Fault Ride-Through Strategy of LCC-MMC Hybrid Multi-Terminal UHVDC System

This paper investigates a hybrid multi-terminal Ultra-High Voltage Direct Current (UHVDC) transmission system, the rectifier adopts line commutated converter (LCC) and two inverters adopt hybrid modular multilevel converter (MMC). Considering the lack of practical experience in such hybrid UHVDC system, many technical problems remain to be solved. This paper mainly studies the AC fault and DC fault ride-through strategy, which are two crucial threats to the safe operation of hybrid multi-terminal UHVDC system. According to the particularity of hybrid multi-terminal UHVDC, a fault ride-though control strategy is proposed. Simulation and real-time experiment results have demonstrated the feasibility and validity of the proposed strategies. The study results can provide an indispensable technical support to the application of LCC-MMC hybrid multi-terminal UHVDC project.