WILEY A JOHN WILEY & SONS, INC., PUBLICATION

Transcription

1 POWER DISTRIBUTION SYSTEM RELIABILITY Practical Methods and Applications Ali A. Chowdhury Don O. Koval IEEE PRESS SERIES ON POWER ENGINEERING IEEE Press WILEY A JOHN WILEY & SONS, INC., PUBLICATION

2 Preface xix 1 OUTLINE OF THE BOOK Introduction Reliability Assessment of Power Systems Generation System Reliability Assessment Transmission System Reliability Assessment Distribution System Reliability Assessment Organization of the Chapters Conclusions 10 References 11 2 FUNDAMENTALS OF PROBABILITY AND STATISTICS Concept of Frequency Introduction Concept of Class Frequency Graphs Cumulative Frequency Distribution Model Important Parameters of Frequency Distribution Mean Median Mode Standard Deviation Variance Theory of Probability Concept Probability Laws and Theorems Probability Distribution Model Random Variable Probability Density Function 20

3 Vlil Parameters of Probability Distributions The Binomial Distribution The Poisson Distribution The Exponential Distribution The Normal Distribution Sampling Theory Concepts of Population and Sample Random Sampling Model Sampling Distributions Concept of Confidence Limit Estimation of Population Statistic Computation of Sample Size Statistical Decision Making Procedure of Decision Making Types of Error Control of Errors Conclusions 42 References 42 RELIABILITY PRINCIPLES Failure Rate Model Concept and Model Concept of Bathtub Curve Concept of Reliability of Population Theory of First Principles Reliability Model The Poisson Probability Distribution Reliability of Equal Time Steps Mean Time to Failures Reliability of Complex Systems Series Systems Parallel Systems Partially Redundant Systems Bayes' Theorem Standby System Modeling Background Spares for One Unit Spares for Multiple Interchangeable Units 63

4 ix 3.6 Concepts of Availability and Dependability Mean Time to Repair Availability Model Markov Model Concept of Dependability Design Considerations Reliability Measurement Concept Accuracy of Observed Data Confidence Limit of Failure Rate Chi-Square Distribution Conclusions 77 References 77 4 APPLICATIONS OF SIMPLE RELIABILITY MODELS Equipment Failure Mechanism Introduction Utilization of Forced Outage Statistics Failure Rate Computation Availability of Equipment Availability Considerations and Requirements Availability Model Long-Run Availability Oil Circuit Recloser (OCR) Maintenance Issues Introduction Study Methods Distribution Pole Maintenance Practices Procedures for Ground Testing Concept Statistical Methods For Ground Testing Insulators Maintenance Background Inspection Program for Insulators Voltage Surges On Lines Critical Flashover Number of Insulators in a String Customer Service Outages Background 93

5 4.7.2 Popular Distribution Reliability Indices Reliability Criteria Cost of Interruption Concept Conclusions 95 References 96 ENGINEERING ECONOMICS Introduction Concept of Interest and Equivalent Common Terms Formulas for Computing Interest Annual Cost Concept of Annual Cost Alternatives with Different Life Times Present Value (PV) Concept Theory of Rate of Return Cost-Benefit Analysis Approach Financial Risk Assessment Basic Concept Principles Concept of Risk Aversion Conclusions 108 References 109 RELIABILITY ANALYSIS OF COMPLEX NETWORK CONFIGURATIONS Introduction State Enumeration Methodologies Basic Assumptions: Criteria for System Success Power is Delivered to All Loads Network Reduction Methods Path Enumeration Methods: Minimum Tie Set Path Enumeration Methods: Minimum Cut Set Bayes' Theorem in Reliability Construction of Fault Tree Diagram Basic Rules for Combining the Probability of Independent Input Failure Events to Evaluate the Probability of a Single-Output Failure Event 140

6 6.6 The Application of Conditional Probability Theory to System Operating Configurations Conclusions 151 References 151 DESIGNING RELIABILITY INTO INDUSTRIALAND COMMERCIAL POWER SYSTEMS Introduction Example 1: Simple Radial Distribution System Description of a Simple Radial System Results: Simple Radial System Example Conclusions: Simple Radial System Example Example 2: Reliability Analysis of a Primary Selective System to the 13.8 kv Utility Supply Description: Primary Selective System to the 13.8 kv Utility Supply Results: A Primary Selective System to the 13.8 kv Utility Supply Conclusions: Primary Selective System to 13.8 kv Utility Supply Example 3: A Primary Selective System to the Load Side of a 13.8 kv Circuit Breaker Description of a Primary Selective System to the Load Side of a 13.8 kv Circuit Breaker Results: Primary Selective System to Load Side of 13.8 kv Circuit Breaker Conclusions: A Primary Selective System to the Load Side of a 13.8 kv Circuit Breaker Example 4: Primary Selective System to the Primary of the Transformer Description of a Primary Selective System to the Primary of the Transformer Results: A Primary Selective System to the Primary of the Transformer Conclusions: Primary Selective system to Primary of Transformer Example 5: A Secondary Selective System Description of a Secondary Selective System Results: A Secondary Selective System Conclusions: A Secondary Selective System 165

