考虑直流断路器的MMC-HVDC系统直流电压保护误动分析

Analysis on Malfunction of MMC-HVDC DC Voltage Protection Consider DC Circuit Breaker Protection

随着柔性直流输电技术的不断发展以及直流断路器研究的不断突破,直流断路器的逐渐应用将对MMC-HVDC系统的继电保护产生重要的影响.在含直流断路器的MMC-HVDC交直流混合系统中,一些原本由交流断路器跳闸的直流侧故障将修改为动作于直流断路器跳闸.在此背景下,交流故障和直流故障时反映在直流侧的暂态响应具有相似性,可能造成直流保护发生误动.通过研究各种交、直流系统故障时直流系统的暂态响应,分析MMC-HVDC直流侧在交流系统故障和直流系统故障下的暂态响应的相似性,研究有可能造成的直流电压保护误动,并针对引起误动的保护特征给出避免保护误动的改进建议.在PSCAD/EMTDC仿真平台中,搭建含MMC-HVDC的交直流混合系统,仿真验证所作分析的正确性.

With the continuous development of flexible direct current transmission technology,and proliferatingbreakthroughs in the research of dc circuit breaker,the gradual application of dc circuit breaker will impact onthe relay protection of MMC-HVDC system. In MMC-HVDC ac / dc hybrid system with dc circuit breaker,somefaults will be cut changing from the dc side of the ac circuit breaker tripping for the action in the dc circuitbreaker tripping. Under this background,the ac failure and dc failure reflected in the transient response of thedc side has the similarity,may cause dc protection misoperation. In this paper,we study all kinds of ac and dcsystem fault transient response of the dc system,to analysis the similarity between MMC-HVDC dc side in theac system fault and dc system fault transient response,research the possibility to cause the dc voltage protectionmaloperation,and cause maloperation of the protection features avoid protection maloperation improvement sug-gestions are presented. Building MMC-HVDC ac / dc hybrid system in PSCAD/ EMTDC simulation platform,thesimulation verify the correctness of the analysis made.