Tài liệu liên quan đến PLC (Programmable Logic Controller) thường cung cấp kiến thức và hướng dẫn về việc thiết kế, lập trình và vận hành các hệ thống điều khiển tự động sử dụng PLC. Nó bao gồm các khía cạnh sau: Giới thiệu về PLC: Tài liệu sẽ cung cấp một cái nhìn tổng quan về PLC, bao gồm lịch sử, nguyên lý hoạt động và ứng dụng của PLC trong các lĩnh vực khác nhau như công nghiệp, hệ thống tự động hóa và điều khiển quy trình. Kiến thức cơ bản về PLC: Tài liệu sẽ giới thiệu các thành phần cơ bản của một PLC, bao gồm vi xử lý, bộ nhớ, các đầu vào và đầu ra, giao diện ngườimáy và các giao thức truyền thông. Lập trình PLC: Tài liệu sẽ cung cấp hướng dẫn về ngôn ngữ lập trình PLC phổ biến như ladder logic, structured text, function block diagram và các ngôn ngữ lập trình khác. Nó sẽ đề cập đến các phương pháp và công cụ lập trình, quy tắc lập trình và các lệnh điều khiển cơ bản. Thiết kế và triển khai hệ thống PLC: Tài liệu sẽ đề cập đến quy trình thiết kế hệ thống PLC, từ phân tích yêu cầu, thiết kế phần cứng, lập trình, kiểm thử đến triển khai và vận hành hệ thống. Các chủ đề nâng cao: Tài liệu có thể bao gồm các chủ đề nâng cao như mạng lưới PLC, giao tiếp với các thiết bị ngoại vi, kiểm soát đa trạng thái, xử lý tín hiệu analog, và các ứng dụng đặc biệt khác của PLC.
PO'WER SYSTEM PROTECTION Volume 1: Principles and components Edited by The Electricity Training Association Volume 2: Systems and methods Edited by The Electricity Training Association Volume 3: Application Edited by The Electricity Training Association Volume 4: Digital protection and signalling Edited by The Electricity Training Association The Institution of Electrical Engineers CuuDuongThanCong.com https://fb.com/tailieudientucntt Published by: The Institution of Electrical Engineers, London, United Kingdom First published 1969 by Macdonald & Co (Publishers) Limited © 1969; The Electricity Council Revised edition 1981 by Peter Peregrinus Limited on behalf of the Institution of Electrical Engineers @ 1981: The Electricity Council Reprinted with minor corrections 1986 Reprinted 1990 Second revised edition 1995 by the Institution of Electrical Engineers ¢ 1998: Electricity Association Services Limited Reprinted 1997 This publication is copyright under the Berne Convention and the Universal Copyright Convention All rights reserved Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act, 1988, this publication may be reproduced, stored or transmitted, in any forms or by any means, only with the prior permission in writing of the copyright holder and publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency, Inquiries concerning reproduction outside those terms should be sent to the publishers at the undermentioned address: The Institution of Electrical Engineers, Michael Faraday House, Six Hills Way, Stevenage, Harts SG1 2AY, United Kingdom While the editor and the publishers believe that the information and guidance given in this work is correct, all parties must rely upon their own skill and judgment when making use of it Neither the editor nor the publishers assume any liability to anyone for any loss or damage caused by any error or omission in the work, whether such error or omission is the result of negligence or any other cause Any and all such liability is disclaimed The moral right of the authors to be identified as authors of this work has been asserted by them in accordance with the Copyright, Designs and Patents Act 1988 British Library Cataloguing in Publication Data A CIP catalogue record for this book is available from the British Library ISBN 85296 834 Printed in the United Kingdom at the UniversityPress, Cambridge CuuDuongThanCong.com https://fb.com/tailieudientucntt Published by: The Institution of Electrical Engineers, London, United Kingdom First published 1969 by Macdonald & Co (Publishers) Limited © 1969: The Electricity Council Revised edition 1981 by Peter Peregrinus Limited on behalf of the Institution of Electrical Engineers © 1981: The Electricity Council Reprinted with minor corrections 1986 Reprinted 1990 Second