MRAC method and its application to single phase shunt active power filter

The model reference adaptive control (MRAC) method wass proposed to reduce the harmonic current of grid and to improve power quality in the single phase shunt active power filter (APF). Since the model of APF system was nonlinear, and it was not easy to design the controller to achieve the perfect effect of suppressing the harmonic current of grid, the proposed method of extended linearization was firstly applied to obtain the approximate linearization model of the nonlinear system. Furthermore, by using the Lyapunov Krasovskii functional theory, an adaptive control law wais designed to guarantee the asymptotic output tracking of the system and to ensure the global asymptotic stability of the system. Simulation and experimental results show that the APF equipment using the proposed control method has the superior dynamic compensation performance of suppressing the harmonic components of grid current through comparing with conventional PI control, and the grid current is nearly in the same phase as source voltage.