中文摘要：

针对目前交直流混联电网交流过电压保护与直流系统控制保护策略之间缺乏有效配合的问题,以直流系统发生单极闭锁导致功率骤降为例,考虑交流滤波器的动作策略,分析了单极闭锁后交流侧无功功率、有功功率的变化特征,提出一种交直流混联系统自适应交流过电压保护新方案。该方案在直流系统单极闭锁等功率骤降情况下,综合考虑一次设备的耐压水平,在不改变原有交流保护动作特性的基础上,能够自适应调整过电压保护的时间定值,躲过交流滤波器组的切除时间,避免由于过电压保护误动带来的负荷损失;而当交流系统扰动引起过电压时,过电压保护能够按照原有的动作逻辑正确动作,保证设备安全。仿真结果表明,该方案加强了交流系统和直流系统继电保护之间的配合,对保证交直流系统稳定运行具有重要的意义。

英文摘要：

Aiming at problem of absence of effective coordination between AC side overvoltage protection and DC control strategy and taking DC system single pole blocking leading abrupt power reduction as example, this paper analyzes filter action strategy and change rate of active and reactive power respectively after single pole blocking failure. Then a new principle of an adaptive AC overvoltage protection is put forward. With single pole blocking in DC system, considering equipment insulation level, the proposed scheme can adaptively adjust overvoltage protection time settings without changing original protection characteristics. It can slid over filter clearing time and prevent load loss caused by AC overvoltage protection action. When overvoltage is caused by AC grid disturbance, it can operate correctly according to original logic and ensure equipment safety. Simulation results show that this new scheme can strengthen protective relay coordination between AC and DC systems, and thus of great importance in improving hybrid system stability.