1、Instrument transformers Part 100: Guidance for application of current transformers in power system protection PD IEC/TR 61869-100:2017 BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06National foreword This Published Document is the UK implementation of IEC/TR 61869-
2、 100:2017. The UK participation in its preparation was entrusted to Technical Committee PEL/38, Instrument transformers. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a c
3、ontract. Users are responsible for its correct application. The British Standards Institution 2017. Published by BSI Standards Limited 2017 ISBN 978 0 580 84959 6 ICS 17.220.20 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document was published und
4、er the authority of the Standards Policy and Strategy Committee on 28 February 2017. Amendments/corrigenda issued since publication Date Text affected PUBLISHED DOCUMENT PD IEC/TR 61869-100:2017 IEC TR 61869-100 Edition 1.0 2017-01 TECHNICAL REPORT Instrument transformers Part 100: Guidance for appl
5、ication of current transformers in power system protection INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 17.220.20 ISBN 978-2-8322-3808-0 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. colour
6、 inside PD IEC/TR 61869-100:2017 2 IEC TR 61869-100:2017 IEC 2017 CONTENTS FOREWORD . 7 INTRODUCTION . 9 1 Scope 10 2 Normative references 10 3 Terms and definitions and abbreviations 10 3.1 Terms and definitions 10 3.2 Index of abbreviations . 12 4 Responsibilities in the current transformer design
7、 process. 14 4.1 History 14 4.2 Subdivision of the current transformer design process 14 5 Basic theoretical equations for transient designing 15 5.1 Electrical circuit 15 5.1.1 General . 15 5.1.2 Current transformer . 18 5.2 Transient behaviour 20 5.2.1 General . 20 5.2.2 Fault inception angle . 22
8、 5.2.3 Differential equation 23 6 Duty cycles 25 6.1 Duty cycle C O . 25 6.1.1 General . 25 6.1.2 Fault inception angle . 27 6.1.3 Transient factor K tfand transient dimensioning factor K td. 28 6.1.4 Reduction of asymmetry by definition of the minimum current inception angle . 50 6.2 Duty cycle C O
9、 C O 53 6.2.1 General . 53 6.2.2 Case A:No saturation occurs until t . 54 6.2.3 Case B:Saturation occurs between t aland t . 56 6.3 Summary 58 7 Determination of the transient dimensioning factor K tdby numerical calculation 61 7.1 General . 61 7.2 Basic circuit 61 7.3 Algorithm 62 7.4 Calculation m
10、ethod . 63 7.5 Reference examples . 64 8 Core saturation and remanence . 69 8.1 Saturation definition for common practice . 69 8.1.1 General . 69 8.1.2 Definition of the saturation flux in the preceding standard IEC 60044-1 69 8.1.3 Definition of the saturation flux in IEC 61869-2 71 8.1.4 Approach
11、“5 % Factor 5” . 72 8.2 Gapped cores versus non-gapped cores . 73 8.3 Possible causes of remanence 75 9 Practical recommendations 79 9.1 Accuracy hazard in case various PR class definitions for the same core . 79 PD IEC/TR 61869-100:2017IEC TR 61869-100:2017 IEC 2017 3 9.2 Limitation of the phase di
12、splacement and of the secondary loop time constant T sby the transient dimensioning factor K tdfor TPY cores 79 10 Relations between the various types of classes . 80 10.1 Overview. 80 10.2 Calculation of e.m.f. at limiting conditions . 80 10.3 Calculation of the exciting (or magnetizing) current at
13、 limiting conditions 81 10.4 Examples 81 10.5 Minimum requirements for class specification . 82 10.6 Replacing a non-gapped core by a gapped core 82 11 Protection functions and correct CT specification 83 11.1 General . 83 11.2 General application recommendations 83 11.2.1 Protection functions and a
14、ppropriate classes . 83 11.2.2 Correct CT designing in the past and today . 85 11.3 Overcurrent protection: ANSI code: (50/51/50N/51N/67/67N); IEC symbol: I . 87 11.3.1 Exposition 87 11.3.2 Recommendation . 89 11.3.3 Example 89 11.4 Distance protection: ANSI codes: 21/21N, IEC code: Z 89 11.4.1 Expo
