Adaptive control strategy of four-leg active power filter with LCL grid filter

This paper presents an indirect adaptive self-tuning regulator for a four-leg active power filter with a high order grid filter which is used for reactive power and unbalanced and harmonic currents. The proposed scheme can guarantee a good performance in the presence of large signal changes in the operating point, uncertainty of the LCL filter components and effect of imperfect modeling. Also a decoupling factor is used for improving the accuracy of the control scheme. The switching of the converter is performed using indirect control scheme which control the grid currents instead of the converter currents. The simulation results demonstrate the effectiveness of the proposed method.