Electrical Power System Protection

by Christopoulos, Christos; Wright, A.

• ISBN13: 9780412817601
• ISBN10: 0412817608
• Edition: 2nd
• Format: Hardcover
• Copyright: 1999-06-01
• Publisher: Chapman & Hall

Summary

This new edition of a successful reference work provides the professional with all the techniques and methods which are required to be incorporated into the design of an electrical power system. The new edition has been comprehensively updated and contains new chapters on the essential topics of digital communications, digital signal processing and protection and, lastly, new relaying concepts. The book provides a sound and complete treatment of the fundamentals of power system protection and illustrates the principles with examples from current practice. The text includes many insights into modern technologies and research areas. Electrical Power System Protection is an essential reference handbook for all engineers working in electrical utilities, as well as for designers and users of electrical protection equipment. It also forms a complete reference text for advanced undergraduate and postgraduate students on courses in electrical engineering.

Table of Contents

Acknowledgements	xv
Preface to the Second Edition	xvii
Preface to the First Edition	xviii
List of Symbols	xx
Fuses	1	(38)
Historical background	1	(4)
Basic requirements	5	(1)
Fuse types and constructions	6	(3)
Cartridge fuses	7	(1)
Semi-enclosed fuses	8	(1)
Expulsion fuses	8	(1)
Liquid fuses	8	(1)
The behaviour of cartridge fuselinks	9	(5)
The pre-arcing period	9	(1)
The arcing period	10	(3)
Determination of fuselink performance	13	(1)
The construction of cartridge fuses	14	(4)
Fuse elements	14	(2)
Fuselink bodies	16	(1)
Filling material	16	(1)
Mountings and ratings	16	(2)
Semi-enclosed fuses	18	(1)
Expulsion fuses	18	(3)
Liquid fuses	21	(1)
The application of fuses	21	(15)
Time/current relationships	22	(1)
I2t	23	(1)
Virtual time	24	(1)
Published time/current characteristics	24	(1)
Cut-off characteristics	25	(1)
Operating frequency	25	(1)
Discrimination and co-ordination	26	(2)
The protection of power-system equipment	28	(8)
The future	36	(3)
References	36	(1)
Further reading	37	(2)
Current transformers	39	(48)
Historical background	39	(3)
Conventional current transformers	42	(35)
Equivalent circuits	42	(2)
Behaviour under normal steady-state conditions	44	(5)
Behaviour under abnormal conditions	49	(10)
The effects of core saturation on transformation behaviour	59	(3)
Remanent core flux	62	(6)
Operation with a secondary circuit open or of a high impedance	68	(3)
The construction of current transformers	71	(6)
Linear couplers	77	(4)
The output of a linear coupler with a burden of infinite impedance	78	(1)
The output of a linear coupler with a burden of finite impedance	79	(2)
Current transformers with air-gapped cores	81	(1)
Non-conventional current transducers	82	(2)
Specifications and testing	84	(1)
The future	85	(2)
References	85	(1)
Further reading	86	(1)
Voltage transformers	87	(16)
Historical background	87	(1)
Electromagnetic voltage transformers	88	(6)
Behaviour during steady-state conditions	89	(1)
Behaviour during abnormal conditions	90	(1)
Voltage transformer construction	91	(3)
Capacitor-voltage transformers	94	(4)
Capacitor dividers	95	(1)
Circuit of a capacitor-voltage transformer	96	(1)
Steady state behaviour	96	(1)
Behaviour during abnormal conditions	97	(1)
Recent developments	98	(1)
Specifications and testing	99	(1)
The future	100	(3)
References	100	(1)
Further reading	101	(2)
Overcurrent and earth fault protection	103	(42)
Historical background	103	(3)
Relay connections and operation	106	(11)
The detection of earth faults	106	(1)
The detection of overcurrents	107	(1)
Electro-mechanical relays	108	(5)
Directional relays	113	(3)
Thermal inverse time/current relays	116	(1)
Electronic relays	117	(7)
