Low-Voltage-Ride-Through (LVRT) Performance of an HVDC Transmission System Using two Modular Multilevel Double-Star Chopper-Cells (DSCC) Converters

This paper presents an intensive discussion on a long-distance high-voltage direct-current (HVDC) transmission system that combines two modular multilevel cascade converters based on double-star chopper cells (MMCC-DSCC) with dc power cables. Hereinafter, a single MMCC-DSCC is referred to as a DSCC converter or just as a DSCC for the sake of simplicity. The HVDC transmission system is required to provide low-voltage-ride-through (LVRT) capability to enhance transmission system availability. This paper proposes a new LVRT method without any direct information exchange between the two DSCC converters. The validity of the method is verified, using simulated waveforms from the software package of “PSCAD/EMTDC” and experimental waveforms from a three-phase 200-V, 400-Vdc, 10-kW, 50-Hz downscaled HVDC system with a set of 300-meter-long dc power cables.