LOSS OF SUPPLY.........................................................................105 6.1 Introduction.......................................................................................................105 6.2 Financial Risk Assessment Including and Excluding Major Outage Years......106 6.3 2004 Actual Payment Including and Excluding Major Outage Year................108 6.4 Financial Risk Assessment Including and Excluding Loss of Supply..............109 6.5 2004 Actual Payment Including and Excluding Loss of Supply......................111 6.6 Summary...........................................................................................................113 7. SUMMARY AND CONCLUSIONS...................................................................114 REFERENCE...………………………………………………………..…………....121 Appendix 1. System Financial Risks Using Different Year Based R/PS...................124 Appendix 2. The Actual Financial Payment for 2004 Using the Three R/PS Slopes..........................................................................................133 Appendix 3. Major Outage Year Analysis.................................................................137 Appendix 4. Major Outage Year Analysis for 2004...................................................171 Appendix 5. Major Outage Year Analysis for 2003...................................................187 Appendix 6. Comparison of the Financial Risks Including and Excluding MOY....205 Appendix 7. The Actual Payment for 2004 Excluding MOY....................................207 Appendix 8. Comparison of Financial Risk Including and Excluding Loss of Supply.......................................................................................209 Appendix 9. 2004 Actual Financial Payment Excluding Loss of Supply..................213 vi LIST OF FIGURES Figure1.1- Subdivision of system reliability 2 Figure1.2- Hierarchical levels in a power system 3 Figure 2.1- An overall electric power system and its subsystems 12 Figure.2.2- A radial distribution system 13 Figure 2.3- A primary loop distribution system 13 Figure 2.4- Feeder 1 at Bus 6 in the RBTS 20 Figure 2.5- SAIFI and SAIDI probability distribution for Bus 6, RBTS [21] 23 Figure 2.6- Annual SAIFI and SAIDI of Canada from 1991-2004 25 Figure 2.7- SAIFI and SAIDI probability distributions for Canada 25 Figure 3.1- Major cause contributions to the SAIFI for Utility 1-1 30 Figure 3.2- Major cause contributions to the SAIDI for Utility 1-1 31 Figure 3.3- Major cause contributions to the SAIFI for Utility 1-2 32 Figure 3.4- Major cause contributions to the SAIDI for Utility 1-2 32 Figure 3.5- Major cause contributions to the SAIFI for Utility 1-3 33 Figure 3.6- Major cause contributions to the SAIDI for Utility 1-3 33 Figure 3.7- Major cause contributions to the SAIFI for Utility 1-4 34 Figure 3.8- Major cause contributions to the SAIDI for Utility 1-4 34 Figure 3.9- Major cause contributions to the SAIFI for Utility 1-5 35 Figure 3.10 Major cause contributions to the SAIDI for Utility 1-5 35 Figure 3.11 Major cause contributions to the SAIFI for Utility 1-6 36 Figure 3.12 Major cause contributions to the SAIDI for Utility 1-6 36 Figure 3.13 Major cause contributions to the SAIFI for Utility 1-7 37 Figure 3.14 Major cause contributions to the SAIDI for Utility 1-7 38 Figure 3.15 Major cause contributions to the SAIFI for Utility 2-1 38 Figure 3.16 Major cause contributions to the SAIFI for Utility 2-1 38 Figure 3.17 Major cause contributions to the SAIFI for Utility 2-2 39 Figure 3.18 Major cause contributions to the SAIDI for Utility 2-2 39 Figure 3.19 Major cause contributions to the SAIFI for Utility 2-3 40 vii Figure 3.19 Major cause contributions to the SAIDI for Utility 2-3 41 Figure 3.21 Major cause contributions to the SAIFI for Utility 2-4 41 Figure 3.22 Major cause contributions to the SAIDI for Utility 2-4 42 Figure 3.23 Major cause contributions to the SAIFI of Utility 2-5 42 Figure 3.24 Major cause contributions to the SAIDI for Utility 2-5 43 Figure 3.25 Major cause contributions to the SAIFI for Utility 2-6 43 Figure 3.26 Major cause contributions to the SAIDI for Utility 2-6 44 Figure 3.27 Major cause contributions to the SAIFI for System Region 1 45 Figure 3.28 Major cause contributions to the SAIDI for System Region 1 45 Figure 3.29 Major cause contributions to the SAIFI for System Region 2 46 Figure 3.30 Major cause contributions to the SAIDI for System Region 2 47 Figure 3.31 Major cause contributions to the SAIFI for System Region T 47 Figure 3.32 Major cause contributions to the SAIDI for System Region T 48 Figure 3.33 Major cause contributions to the SAIFI for the Canada system 49 Figure 3.34 Major cause contributions to the SAIDI for the Canada system 49 Figure 3.35 Major cause contributions to the SAIFI for the Canada system 50 Figure 3.36 Major cause contributions to the SAIDI for the Canada system 50 Figure 4.1- Index distributions for Utility 1-3 55 Figure 4.2- Index distributions for Utility 2-3 55 Figure 4.3- A general reward/penalty structure 56 Figure 4.4- Combined SAIFI and SAIDI histograms and hypothetical reward/ penalty structures (U1-3) 59 Figure 4.5- Combination of the SAIFI and SAIDI histograms and hypothetical reward/penalty structures (U2-3) 59 Figure 4.6- The reward/penalty structure without a dead zone 60 Figure 4.7 - SAIFI and SAIDI distributions for the thirteen utilities 61 Figure 4.7- SAIFI and SAIDI distributions for the thirteen utilities (Continued) 63 Figure 4.8- The hypothetical Reward /Penalty Structure 65 Figure 4.9- Different R/PS with the SAIDI distribution for Utility 1-3. 67 Figure 4.10 Three hypothetical dead zone widths on the SAIFI distribution for U1-3 70 viii Figure 4.11 Three hypothetical dead zone widths on the SAIDI distribution for U1-3 72 Figure 4.12 Three hypothetical dead zone widths on the SAIFI distribution for U2-3 73 Figure 4.13 Three hypothetical dead zone widths on the SAIDI distribution for U2-3 74 Figure 4.14 Three possible boundary slopes in an R/PS 76 Figure 4.15 Three boundary slopes in a SAIFI R/PS 76 ix