Details

Short Circuits in Power Systems


Short Circuits in Power Systems

A Practical Guide to IEC 60909-0
2. Aufl.

von: Ismail Kasikci

97,99 €

Verlag: Wiley-VCH
Format: PDF
Veröffentl.: 09.11.2017
ISBN/EAN: 9783527803361
Sprache: englisch
Anzahl Seiten: 278

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Beschreibungen

Reflecting the changes to the all-important short circuit calculations in three-phase power systems according to IEC 60909-0 standard, this new edition of the practical guide retains its proven and unique concept of explanations, calculations and real-life examples of short circuits in electrical networks. It has also been completely revised and expanded by 20% to include the standard-compliant prevention of short circuits in electrical networks for photovoltaics and wind energy. By understanding the theory any software allows users to perform all the necessary calculations with ease so they can work on the design and application of low- and high-voltage power systems. This book is a practitioner's guide intended for students, electrical engineers, engineers in power technology, the electrotechnical industry, engineering consultants, energy suppliers, chemical engineers and physicists in industry.
Preface xi Acknowledgments xiii 1 Definitions:Methods of Calculations 1 1.1 Time Behavior of the Short-Circuit Current 2 1.2 Short-Circuit Path in the Positive-Sequence System 3 1.3 Classification of Short-Circuit Types 5 1.4 Methods of Short-Circuit Calculation 7 1.4.1 Superposition Method 7 1.4.2 Equivalent Voltage Source 10 1.4.3 Transient Calculation 11 1.4.4 Calculating with Reference Variables 12 1.4.4.1 The Per-Unit Analysis 12 1.4.4.2 The %/MVA Method 14 1.4.5 Examples 14 1.4.5.1 Characteristics of the Short-Circuit Current 14 1.4.5.2 Calculation of Switching Processes 14 1.4.5.3 Calculation with pu System 14 1.4.5.4 Calculation with pu Magnitudes 16 1.4.5.5 Calculation with pu System for an Industrial System 17 1.4.5.6 Calculation with MVA System 19 2 Fault Current Analysis 23 3 The Significance of IEC 60909-0 29 4 Supply Networks 33 4.1 Calculation Variables for Supply Networks 34 4.2 Lines Supplied from a Single Source 35 4.3 Radial Networks 35 4.4 Ring Networks 35 4.5 Meshed Networks 37 5 Network Types for the Calculation of Short-Circuit Currents 39 5.1 Low-Voltage Network Types 39 5.2 Medium-Voltage Network Types 39 5.3 High-Voltage Network Types 44 6 Systems up to 1 kV 47 6.1 TN Systems 48 6.1.1 Description of the System is Carried Out by Two Letters 48 6.2 Calculation of Fault Currents 49 6.2.1 System Power Supplied from Generators: 50 6.3 TT systems 52 6.3.1 Description of the System 52 6.4 IT Systems 53 6.4.1 Description of the System 53 6.5 Transformation of the Network Types Described to Equivalent Circuit Diagrams 54 6.6 Examples 56 6.6.1 Example 1: Automatic Disconnection for a TN System 56 6.6.1.1 Calculation for a Receptacle 56 6.6.1.2 For the Heater 56 6.6.2 Example 2: Automatic Disconnection for a TT System 57 7 Neutral Point Treatment in Three-Phase Networks 59 7.1 Networks with Isolated Free Neutral Point 63 7.2 Networks with Grounding Compensation 64 7.3 Networks with Low-Impedance Neutral Point Treatment 66 7.4 Examples 69 7.4.1 Neutral Grounding 69 8 Impedances of Three-Phase Operational Equipment 71 8.1 Network Feed-Ins, Primary Service Feeder 71 8.2 Synchronous Machines 73 8.2.1 a.c. Component 78 8.2.2 d.c. Component 78 8.2.3 Peak Value 78 8.3 Transformers 80 8.3.1 Short-Circuit Current on the Secondary Side 81 8.3.2 Voltage-Regulating Transformers 83 8.4 Cables and Overhead Lines 85 8.5 Short-Circuit Current-Limiting Choke Coils 96 8.6 Asynchronous Machines 97 8.7 Consideration of Capacitors and Nonrotating Loads 98 8.8 Static Converters 98 8.9 Wind Turbines 99 8.9.1 Wind Power Plant with AG 100 8.9.2 Wind Power Plant with a Doubly Fed Asynchronous Generator 101 8.9.3 Wind Power with Full Converter 101 8.10 Short-Circuit Calculation on Ship and Offshore Installations 102 8.11 Examples 104 8.11.1 Example 1: Calculate the Impedance 104 8.11.2 Example 2: Calculation of a Transformer 104 8.11.3 Example 3: Calculation of a Cable 105 8.11.4 Example 4: Calculation of a Generator 105 8.11.5 Example 5: Calculation of a Motor 106 8.11.6 Example 6: Calculation of an LV motor 106 8.11.7 Example 7: Design and Calculation of aWind Farm 106 8.11.7.1 Description of theWind Farm 106 8.11.7.2 Calculations of Impedances 111 8.11.7.3 Backup Protection