The control strategy for Hybrid HVDC using voltage margin control and voltage dependent current order limiter control

Hybrid-HVDC is a new topology which is consisted of Line-Commutated-Converter (LCC) and Voltage Source Converter (VSC). It combines the advantages of LCC and VSC. Two topologies of Hybrid-HVDC were studied and found their application prospects. The structure which the rectifier station using VSC is suitable for connecting offshore wind farms, while the inverter station using VSC is suitable for supplying the passive network. The control strategy for Hybrid-HVDC is designed which introduce the voltage margin control and voltage dependent current order limiter control. The simulation of the Hybrid-HVDC which consists of a two level VSC converter and a bipolar12-pulsation converter is done in PSCAD. The designed structure can be run in monopole when DC fault occurs. The steady state characteristics and the fault conditions were studied. Furthermore, the optimal control strategy for this hybrid structure is selected.