AC-side Fault Crossing Optimization Control Strategy for VSC-HVDC

Flexible HVDC transmission based on modular multi-level converter (MMC) has broad prospects for development in large-scale wind power grid-connected. The fault-crossing capability of MMC in AC side fault under wind power access is studied, a fault-crossing control method for AC side based on predictive direct power control is proposed. A predictive power model and a circulating current predictive control model are established through a new instantaneous power theory. Compared with the traditional power control theory, the insertion of sub-modules into the lower arm is a control variable, which can realize the synchronous control of reactive power and active power without calculating the power compensation term. The hierarchical predictive control model is adopted without introducing the weight factor. The control structure is simple and accurate. Finally, the simulation model is established through the simulation platform of Matlab/Simulink. The simulation results show that the proposed model can achieve the synchronous control of reactive power and active power without calculating the power compensation term. The control strategy can achieve effective control in the case of steady state and unbalanced network voltage.