基于限流器和断路器配合的柔性直流输电故障保护策略

Flexible DC Transmission Fault Protection Strategy Based on Coordination of Current Limiter and Circuit Breaker

由于柔性直流电网具有低阻尼的特点,直流侧发生短路后故障电流上升速度极快。若不能限制电流上升速率、及时切除故障,会造成设备损坏,同时将会造成换流站闭锁,影响供电可靠性。本文通过分析直流系统故障清除条件,提出了基于电阻型超导限流器和混合式直流断路器配合的故障处理策略。参考实际工程参数,在PSCAD/EMTDC仿真平台搭建了双端伪双极VSC-HVDC系统,验证了所提保护策略能够在发生极间短路故障时快速隔离故障线路,并实现换流站的故障穿越,对故障清除后系统恢复具有积极意义。

Due to the low damping characteristics of the flexible DC grid, the fault current rises extremely rapidly after a short circuit occurs on the DC side. If the rate of current rise cannot be limited and the fault cannot be removed, the damage of equipment and the block of converter station will occur, which will affect the reliability of the power supply. Based on the analysis of DC system fault clearing conditions, this paper proposes a fault handling strategy based on the combination of resistive superconducting current limiter and hybrid DC circuit breaker. With reference to actual engineering parameters, a two-terminal pseudo-bipolar VSC-HVDC system is built on the PSCAD/EMTDC simulation platform. It is proved that the proposed protection strategy can isolate the fault line quickly and realize the fault crossing of the converter station, which is of positive significance to the restoration of the system after the fault being cleared.