(EN) The invention provides a method for calculating steady-state fault current of a modular multilevel converter (MMC). The method comprises the following steps: calculating direct-current side critical resistance values R < A >/B, R < B >/C and R < C >/D of the MMC according to a bridge arm inductance coefficient k and alternating-current side reactance X < ac > of the MMC; judging the working mode of the MMC according to the RA/B, the RB/C and the RC/D; parameter k, the Us, the Rdc and the direct current side critical resistance values RA/B, RB/C and RC/D respectively calculate steady-state direct current fault current and conduction overlapping angles in various working modes when the alternating current side resistance is not considered; and according to the direct currents and the conduction overlapping angles in various working modes, respectively calculating steady-state alternating current fault current amplitudes and phase angles in various working modes when the alternating current side resistance is not considered. And calculating the steady-state AC fault current amplitude and phase angle in various working modes when the AC side resistance is considered. According to the method, the fault currents of the alternating current side and the direct current side of the MMC fault steady-state stage can be obtained at the same time; the calculation precision is high, and an additional iterative algorithm is not needed; and the method can adapt to a scene with large alternating-current-side power grid damping.
(ZH) 本发明提供了一种模块化多电平换流器(MMC)的稳态故障电流的计算方法。该方法包括：根据MMC的桥臂电感系数k和交流侧电抗Xac计算出MMC的直流侧临界电阻值RA/B、RB/C和RC/D；根据RA/B、RB/C和RC/D判断MMC的工作模式；根据参数k,Us,Rdc和直流侧临界电阻值RA/B、RB/C和RC/D分别计算出不考虑交流侧电阻时的各种工作模式下稳态直流故障电流和导通重叠角，根据各种工作模式下的直流电流和导通重叠角，分别计算出不考虑交流侧电阻时各种工作模式下的稳态交流故障电流幅值和相角。进而计算出考虑交流侧电阻时各种工作模式下的稳态交流故障电流幅值和相角。本发明的方法能够同时获得MMC故障稳态阶段交流侧和直流侧的故障电流；计算精度高，不需要额外的迭代算法；能够适应交流侧电网阻尼较大的场景。