and Protection Equipment 116 8.11.7.4 Thermal Stress of Cables 118 8.11.7.5 Neutral Point Connection 119 8.11.7.6 Neutral Point Transformer (NPT) 119 8.11.7.7 Network with Current-Limiting Resistor 120 8.11.7.8 Compensated Network 124 8.11.7.9 Insulated Network 125 8.11.7.10 Grounding System 125 9 Impedance Corrections 127 9.1 Correction Factor KG for Generators 128 9.2 Correction Factor KKW for Power Plant Block 129 9.3 Correction Factor KT for Transformers with Two and Three Windings 130 10 Power SystemAnalysis 133 10.1 The Method of Symmetrical Components 136 10.2 Fundamentals of Symmetrical Components 137 10.2.1 Derivation of the Transformation Equations 139 10.3 General Description of the Calculation Method 140 10.4 Impedances of Symmetrical Components 142 11 Calculation of Short-Circuit Currents 147 11.1 Three-Phase Short Circuits 147 11.2 Two-Phase Short Circuits with Contact to Ground 148 11.3 Two-Phase Short CircuitWithout Contact to Ground 149 11.4 Single-Phase Short Circuits to Ground 150 11.5 Peak Short-Circuit Current, ip 153 11.6 Symmetrical Breaking Current, Ia 155 11.7 Steady-State Short-Circuit Current, Ik 157 12 Motors in Electrical Networks 161 12.1 Short Circuits at the Terminals of Asynchronous Motors 161 12.2 Motor Groups Supplied from Transformers with TwoWindings 163 12.3 Motor Groups Supplied from Transformers with Different Nominal Voltages 163 13 Mechanical and Thermal Short-Circuit Strength 167 13.1 Mechanical Short-Circuit Current Strength 167 13.2 Thermal Short-Circuit Current Strength 173 13.3 Limitation of Short-Circuit Currents 176 13.4 Examples for Thermal Stress 176 13.4.1 Feeder of a Transformer 176 13.4.2 Mechanical Short-Circuit Strength 178 14 Calculations for Short-Circuit Strength 185 14.1 Short-Circuit Strength for Medium-Voltage Switchgear 185 14.2 Short-Circuit Strength for Low-Voltage Switchgear 186 15 Equipment for Overcurrent Protection 189 16 Short-Circuit Currents in DC Systems 199 16.1 Resistances of Line Sections 201 16.2 Current Converters 202 16.3 Batteries 203 16.4 Capacitors 204 16.5 Direct Current Motors 205 17 Power Flow Analysis 207 17.1 Systems of Linear Equations 208 17.2 Determinants 209 17.3 Network Matrices 212 17.3.1 Admittance Matrix 212 17.3.2 Impedance Matrix 213 17.3.3 Hybrid Matrix 213 17.3.4 Calculation of Node Voltages and Line Currents at Predetermined Load Currents 214 17.3.5 Calculation of Node Voltages at Predetermined Node Power 215 17.3.6 Calculation of Power Flow 215 17.3.6.1 Type of Nodes 216 17.3.6.2 Type of Loads and Complex Power 216 17.3.7 Linear Load Flow Equations 218 17.3.8 Load Flow Calculation by Newton–Raphson 219 17.3.9 Current Iteration 223 17.3.9.1 Jacobian Method 223 17.3.10 Gauss–Seidel Method 224 17.3.11 Newton–Raphson Method 224 17.3.12 Power Flow Analysis in Low-Voltage Power Systems 226 17.3.13 Equivalent Circuits for Power Flow Calculations 227 17.3.14 Examples 228 17.3.14.1 Calculation of Reactive Power 228 17.3.14.2 Application of Newton Method 228 17.3.14.3 Linear Equations 229 17.3.14.4 Application of Cramer’s Rule 229 17.3.14.5 Power Flow Calculation with NEPLAN 230 18 Examples: Calculation of Short-Circuit Currents 233 18.1 Example 1: Radial Network 233 18.2 Example 2: Proof of Protective Measures 235 18.3 Example 3: Connection Box to Service Panel 237 18.4 Example 4: Transformers in Parallel 238 18.5 Example 5: Connection of a Motor 240 18.6 Example 6: Calculation for a Load Circuit 241 18.7 Example 7: Calculation for an Industrial System 243 18.8 Example 8: Calculation ofThree-Pole Short-Circuit Current and Peak Short-Circuit Current 244 18.9 Example 9: Meshed Network 246 18.10 Example 10: Supply to a Factory 249 18.11 Example 11: Calculation with Impedance Corrections 250 18.12 Example 12: Connection of a TransformerThrough an External Network and a Generator 253 18.13 Example 13: Motors in Parallel and their Contributions to the Short-Circuit Current 255 18.14 Example 14: Proof of the Stability of Low-Voltage Systems 257 18.15 Example 15: Proof of the Stability of Medium-Voltage and High-Voltage Systems 259 18.16 Example 16: Calculation for Short-Circuit Currents with Impedance Corrections 269 Bibliography 273 Standards 277 Explanations of Symbols 281 Symbols and Indices 283 Indices 286 Secondary Symbols, Upper Right, Left 287 American Cable Assembly (AWG) 287 Index 289
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.

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