A Modular Commutated Converter With DC Fault Ride-Through Capability for Overhead-Line-Based VSC-HVDC Application

Abstract

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VSC-HVDC systems based on overhead transmission lines suffer from transient DC short-current faults frequently, for which converters with DC-fault ride-through (DC-FRT) capability are required. This paper proposes a hybrid modular commutated converter (H-MCC) with DC-FRT capability. HMCC applies a hybrid DC switch to isolate fault lines and adopts an energy-absorption branch to facilitate rapid arc quenching. The control sequences and dynamic process of H-MCC during DC-FRT are analyzed in detail, deducing analytical model of electrical stress. On this basis, the parameter design methodology is presented, and a comprehensive comparison with the conventional hybrid MMC scheme shows that the proposed HMCC achieves notable improvements in power density, costeffectiveness, and operational efficiency. Finally, the feasibility of H-MCC is verified by simulation and experiment. The proposal offers a technically and economically attractive solution for power conversion in overhead-line-based VSC-HVDC systems.