Design and Simulation for the Control and Protection of Hybrid LCC-VSC MTDC System

The merit of line commutated converter (LCC) which has low cost and low loss, and the advantage of voltage source converter (VSC) in reactive power support and fault ride-through, are combined in the hybrid LCC-VSC voltage direct current (HVDC) transmission system. The multi-terminal HVDC (MTDC) system can provide more economical and more flexible power transmission modes. The combination of hybrid LCC-VSC and MTDC is promising in the future development of HVDC transmission. The configuration of hybrid LCC-VSC MTDC system is introduced. The control and protection for hybrid LCC-VSC MTDC system is investigated, focusing on the design scheme and the simulation. The functional laying, basic control modes, basic control strategies, protection zone and the feature of protection in this system are proposed. The simulation test systems of RTDS and PSACD/EMTDC are built based on the Wudongde (WDD) hybrid LCC-VSC MTDC project. The feasibility of the proposed design scheme is verified.