A Control Strategy of Photovoltaic‐Storage–Assisted Frequency Modulation Based on Sliding Mode Controller

ABSTRACT High‐proportion photovoltaic (PV) grid‐connected systems are prone to frequency fluctuations and deterioration of power quality due to the randomness of output. Therefore, traditional PI control is difficult to cope with dynamic regulation requirements under complex working conditions. To improve the power quality of high‐penetration PV grid‐connected systems, this paper proposes a frequency modulation control strategy with PV and energy storage auxiliary based on a sliding mode controller. The strategy replaces the PI controller with an Integral sliding mode controller (ISMC), establishes a quantitative relationship between PV penetration and virtual synchronous generator (VSG) parameters, and enhances robustness. Furthermore, the strategy uses communication between PV clusters to generate a load shedding curve for the maximum power point (MPP) of PV, dynamically adjusting the load shedding rate. The PV array employs a variable step‐size voltage control algorithm to adaptively track the load shedding rate curve. A storage adaptive distribution strategy is designed to store the load‐shedding power in energy storage batteries, thus preventing resource waste caused by curtailing solar power. This control strategy can provide auxiliary frequency modulation services for virtual power plants under high PV penetration, improving the anti‐interference capability of high‐penetration PV grid‐connected systems.