IEC 60071-12:2022 applies guidelines on the procedures for insulation co-ordination of line commutated converter (LCC) stations for high-voltage direct current (HVDC) project, whose aim is evaluating the overvoltage stresses on the converter station equipment subjected to combined DC, AC power frequency, harmonic and impulse voltages, and determining the specified withstand voltages for equipment. This document deals only with metal-oxide surge arresters, without gaps, which are used in modern HVDC converter stations. The criteria for determining the protective levels of series and\/or parallel combinations of surge arresters used to ensure optimal protection are also presented. Typical arrester protection schemes and stresses of arresters are presented. Annex A contains examples of insulation co-ordination for LCC HVDC converters which support the concepts described in the main text, and the basic analytical techniques used.<\/p>\n
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| 2<\/td>\n | undefined <\/td>\n<\/tr>\n | ||||||
| 5<\/td>\n | Annex ZA (normative)Normative references to international publicationswith their corresponding European publications <\/td>\n<\/tr>\n | ||||||
| 6<\/td>\n | Blank Page <\/td>\n<\/tr>\n | ||||||
| 7<\/td>\n | English CONTENTS <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | FOREWORD <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 1 Scope 2 Normative references 3 Terms, definitions, symbols and abbreviated terms 3.1 Terms and definition <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 3.2 Symbols and abbreviated terms 3.2.1 General 3.2.2 Subscripts 3.2.3 Letter symbols <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 3.2.4 Abbreviated terms 4 Typical LCC HVDC converter station schemes <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | Figures Figure 1 \u2013 Possible arrester locations ina pole with two 12-pulse converters in series <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 5 Voltages and overvoltages in service 5.1 Continuous operating voltages at various locations in the converter station Figure 2 \u2013 Possible arrester locations for a back-to-back converter station Tables Table 1 \u2013 Symbol description <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | Figure 3 \u2013 LCC HVDC converter station in a pole with one 12-pulse converter <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | Figure 4 \u2013 Continuous operating voltages at various locations(location identification according to Figure 3) <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | 5.2 Peak continuous operating voltage (PCOV) and crest continuous operating voltage (CCOV) <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | Figure 5 \u2013 Operating voltage of a valve arrester (V), rectifier operationand definition of PCOV and CCOV Figure 6 \u2013 Operating voltage of a mid-point arrester (M), rectifier operation Figure 7 \u2013 Operating voltage of a converter bus arrester (CB), rectifier operation <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | 5.3 Sources and types of overvoItages 5.4 Temporary overvoltage 5.4.1 General 5.4.2 Temporary overvoltage on the AC side <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | 5.4.3 Temporary overvoltages on the DC side 5.5 Slow-front overvoltages 5.5.1 General 5.5.2 Slow-front overvoltages on the AC side <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | 5.5.3 Slow-front overvoltages on the DC side 5.6 Fast-front, very-fast-front and steep-front overvoltages <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | 6 Arrester characteristics and stresses 6.1 Arrester characteristics <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | 6.2 Arrester specification <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | 6.3 Arrester stresses 6.3.1 General <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | 6.3.2 AC bus arrester (A) 6.3.3 AC filter arrester (FA) <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | 6.3.4 Transformer valve winding arresters (T) 6.3.5 Valve arrester (V) <\/td>\n<\/tr>\n | ||||||
| 33<\/td>\n | 6.3.6 Bridge arrester (B) 6.3.7 Converter unit arrester (C) <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | 6.3.8 Mid-point DC bus arrester (M) 6.3.9 Converter unit DC bus arrester (CB) <\/td>\n<\/tr>\n | ||||||
| 35<\/td>\n | 6.3.10 DC bus and DC line\/cable arrester (DB and DL\/DC) 6.3.11 Neutral bus arrester (E, EL, EM in Figure 3, EB, E1, EL, EM in Figure 1) <\/td>\n<\/tr>\n | ||||||
| 36<\/td>\n | 6.3.12 DC reactor arrester (DR) <\/td>\n<\/tr>\n | ||||||
| 37<\/td>\n | 6.3.13 DC filter arrester (FD) 6.3.14 Earth electrode station arrester 6.4 Protection strategy 6.4.1 General 6.4.2 Insulation directly protected by a single arrester 6.4.3 Insulation protected by more than one arrester in series <\/td>\n<\/tr>\n | ||||||
