An Internal Voltage Robust Control of Battery Energy Storage System for Suppressing Wideband Harmonics in VF Control-Based Islanded Microgrids

In constant voltage and frequency (VF) control-based islanded microgrids, the nonlinear load can easily cause voltage harmonics and degrade the power quality of the islanded microgrids. First, the mechanism and characteristics of the voltage distortion are analyzed based on the impedance method. Due to the large internal impedance of the energy storage inverter, the harmonic voltage generated on the internal resistance is relatively large, leading to the microgrids' voltage distortion. To address this issue, this article proposes an internal voltage robust control of battery energy storage system for suppressing the wideband harmonics, which can achieve the voltage stability control of islanded microgrids under load disturbance. Compared with the traditional energy storage inverter, the impedance amplitude of the improved inverter is relatively small, which is more like an ideal voltage source. Under the nonlinear load and pulse load disturbances, the voltage of the islanded microgrids controlled by the proposed control strategy can operate normally. Finally, the effectiveness of the proposed control strategy and the above theoretical analysis is verified by simulation and experiment.