Unified iterative power flow algorithm of AC/DC networks incorporating hybrid HVDC

Hybrid HVDC is a novel topology which combines advantages of both line commuted converter (LCC) and the voltage source converter (VSC). In this paper, the power flow model of hybrid HVDC, which contains mathematical models of LCC and VSC stations, is built first, concerning the control modes of hybrid HVDC and converter transformers ratios. Based on that, the unified iterative power flow calculation algorithm of hybrid AC/DC networks incorporating hybrid HVDC is proposed. The algorithm is suitable for hybrid HVDC embedded in an AC grid or connecting different asynchronous AC grids. Finally, the accuracy of the mathematical model and the validity of the proposed algorithm are verified by a case study.