Basic electronic processing	118	(1)
Current-operated relay	119	(1)
Directional relay	119	(5)
Applications of overcurrent, earth fault and directional relays	124	(11)
Current grading	125	(1)
Time grading using relays with definite operating times	126	(1)
Time grading using relays with inverse time/current characteristics	127	(8)
The application of directional and current-operated relays	135	(4)
Current and voltage transformers	139	(1)
Electro-mechanical relays with a fixed current setting	139	(1)
Electro-mechanical IDMT overcurrent relays	139	(1)
Electro-mechanical directional relays	140	(1)
Electronic relays	140	(1)
Standard specifications	140	(3)
IDMT relays	141	(1)
Directional relays	142	(1)
The future	143	(2)
References	143	(1)
Further reading	144	(1)
Current-differential protective schemes	145	(34)
Historical background	147	(1)
Factors affecting current-differential schemes	148	(8)
Current transformer errors	148	(2)
Current transformer secondary ratings	150	(1)
Interconnecting cables (pilot wires)	150	(1)
Symmetry of protective circuits	151	(3)
The setting of low-impedance relays	154	(2)
The use of biasing features	156	(2)
Implementation of schemes	158	(11)
Units of short physical length	158	(1)
Units of considerable physical length	159	(3)
Balanced-voltage schemes	162	(3)
Schemes to protect zones with more than two ends	165	(2)
The protection of busbars	167	(2)
Earth fault protective schemes	169	(2)
Schemes employing high-impedance relays	171	(3)
Relays used in current-differential schemes	174	(3)
Application of current-differential schemes	177	(2)
References	177	(1)
Further reading	177	(2)
The protection of transformers	179	(48)
Historical background	180	(1)
The construction and behaviour of transformers	180	(18)
Construction	181	(3)
Operation during normal and external fault conditions	184	(7)
Behaviour during internal fault conditions	191	(3)
Causes of internal electrical faults	194	(4)
The application of protective schemes and devices to power transformers with two or more windings per phase	198	(18)
Inverse time/current relays	198	(1)
Current-differential schemes	198	(10)
Restricted earth fault protection	208	(2)
Combined differential and restricted earth fault protection	210	(1)
Earth fault protection of delta-connected windings	211	(1)
Tank earth protection	212	(1)
Overfluxing protection	212	(1)
Protection against overheating	213	(1)
Buchholz relays	213	(3)
The protection of large three-phase transformers	216	(1)
The protection of earthing transformers	216	(3)
Auto transformers and their protection	219	(4)
Current-differential schemes	222	(1)
Tank earth protective equipment	223	(1)
Other protective equipment	223	(1)
The future	223	(4)
References	224	(1)
Further reading	225	(2)
The protection of rotating machines	227	(52)
Historical background	228	(2)
Protective devices and schemes	230	(4)
Fuses	230	(1)
Thermal relays	230	(1)
Thermal devices	231	(1)
Instantaneous electromagnetic relays	231	(1)
Current-differential schemes	232	(1)
Current-balance schemes	232	(1)
Phase-unbalance relays	233	(1)
Voltage-operated relays	233	(1)
Control equipment	233	(1)
Applications of protective schemes to machines	233	(1)
The protection of motors	234	(21)
The protection of small motors	234	(1)
The protection of large induction motors	235	(9)
The protection of synchronous motors	244	(7)
The protection of d. c. motors	251	(3)
The protection of variable-speed drives	254	(1)
The protection of alternators	255	(23)
Alternator construction and behaviour	255	(6)
The application of protective equipment to alternators	261	(17)
The future	278	(1)
References	278	(1)
Further reading	278	(1)
The protection of busbars	279	(28)
Historical background	279	(2)
Busbars	281	(3)
The construction of enclosed switchgear units	281	(2)
Open-type switching sites	283	(1)
Further methods to reduce the incidence of busbar faults	283	(1)
