Distribution System Modeling and Analysis with MATLAB® and WindMil®

Description

This Fifth Edition includes new sections on electric vehicle loads and the impact they have on voltage drop and transformers in distribution systems. A new and improved tape-shield cable model has been developed to produce more accurate impedance modeling of underground cables. In addition, the book uses state-of-the-art software, including the power distribution simulation software Milsoft WindMil® and programming language Mathworks MATLAB®. MATLAB scripts have been developed for all examples in the text, in addition to new MATLAB-based problems at the end of the chapters. This book illustrates methods that ensure the most accurate results in computational modeling for electric power distribution systems. It clearly explains the principles and mathematics behind system models and discusses the smart grid concept and its special benefits. Including numerous models of components and several practical examples, the chapters demonstrate how engineers can apply and customize computer programs to help them plan and operate systems. The book also covers approximation methods to help users interpret computer program results and includes references and assignments that help users apply MATLAB and WindMil programs to put their new learning into practice. Cover Half Title Title Page Copyright Page Table of Contents Preface Acknowledgments Authors Chapter 1: Introduction to Distribution Systems 1.1 The Distribution System 1.2 Distribution Substations 1.3 Radial Feeders 1.4 Distribution Feeder Map 1.5 Distribution Feeder Electrical Characteristics 1.6 Summary References Chapter 2: The Nature of Loads 2.1 Definitions 2.2 Individual Customer Load 2.2.1 Demand 2.2.2 Maximum Demand 2.2.3 Average Demand 2.2.4 Load Factor 2.3 Distribution Transformer Loading 2.3.1 Diversified Demand 2.3.2 Maximum Diversified Demand 2.3.3 Load Duration Curve 2.3.4 Maximum Non-coincident Demand 2.3.5 Diversity Factor 2.3.6 Demand Factor 2.3.7 Utilization Factor 2.3.8 Load Diversity 2.4 Feeder Load 2.4.1 Load Allocation 2.4.1.1 Application of Diversity Factors 2.4.1.2 Load Survey 2.4.1.3 Transformer Load Management 2.4.1.4 Metered Feeder Maximum Demand 2.4.1.5 What Method to Use? 2.4.2 Voltage Drop Calculations Using Allocated Loads 2.4.2.1 Application of Diversity Factors 2.4.2.2 Load Allocation Based Upon Transformer Ratings 2.5 Individual Customer Loads with Electric Vehicles 2.6 Summary Problems References Chapter 3: Balanced System Method of Analysis 3.1 Line Impedance 3.2 Voltage Drop 3.3 The LIT 3.3.1 Linear Network 3.3.2 Non-linear Network 3.4 Summary Problems References Chapter 4: Series Impedance of Overhead and Underground lines 4.1 Series Impedance of Overhead Lines 4.1.1 Transposed and Balanced Three-Phase Lines 4.1.2 Untransposed Distribution Lines 4.1.3 Carson’s Equations 4.1.4 Modified Carson’s Equations 4.1.5 Primitive Impedance Matrix for Overhead Lines 4.1.6 Phase Impedance of Matrix for Overhead Lines 4.1.7 Parallel Overhead Distribution Lines 4.2 Series Impedance of Underground Lines 4.2.1 Concentric Neutral Cable 4.2.2 Tape Shielded Cables 4.2.3 Parallel Underground Distribution Lines 4.3 Summary Problems WindMil Assignment References Chapter 5: Shunt Admittance of Overhead and Underground Lines 5.1 General Voltage Drop Equation 5.2 Overhead Lines 5.2.1 The Shunt Admittance of Overhead Parallel Lines 5.3 Concentric Neutral Cable Underground Lines 5.4 Tape Shielded Cable Underground Lines 5.5 The Shunt Admittance of Parallel Underground Lines 5.6 Summary Problems WindMil Assignment References Chapter 6: Distribution System Line Models 6.1 Exact Line Segment Model 6.2 The Modified Line Model 6.2.1 The Three-Wire Line 6.2.2 The Computation of Neutral and Ground Currents 6.3 Source Impedances 6.4 The LIT 6.5 The General Matrices for Parallel Lines 6.5.1 Physically Parallel Lines 6.5.2 