Real-Time Harmonic Compensation in Nonlinear Power Systems Using Hybrid Active-Passive Filters

Abstract

Due to increased use of nonlinear loads such as variable frequency drives, uninterruptible power supplies and rectifier based devices, there is an increase in harmonic pollution which is detrimental to power quality as well as the reliability of the system. In this paper a real time method based on an HAPF is presented that reduces both small and large harmonic distortions in nonlinear distribution systems. A hybrid topology combines a tuned passive filter to aim at selective harmonic reduction and a shunt-connected active filter with a VSC to achieve wide and fast harmonic cancellation. The active filter extracts harmonics using Synchronous Reference Frame (SRF) theory and provides an accurate and fast outcome using a Proportional-Integral (PI) hysteresis current controller during the injection of current. Following the simulations in MATLAB/Simulink, it is depicted that the proposed system significantly enhances the power quality of the system by decreasing the Total Harmonic Distortion (THD) of 23.6 % to 3.1%, which is in compliance with the requirements of IEEE-519. Besides that, simulation in a prototype implemented on a TMS320F28379D DSP demonstrates that the control strategy is functional under dynamic variations of the load. The developed HAPF discovered in the work provides an outstanding harmonic mitigation, improved stability and flexibility, which determine its applicability in the industry and utilities.