Sectionalization	284	(2)
Faults on or near busbars	286	(1)
Internal faults	286	(1)
External faults	286	(1)
Positioning of current transformers and incorrectly protected zones	287	(1)
Protective arrangements for busbars	288	(8)
Application to simple single-phase unsectionalized busbars	289	(1)
Application to simple three-phase unsectionalized busbars	290	(2)
Application to complex three-phase sectionalized busbars	292	(4)
Interconnections in current-differential schemes applied to busbars	296	(1)
Relays used in current-differential schemes	296	(7)
High-impedance relays	296	(1)
Low-impedance relays	297	(2)
Low-impedance relays with compensation for current-transformer saturation	299	(2)
The duplication of current-differential protective schemes	301	(2)
Manual and automatic testing	303	(1)
The future	304	(3)
References	304	(1)
Further reading	305	(2)
The protection of overhead lines and cables by current-differential schemes	307	(38)
Historical background	307	(3)
Cables and overhead transmission and distribution lines	310	(2)
The application of current-differential protective schemes	312	(25)
Comparison arrangements	312	(3)
Circulating-current schemes	315	(2)
Balanced-voltage schemes	317	(12)
Pilot wires	329	(1)
Protective schemes which use rented telephone circuits	330	(1)
Monitoring of pilot wires	331	(2)
Current-differential schemes incorporating optical-fibre links	333	(4)
The application of current-differential schemes to multi-ended circuits	337	(3)
The application of current-differential schemes to lines and cables terminated with transformers	340	(3)
The future	343	(2)
References	343	(2)
Interlock and phase-comparison schemes for the protection of overhead lines	345	(40)
Introduction	345	(1)
Historical background	346	(1)
The construction and behaviour of transmission lines	347	(2)
Features of interlock protective schemes	349	(16)
Relaying arrangements	349	(11)
Interlocking signals	360	(1)
Starting relay	361	(2)
Signalling channels	363	(2)
Interlock protective schemes	365	(2)
Reyrolle interlock protective scheme	365	(1)
Modern schemes	365	(2)
Features of phase-comparison protective schemes	367	(5)
The phase displacements of line currents	368	(1)
The production of comparison signals	368	(1)
The comparison process	369	(2)
Comparison signals	371	(1)
Signalling equipment	371	(1)
Starting relays	372	(1)
Current transformers	372	(1)
Phase comparison schemes	372	(9)
Telephase protective schemes	373	(7)
Contraphase protective schemes	380	(1)
Other schemes	381	(1)
Auto-reclosing	381	(2)
The future	383	(2)
References	383	(2)
Distance-type protective schemes for overhead lines and cables	385	(54)
Historical background	386	(1)
The behaviour of overhead lines	387	(6)
The input impedance of a short single-phase line	387	(3)
The input impedance of a long single-phase line	390	(2)
The input impedances of a three-phase line	392	(1)
Impedance measurement	393	(10)
Relays dependent on the magnitude of impedance	393	(2)
Relay characteristics	395	(5)
The effects of system transients	400	(3)
Basic schemes	403	(16)
Application to three-phase lines	405	(1)
The detection of faults close to the input ends of lines	406	(1)
The settings of impedance-measuring relays	407	(9)
The operating times of relays	416	(2)
Relay performance standards	418	(1)
Conditions when a healthy line is affected by asynchronous system operation	419	(3)
Schemes applied in the past	422	(1)
Present-day schemes	423	(2)
Optimho static-distance protection schemes	423	(1)
Distance protection relay 7SL32	424	(1)
The duplicate protection of transmission lines	425	(1)
The protection of feeder transformers	426	(1)
The protection of cables	427	(1)
The setting of distance type schemes	427	(1)
Accelerated clearance of faults near the ends of lines	428	(1)
The protection of teed lines	429	(1)
The protection of series-compensated lines	430	(4)
