一种抑制过电流并抵御LCC-HVDC系统换相失败的非线性电阻子模块控制方案

To resist commutation failure (CF) in line-commutated converter-based high-voltage direct current (LCC-HVDC) systems, this paper proposes a topology of nonlinear resistance submodules (NRSMs). In the first power cycle after a fault, according to specific control logic, NRSMs put the metal oxide arresters (MOAs) into the system through the integrated gate-commutated thyristors (IGCTs), which can not only suppress DC overcurrent but also assist in commutation. NRSMs can effectively reduce the requirements for other auxiliary commutation devices to completely eliminate CF. In this paper, the occurrence of DC overcurrent and its influencing factors are analyzed at first. Based on this, the working principle and the coordinated control strategy of NRSMs are introduced. Then, the relationship between the arrester voltage and the DC overcurrent and the extinction angle is studied. To verify the effectiveness of the NRSM control strategy, PSCAD simulation results under different fault states are given, which shows that NRSMs can significantly suppress DC overcurrent and cooperate with other auxiliary devices to eliminate CF.