Research on Subsynchronous Oscillation of Photovoltaic and Battery Storage Systems Integrated to Weak Grid

This paper investigates the subsynchronous oscillation of photovoltaic(PV) and battery storage systems integrated to weak grid. In order to analyze the subsynchronous oscillation of the systems, a small signal model of the PV and battery storage systems is established. Based on the model, the effects of control parameters of PV and battery storage systems on the sub-synchronous oscillation of the systems are investigated. Analysis results show that the subsynchronous oscillation are closely related with PV's DC voltage control(DVC) and battery storage system's PLL. It is found that with increase of PV DVC bandwidth, the subsynchronous oscillation frequency of the systems will increase first and then almost unchanged, which improves the stability of system. However, with increase of battery storage PLL bandwidth, the subsynchronous oscillation frequency first decreases and then increases, decreasing the stability of system. Finally, the time-domain model of PV and battery energy storage systems connected to the weak grid is built to verify the correctness of the analysis.