Research on resonance mechanism and damping method of grid-connected inverter with LCL filter for battery energy storage system

To improve the stability of the grid-connected of the battery energy storage system, Firstly, a mathematical model of the inverter with current feedback control on the inverter side is established in a two-phase static frame. Secondly, based on the inverter model, the resonance mechanism of the inverter grid-connected system is studied. By means of the combination of the digital control and passive damping, a novel method of inverter output admittance reshaping is proposed afterward. The procedure of the novel method is given as well as the exemplary applications. The validity of the inverter-grid resonance mechanism and the effectiveness of the novel method to damp the resonance is identified by simulation results.