revised edition 1995 by the Institution of Electrical Engineers © 1995: Electricity Association Services Limited This publication is copyright under the Berne Convention and the Universal Copyright Convention All rights reserved Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act, 1988, this publication may be reproduced, stored or transmitted, in any forms or by any means, only with the prior permission in writing of the copyright holder and publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency Inquiries concerning reproduction outside those terms should be sent to the publishers at the undermentioned address: The Institution of Electrical Engineers, Michael Faraday House, Six Hills Way, Stevenage, Herts SG1 2AY, United Kingdom While the editor and the publishers believe that the information and guidance given in this work is correct, all parties must rely upon their own skill and judgment when making use of it Neither the editor nor the publishers assume any liability to anyone for any loss or damage caused by any error or omission in the work, whether such error or omission is the result of negligence or any other cause Any and all such liability is disclaimed The moral right of the authors to be identified as authors of this work has been asserted by them in accordance with the Copyright, Designs and Patents Act 1988 British Library Cataloguing in Publication Data A CIP catalogue record for this book is available from the British Library ISBN 85296 836 Printed in United Kingdom at the University Press, Cambridge CuuDuongThanCong.com https://fb.com/tailieudientucntt Published by: The Institution of Electrical Engineers, London, United Kingdom First published 1969 by Macdonald & Co (Publishers) Limited © 1969: The Electricity Council Revised edition 1981 by Peter Peregrinus Limited on behalf of the Institution of Electrical Engineers © 1981: The Electricity Council Reprinted with minor corrections 1986 Reprinted 1990 Second revised edition 1995 by the Institution of Electrical Engineers © 1995: Electricity Association Services Limited Reprinted 1997 This publication is copyright under the Berne Convention and the Universal Copyright Convention All rights reserved Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act, 1988, this publication may be reproduced, stored or transmitted, in any forms or by any means, only with the prior permission in writing of the copyright holder and publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency Inquiries concerning reproduction outside those terms should be sent to the publishers at the undermentioned address: The Institution of Electrical Engineers, Michael Faraday House, Six Hills Way, Stevenage, Herts SG1 2AY, United Kingdom While the editor and the publishers believe that the information and guidance given in this work is correct, all parties must rely upon their own skill and judgment when making use of it Neither the editor nor the publishers assume any liability to anyone for any loss or damage caused by any error or omission in the work, whether such error or omission is the result of negligence or any other cause Any and all such liability is disclaimed The moral right of the authors to be identified as authors of this work has been asserted by them in accordance with the Copyright, Designs and Patents Act 1988 Bdtish Library Cataloguing in Publication Data A CIP catalogue record for this book is available from the British Library ISBN 85296 837 X Printed in the United Kingdom at the University Press, Cambridge CuuDuongThanCong.com https://fb.com/tailieudientucntt Published by: The Institution of Electrical Engineers, London, United Kingdom © 1995: Electricity Association Services Limited Reprinted 1997, 2005 This publication is copyright under the Berne Convention and the Universal Copyright Convention All rights reserved Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act, 1988, this publication may be reproduced, stored or transmitted, in any forms or by any means, only with the prior permission in writing of the copyright holder and publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency Inquiries concerning reproduction outside those terms should be sent to the publishers at the undermentioned address: The Institution of Electrical Engineers, Michael Faraday House, Six Hills Way, Stevenage, Herts SG1 2AY, United Kingdom While the editor and the publishers believe that the information and guidance given in this work is correct, all parties must rely upon their own skill and judgment when making use of it Neither the editor nor the publishers assume any liability to anyone for any loss or damage caused by any error or omission in the work, whether such error or omission is the result of negligence or any other cause Any and all such liability is disclaimed The moral right of the authors to be identified as authors of this work has been asserted by them in accordance with the Copyright, Designs and Patents Act 1988 British Library Cataloguing in Publication Data A CIP catalogue record for this book is available from the British Library ISBN 85296 838 Printed In Great BrlUan at the University Press, Cambridge CuuDuongThanCong.com https://fb.com/tailieudientucntt Contents Foreword xiv Chapter authors xvi Editorial panel xvii Protection symbols used in circuit diagrams XVIII ~°° Role of protection M.Kaufmann and G.S.H.Jarrett 1.1 Introduction 1.1.1 General considerations 1.1.2 Role of protection in a power station 1.2 System 1.2.1 1.2.2 1.2.3 1.3 System earthing 1.3.1 Neutral-earthing methods 1.3.2 Special cases of resistance earthing 7 I0 1.4 Faults 1.4.1 1.4.2 1.4.3 I0 I0 II 12 and substation layout System layout Substation layout (electrical) Current transformer location Faults and other abnormalities Nature and causes of faults Fault statistics 3 1.5 Basic terms used in protection 15 1.6 Necessity for back-up protection 16 1.7 Economic considerations 1.7 I General 1.7.2 Distribution systems 1.7.3 Transmission systems 18 18 19 19 CuuDuongThanCong.com https://fb.com/tailieudientucntt Conten~ 1,8 Bibliography 20 Protection principles and components H.S.Petch and J.Rushton 21 2,1 Fundamental principles 2.1.1 Methods of discrimination 2.1.2 Derivation of relaying quantities 2.1.3 Combined overcurrent and earth fault relays 2.1.4 Derivation of a representative single-phase quantity from a three-phase system 21 21 30 33 2,2 Components of protection Relays 2,2.1 Current transformers 2,2.2 Voltage transforming devices 2.2.3 Capacitor dividers 2.2.4 H.F capacitor couplers 2.2.5 Line traps 2.2.6 Circuit-breakers 2.2.7 Tripping and other auxiliary supplies 2.2.8 Fuses, small wiring, terminals and test links 2.2.9 2,2.10 Pilot circuits 37 37 37 38 39 39 40 41 42 44 47 2,3 Consideration of the protection problem 48 2,4 Bibliography 52 Fault calculations J.H.Naylor 53 3,1 Introduction 3.1.1 Purpose of fault calculation 3.1.2 Types of fault 3.1.3 Factors affecting fault severity 3.1.4 Methods of fault calculation 53 53 54 58 59 3,2 Basic principles of network analysis 3.2.1 Fundamental network laws 3.2.2 Mesh-current analysis 3.2.3 Nodal-voltage analysis 3,2.4 Application of mesh-current and nodal-voltage analysis 3,2.5 Network theorems and reduction formulas 60 60 65 66 68 69 3,3 Calculations of balanced fault conditions 3,3.1 Single-phase representation 3.3.2 Use of a common voltage base Representation of nominal-ratio transformer circuits 3.3.3 3.3.4 Representation of off-nominal-ratio transformer circuits 3.3.5 Transformer phase-shifts 3.3.6 Representation of synchronous machines 3,3.7 Use of per-unit and per-cent values 3,3.8 Fault-calculation procedure 3.3.9 Example 3.3.10 Example 77 77 81 87 94 95 98 104 108 110 115 CuuDuongThanCong.com https://fb.com/tailieudientucntt 33 Contenta 3.4 Calculation of unbalanced fault conditions Symmetrical components 3.4.1 Phase-sequence networks and impedances 3.4.2 Phase-sequence equivalent circuits 3.4.3 Analysis of short-circuit conditions 3A.4 Effect of fault impedance 3.4.5 Analysis of open-circuit conditions 3.4.6 Transformer phase-shifts 3.4.7 Fauit-calculation procedure 3.4.8 Example 3.4.9 3.4.10 Example 3.4.11 Example 3.4.12 Example 126 126 129 134 153 168 173 178 182 182 186 189 198 3.5 Calculation of simuRaneons fault conditions 3.5.1 Sequence networks 3.5.2 Cross-country earth-fauR 3.5.3 Sequence network interconnections 3.5.4 Example 3.5.5 Example 202 202 204 206 210 213 3.6 Practical network analysis 3.6.1 Network analysers 3.6.1.1 A.C.analyser 3.6.1.2 D.C.analyser 3.6.2 Digital-computer analysis 3.6.3 Transient analysts 217 217 220 221 22! 