Study on transient shock suppression strategy for fault recovery on the alternating current side of the receiving end of a flexible system

With the continuous optimization of China's new energy industry, UHV technology has become an important means to solve the problem of uneven distribution of wind and solar energy resources. Flexible DC transmission technology based on modular multilevel converter (MMC) is gradually applied in new energy large-scale grid connection and islanding power supply because of its advantages such as flexible control and no phase change fault. However, when the flexible DC system is connected to a large-scale power grid, a short-circuit fault on the AC side of the converter station at the receiving end may trigger excess power on the DC side, and fluctuations in system parameters will occur during fault recovery, leading to overvoltage and overcurrent. Aiming at this problem, this paper proposes a transient impact suppression strategy based on the control and energy dissipation devices of the receiving end converter station, and verifies it through the Simulink/MATLAB platform, and the results show that the strategy can effectively suppress the transient fluctuations after the fault is lifted.