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UDC 621.311(075.8)
P 27

Confirmed by Ministry of Education and Science of Ukraine

Reviewers:

A. Shidlovsky, Academician of the National Academy of Sciences of Ukraine (The Institute of Electrodynamics of the National Academy of Sciences of Ukraine);

I. Zhezhelenko, Academician of the Academy of Sciences of Ukrainian Higher School, Ph.D, professor (The Priazovye State Technical University);

The Department of Theoretical Electrical Engineering and Electric Power Supply of The Vinnitsa State Technical University.

Authors: G. Pivnyak, V. Vinoslavskiy, A. Rybalko, L. Nesen

Transients in Electric Power Supply Systems. Volume I: the textbook for institutions of higher education. / G. Pivnyak, V. Vinoslavskiy, A. Rybalko, L. Nesen; under the general editorship of G. Pivnyak, Academician of the National Academy of Sciences of Ukraine. Editorship of the English version and terminology by Professors O. Ivanov and S. Kostritskaya - 4th edition: Translation from Ukrainian. - Dnipropetrovsk: National Mining University. - 2005.


ISBN 966-350-016-6

The electromagnetic processes in electric power supply systems are considered. Physical phenomena leading to transients and methods of their calculation are described. The material is illustrated by practical examples and assisted by control questions and topics for essay.

The textbook is meant for students of institutions of higher education, for use in learning professional English in the field of electric power engineering. Can be used by undergraduate and post-graduate students, scientists and practical engineers for design, maintenance of electric power supply systems and enterprises, and also for EST training.

Розглянуті електромагнітні процеси в системах електропостачання. Викладені фізичні явища, які обумовлюють перехідні процеси, методи їх аналізу і розрахунку. Матеріал проілюстрований практичними прикладами і супроводжується контрольними запитаннями для освоєння англійської мови у сфері професійної діяльності.

Для студентів вузів, які вчаться за спеціальностями електроенергетичних напрямів і вивчають англійську мову. Може бути використаний студентами, магістрами, аспірантами і інженерно-технічними працівниками для вирішення задач проектування, експлуатації систем електропостачання підприємств і виробництв, освосння англійської мови.


© G. Pivnyak, V. Vinoslavskiy, A. Rybalko, L. Nesen, 2005
© National Mining University, 2005

ISBN 966-350-016-6



CONTENT
INTRODUCTION 7

CHAPTER 1.

GENERAL INFORMATION ABOUT TRANSIENTS
13
 
1.1. Kinds, reasons and consequences of short circuits
14
  1.2. Purpose of electromagnetic transients calculation, design conditions 17
  1.3. Basic regularities of snort circuit currents calculation 14
  1.4. Design circuit of electric power supply system and its components description 21
  1.5. Equivalent circuit and methods of its parameters calculation 24
  1.6. Transformations of equivalent circuits 31
  1.7. Application of approximate reduction in per unit 35
  Test questions 37
  Topics for essay 37

CHAPTER 2.

TRANSIENTS AT THREE-PHASE SHORT CIRCUITS
38
 
2.1. Short circuit in radial network without transformer coupling
39
  2.2. Short circuit on generator's terminals 47
  2.3. Short circuit at remote points of electric supply network 51
  2.4. Initial value of periodic component of short circuit current 53
  2.5. Periodic component of short circuit current for any instant of time 56
  2.6. Short circuit current of emergency steady state 58
  Test questions 60
  Topics for essay 60

CHAPTER 3.

EVALUATION OF TRANSIENTS UNDER THREE-PHASE SHORT CIRCUITS
61
 
3.1. Basic statements
62
  3.2. Use of short circuit periodical component diagrams in network with one source 66
  3.3. Use of short circuit current periodical component diagrams in a network with several sources 69
  3.4. Calculation of short circuit current periodical component for any time instant by rectified characteristics method 71
  3.5. Short circuit currents calculation on the principle of superposition 78
  3.6. Calculation of short circuit current components stipulated by load centers 80
  3.7. Calculation of short circuit currents in electrical installations with voltage up to 1 kV 90
  3.8. Computer-aided calculation of short circuit current 106
  Test questions 110
  Topics for essay 110

CHAPTER 4.

KEY ITEMS CONCERNING ANALYSIS OF TRANSIENTS UNDER ASYMMETRY IN THREE-PHASE NETWORK
111
 
4.1. General information
112
  4.2. Generation of higher harmonics by synchronous generator 112
  4.3. Method of symmetric components 115
  4.4. Relationships between symmetrical components of current and voltage 118
  4.5. Resistances of negative and zero sequences of circuit elements 120
  4.6. Drawing up equivalent circuits for symmetrical components 138
  4.7. Resulting electromotive forces and impedances of equivalent circuits for separate sequences 141
  Test questions 143
  Topics for essay 143

CHAPTER 5.

