Combined Wind-BESS-Assisted Thermal Unit Primary Frequency Modulation Strategy

Large-scale wind power integration significantly affects power system frequency stability, making it an increasingly important research topic. This paper proposes a coordinated control strategy for primary frequency modulation, involving a doubly-fed induction generator (DFIG) and battery energy storage system (BESS). By establishing a coupling model of DFIG rotor rotational energy and virtual inertia, an integrated control strategy with synergistic response of inertia control and droop control is proposed to break through the defects of a single control strategy for traditional wind turbine frequency modulation. A state-of-charge (SOC)-based adaptive regulation mechanism is developed for the BESS, and a coordinated control strategy based on SOC-adaptive droop and inertia coefficients is designed to optimize the power output and improve the operational lifetime of the BESS. The model constructed based on MATLAB/Simulink is verified by several sets of simulation experiments to show that the control strategy proposed in this paper can effectively reduce the system frequency deviation by 47.8%. In addition, the control strategy proposed in this paper can reduce the output of thermal power and wind turbines, effectively improve the system frequency stability, and extend the service life of each part of the system.