Research on VSC-LVDC with DC Energy Storage to Improve the Stability of Microgrid Connected to Grid Operation

Abstract

In order to improve stability of the microgrid operation connected to distribute network, the power flow fluctuations are smoothed. In this paper, a kind of flexible interconnection interface was studied in this paper, based on voltage source converter low voltage direct current(VSC-LVDC) containing energy storage. According to the mathematical model of VSC-LVDC and battery, a dual vector decoupling three-loop control strategy consisted of stages charging is proposed, and the battery charging and discharging switch control is offered, for charging and discharging of the energy storage, the bidirectional power transmission and suppressing power fluctuations. A simulation model is built that microgrid connected to distribute network using the flexible interconnection interface, and the conditions of power fluctuation, battery charging and discharging switch and the short-circuit fault at the microgrid side AC bus are simulated. The simulation results show that the control strategy effectively suppresses the power fluctuations of point of common coupling(PCC), guarantee the stability of the power flow.