A Novel FRT Scheme Combining DC Side Voltage Limitation and AC Side Energy Dissipation for the Long-distance Renewable Energy VSC-HVDC Transmission System

Aiming at the existing fault ride through (FRT) schemes which is difficult to adapt to the large-scale, long-distance transmission of renewable energy via VSC-HVDC, this paper proposes a novel FRT scheme that combines DC side voltage limiting and AC side energy dissipation. Firstly, a MMC with short-term overvoltage limitation capability is adopted on the receiving-end DC side, and simultaneously an AC chopper is configured on the sending-end AC side. Moreover, a collaborative strategy is proposed, in which the voltage limiting module in the receiving-end MMC only operates for a few tens of milliseconds in the early stages of the fault, and the surplus power is mainly dissipated by the AC chopper. The voltage limiting module operates without the need for a water-cooling system and shares power supply and insulation framework with the MMC, greatly reducing the cost. Meanwhile, a design method for key parameters is proposed, and simulations of a ±800 kV/5000 MW system are conducted to verify the effectiveness of the proposed scheme.