Small-Signal Stability Modeling and Analysis of Power System with Integrated Photovoltaic Energy Storage

As the current penetration of renewable energy generation in the power system is gradually increasing, small disturbances in the power system are inevitable. Combining the grid-connected photovoltaic (PV) system with energy storage is an effective way to improve the immunity of the new-type power system. This paper firstly uses an eigenvalue-based small-signal stability analysis method to model the small-signal of the grid-connected PV-storage system. Then calculate the eigenvalues of the state matrix to summarize the oscillation modes and main participating variables in different modes. The system stability is judged by observing the trace of the eigenvalues with varied grid strength and controller parameters. The results show that there are nine oscillation modes of the system. The grid strength is the main factor affecting the system’s stability. When grid strength is weakened, the system stability decreases. Due to the occurrence of medium frequency oscillations, the system is destabilized under the very weak grid. The controller parameter is the second factor affecting the system stability, and appropriate adjustment of the phase-locked loop (PLL) proportional factors can improve the system stability of small disturbances. The state variables related to energy storage will become the dominant part affecting the stability of the PV-storage system.