Adaptive frequency regulation control strategy for flywheel energy storage coupled thermal power units based on optimal variational mode decomposition

As the proportion of renewable energy sources such as wind and solar power connected to the grid continues to increase, maintaining grid frequency stability faces severe challenges. Traditional thermal power units exhibit insufficient frequency regulation capabilities, necessitating the integration of rapid response resources like flywheel energy storage. This paper investigates the frequency regulation models of flywheels and thermal power units, proposes an improved frequency regulation command decomposition method, and designs an adaptive integrated control strategy for grid frequency characteristics and SOC (State of Charge) under various frequency regulation scenarios. This enables the flywheel-thermal power hybrid system to respond flexibly to grid frequency demands. Simulation results demonstrate that under step load conditions, this strategy reduces the maximum frequency deviation by 36.66% and shortens the steady-state regulation time by 33.44%. Under continuous load conditions, the standard deviation of frequency deviation decreases by over 5.03%, with significantly reduced output fluctuations in the thermal power unit. The proposed strategy not only effectively enhances system frequency stability but also alleviates the frequency regulation burden on thermal power units while ensuring the flywheel’s SOC remains within a safe range.