Short Circuits in Power Systems

Ismail Kasikci is Professor at the University of Applied Sciences Biberach, Germany. His main research area is electrical energy supply, design of electrical installations of buildings, solar electricity, wind power generation, building integrated renewables, design and protection of distribution power system, smart grids, solar and wind power, connectivity requirements, focused on the IEC/EN and VDE regulations. Ismail Kasikci received his Bachelor in electrical and electronics engineering from the Technical University Darmstadt and his PhD from the University of Brunel, United Kingdom. He published 17 books in German, English and Turkish and more than 64 international scientific publications. He is a member by VDE and IEEE. He is Associated Editor of the international Journal of Power and Energy Systems by ACTA press in the States and Canada. Since 2005 he is a member of the German norm group, K221 [IEC TC 64 (VDE 0100)]. He has more than 18 years of professional experience in planning and design of electrical power systems.He plays since 1994 an active role in Turkey for educational purposes and in the regulation of IEC and EN. Within the scope of the EU Erasmus program he gives lectures at the University of Pamukkale and Ege University in the field of Electric Power Systems, Grounding and Protection.

• Preface xiAcknowledgments xiii1 Definitions:Methods of Calculations 11.1 Time Behavior of the Short-Circuit Current 21.2 Short-Circuit Path in the Positive-Sequence System 31.3 Classification of Short-Circuit Types 51.4 Methods of Short-Circuit Calculation 71.4.1 Superposition Method 71.4.2 Equivalent Voltage Source 101.4.3 Transient Calculation 111.4.4 Calculating with Reference Variables 121.4.4.1 The Per-Unit Analysis 121.4.4.2 The %/MVA Method 141.4.5 Examples 141.4.5.1 Characteristics of the Short-Circuit Current 141.4.5.2 Calculation of Switching Processes 141.4.5.3 Calculation with pu System 141.4.5.4 Calculation with pu Magnitudes 161.4.5.5 Calculation with pu System for an Industrial System 171.4.5.6 Calculation with MVA System 192 Fault Current Analysis 233 The Significance of IEC 60909-0 294 Supply Networks 334.1 Calculation Variables for Supply Networks 344.2 Lines Supplied from a Single Source 354.3 Radial Networks 354.4 Ring Networks 354.5 Meshed Networks 375 Network Types for the Calculation of Short-Circuit Currents 395.1 Low-Voltage Network Types 395.2 Medium-Voltage Network Types 395.3 High-Voltage Network Types 446 Systems up to 1 kV 476.1 TN Systems 486.1.1 Description of the System is Carried Out by Two Letters 486.2 Calculation of Fault Currents 496.2.1 System Power Supplied from Generators: 506.3 TT systems 526.3.1 Description of the System 526.4 IT Systems 536.4.1 Description of the System 536.5 Transformation of the Network Types Described to Equivalent Circuit Diagrams 546.6 Examples 566.6.1 Example 1: Automatic Disconnection for a TN System 566.6.1.1 Calculation for a Receptacle 566.6.1.2 For the Heater 566.6.2 Example 2: Automatic Disconnection for a TT System 577 Neutral Point Treatment in Three-Phase Networks 597.1 Networks with Isolated Free Neutral Point 637.2 Networks with Grounding Compensation 647.3 Networks with Low-Impedance Neutral Point Treatment 667.4 Examples 697.4.1 Neutral Grounding 698 Impedances of Three-Phase Operational Equipment 718.1 Network Feed-Ins, Primary Service Feeder 718.2 Synchronous Machines 738.2.1 a.c. Component 788.2.2 d.c. Component 788.2.3 Peak Value 788.3 Transformers 808.3.1 Short-Circuit Current on the Secondary Side 818.3.2 Voltage-Regulating Transformers 838.4 Cables and Overhead Lines 858.5 Short-Circuit Current-Limiting Choke Coils 968.6 Asynchronous Machines 978.7 Consideration of Capacitors and Nonrotating Loads 988.8 Static Converters 988.9 Wind Turbines 998.9.1 Wind Power Plant with AG 1008.9.2 Wind Power Plant with a Doubly Fed Asynchronous Generator 1018.9.3 Wind Power with Full Converter 1018.10 Short-Circuit Calculation on Ship and Offshore Installations 1028.11 Examples 1048.11.1 Example 1: Calculate the Impedance 1048.11.2 Example 2: Calculation of a Transformer 1048.11.3 Example 3: Calculation of a Cable 1058.11.4 Example 4: Calculation of a Generator 1058.11.5 Example 5: Calculation of a Motor 1068.11.6 Example 6: Calculation of an LV motor 1068.11.7 Example 7: Design and Calculation