7 XII 7.7 Example 6: A Simple Radial System with Spares Description of a Simple Radial System with Spares Results: A Simple Radial System with Spares Conclusions: Simple Radial System with Spares Example 7: A Simple Radial System with Cogeneration Description of a Simple Radial System with Cogeneration Results: Simple Radial System with Cogeneration Conclusions: A Simple Radial System with Cogeneration Reliability Evaluation of Miscellaneous System Configurations Conclusions 188 References ZONE BRANCH RELIABILITY METHODOLOGY Introduction Zone Branch Concepts Industrial System Study Application of Zone Branch Methodology: Case Studies Case 1: Design "A" Simple Radial Substation Configuration Case 2: Design "B" Dual Supply Radial Single Bus Case 3: Design "C" Dual Supply Radial with Tiebreaker Case 4: Design "D" Dual Supply Loop with Tiebreaker Case 5: Design "E" Dual Supply Primary Selective Case 6: Design "F" Double Bus/Double Breaker Radial Case 7: Design "G" Double Bus/Double Breaker Loop Case 8: Design "H" Double Bus/Breaker Primary Selective Conclusions 251 References EQUIPMENT OUTAGE STATISTICS Introduction Interruption Data Collection Scheme Typical Distribution Equipment Outage Statistics Conclusions 265 References HISTORICAL ASSESSMENT Introduction Automatic Outage Management System Definitions of Terms and Performance Indices 269

8 XIII Customer-Oriented Indices Classification of Interruption as to Causes Historical Assessment A Utility Corporate Level Analysis Utility Region-Level Analysis Crew Center-Level Analysis Development of a Composite Index for Reliability Performance Analysis at the Circuit Level Conclusions 283 References DETERMINISTIC CRITERIA Introduction Current Distribution Planning and Design Criteria Outage Data Collection and Reporting Reliability Indices Targets for Customer Service Reliability Examples of Distribution Reliability Standards in a Deregulated Market Reliability Cost Versus Reliability Benefit Trade-Offs in Distribution System Planning Alternative Feed Requirements for Overhead Distribution Systems Examples of Deterministic Planning Guidelines for Alternative Feed Requirements Reliability of Supply to 25 kv Buses Reliability of Supply to Towns/Cities Reliability of Supply to Large Users and Industrial Customers Value-Based Alternative Feeder Requirements Planning Customer Interruption Cost Data An Illustrative Example for Justification of an Alternate Feed to a Major City Conclusions 299 References IMPORTANT FACTORS RELATED TO DISTRIBUTION STANDARDS Introduction Relevant Issues and Factors in Establishing Distribution Reliability Standards 304

9 xiv Data Pool Definitions of Terms System Characteristics Outage Data Collection Systems Performance Indices at Different System Levels of a Utility Performance Indices for Different Utility Types Conclusions 314 References STANDARDS FOR REREGULATED DISTRIBUTION UTILITY Introduction Cost of Service Regulation versus Performance-Based Regulation A Reward/Penalty Stracture in the Performance-Based Rates Historical SAIFI and SAIDI Data and their Distributions Computation of System Risks Based on Historical Reliability Indices Cause Contributions to SAIFI and SAIDI Indices Conclusions 334 References CUSTOMER INTERRUPTION COST MODELS FOR LOAD POINT RELIABILITY ASSESSMENT Introduction Customer Interruption Cost Series and Parallel System Model Equations Dedicated Distribution Radial Feeder Configuration Distribution Radial Feeder Configuration Serving Multiple Customers Distribution Radial Feeder Configuration Serving Multiple Customers with Manual Sectionalizing Distribution Radial Feeder Configuration Serving Multiple Customers with Automatic Sectionalizing Distribution System Looped Radial Feeders Operating Procedures Feeder Characteristics: Looped Radial Feeders Manual Sectionalizing Conclusions 355 References 355

