Experimental investigations on Ant Colony Optimized PI control algorithm for Shunt Active Power Filter to improve Power Quality Aruchamy Sakthivel a,n , P. Vijayakumar b , A. Senthilkumar a , L. Lakshminarasimman c , S. Paramasivam d a Department of Electrical and Electronics Engineering, Dr. Mahalingam College of Engineering and Technology, Pollachi, Tamil Nadu, India b Department of Electrical and Electronics Engineering, Karpagam College of Engineering, Coimbatore, Tamil Nadu, India c Department of Electrical Engineering, Annamalai University, Chidambaram, Tamil Nadu, India d DON FOSS Industries Private Ltd, Chennai, Tamil Nadu, India article info Article history: Received 6 August 2014 Accepted 26 April 2015 Available online 27 June 2015 Keywords: Power Quality Shunt Active Power Filter Ant Colony Optimization Genetic Algorithm Differential Evolution algorithm Dynamic performance of controller abstract Active Power Filters (APFs) have become a potential option in mitigating the harmonics and reactive power compensation in single-phase and three-phase AC power networks with Non-Linear Loads (NLLs). Conventionally, the assessment of gain values for Proportional plus Integral (PI) controllers used in APF employs model based controllers. The gain values obtained using traditional method may not give better results under various operating conditions. This paper presents Ant Colony Optimization (ACO) technique to optimize the gain values of PI controller used in Shunt Active Power Filter (SAPF) to improve its dynamic performance. The minimization of Integral Square Error (ISE), Integral Time Square Error (ITSE), Integral Absolute Error (IAE) and Integral Time Absolute Error (ITAE) are considered as cost functions for the proposed system. The proposed SAPF is modeled and simulated using MATLAB software with Simulink and SimPowerSystem Blockset Toolboxes. The simulation results of the SAPF using the proposed methodology demonstrates improved settling time (T s ) with ISE as cost function. For instance, the T s for ISE 4.781 is found to be 28.5 ms. Finally, hardware implementation of the proposed SAPF system is done using Xilinx XCS500E Spartan 3E FPGA board. & 2015 Elsevier Ltd. All rights reserved. 1. Introduction Utility system generates pure sinusoidal waveform at their terminals. This sinusoidal waveform is the pure form of the AC voltage and any deviation from it is called as distortion, which degrades the quality of electric power. Many loads absorb non- sinusoidal current from the utility mains called as NLLs, which leads to harmonic distortion. These distortion in mains supply system is due to large harmonic currents drawn by residential, commercial and industrial NLLs such as adjustable speed drives, arc furnaces, air conditioners, battery chargers, copier machines, computers, fluores- cent lightings, frequency converters, medical equipments, switch- mode power supplies, printers, uninterrupted power supplies, weld- ing machines and x-ray equipment. NLLs act as a source of harmonic current and inject harmonic currents into the grid system. These currents can interact adversely with a wide range of power system equipments causing additional losses, overheating, overloading, interference with telecommunication networks and also results in erroneous readings in watthour and demand meters (Dugan, McGranaghan, Santoso, & Beaty, 2002; Kennedy., 2000; Cividino, 1992; Mahmoud & Owen, 1983). The IEEE 519-1992 (Institute of Electrical and Electronics Engineers) standard furnishes guidelines for harmonic voltage and current distortion limits at the Point of Common Coupling (PCC). Traditionally, passive LC filters are used to suppress the harmo- nic distortion in power systems. Parallel passive filters are used to reduce harmonics in current source type harmonic generating loads. The principle of the parallel passive filter is to provide a low impedance shunt path to the harmonic current, thus reducing harmonic current flowing into the source. Series passive filters on the other hand are used to compensate for voltage source harmonic generating loads. In general, passive filters have the demerits of fixed compensation, larger size and resonance. To overcome these limitations, APF is used as an alternative. APF is a power electronic converter that produces and injects into the system the necessary harmonic components to cancel the harmonic present in the load current. It can be connected at PCC of an AC system to compensate one or more loads. The voltage source Pulse Width Modulated (PWM) inverter based SAPF is preferred by the utilities due to its larger efficiency compared to current source PWM inverter (Akagi, 1994; Grady, Samotyj, & Noyola, 1990; Routimo, Salo, & Tuusa, 2007). Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/conengprac Control Engineering Practice http://dx.doi.org/10.1016/j.conengprac.2015.04.013 0967-0661/& 2015 Elsevier Ltd. All rights reserved. n Corresponding author. Tel.: þ91 9865282841. E-mail address: ersakthi@yahoo.com (A. Sakthivel). Control Engineering Practice 42 (2015) 153–169