The future	434	(5)
References	436	(1)
Further reading	437	(2)
Ultra-high-speed schemes for the protection of long transmission lines	439	(40)
Introduction	439	(1)
Historical background	440	(1)
Travelling waves	441	(15)
Initial waves on d. c. lines when short-circuits occur	441	(2)
Initial waves on ideal single-phase a. c. lines when short-circuits occur	443	(1)
Initial waves on ideal lines when resistive faults occur	444	(1)
The effects of line resistance and leakage conductance	444	(1)
Later travelling waves resulting from reflections	445	(7)
Travelling waves on three-phase lines	452	(4)
Protective schemes which detect travelling waves	456	(18)
Directional-comparison schemes	457	(11)
Schemes which determine the positions of faults	468	(6)
The application of ultra-high-speed relays to series-compensated lines	474	(2)
The future	476	(3)
References	477	(1)
Further reading	478	(1)
Digital communications	479	(22)
Introduction and historical background	479	(1)
Basic communication principles	479	(6)
Basic theorems	481	(2)
Basic structure of transmission networks	483	(2)
Transmission media and interfaces	485	(4)
Transmission media	485	(2)
Interfaces for protection and communication	487	(2)
Communication systems and protocols	489	(10)
The encoding of data	489	(4)
Multiplexing	493	(1)
Error detection	494	(2)
Open systems interconnection (OSI) model	496	(2)
Message structure and protocols	498	(1)
Electromagnetic compatibility	498	(1)
The future	499	(2)
References	499	(1)
Further reading	500	(1)
Digital signal processing (DSP) and protection	501	(24)
Introduction and historical background	501	(1)
Impact of DSP on protection	501	(2)
Hardware and software environments	503	(10)
Principles of digital signal processing (DSP)	513	(10)
General DSP principles	513	(6)
DSP algorithms in protection	519	(4)
The future	523	(2)
References	523	(2)
New relaying concepts	525	(30)
Introduction	525	(1)
Expert systems	526	(3)
Fuzzy logic	529	(4)
Artificial neural networks	533	(6)
Adaptive relaying	539	(2)
Integrated protection	541	(5)
The Global Positioning System (GPS)	546	(1)
Genetic algorithms and simulated annealing	547	(1)
Flexible AC Transmission Systems (FACTS)	548	(2)
Embedded generation	550	(1)
The future	550	(5)
References	551	(4)
Appendix A The testing and application of power-system protective equipment	555	(14)
A.1 Performance requirements	555	(1)
A.2 Testing of protective devices and equipment	556	(11)
A.2.1 Fuselinks	556	(3)
A.2.2 Current and voltage transformers	559	(1)
A.2.3 The testing of relays	560	(1)
A.2.4 The testing of protective schemes	561	(6)
Automatic testing of relays and protective schemes	567	(2)
References	568	(1)
Appendix B Percentage and per-unit quantities	569	(6)
Appendix C Transformations of three-phase quantities	575	(8)
C.1 Voltage, current and impedance transformation	575	(2)
C.2 Transformation into symmetrical components	577	(2)
C.3 Other transformations	579	(4)
References	581	(2)
Appendix D The determination of power-system behaviour using symmetrical components	583	(16)
D.1 Sequence impedances	583	(3)
D.1.1 Three-phase synchronous machines	583	(2)
D.1.2 Transformers	585	(1)
D.1.3 Overhead lines and cables	585	(1)
D.1.4 The effects of physical asymmetry	586	(1)
D.2 Sequence networks	586	(6)
D.2.1 Earthing of neutral points	586	(2)
D.2.2 Transformer connections	588	(4)
D.3 The interconnection of sequence networks	592	(3)
D.3.1 Balanced three-phase normal or fault conditions	592	(1)
D.3.2 Conditions when a phase-to-phase fault is present	592	(2)
D.3.3 Conditions when a single phase to earth fault is present	594	(1)
D.3.4 Impedances used in sequence networks	595	(1)
D.4 Numerical example	595	(4)
D.4.1 Short-circuit between phases `b' and `c' and earth	597	(1)
D.4.2 Short-circuit between phase `a' and earth	597	(1)
Reference	597	(1)
Concluding remarks	598	(1)
Index	599