PLL less shunt active filter with direct current control for power quality conditioning

In this paper, a novel neural network based phase locked loop (PLL) less reference current computation method for active power filter (APF) control under non-ideal mains voltage conditions with different load condition is proposed. The neural network controller comprises two similar adaptive linear neurons (ADALINE), and it has been designed to extract fundamental frequency components from non-sinusoidal and unbalanced currents. The compensation process is based on sensing source currents only, without sensing source voltage and load currents, which gives more simplicity in control with less number of sensors. The APF realized by a current controlled IGBT based PWM-VSI bridges with a common dc bus capacitor. The proposed neural network compensation approach has been evaluated in simulations. The results show excellent performance, as well as robustness and usefulness under steady state and transient loading conditions.