Optimal Power Flow in Hybrid AC/DC Distribution Network Considering Different Control Strategies of VSC Stations

The current research of optimal power flow (OPF) in the AC/DC distribution network mainly considers the modeling of active management equipment. It seldom takes account of the influence of the operation loss of converter stations of voltage source converter (VSC) and their control strategies. On the basis of controlling the active management equipment of AC distribution networks and the steady operation model of VSC converter stations, this paper constructs the mathematical model of OPF for AC/DC hybrid distribution network with multi-terminal flexible interconnection under the condition of satisfying the safe operation constraints of AC/DC distribution networks and converter stations. The control parameters of VSC operation and the active management equipment are taken as decision variables. The AC/DC network loss including the exact active power loss of converter stations is taken as the target function. The alternating iterative power flow algorithm for hybrid AC/DC networks and dual particle swarm optimization algorithm are used to establish and solve the model. Finally, a case study based on the modified IEEE33 system with multi-terminal flexible interconnection is carried out. The influence of different VSC control strategies and power flow optimization methods on the OPF results is analyzed. The result shows that the AC/DC network loss can be effectively reduced after considering the optimization of VSC control parameters and the proposed model has good practicability and good convergence.