Design and Control of Modular Multilevel Converter Integrated With Energy Consumption Circuit Used in Offshore Wind Power VSC-HVDC System

VSC-HVDC has become an attractive choice for the grid connection of large-scale offshore wind power generation system. The operation under receiving-end AC side short-circuit fault condition should be paid attention. The DC bus is prone to overvoltage due to the the excess energy accumulated on DC transmission line, affecting the safety and reliability of the whole system during the fault. In this paper, a novel topology of MMC integrated with energy consumption circuit is proposed, and the circuit design and control strategy are also introduced and analyzed. The added energy consumption circuit has a simple close-loop controller, and has little impacts on the original MMC operation and performance. Finally the accuracy of analysis and effectiveness of FRT control are verified by a MATLAB/Simulink model.