LATERAL ASYMMETRY
144
 
5.1. Starting statements
145
  5.2. Single-phase short circuit 147
  5.3. Two-phase short circuit 149
  5.4. Two-phase short circuit to ground 152
  5.5. Account of contact resistance at the point of short circuit 154
  5.6. Equivalence rule for the current of positive sequence 156
  5.7. Integrated equivalent circuits 159
  5.8. Comparison of currents at different short circuits 162
  5.9. Symmetrical current and voltage components transformation 165
  5.10. Methods of asymmetrical short circuit calculation 172
  Test questions 177
  Topics for essay 177

CHAPTER 6.

LONGITUDINAL ASYMMETRY AND COMPLEX FAULTS
178
 
6.1. General statements
179
  6.2. Open-phase fault in three-phase network 180
  6.3. Two-phases open fault 182
  6.4. Connection or unequal resistors in network phases 184
  6.5. Double ground connection 187
  6.6. Single-phase short circuit with simultaneous open-phase fault 193
  Test questions 196
  Topics for essay 196

CHAPTER 7.

TRANSIENTS UNDER SPECIFIC CONDITIONS
197
 
7.1. Short circuits in the network of external electric power supply
198
  7.2. Short-circuit to ground in the network with insulated neutral 200
  7.3. Short circuits in the networks of increased frequency 205
  7.4. Transients stipulated by peculiarities of production process 205
  7.5. Processes taking place under capacitor banks commutation 208
  7.6. Short circuits in DC lines 210
  Test questions 215
  Topics for essay 215

CHAPTER 8.

LEVELS OF CURRENTS AND POWER OF SHORT CIRCUIT
216
 
8.1. Quality of electromagnetic transients
217
  8.2. Ways of short circuit currents limiting 219
  8.3. Use of technical facilities for short circuit current level optimization 225
  8.4. Short circuit current level optimization 236
  8.5. Short circuit currents levels coordination 238
  Test questions 240
  Topics for essay 240

REFERENCE
241

GLOSSARY
244



PREFACE

The need to improve electric supply systems is stipulated by development of industry, transport, civil engineering and the agroindustrial complex. These enterprises are the main consumers of electric power in complex infrastructure of industrial centers. They consume electric power with different frequencies, voltages and currents. They are also characterized by high density of electric loads. Their electric supply systems have multilevel stages of power distribution; large-scale load centers with different transformations of electromagnetic energy parameters, power consumers of various types; power sources of power system, local thermal power stations, synchronous compensators, sources of reactive power, in emergencies - motors went to generating mode; significant degree of branching; characterized by negative feedback of electric technological processes and powerful consumers on the system operation in emergencies.

Construction and maintenance of the electric power supply systems involves considerable material resources. That is why it is very important to improve their efficiency and reliability in different operating conditions, including malfunctions and post-emergency inodes. This stipulates high requirements to these systems, to their operating modes and electric power quality. These requirements can be assessed on the basis of transients investigation.

Methods of investigation and evaluations of transients is the important field of research and development in NIS and western countries. Their aim is the development of new level electric power supply systems, sustaining their modes stability with required levels of economy, electric power quality, reliability, and maintenance safety. Use of simulation methods and computing aids greatly contributes to solving tasks arising at analysis and evaluations of transients. They allow to choose the most appropriate circuit designs and electric characteristics of the system components, and also to forecast their economical and technical performances not only in normal, but also in transient modes.

Questions are analyzed and illustrated by examples with use of language structures, which will assist to students’ self-instruction, their comprehension of teaching material and mastering in modem research and evaluations principles in English.

The book consists of introduction and the main part, were electromagnetic transients caused by shorts, longitudinal and lateral asymmetry are considered. Chapter 1 covers starting positions, basic assumptions and principles of equivalent representation for analysis of transients in electric power supply system. Equivalents of electric supply system elements and its mode parameters are the basis for construction of equivalent circuits (chapter 1), which are used for analytical (chapter 2) and practical (chapter 3) calculations of three-phase short circuits. Various types of lateral (chapter 5), longitudinal asymmetry (chapter 6), their combinations and complex faults are analyzed using method of symmetrical components. Influence of technologies and electric consumers operating modes on supply networks is illustrated in chapter 7. Measures of short circuit currents and power limitation are considered in chapter 8. There are also conditions for their levels’ optimization formulated.

There are control questions and topics for essays at the end of each chapter for better comprehension of given material. They will help students’ self-dependent activities in EST learning terminology of the discipline.

Authors will gratefully accept remarks and readers’ opinion, which will assist to further development of this text-book.

Authors

Acknowledgments

Authors wish to thank O. Balakhontsev, V. Gavrilyuk and L. Tokar, who have translated the book into English; Professors S. Kostritskaya and O. Ivanov for editing the English version of the textbook; assisting lecturer S. Dybrin and students A. Yefimenko, O. Mikhaylenko who have prepared the computer version of the edition.


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