Primary Frequency Modulation of Solar Photovoltaic-energy Storage Hybrid System Based on Virtual Synchronous Generator

Distributed photovoltaic could not respond to frequency deviation, and the photovoltaic modules, connected to the grid through the inverter, are non-rotating static component, which means that it does not have the rotary inertia of the synchronous generator. When distributed photovoltaic is connected to the grid in a dense manner, it will reduce the system inertia. Under the same boundary conditions, the system frequency may drop even lower. To solve this problem, this paper proposes to add energy storage system on the DC side to satisfy the frequency regulation requirements. By adopting the virtual synchronous generator control strategy, the solar photovoltaic-energy storage hybrid system is equivalent to a voltage source on the DC side. And it has similar characteristics to the synchronous generator on the AC side. This improves the stability of the external output power of photovoltaic, and also enables the distributed photovoltaic to respond to frequency deviation. the effectiveness of the proposed control strategy is verified in MATLAB/Simulink.