Power Distribution System Reliability

ALI A. CHOWDHURY, PhD, FIEEE, is Director of Regional Transmission for the California Independent System Operator. He has nearly thirty years of experience in teaching, research and development, electric utility industry, electric equipment manufacturing, and consulting in power system reliability and security assessments. DON O. KOVAL, PhD, FIEEE, is a Professor in the Department of Electrical and Computer Engineering at the University of Alberta, Canada. Previously, he worked as a distribution special studies engineer for B.C. Hydro and Power Authority in Vancouver and as a subtransmission design engineer for Saskatchewan Power.

“Using numerous examples and case studies, they thoroughly describe the determination of failure rates and associated outage timing for various systems including the radial, primary selective, and secondary selective versions.”  (Electrical Apparatus, 1 August 2012)

• Preface. 1 OUTLINE OF THE BOOK.1.1 Introduction.1.2 Reliability Assessment of Power Systems.1.3 Organization of the Chapters.1.4 Conclusions.References.2 FUNDAMENTALS OF PROBABILITY AND STATISTICS.2.1 Concept of Frequency.2.2 Important Parameters of Frequency Distribution.2.3 Theory of Probability.2.4 Probability Distribution Model.2.5 Sampling Theory.2.6 Statistical Decision Making.2.7 Conclusions.References.3 RELIABILITY PRINCIPLES.3.1 Failure Rate Model.3.2 Concept of Reliability of Population.3.3 Mean Time to Failures.3.4 Reliability of Complex Systems.3.5 Standby System Modeling.3.6 Concepts of Availability and Dependability.3.7 Reliability Measurement.3.8 Conclusions.References.4 APPLICATIONS OF SIMPLE RELIABILITY MODELS.4.1 Equipment Failure Mechanism.4.2 Availability of Equipment.4.3 Oil Circuit Recloser (OCR) Maintenance Issues.4.4 Distribution Pole Maintenance Practices.4.5 Procedures for Ground Testing.4.6 Insulators Maintenance.4.7 Customer Service Outages.4.8 Conclusions.References.5 ENGINEERING ECONOMICS.5.1 Introduction.5.2 Concept of Interest and Equivalent.5.3 Common Terms.5.4 Formulas for Computing Interest.5.5 Annual Cost.5.6 Present Value (PV) Concept.5.7 Theory of Rate of Return.5.8 Cost–Benefit Analysis Approach.5.9 Financial Risk Assessment.5.10 Conclusions.References.6 RELIABILITY ANALYSIS OF COMPLEX NETWORK CONFIGURATIONS.6.1 Introduction.6.2 State Enumeration Methodologies.6.3 Network Reduction Methods.6.4 Bayes. Theorem in Reliability.6.5 Construction of Fault Tree Diagram.6.6 The Application of Conditional Probability Theory to System Operating Configurations.6.7 Conclusions.References.7 DESIGNING RELIABILITY INTO INDUSTRIAL AND COMMERCIAL POWER SYSTEMS.7.1 Introduction.7.2 Example 1: Simple Radial Distribution System.7.3 Example 2: Reliability Analysis of a Primary Selective System to the 13.8 kV Utility Supply.7.4 Example 3: A Primary Selective System to the Load Side of a 13.8 kV Circuit Breaker.7.5 Example 4: Primary Selective System to the Primary of the Transformer.7.6 Example 5: A Secondary Selective System.7.7 Example 6: A Simple Radial System with Spares.7.8 Example 7: A Simple Radial System with Cogeneration.7.9 Reliability Evaluation of Miscellaneous System Configurations.7.10 Conclusions.References.8 ZONE BRANCH RELIABILITY METHODOLOGY.8.1 Introduction.8.2 Zone Branch Concepts.8.3 Industrial System Study.8.4 Application of Zone Branch Methodology: Case Studies..4.5 Case 5: Design .E.—Dual Supply Primary Selective.8.4.6 Case 6: Design .F.—Double Bus/Double Breaker Radial.8.4.7 Case 7: Design .G.—Double Bus/Double Breaker Loop.8.4.8 Case 8: Design .H.—Double Bus/Breaker Primary Selective.8.5 Conclusions.References.9 EQUIPMENT OUTAGE STATISTICS.9.1 Introduction.9.2 Interruption Data Collection Scheme.9.3 Typical Distribution Equipment Outage Statistics.9.4 Conclusions.References.10 HISTORICAL ASSESSMENT.10.1 Introduction.10.2 Automatic Outage Management System.10.3 Historical Assessment.10.4 Crew Center-Level Analysis.10.5 Development of a Composite Index for Reliability Performance Analysis at the Circuit Level.10.6 Conclusions.References.11 DETERMINISTIC CRITERIA.11.1 Introduction.11.2 Current Distribution Planning and Design Criteria.11.3 Reliability Cost Versus Reliability Benefit Trade-Offs in Distribution System Planning.11.4 