HVDC换流站换流器桥差保护动作行为的仿真分析

Simulation analysis of action behaviors for bridge differential protection in HVDC converter station

对高压直流输电工程在运行中发生的换流站换流器桥差保护异常动作情况进行阐述与分析。基于PSCAD/EMTDC平台建模,在多种故障情况下对桥差保护动作情况进行仿真分析,在此基础上,剖析换流器桥差保护异常动作的原因。PSCAD仿真结果表明:△桥、Y桥阀侧电流互感器(TA)采样值存在故障电流差值,桥差保护才能正确动作;若故障电流同时流入或同时不流入△桥、Y桥TA,桥差保护将发生拒动。

The abnormal action situation on converter bridge differential protection of the HVDC （high voltage direct current） system were explained and analyzed in this paper. Based on the PSCAD/EMTDC model, the simulation on action behavior of the bridge differential protection was carried out under various fault conditions and the reasons for the abnormal action of bridge differential protection were analyzed. The PSCAD simulation results show that a fault current difference exists between the sampled values of current transformers （TA） on the △ bridge and Y bridge of the valve side, the bridge differential protection can operate correctly. When the fault current flows simultaneously, or doesn＇t flow, into the TAs on the △ bridge and Y bridge of the valve side, the bridge differential protection will maloperation.