Electrically Parallel Lines 6.6 Summary Problems WindMil Assignment References Chapter 7: Voltage Regulation 7.1 Standard Voltage Ratings 7.2 Two-Winding Transformer Theory 7.3 Two-Winding Autotransformer 7.3.1 Autotransformer Ratings 7.3.2 Per-Unit Impedance 7.4 Step-Voltage Regulators 7.4.1 Single-Phase, Step-Voltage Regulators 7.4.1.1 Type A Step-Voltage Regulator 7.4.1.2 Type B Step-Voltage Regulator 7.4.1.3 Generalized Constants 7.4.1.4 The Line-Drop Compensator 7.4.2 Three-Phase, Step-Voltage Regulators 7.4.2.1 Wye-Connected Regulators 7.4.2.2 Closed Delta-Connected Regulators 7.4.2.3 Open Delta-Connected Regulators 7.5 Summary Problems Windmil Assignment: References Chapter 8: Three-Phase Transformer Models 8.1 Introduction 8.2 Generalized Matrices 8.3 The Delta-Grounded Wye Step-Down Connection 8.3.1 Voltages 8.3.2 Currents 8.4 The Delta-Grounded Wye Step-Up Connection 8.5 The Ungrounded Wye-Delta Step-Down Connection 8.6 The Ungrounded Wye-Delta Step-Up Connection 8.7 The Grounded Wye-Delta Step-Down Connection 8.8 Open Wye – Open Delta 8.9 The Grounded Wye – Grounded Wye Connection 8.10 The Delta – Delta Connection 8.11 Open Delta – Open Delta 8.12 Thevenin Equivalent Circuit 8.13 Summary Problems WindMil Assignment Chapter 9: Load Models 9.1 Wye-Connected Loads 9.1.1 Constant Real and Reactive Power Loads 9.1.2 Constant Impedance Loads 9.1.3 Constant Current Loads 9.1.4 Combination Loads 9.2 Delta-Connected Loads 9.2.1 Constant Real and Reactive Power Loads 9.2.2 Constant Impedance Loads 9.2.3 Constant Current Loads 9.2.4 Combination Loads 9.2.5 Line Currents Serving a Delta-Connected Load 9.3 Two-Phase and Single-Phase Loads 9.4 Shunt Capacitors 9.4.1 Wye-Connected Capacitor Bank 9.4.2 Delta-Connected Capacitor Bank 9.5 Three-Phase Induction Machine 9.5.1 Induction Machine Model 9.5.2 Symmetrical Component Analysis of a Motor 9.5.3 Phase Analysis of an Induction Motor 9.5.4 Voltage and Current Unbalance 9.5.5 Motor Starting Current 9.5.6 The Equivalent T Circuit 9.5.7 Computation of Slip 9.5.8 Induction Generator 9.5.9 Induction Machine Thevenin Equivalent Circuit 9.5.10 The Ungrounded Wye – Delta Transformer Bank with an Induction Motor 9.6 Electric Vehicle (EV) Chargers 9.7 Summary Problems References Chapter 10: Distribution Feeder Analysis 10.1 Power-Flow Analysis 10.1.1 General Feeder 10.1.2 Uniformly Distributed Loads 10.1.3 Series Feeder 10.1.4 The Unbalanced Three-Phase Distribution Feeder 10.1.4.1 Shunt Components 10.1.5 Applying the Iterative Technique 10.1.6 Let's Put It All Together 10.1.7 Load Allocation 10.1.8 Loop Flow 10.1.8.1 Single-Phase Feeder 10.1.8.2 IEEE 13 Bus Test Feeder 10.1.8.3 Summary of Loop Flow 10.1.9 Summary of Power-Flow Studies 10.2 Short-Circuit Studies 10.2.1 General Short-Circuit Theory 10.2.2 Specific Short Circuits 10.2.3 Back-Feed, Ground-Fault Currents 10.2.3.1 One Downstream Transformer Bank 10.2.3.2 Complete Three-Phase Circuit Analysis 10.2.3.3 Back-Feed Currents Summary 10.3 Summary Problems WindMil Assignment References Chapter 11: Center-Tapped Transformers and Secondaries 11.1 Center-Tapped, Single-Phase Transformer Model 11.1.1 Matrix Equations 11.1.2 Center-Tapped Transformer Serving Loads through a Triplex Secondary 11.2 Ungrounded Wye – Delta Transformer Bank with Center-Tapped Transformer 11.2.1 Basic Transformer Equations 11.2.2 Forward Sweep 11.2.3 Backward Sweep 11.2.4 Summary 11.3 Open Wye – Open Delta Transformer Connections 11.3.1 The Leading Open Wye – Open Delta Connection 11.3.2 The Lagging Open Wye – Open Delta Connection 11.3.3 Forward Sweep 11.3.4 Backward Sweep 11.4 Four-Wire Secondary 11.5 Putting It All Together 11.5.1 Ungrounded Wye – Delta Connection 11.5.2 Open Wye – Delta Connections 11.5.3 Comparisons of Voltage and Current Unbalances 11.6 Summary Problems WindMil Assignment References Appendix A: Conductor Data Appendix B: Concentric Neutral 15 kV Cable Index