222 3.7 Winding faults 3.7.1 General considerations 3.7.2 Generator-winding faults 3.7.3 Transformer-winding faults 223 223 223 228 3.8 Appendixes 3.8.1 Representation of off-nominal-ratio transformers 3.8.2 Effects of overhead-fine asymmetry 230 230 242 3.9 Bibliography 245 Protective transformers N.Ashton and EJ.MeUor 247 4.1 General I I Introduction 1.2 Basictransformer principles 247 247 247 4.2 Steady-state theory of current transformers 4.2.1 Equivalent circuit, vector diagram, errors 4.2.2 Influence of the core, magnetic materials, and magnetisation curves 4.2.3 Single-turn primary current transformers 4.2.4 Flux leakage 4.2.5 Balancing windings and eddy-current shielding 4.2.6 Open-circuit secondary voltage 248 248 CuuDuongThanCong.com https://fb.com/tailieudientucntt 250 253 253 25~ 258 Contents 4.2.7 4.2.8 Secondary currents, borders and connecting lead resistance Test windings 258 259 Current transformers for protection Saturation of the core and ratio on overcurrents BS 3938 4.3.1 Trip-coil operation 4,3.2 Overcurrent-relay operation 4,3.3 Earth-fault relays with inverse-time characteristics 4,3.4 Relay settings and primary operating currents 4.3.5 Current transformers for balanced differential protective 4.3.6 schemes Simple transient-state theory 4.3.7 259 259 260 260 261 261 4.4 Construction of current transformers 4.4.1 Basic types 4.4.2 Forms of cores 4.4.3 Windings and insulation 4.4.4 High-voltage current transformers 267 267 269 270 272 4.S Testing 4.5.1 4.5.2 4.5.3 4.5.4 274 274 276 276 4.3 4.5.5 4.5.6 of current transformers Error measurements Turns ratio tests Exciting current Current transformers for balanced differential protective schemes Polarity Insulation tests 262 264 277 277 277 4.6 Voltage-transformer theory 4.6.1 Electromagnetic-type voltage transformers 4.6.2 Capacitor-type voltage transformers 4.6.3 Burdens and lead resistances 278 278 279 283 4.7 Voltage transformers for protection 4.7.1 Electromagnetic type, categories, residual voltages 4.7.2 Capacitor type 285 285 287 4,8 Construction of voltage transformers 4.8.1 Electromagnetic type 4.8.2 Cascade type 4.8.3 Capacitor type 4.8.4 Capacitor divider voltage sensor 4,8.5 Voltage transformers for SF6 metalclad switchgear 293 293 300 302 302 303 4.9 Fusing and protection of voltage transformers 304 4,10 Testing 4,10.1 4.10.2 4.10.3 4.10.4 304 304 305 305 305 4,11 Bibliography CuuDuongThanCong.com of voltage transformers Error measurements Core losses Insulation tests Polarity 306 https://fb.com/tailieudientucntt Contents Fuses H W Turner and C Turner 307 5.1 Introduction 5.1.1 Definition of a fuse 5.1.2 Definition of a fuselink 5.1.3 Categories of fuse 307 307 307 307 5.2 Fuse design 5.2.1 Powder-filled cartridge fuse 5.2.1.1 High-voltage powder-filled fuses 5.2.2 Miniature fuselink 5.2.3 Semi-enclosed fuse 5.2.4 Expulsion fuse 5.2.5 Other fuse developments 311 311 313 314 315 316 316 5.3 Mechanism of fuse operation 5.3.1 Operation on small overcurrents 5.3.2 Operation on large overcurrents 5.3,3 Operation on intermediate overcurrents 5.3.4 Operation on pulsed loading 5.3.5 Fulgarite (roping) 5.3.6 Typical oscillograms 318 318 319 320 322 322 323 5.4 Peak arc voltage 323 5.5 Time/current characteristic and factors affecting it 5.5.1 Definitions related to the operation of fuses at the small overcurrent region of the time/current characteristic and the assignment of current rating 326 Discrimination 5.6.1 Discrimination between fuselinks 5.6.2 Discrimination between h.v and l.v fuses and circuitbreaking devices 331 331 5.7 Testing of fuses 5.7.1 Fuse testing on a.c 5.7.1.1 Breaking capacity 