Adaptive interval type2 fuzzy hysteresis-band current-controlled active power filter for power quality improvement

This paper presents a novel adaptive hysteresis current control based on interval type2 fuzzy logic for active power filter to eliminate harmonics and compensate for reactive power. A new method to generate reference compensating current for the fundamental active current component is also proposed using the recursive discrete Fourier transform. The switching frequency of the conventional fixed hysteresis band (HB) control during the fundamental period is varied; thus causing harmonic ripple of the load current. This problem can be solved using adaptive HB control strategy. In this study, a fuzzy logic controller is used for base control because of its advantages over other adaptive HB techniques, such as mathematical simplicity, ease in adding heuristic knowledge, and robust changes in system operating conditions. An interval type2 fuzzy-adaptive HB technique is utilized for the current control to enhance the switching signals produced by the voltage source inverter. Based on the supply voltage and the slope of the reference current, this controller changes the hysteresis bandwidth. To control the DC capacitor voltage, an interval type2 fuzzy logic based controller is developed. Simulation results of the shunt active power filter with an interval type2 fuzzy adaptive HB current controller are examined and compared with the conventional controller. The results verify the effectiveness of the proposed controller in reducing total harmonic distortion from 21.03% to 2.12% and reactive power from 2616 Var to 6.28Var.