Alternative Feed Requirements for Overhead Distribution Systems.11.5 Examples of Deterministic Planning Guidelines for Alternative Feed Requirements.11.6 Value-Based Alternative Feeder Requirements Planning.11.7 Conclusions.References.12 IMPORTANT FACTORS RELATED TO DISTRIBUTION STANDARDS.12.1 Introduction.12.2 Relevant Issues and Factors in Establishing Distribution Reliability Standards.12.3 Performance Indices at Different System Levels of a Utility.12.4 Performance Indices for Different Utility Types.12.5 Conclusions.References.13 STANDARDS FOR REREGULATED DISTRIBUTION UTILITY.13.1 Introduction.13.2 Cost of Service Regulation versus Performance-Based Regulation.13.3 A Reward/Penalty Structure in the Performance-Based Rates.13.4 Historical SAIFI and SAIDI Data and their Distributions.13.5 Computation of System Risks Based on Historical Reliability Indices.13.6 Cause Contributions to SAIFI and SAIDI Indices.13.7 Conclusions.References.14 CUSTOMER INTERRUPTION COST MODELS FOR LOAD POINT RELIABILITY ASSESSMENT.14.1 Introduction.14.2 Customer Interruption Cost.14.3 Series and Parallel System Model Equations.14.4 Dedicated Distribution Radial Feeder Configuration.14.5 Distribution Radial Feeder Configuration Serving Multiple Customers.14.6 Distribution Radial Feeder Configuration Serving Multiple Customers with Manual Sectionalizing.14.7 Distribution Radial Feeder Configuration Serving Multiple Customers with Automatic Sectionalizing.14.8 Distribution System Looped Radial Feeders.14.9 Conclusions.References.15 VALUE-BASED PREDICTIVE RELIABILITY ASSESSMENT.15.1 Introduction.15.2 Value-Based Reliability Planning.15.3 Distribution System Configuration Characteristics.15.4 Case Studies.15.5 Illustrative Example System Problem and Its Reliability Calculations.15.6 Conclusions.References.16 ISOLATION AND RESTORATION PROCEDURES.16.1 Introduction.16.2 Distribution System Characteristics.16.3 Case Studies.16.4 Major Substation Outages.16.5 Summary of Load Point Interruption Costs.16.6 Conclusions.References.17 MESHED DISTRIBUTION SYSTEM RELIABILITY.17.1 Introduction.17.2 Value-Based Reliability Assessment in a Deregulated Environment.17.3 The Characteristics of the Illustrative Urban Distribution System.17.4 Discussion of Results.17.5 Feeder and Transformer Loading Levels.17.6 Bus and Feeder Tie Analysis.17.7 Maintenance.17.8 Feeders with Nonfused (Lateral) Three-Phase Branches.17.9 Feeder Tie Placement.17.10 Finding Optimum Section Length.17.11 Feeder and Transformer Loading.17.12 Feeder Tie Cost Calculation.17.13 Effects of Tie Maintenance.17.14 Additional Ties for Feeders with Three-Phase Branches.17.15 Conclusions.References.18 RADIAL FEEDER RECONFIGURATION ANALYSIS.18.1 Introduction.18.2 Predictive Feeder Reliability Analysis.18.3 Reliability Data and Assumptions.18.4 Reliability Assessment for an Illustrative Distribution Feeder.18.5 Alternative Improvement Options Analysis.18.6 Summary of the Illustrative Feeder Reliability Performance Improvement Alternatives.18.7 Conclusions.References.19 DISTRIBUTED GENERATION.19.1 Introduction.19.2 Problem Definition.19.3 Illustrative Distribution System Configuration Characteristics.19.4 Reliability Assessment Model.19.5 Discussion of Results.19.6 Conclusions.References.20 MODELS FOR SPARE EQUIPMENT.20.1 Introduction.20.2 Development of Probabilistic Models for Determining Optimal Number of Transformer Spares.20.3 Optimal Transformer Spares for Illustrative 72 kV Distribution Transformer Systems.20.4 Conclusions.References.21 VOLTAGE SAGS AND SURGES AT INDUSTRIAL AND COMMERCIAL SITES.21.1 Introduction.21.2 ANSI/IEEE Standard 446—IEEE Orange Book.21.3 IEEE Standard 493-2007—IEEE Gold Book.21.4 Frequency of Voltage Sags.21.5 Example Voltage Sag Problem: Voltage Sag Analysis of Utility and Industrial Distribution Systems.21.6 Frequency and Duration of Voltage Sags and Surges at Industrial Sites: Canadian National Power Quality Survey.21.7 Scatter Plots of Voltage Sag Levels as a Function of Duration.21.8 Scatter Plots of Voltage Surge Levels as a Function of Duration.21.9 Primary and Secondary Voltage Sages Statistical Characteristics.21.10 Primary and Secondary Voltage Surges Statistical Characteristics.21.11 Conclusions.References.SELECTED PROBLEMS AND ANSWERS.Index.