Optimizing current harmonics compensation in three-phase power systems with an Enhanced Bacterial foraging approach

A shunt active power filter (APF) comprising of pulse-width modulation (PWM) based voltage-source inverter (VSI) is presented in this paper, because it has grabbed tremendous attention as a promising power conditioner. However, it involves huge power loss due to the presence of inductors and semiconductor switching devices, resulting in deterioration of APF performance. So, a Proportional-Integral (PI) controller has been used to minimize this undesirable power loss by regulating the dc-link voltage of VSI. Conventional linearized tuning of PI controller gains does not yield satisfactory results for a range of operating conditions due to the complex, non-linear and time-varying nature of power system networks. The goal of this paper is to find out optimized values of PI controller gains by the implementation of optimization techniques. Developed by hybridization of Particle swarm optimization (PSO) and Bacterial foraging optimization (BFO), an Enhanced BFO technique is presented in this paper so as to overcome the drawbacks in both PSO and BFO, and accelerate the convergence of optimization problem. Comparative evaluation of PSO, BFO and Enhanced BFO has been carried out with regard to compensation of harmonics in source current in a three-phase three-wire system. Extensive MATLAB simulations followed by real-time performance analysis in Opal-RT Lab simulator validate that, the APF employing Enhanced BFO gives superior load compensation compared to the other alternatives, under a range of supply and sudden load change conditions. It drastically lowers down the source current total harmonic distortion (THD), thereby satisfying the IEEE-519 standard recommendations on harmonic limits.