A sequential power flow algorithm for AC/DC networks incorporating hybrid HVDC

Hybrid HVDC system combines the advantages of line commuted converter HVDC (LCC-HVDC) and voltage sourced converter HVDC (VSC-HVDC) and has become a popular trend for future grids. In this paper, the hybrid HVDC system, integrated in either a synchronous grid or connecting asynchronous grids, is introduced and studied. The LCC station model, VSC station model as well as the dc network model are established. The tap ratio of converter transformer is considered and its effect on HVDC is analyzed through case study. The control scheme of the hybrid HVDC system is proposed and the corresponding equation is developed. Based on this, a sequential iterative power flow calculation algorithm of AC/DC networks incorporating hybrid HVDC is proposed, and its validity and effectiveness are verified by case study.