5.7.1.2 Other parameters tested 334 334 334 336 5.8 Bibliography 336 Relays J' W.Hodgkiss 339 6.1 Introduction 339 6.2 Principal types of relays 6.2.1 Attracted-armature relays 6.2.2 Moving-coil relays 6.2.3 Induction relays 6.2.4 Thermal relays 6.2.5 Motor-operated relays 6.2.6 Gas- and oil-operated relays (Buchholz relays) 341 341 351 357 372 378 378 5.6 CuuDuongThanCong.com https://fb.com/tailieudientucntt 330 333 Protection signalling 511 correct recognition of a sequence of a predetermined number Accurate timing equipment in the receiver will reject spurious pulses of incorrect length, even if they coincide with the operating frequencies fl and/'2 By adjusting the number of pulses in the operate signal sequence, it is possible to vary the degree of security provided by the equipment Since the I"1//'2 pulse sequence is continuous, signalling in the presence of random noise in the communication channel is improved Intertripping equipment using standard data transmission 'modems' (modulator and demodulator) which are single-frequency shift, equal mark/space ratio, have also been designed These systems use a 12-bit code Frequenciesfl and f2 transmit a data word continuously in the quiescent condition to monitor the communication channel and a considerable proportion of the terminal equipment This 12-bit code can be made unique to a particular intertripping equipment, thus allowing an alarm condition to be generated if two otherwise similar intertripping equipments were to be accidentally transposed On the command to operate, the 12-bit 'quiescent' code is disconnected, bits of frequency f~ are transmitted to reset the receiving equipment followed by the continuous transmission of a 12-bit 'operate' code The 12-bit 'operate' code is deliberately chosen to be dissimilar to the corresponding 'quiescent' code Security against maloperation is provided by the rejection of all received codes other than the 12-bit 'operate' code assigned to the particular equipment Continuous transmission of the 'operate' code assists in signalling in the presence of random noise in the communication channel Failure to recognise either the 'operate' code or the 'quiescent' code by the receiving equipment causes a 'system fail' alarm to be generated A double-frequency-shift intertripping system is shown in Fig 7.5.3.3H The system normally transmits two voice-frequency signals je~ and fa in the quiescent state To produce operation fl is changed to f2 and f3 is changed to f4 simultaneously Security against maloperation is provided by the simultaneous frequency change, and in these systems it is arranged for the presence of a single guard frequency to block both trip channels Another double-frequency shift system uses 'point-on-wave' signalling techniques where the precise point of frequency change is predetermined By the use of timing devices in the intertripping equipment receiver, it is therefore possible to detect with considerable accuracy a genuine change from the 'quiescent' to the 'operate' condition In the system shown, the operate tones f2 and f4 are transmitted continuously for as long as the operate condition is maintained, but in some systems, arrangements are made in the transmitting circuit for a constant repetition of the transition from 'quiescent' to 'operate' condition for as long as the command to operate is present Failure to receive frequencies fl or/'3 in the quiescent state results in the generation of a 'system fail alarm' by the receiving equipment It is important to note that in double-frequency shift systems the frequency-shift channels are arranged to shift such that the frequencies of adjacent channels converge (as shown in Fig 7.5.3.3H) or diverge, in the change from the guard to the operate state This is to avoid maloperation that can occur where frequency translation in carrier telephone links takes place via a common oscillator and where, if the above precautions were not taken, oscillator drift could result in both 'guard' CuuDuongThanCong.com https://fb.com/tailieudientucntt 512 fl Protection signalling