| 38<\/td>\n | 6.4.4 Valve side neutral point of transformers 6.4.5 Insulation between phase conductors of the converter transformer 6.4.6 Summary of protection strategy <\/td>\n<\/tr>\n | ||||||
| 39<\/td>\n | Table 2 \u2013 Arrester protection on the DC side: one 12-pulse converter (Figure 3) <\/td>\n<\/tr>\n | ||||||
| 40<\/td>\n | Table 3 \u2013 Arrester protection on the DC side: two 12-pulseconverters in series (Figure 1) <\/td>\n<\/tr>\n | ||||||
| 41<\/td>\n | 6.5 Summary of events and stresses Table 4 \u2013 Events stressing arresters: one 12-pulse converter (Figure 3) <\/td>\n<\/tr>\n | ||||||
| 42<\/td>\n | 7 Design procedure of insulation co-ordination 7.1 General Table 5 \u2013 Types of arrester stresses for different events:one 12-pulse converter (Figure 3) <\/td>\n<\/tr>\n | ||||||
| 43<\/td>\n | 7.2 Arrester requirements 7.3 Representative overvoltages (Urp) Table 6 \u2013 Arrester requirements <\/td>\n<\/tr>\n | ||||||
| 44<\/td>\n | Table 7 \u2013 Representative overvoltages and required withstand voltages <\/td>\n<\/tr>\n | ||||||
| 45<\/td>\n | 7.4 Determination of the co-ordination withstand voltages (Ucw) 7.5 Determination of the required withstand voltages (Urw) 7.6 Determination of the specified withstand voltage (Uw) 8 Study tools and system modelling 8.1 General 8.2 Study approach and tooIs <\/td>\n<\/tr>\n | ||||||
| 46<\/td>\n | 8.3 System details 8.3.1 Modelling and system representation <\/td>\n<\/tr>\n | ||||||
| 47<\/td>\n | Table 8 \u2013 Origin of overvoltages and associated frequency ranges <\/td>\n<\/tr>\n | ||||||
| 48<\/td>\n | 8.3.2 AC network and AC side of the LCC HVDC converter station Figure 8 \u2013 One pole of an LCC HVDC converter station <\/td>\n<\/tr>\n | ||||||
| 49<\/td>\n | 8.3.3 DC overhead line\/cable and earth electrode line details 8.3.4 DC side of an LCC HVDC converter station details <\/td>\n<\/tr>\n | ||||||
| 50<\/td>\n | Annex A (informative)Example of insulation co-ordination forLCC HVDC converter stations A.1 General A.2 Example for LCC HVDC converter station in a pole with one 12-pulse converter A.2.1 Arrester protective scheme A.2.2 Arrester stresses, protection and insulation levels A.2.2.1 General <\/td>\n<\/tr>\n | ||||||
| 51<\/td>\n | A.2.2.2 Slow-front overvoltages transferred from the AC side A.2.2.3 Earth fault between valve and upper bridge transformer bushing <\/td>\n<\/tr>\n | ||||||
| 55<\/td>\n | A.2.3 Transformer valve side withstand voltages A.2.3.1 Phase-to-phase A.2.3.2 Upper bridge transformer phase-to-earth (star) A.2.3.3 Lower bridge transformer phase-to-earth (delta) A.2.4 Air-insulated smoothing reactors withstand voltages A.2.4.1 Terminal-to-terminal slow-front overvoltages <\/td>\n<\/tr>\n | ||||||
| 56<\/td>\n | A.2.4.2 Terminal-to-earth <\/td>\n<\/tr>\n | ||||||
| 57<\/td>\n | A.2.5 Results Figure A.1 \u2013 AC and DC arresters (LCC HVDC converterstation in a pole with one 12-pulse converter) <\/td>\n<\/tr>\n | ||||||
| 58<\/td>\n | Figure A.2 \u2013 Valve arrester stresses for slow-front overvoltages from AC side Figure A.3 \u2013 Arrester V2 stress for slow-front overvoltage from AC side <\/td>\n<\/tr>\n | ||||||
| 59<\/td>\n | A.3 Example for LCC HVDC converter station in a pole with two 12-pulse converters in series A.3.1 Arrester protective scheme Figure A.4 \u2013 Valve arrester stresses for earth fault between valve and upper bridge transformer bushing Figure A.5 \u2013 Arrester V1 stress for earth fault between valve and upper bridge transformer bushing <\/td>\n<\/tr>\n | ||||||
| 60<\/td>\n | A.3.2 Arrester stresses, protection and insulation levels A.3.2.1 General <\/td>\n<\/tr>\n | ||||||
| 61<\/td>\n | A.3.2.2 Slow-front overvoltages transferred from the AC side A.3.2.3 Upper bridge transformer bushing to earth fault while lower 400 kV converter unit operating alone A.3.2.4 Earth fault between valve and upper bridge transformer bushing <\/td>\n<\/tr>\n | ||||||
| 64<\/td>\n | A.3.3 Transformer valve side withstand voltages A.3.3.1 Phase-to-phase <\/td>\n<\/tr>\n | ||||||
| 65<\/td>\n | A.3.3.2 HV bridge transformer phase-to-earth (star) A.3.3.3 HV bridge transformer neutral point (star) A.3.3.4 HV bridge transformer phase-to-earth (delta) A.3.3.5 LV bridge transformer phase-to-earth (star) A.3.3.6 LV bridge transformer phase-to-earth (delta) <\/td>\n<\/tr>\n | ||||||
| 66<\/td>\n | A.3.4 Smoothing reactor withstand voltages A.3.4.1 Pole line smoothing reactors A.3.4.2 Neutral bus smoothing reactors <\/td>\n<\/tr>\n | ||||||
| 67<\/td>\n | A.3.5 Results <\/td>\n<\/tr>\n | ||||||
| 68<\/td>\n | Figure A.6 \u2013 AC and DC arresters (LCC HVDC converter stationin a pole with two 12-pulse converters in series) <\/td>\n<\/tr>\n | ||||||
| 69<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Insulation co-ordination – Application guidelines for LCC HVDC converter stations<\/b><\/p>\n |