首页|传统直流换流阀动态关断模型及对换相失败评估准确性的影响

传统直流换流阀动态关断模型及对换相失败评估准确性的影响

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传统高压直流输电系统逆变侧发生交流故障时，换流阀晶闸管的关断特性会随正向电流、电流过零点下降率和结温等外部条件的改变而动态变化，而现有研究多将晶闸管视为理想器件或仅保留一定的关断裕度，很可能会导致换相失败判别结果不准确等问题。为掌握晶闸管关断特性的动态变化对换相失败评估准确性的影响，首先从理论上分析晶闸管关断特性影响换相过程的机理;然后考虑多维因素综合作用下的晶闸管关断特性，提出并建立换流阀动态关断模型，通过与SABER中晶闸管详细物理模型对比验证关断模型的正确性;最后在PSCAD/EMTDC中分别对比采用换流阀动态关断模型和采用传统模型的基于电网换相换流器的高压直流输电(line commutated converter based high voltage direct current，LCC-HVDC)在单相和三相故障情况下的换相失败判别结果。结果表明，采用传统模型可能会在未发生换相失败时判断为已发生换相失败，对系统提出更高的关断要求，还可能会导致换相失败发生时刻判断不准确的问题;采用所提出的换流阀动态关断模型，能够使换相失败的判别结果更加准确。
Thyristor Valve Dynamic Turnoff Model for LCC-HVDC and Its Impact on Commutation Failure Assessment Accuracy
The turn-off characteristics of converter valve thyristor will change with outer circuit condition dynamically such as forward current,current zero-crossing declined rate and thyristor junction,when an AC fault occurs at the inverter side of a line-commutated converter-based high voltage direct current(LCC-HVDC)system.However,regarding the thyristor as an ideal switching device or only remaining fixed margin for it as most research may cause inaccuracy of commutation failure judgement.To clarify the influence of variation of thyristor turn-off characteristics on precision of the commutation failure judgement,this paper analyzes how thyristor turn-off characteristics affect commutation process in theory.Then,it proposes and builds a converter dynamic turn-off model with proved correctness by comparing with the thyristor's detailed physical model in SABER.Finally,the simulation results of the converter dynamic turn-off model with the traditional model under the single and three-phase earth faults in PSCAD/EMTDC are compared separately.The results show that using a fixed turn-off margin model is considered as preventing commutation failures,which could lead to high turn-off demands on the system.However,in certain scenarios,it may also result in inaccuracies in the timing of commutation failures.By adopting the proposed converter dynamic model,the prediction of commutation failures can be made more precise.

line commutated converter based high voltage direct current(LCC-HVDC)thyristor valvethyristor turn-off characteristicsconverter dynamic turn-off modelcommutation failure

江帆、郭春义、丁银香、高冲

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新能源电力系统全国重点实验室(华北电力大学),北京市 昌平区 102206

中国电力科学研究院有限公司,北京市 海淀区 100192

基于电网换相换流器的高压直流输电 晶闸管换流阀 晶闸管关断特性 换流阀动态关断模型 换相失败

国家重点研发计划项目

2021YFB2400900

2024

10.13334/j.0258-8013.pcsee.230943

中国电机工程学报
中国电机工程学会

中国电机工程学报

CSTPCD北大核心
影响因子：2.712
ISSN：0258-8013
年,卷(期)：2024.44(21)