With the increase of proportion for PV, the characteristics as three-phase unbalance of distribution network are more and more prominent. Considering the unbalance property and the flexible reactive power support of PV inverters, the dynamic reactive power optimization (DRPO) method which optimizes the PV reactive power output based on global information is proposed to improve the economy and safety of network operation. The traditional “Q-V” droop control method is improved and the flexible “Q-V” droop control model of PV inverter without dead zone is established. Moreover, based on three-phase unbalance power flow model, the DRPO model which aims to reduce power losses is constructed. The linearization method and stochastic programming (SP) theory are used to transfer the DRPO model into deterministic convex optimization model which is easy to solve. Finally, the effectiveness of the proposed model and method are verified by the numerical simulations on the IEEE 123-node test system.

Three-phase unbalanced distribution network,photovoltaic,flexible reactive power support,dynamic reactive power optimization