A Novel Transient Stability Control Strategy for an AC/MTDC Grid Under $N-k$ Contingency Induced by Typhoon Extreme Weather

Due to the severe global warming, the frequency and intensity of typhoon extreme weather events have increased around the world. These events would cause serious $N-k$ contingency of coastal AC/multi-terminal high voltage DC (MTDC) power grid, resulting in a high possibility of transient instability. To address this problem, this article develops a novel two-stage resilient control strategy. In the first stage, an optimization model is established to obtain a control scheme that involves generator rescheduling, load shedding and MMC operation point adjustment after $N-k$ contingency. In the second stage, an active power modulation method of modular multi-level converters (MMC) based on the model predictive control algorithm is proposed to improve the transient stability of the coastal AC/MTDC grid. The proposed control strategy makes full use of the flexible control resources of MMC-MTDC, thereby increasing the transient stability margin of the coastal AC/MTDC grid. The effectiveness of the proposed strategy has been validated on an AC/MTDC power grid built on MATMTDC that is an open source software based on MATLAB. Simulation results demonstrate that the proposed two-stage resilience control strategy exhibits promising performance in enhancing the transient stability of the coastal AC/MTDC power system when suffering a typhoon event.