15、sition 89 11.4.2 Recommendations . 91 11.4.3 Examples. 91 11.5 Differential protection 98 11.5.1 Exposition 98 11.5.2 General recommendations . 99 11.5.3 Transformer differential protection (87T) 99 11.5.4 Busbar protection: Ansi codes (87B) 104 11.5.5 Line differential protection: ANSI codes (87L)
16、(Low impedance) 107 11.5.6 High impedance differential protection . 109 Annex A (informative) Duty cycle C O software code. 128 Annex B (informative) Software code for numerical calculation of K td130 Bibliography 135 Figure 1 Definition of the fault inception angle . 12 Figure 2 Components of prote
17、ction circuit 16 Figure 3 Entire electrical circuit 17 Figure 4 Primary short circuit current . 18 Figure 5 Non-linear flux of L ct19 Figure 6 Linearized magnetizing inductance of a current transformer . 20 Figure 7 Simulated short circuit behaviour with non-linear model . 21 Figure 8 Three-phase sh
18、ort circuit behaviour . 23 Figure 9 Composition of flux 24 Figure 10 Short circuit current for two different fault inception angles 26 Figure 11 maxas the curve of the highest flux values 26 Figure 12 Primary current curves for the 4 cases for 50 Hz and = 70 . 27 Figure 13 Four significant cases of
19、short circuit currents with impact on magnetic saturation of current transformers . 28 PD IEC/TR 61869-100:2017 4 IEC TR 61869-100:2017 IEC 2017 Figure 14 Relevant time ranges for calculation of transient factor 31 Figure 15 Occurrence of the first flux peak depending on T p, at 50 Hz . 32 Figure 16
20、 Worst-case angle tf,max as function of T pand t al. 33 Figure 17 Worst-case fault inception angle tf,maxas function of T pand t al. 34 Figure 18 K tf,maxcalculated with worst-case fault inception angle max34 Figure 19 Polar diagram with K tf,maxand tf,max. 35 Figure 20 Determination of K tfin time
21、range 1 . 40 Figure 21 Primary current curves for 50Hz, T p= 1 ms, max = 166 for t al= 2 ms . 41 Figure 22 worst-case fault inception angles for 50Hz, T p= 50 ms and T s= 61 ms . 42 Figure 23 transient factor for different time ranges . 43 Figure 24 K tfin all time ranges for T s= 61 ms at 50 Hz wit
22、h t alas parameter 44 Figure 25 Zoom of Figure 24 44 Figure 26 Primary current for a short primary time constant . 45 Figure 27 K tfvalues for a short primary time constant 46 Figure 28 Short circuit currents for various fault inception angles . 47 Figure 29 Transient factors for various fault incep
23、tion angles (example) 48 Figure 30 Worst-case fault inception angles for each time step (example for 50 Hz) 48 Figure 31 Primary current for two different fault inception angles (example for 16,67 Hz) 49 Figure 32 Transient factors for various fault inception angles (example for 16,67 Hz) 50 Figure
24、33 Worst-case fault inception angles for every time step (example for 16,67 Hz) 50 Figure 34 Fault occurrence according to Warrington 51 Figure 35 estimated distribution of faults over several years 52 Figure 36 Transient factor K tfcalculated with various fault inception angles 53 Figure 37 Flux co
25、urse in a C-O-C-O cycle of a non-gapped core 54 Figure 38 Typical flux curve in a C-O-C-O cycle of a gapped core, with higher flux in the second energization 55 Figure 39 Flux curve in a C-O-C-O cycle of a gapped core, with higher flux in the first energization . 56 Figure 40 Flux curve in a C-O-C-O
26、 cycle with saturation allowed . 57 Figure 41 Core saturation used to reduce the peak flux value 58 Figure 42 Curves overview for transient designing . 59 Figure 43 Basic circuit diagram for numerical calculation of K td. 62 Figure 44 K tdcalculation for C-O cycle 64 Figure 45 K tdcalculation for C-
27、O-C-O cycle without core saturation in the first cycle . 65 Figure 46 K tdcalculation for C-O-C-O cycle considering core saturation in the first cycle . 66 Figure 47 K tdcalculation for C-O-C-O cycle with reduced asymmetry 67 Figure 48 K tdcalculation for C-O-C-O cycle with short t aland t al68 Figu
28、re 49 K tdcalculation for C-O-C-O cycle for a non-gapped core . 69 Figure 50 Comparison of the saturation definitions according to IEC 60044-1 and according to IEC 61869-2 . 70 Figure 51 Remanence factor K raccording to the previous definition IEC 60044-1 71 PD IEC/TR 61869-100:2017IEC TR 61869-100:
29、2017 IEC 2017 5 Figure 52 Determination of saturation and remanence flux using the DC method for a gapped core 72 Figure 53 Determination of saturation and remanence flux using DC method for a non-gapped core . 72 Figure 54 CT secondary currents as fault records of arc furnace transformer . 76 Figur
30、e 55 4-wire connection . 77 Figure 56 CT secondary currents as fault records in the second fault of auto reclosure 78 Figure 57 Application of instantaneous/time-delay overcurrent relay (ANSI codes 50/51) with definite time characteristic 88 Figure 58 Time-delay overcurrent relay, time characteristi
31、cs 88 Figure 59 CT specification example, time overcurrent 89 Figure 60 Distance protection, principle (time distance diagram) 90 Figure 61 Distance protection, principle (R/X diagram) . 91 Figure 62 CT Designing example, distance protection 92 Figure 63 Primary current with C-O-C-O duty cycle 96 Fi
32、gure 64 Transient factor K tfwith its envelope curve K tfp. 96 Figure 65 Transient factor K tffor CT class TPY with saturation in the first fault . 97 Figure 66 Transient factor K tffor CT class TPZ with saturation in the first fault 97 Figure 67 Transient factor K tffor CT class TPX . 98 Figure 68
33、Differential protection, principle 99 Figure 69 Transformer differential protection, faults . 100 Figure 70 Transformer differential protection 101 Figure 71 Busbar protection, external fault . 104 Figure 72 Simulated currents of a current transformer for bus bar differential protection . 107 Figure
34、 73 CT designing for a simple line with two ends 108 Figure 74 Differential protection realized with a simple electromechanical relay . 110 Figure 75 High impedance protection principle . 111 Figure 76 Phasor diagram for external faults 112 Figure 77 Phasor diagram for internal faults . 113 Figure 7
35、8 Magnetizing curve of CT. 114 Figure 79 Single-line diagram of busbar and high impedance differential protection . 117 Figure 80 Currents at the fault location (primary values) 119 Figure 81 Primary currents through CTs, scaled to CT secondary side . 120 Figure 82 CT secondary currents . 120 Figure
36、 83 Differential voltage . 121 Figure 84 Differential current and r.m.s. filter signal . 121 Figure 85 Currents at the fault location (primary values) 122 Figure 86 Primary currents through CTs, scaled to CT secondary side . 122 Figure 87 CT secondary currents . 123 Figure 88 Differential voltage .
37、123 Figure 89 Differential current and r.m.s. filtered signal . 124 Figure 90 Currents at the fault location (primary values) 124 Figure 91 Primary currents through CTs, scaled to CT secondary side . 125 PD IEC/TR 61869-100:2017 6 IEC TR 61869-100:2017 IEC 2017 Figure 92 CT secondary currents . 125
38、Figure 93 Differential voltage . 126 Figure 94 Differential current and r.m.s. filtered signal . 126 Figure 95 Differential voltage without varistor limitation 127 Table 1 Four significant cases of short circuit current inception angles 27 Table 2 Equation overview for transient designing . 60 Table
39、 3 Comparison of saturation point definitions . 73 Table 4 Measured remanence factors 74 Table 5 Various PR class definitions for the same core 79 Table 6 e.m.f. definitions 80 Table 7 Conversion of e.m.f. values . 80 Table 8 Conversion of dimensioning factors . 81 Table 9 Definitions of limiting cu
40、rrent . 81 Table 10 Minimum requirements for class specification 82 Table 11 Effect of gapped and non-gapped cores 83 Table 12 Application recommendations 84 Table 13 Calculation results of the overdimensioning of a TPY core 103 Table 14 Calculation results of overdimensioning as PX core . 103 Table
41、 15 Calculation scheme for line differential protection 109 Table 16 Busbar protection scheme with two incoming feeders 117 PD IEC/TR 61869-100:2017IEC TR 61869-100:2017 IEC 2017 7 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ INSTRUMENT TRANSFORMERS Part 100: Guidance for application of current trans
42、formers in power system protection FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all question
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