Reserach on VSG LVRT Control Strategy of Photovoltaic Storage Microgrid

To enable photovoltaic storage microgrid to support system frequency and voltage without disconnecting from power grid during power grid faults, an improved VSG low voltage ride through(LVRT) control strategy is proposed. Firstly, the transient characteristics of VSG are analyzed under short circuit fault. Secondly, the active power and reactive power loop are redesigned, the improved VSG control strategy is established. Meanwhile, short-circuit fault reference current is set to prevent the fault current from exceeding the limit. Finally, a simulation model of improved VSG LVRT control strategy is established for simulation tests. The test results show that improved VSG LVRT control strategy can not only achieve active power compensation to support power angle recovery during voltage sag fault, but also achieve reactive power compensation, effectively support voltage recovery, suppress voltage sags. Meanwhile, it has better effect of restraining short circuit current, to improve system transient stability. To further verify the feasibility of this method, it is applied to photovoltaic storage microgrid. The feasibility of this method is verified by setting up application scenarios for single-phase and three-phase short-circuit faults in the power grid.