针对柔性直流输电系统运行时线路发生短路故障,识别故障线路所在以及解决电网短路电流快 速上升产生的过能量难题,提出利用输电线两端加装电感的电压信息作为故障判据的线路保护方法。 该方 法利用短路发生后电流上升,使得电感感应电压的极性发生变化的原理确定故障线路并启动直流断路器,此 为主保护;主保护拒动时,启动后备保护,通过检测电感感应电压是否超过整定值以确定故障线路并断开,利 用设计的 BPI(Buffer Protection Identification)将线路中的过电流缓冲吸收以保护整个故障线路;在 PSCAD/ EMTDC 上搭建三端环状柔性直流输电系统,模拟线路发生单极短路、双极短路,仿真结果表明:线路发生故 障时,主保护可以快速识别故障线路所在并切开线路,提高了故障识别的灵敏性,主保护拒动时,后备保护启 动识别故障线路,提高了线路整个保护方法的可靠性。
Aiming at the problem of identifying the fault line and solving the over-energy caused by the rapid rise of short-circuit current when flexible DC transmission system is in operation a line protection method using the voltage information of the inductor installed at both ends of the transmission line as the fault criterion is proposed. This method determines the fault line and starts the DC circuit breaker by using the change of inductance induced voltage polarity caused by the rise of current after the occurrence of short circuit. This is main protection. When the main protection is rejected the backup protection is started to determine the fault line and disconnect the line by detecting the inductance induced voltage exceeding the setting value. Finally BPI Buffer Protection Identification is used to buffer and absorb the over-current to protect the whole fault line. A three-terminal ring flexible DC transmission system was built on PSCAD/ EMTDC to simulate the occurrence of unipolar short circuit and bipolar short circuit. The simulation results show that the main protection can quickly identify the location of the fault line and cut the line when the fault occurs which improves the sensitivity of fault identification. When the main protection stops the backup protection can start to identify the fault line. The reliability of the whole protection method has been improved.
童 威.基于电压信息的 MMC 直流电网直流侧保护方案[J].重庆工商大学学报（自然科学版）,2022,39(6):112-117
TONG Wei. DC Side Protection Scheme of MMC DC Power Grid Based on Voltage Information[J]. Journal of Chongqing Technology and Business University(Natural Science Edition）,2022,39(6):112-117