A combined AC-DC control strategy for commutation failure mitigation

With the development and maturity of DC technology, it will have great potential in modern active distribution network, smart grids, micro grids, and energy internets. Commutation Failure (CF) is one of the critical problems for DC system operations. The existing control strategies to mitigate CF focus mainly on the control of DC converters, such as directly controlling the firing angle of the inverter valves. A novel Combined AC-DC control method to mitigate CF is proposed in this study, which integrates the commutation failure preventive (CFPREV) control and DC current prediction and SVC phase separation control modules together. Simulation studies are carried out on the MATLAB/Simulink platform, the results show that the proposed combined AC-DC control strategy can effectively mitigate CFs and improve the dynamic performance of the HVDC system.