换流站桥差保护误动机理及基于互近似熵的闭锁新方案

Mal-operation mechanism and novel cross-approximate entropy based blocking scheme of bridge differential protection in converter stations

针对高压直流输电工程在运行过程中多次发生换流站桥差保护误动的情况,对换流站桥差保护误动机理开展研究。利用PSCAD/EMTDC搭建特高压直流输电仿真模型,对空载合闸和外部故障切除情况下桥差保护误动行为进行仿真分析,揭示其误动原因,并提出一种基于互近似熵算法的桥差保护防误动闭锁新方案,以防止因电流互感器(TA)传变异常引起的桥差保护误动作。仿真结果表明所提闭锁方案在励磁涌流和恢复性涌流情况下能够有效防止桥差保护误动作。

Aiming at the situation that multiple mal-operation events of bridge differential protection in converter stations occurred during the operation process of HVDC transmission projects, the mal-operation mecha-nism is researched. The UHVDC transmission simulation model is built in PSCAD/EMTDC, the mal-operation behaviors of bridge differential protection in the cases of no-load closing and external fault removal are simulated and analyzed to reveal themal-operation reasons, and a novel blocking scheme for preventing mal-operation of bridge differential protection based on cross-approximate entropy algorithm is proposed, which can prevent mal-operation of bridge differential protection caused by CT transformation abnormality. The simulative results show that the proposed scheme can effectively prevent mal-operation of bridge diffe-rential protection in the cases of magnetizing and recovery inrush current.