H∞ robust control of APF considering the parameter perturbation of the grid-connected reactor

Active power filter (APF) can effectively compensate the harmonic current in the power grid. As APF is a nonlinear, multivariable, strong coupling system, it brings complexity to the controller design. Thus, a mathematical model is proposed to make the control law expression be effective and simple. Since the parameter perturbation of the grid-connected reactor during the operation process affected by external uncertain factors, the harmonic compensation effect of APF would be unstable. Therefore, an H_∞ robust control strategy against the parameter fluctuations is proposed. Simulation results show that the proposed control strategy has better parameter robustness than PI control strategy. The approach also guarantees the accurate compensation and fast dynamic response of the APF.