Research on Frequency Regulation Strategy of DFIG-BESS System Based on Frequency Regulation Coefficient Adaptive Control

Abstract

At present, the combined frequency regulation of doubly-fed induction generator (DFIG) and battery energy storage system (BESS) is widely concerned. The fast frequency response control (FFRC), including droop control of DFIG and virtual inertia control of BESS, is beneficial to improve the frequency response capability of the power system. When the rotor speed (RS) of DFIG and the state of charge (SOC) of BESS are low, the FFRC cannot adjust its frequency regulation coefficient (FRC) according to the actual operating conditions of DFIG and BESS, which may reduce the RS and SOC to the minimum value, which is not conducive to the frequency safety of the power system. In view of the above problems, this paper proposes an adaptive control for the frequency regulation coefficient (FRCAC) of the DFIG augmented with BESS system (DFIG-BESS System), which multiplies the frequency regulation coefficient (FRC) of the FFRC by the frequency regulation factor (FRF) and reduces the FRF to reduce the FRC when the RS of DFIG and the SOC of BESS are low, so as to reduce the frequency regulation (FR) power of the DFIG-BESS System, which is conducive to restraining the RS of DFIG and the SOC of BESS from falling to the minimum value, which is beneficial to protect DFIG and BESS. A two-region simulation model of the power system is built in DIgSILENT, and the simulation results show that the FFRC significantly improves the frequency response capability of the DFIG-BESS System, and the FRCAC is beneficial to restrain the RS and SOC of the DFIG-BESS System from falling to the minimum value and improve the protection of the DFIG-BESS System.