Research on photovoltaic grid-connected system with energy storage based on improved energy management strategy

This paper proposes an improved energy management strategy for simultaneous power management of the photovoltaic grid-connected system with energy storage. Based on the DC bus voltage and the working states of grid, the PV system is divided into six working modes by the proposed energy management strategy. This can avoid the effect of grid failure on PV system, and achieve the optimal utilization of light energy. Firstly, based on the management strategy, a photovoltaic grid-connected system with energy storage units is constructed in this paper, which is consisted of the photovoltaic units, energy storage units, an inverter and the local loads. Then, the working conditions of different modes and the switching process between modes are described in detail. Finally, the control method of the photovoltaic system is given, so that the system can be switched smoothly between different working modes. The simulation results show that, through the improved energy management strategy, the PV grid-connected system with energy storage units is capable of ensuring normal running of the local loads when the grid fails and achieving system stability when the local loads are changed.