摘要
在基于环形直流电网的多端柔性直流输电系统中,极间短路故障严重影响系统的安全运行。虽然直流断路器可以迅速地隔离直流故障,但是残余过电流仍会构成威胁。残余过电流注入近故障端换流站,致使换流站触发过电压保护而脱网运行。此外,在直流断路器动作后,环网拓扑发生改变,直流潮流随之转移,需要考虑非故障线路的过载情况。针对上述问题,提出了一种加装在换流站出口处的辅助电路,通过控制辅助电路引导能量转移,消耗不平衡功率,从而提升系统的直流故障穿越能力;此外,通过调整换流站输送的有功功率,可以减轻非故障线路的过载情况,并且基于增强型自适应下垂控制策略,控制换流站在故障穿越期间尽快恢复功率平衡;最后,基于Matlab/Simulink搭建了四端环网MMC-MTDC系统的仿真模型,验证了所提直流故障穿越策略的有效性。
In MMC-MTDC systems,DC faults endanger the operation of power system.Although DC circuit breaker isolates DC faults in a short time,residual overcurrent still poses a threat,and the unbalanced power of DC grid will cause DC overvoltage.Moreover,after the DC circuit breaker trips,the topology and power flow of the DC power grid will change,which is concerned with overload of non-faulty lines and misoperation of the DC circuit breaker.In view of the above problems,the method of blocking the converter station and installing auxiliary circuits is proposed to achieve DC fault ride-through.By adjusting the active power delivered by the converter station,the overload of the non-fault line is reduced.Under the adaptive droop control strategy,the converter station is controlled to restore power balance as soon as possible under DC fault.Therefore,based on Matlab/Simulink,a four-terminal MMC-MTDC system simulation model is built to verify the effectiveness of the proposed strategy.
作者
周鑫
邱子鉴
刘晋
ZHOU Xin;QIU Zijian;LIU Jin(School of Electrical and Electronic Engineering,North China Electric Power University,Beijing 102206,China)
出处
《华北电力大学学报（自然科学版）》
CAS
北大核心
2021年第3期39-46,共8页
Journal of North China Electric Power University：Natural Science Edition
关键词
多端柔性直流输电系统
直流故障
故障穿越
直流断路器
辅助电路
multi-terminal direct current system
DC fault
fault ride through
DC circuit breaker
auxiliary circuit
