Improved Shunt Active Filter for Non-Ideal Grid Using Model Predictive and Sliding Mode Control

Abstract

Filters have become almost indispensable to counter the harmonics injection by the widely used power converters and other non-linear devices. Shunt active power filters (SAPF) controlled by direct power control (DPC) serve as a good option as they offer various advantages. The performance of the existing controllers deteriorates when the three-phase supply system deviates from its ideal situation of balanced and sinusoidal voltages. Unlike the existing methods, this work develops and employs a detailed and accurate system model based on the extended pq theory. With its proven high accuracy, the model predictive control (MPC) is used as the control algorithm for PWM generation. An in-depth comparison between MPC and other predictive methods is presented, aiming to substantiate the superior performance of MPC. Furthermore, an adaptive sliding mode control-based reactive power reference is proposed to eliminate the steady-state error in the reactive power. The proposed controller’s feasibility is rigorously evaluated through meticulous MATLAB simulations and real-world laboratory experiments. Comparative analysis against existing SAPF controllers in similar conditions undeniably establishes better grid power quality by lowering source current THD and overall reactive power consumption.