10 XV 15 VALUE-BASED PREDICTIVE RELIABILITY ASSESSMENT Introduction Value-Based Reliability Planning Distribution System Configuration Characteristics Case Studies Illustrative Example System Problem and Its Reliability Calculations Operating Procedures Conclusions 373 References ISOLATION AND RESTORATION PROCEDURES Introduction Distribution System Characteristics Distribution Load Transfer Characteristics Operating Procedures: Line Section Outages Feeder Circuit Reliability Data Cost of Load Point Interruptions Case Studies Case Study Case Study Case Study Major Substation Outages Summary of Load Point Interruption Costs Conclusions 392 References MESHED DISTRIBUTION SYSTEM RELIABILITY Introduction Value-Based Reliability Assessment in a Deregulated Environment The Characteristics of the Illustrative Urban Distribution System Discussion of Results Feeder and Transformer Loading Levels Bus and Feeder Tie Analysis Tie Costs and Descriptions Maintenance Single Transformer Conductor Sizing 403

11 XVI 17.8 Feeders with Nonfused (Lateral) Three-Phase Branches Feeder Tie Placement Finding Optimum Section Length Definition of Terms Feeder and Transformer Loading Feeder Tie Cost Calculation Effects of Tie Maintenance Additional Ties for Feeders with Three-Phase Branches Definition of Terms Conclusions 413 References RADIAL FEEDER RECONFIGURATION ANALYSIS Introduction Predictive Feeder Reliability Analysis Reliability Data and Assumptions Reliability Assessment for an Illustrative Distribution Feeder Base Case Circuit Description Circuit Tie Circuit Tie Circuit Tie Circuit Tie Base Case Reliability Alternative Improvement Options Analysis Incremental Improvement Alternative 1: Add Distribution Automation Switch Incremental Improvement Alternative 2: Add Sectionalizing Switch Incremental Alternative 3: Relocate Recloser Incremental Improvement Alternative 4: Place 2 New Switches Summary of the Illustrative Feeder Reliability Performance Improvement Alternatives Conclusions 426 References DISTRIBUTED GENERATION Introduction Problem Definition 428

12 xvii 19.3 Illustrative Distribution System Configuration Characteristics Reliability Assessment Model Reliability Indices Reliability Data Discussion of Results Equivalent Distributed Generation Reinforcement Alternative Conclusions 438 References MODELS FOR SPARE EQUIPMENT Introduction Development of Probabilistic Models for Determining Optimal Number of Transformer Spares Reliability Criterion Model for Determining the Optimal Number of Transformer Spares Mean Time Between Failures (MTBFJ Criterion Model for Determining the Optimal Number of Transformer Spares Determination of Optimal Transformer Spares Based on the Model of Statistical Economics Optimal Transformer Spares for Illustrative 72 kv Distribution Transformer Systems Determination of Optimal Transformer Spares Based on the Minimum Reliability Criterion Determination of Optimal Transformer Spares Based on the Minimum MTBF U Criterion Determination of Optimal Transformer Spares Based on the Criterion of Statistical Economics Conclusions 450 References VOLTAGE SAGS AND SURGES AT INDUSTRIAL AND COMMERCIAL SITES Introduction ANSI/IEEE Standard 446 IEEE Orange Book Typical Range for Input Power Quality and Load Parameters of Major Computer Manufacturers Typical Design Goals of Power Conscious Computer Manufacturers (Often Called the CBEMA Curve) IEEE Standard IEEE Gold Book Background 455

13 XVIII Case Study: Radial Distribution System Frequency of Voltage Sags Industrial Customer Group Commercial Customer Group Example Voltage Sag Problem: Voltage Sag Analysis of Utility and Industrial Distribution Systems Utility Distribution Systems Industrial Distribution System Frequency and Duration of Voltage Sags and Surges at Industrial Sites: Canadian National Power Quality Survey Background Voltage Sags and Surges (Time of Day) Voltage Sags and Surges (Day of Week) Frequency of Disturbances Monitored on Primary and Secondary Sides of Industrial Sites Scatter Plots of Voltage Sag Levels as a Function of Duration Scatter Plots of Voltage Surge Levels as a Function of Duration Primary and Secondary Voltage Sages Statistical Characteristics Primary and Secondary Voltage Surges Statistical Characteristics Conclusions 486 References 486 SELECTED PROBLEMS AND ANSWERS 489 Problem Set for Chapters 2 and Answers to Problem Set for Chapters 2 and Problem Set for Chapter Answers to Problem Set for Chapter Problem Set for Chapter Answers to Problem Set for Chapter Problem Set for Chapter Answers to Problem Set for Chapter Problem Set for Chapter Answers to Problem Set for Chapter Problem Set for Chapter Answers to Problem Set for Chapter Problem Set for Chapter Answers to Problem Set for Chapter Index 519