of aWind Farm 1068.11.7.1 Description of theWind Farm 1068.11.7.2 Calculations of Impedances 1118.11.7.3 Backup Protection and Protection Equipment 1168.11.7.4 Thermal Stress of Cables 1188.11.7.5 Neutral Point Connection 1198.11.7.6 Neutral Point Transformer (NPT) 1198.11.7.7 Network with Current-Limiting Resistor 1208.11.7.8 Compensated Network 1248.11.7.9 Insulated Network 1258.11.7.10 Grounding System 1259 Impedance Corrections 1279.1 Correction Factor KG for Generators 1289.2 Correction Factor KKW for Power Plant Block 1299.3 Correction Factor KT for Transformers with Two and Three Windings 13010 Power SystemAnalysis 13310.1 The Method of Symmetrical Components 13610.2 Fundamentals of Symmetrical Components 13710.2.1 Derivation of the Transformation Equations 13910.3 General Description of the Calculation Method 14010.4 Impedances of Symmetrical Components 14211 Calculation of Short-Circuit Currents 14711.1 Three-Phase Short Circuits 14711.2 Two-Phase Short Circuits with Contact to Ground 14811.3 Two-Phase Short CircuitWithout Contact to Ground 14911.4 Single-Phase Short Circuits to Ground 15011.5 Peak Short-Circuit Current, ip 15311.6 Symmetrical Breaking Current, Ia 15511.7 Steady-State Short-Circuit Current, Ik 15712 Motors in Electrical Networks 16112.1 Short Circuits at the Terminals of Asynchronous Motors 16112.2 Motor Groups Supplied from Transformers with TwoWindings 16312.3 Motor Groups Supplied from Transformers with Different Nominal Voltages 16313 Mechanical and Thermal Short-Circuit Strength 16713.1 Mechanical Short-Circuit Current Strength 16713.2 Thermal Short-Circuit Current Strength 17313.3 Limitation of Short-Circuit Currents 17613.4 Examples for Thermal Stress 17613.4.1 Feeder of a Transformer 17613.4.2 Mechanical Short-Circuit Strength 17814 Calculations for Short-Circuit Strength 18514.1 Short-Circuit Strength for Medium-Voltage Switchgear 18514.2 Short-Circuit Strength for Low-Voltage Switchgear 18615 Equipment for Overcurrent Protection 18916 Short-Circuit Currents in DC Systems 19916.1 Resistances of Line Sections 20116.2 Current Converters 20216.3 Batteries 20316.4 Capacitors 20416.5 Direct Current Motors 20517 Power Flow Analysis 20717.1 Systems of Linear Equations 20817.2 Determinants 20917.3 Network Matrices 21217.3.1 Admittance Matrix 21217.3.2 Impedance Matrix 21317.3.3 Hybrid Matrix 21317.3.4 Calculation of Node Voltages and Line Currents at Predetermined Load Currents 21417.3.5 Calculation of Node Voltages at Predetermined Node Power 21517.3.6 Calculation of Power Flow 21517.3.6.1 Type of Nodes 21617.3.6.2 Type of Loads and Complex Power 21617.3.7 Linear Load Flow Equations 21817.3.8 Load Flow Calculation by Newton–Raphson 21917.3.9 Current Iteration 22317.3.9.1 Jacobian Method 22317.3.10 Gauss–Seidel Method 22417.3.11 Newton–Raphson Method 22417.3.12 Power Flow Analysis in Low-Voltage Power Systems 22617.3.13 Equivalent Circuits for Power Flow Calculations 22717.3.14 Examples 22817.3.14.1 Calculation of Reactive Power 22817.3.14.2 Application of Newton Method 22817.3.14.3 Linear Equations 22917.3.14.4 Application of Cramer’s Rule 22917.3.14.5 Power Flow Calculation with NEPLAN 23018 Examples: Calculation of Short-Circuit Currents 23318.1 Example 1: Radial Network 23318.2 Example 2: Proof of Protective Measures 23518.3 Example 3: Connection Box to Service Panel 23718.4 Example 4: Transformers in Parallel 23818.5 Example 5: Connection of a Motor 24018.6 Example 6: Calculation for a Load Circuit 24118.7 Example 7: Calculation for an Industrial System 24318.8 Example 8: Calculation ofThree-Pole Short-Circuit Current and Peak Short-Circuit Current 24418.9 Example 9: Meshed Network 24618.10 Example 10: Supply to a Factory 24918.11 Example 11: Calculation with Impedance Corrections 25018.12 Example 12: Connection of a TransformerThrough an External Network and a Generator 25318.13 Example 13: Motors in Parallel and their Contributions to the Short-Circuit Current 25518.14 Example 14: Proof of the Stability of Low-Voltage Systems 25718.15 Example 15: Proof of the Stability of Medium-Voltage and High-Voltage Systems 25918.16 Example 16: Calculation for Short-Circuit Currents with Impedance Corrections 269Bibliography 273Standards 277Explanations of Symbols 281Symbols and Indices 283Indices 286Secondary Symbols, Upper Right, Left 287American Cable Assembly (AWG) 287Index 289