The Thyristor based Hybrid Multiterminal HVDC System

In the multiterminal high voltage dc current (MTDC) transmission system, the line commutated converter (LCC) MTDC was capable of achieving high power rating with low cost and low losses. By far, there were two types of LCC MTDC studied in the world, i.e. parallel MTDC and series MTDC. Both of these two types had respective pros and cons in terms of economic and technique. In the paper, a new kind of thyristor based hybrid MTDC system was presented, which consists of both parallel and series LCC converter stations. The structures and application scenarios were explained. The New control strategies were proposed for the hybrid MTDC system, and the control methods were illustrated. The system operation characteristics were analyzed under different situations. Finally, a simulation model was established to verify the hybrid MTDC system and the proposed control method.