Topology of a hybrid HVDC transmission system for wind power grid connection

Hybrid high voltage direct current (HVDC) system is a new topology consisting of a line commutated converter (LCC) and voltage source converter (VSC). It combines the advantages of LCC and VSC, and has a wide range of application prospects. It is necessary to study its operating characteristics, control strategy and failure characteristics which are different from that of LCC-HVDC system and/or VSC-HVDC system. This paper studies a hybrid HVDC system with rectifier using VSC while inverter using LCC technology. Simulation under normal and fault conditions are carried out, and the ability to reduce the impact of commutation failure and recovery time with different control strategies is compared using PSCAD/EMTDC. Furthermore, the optimal control strategy for this hybrid structure is proposed. © 2013 State Grid Electric Power Research Institute Press.