Dynamic performance of embedded HVDC with frequency control strategy

An embedded HVDC system is a HVDC link connected in parallel with an AC transmission line or a mashed AC system. This paper proposes a control strategy cooperating with conventional d-q vector control for embedded HVDC system. The novel control method employs frequency features at two terminal stations to eliminate power oscillation. Dynamic simulation models are constructed in PSCAD platform to compare the transient stability of the proposed strategy with the conventional d-q vector control. According to the simulation results, the average Critical Clearing Time after contingencies is improved by 22.93% when equipped with the proposed frequency control method.