RESEARCH ARTICLE Suresh MIKKILI, A. K. PANDA RTDS hardware implementation and simulation of SHAF for mitigation of harmonics using p-q control strategy with PI and fuzzy logic controllers © Higher Education Press and Springer-Verlag Berlin Heidelberg 2012 Abstract The main objective of this paper is to develop PI and fuzzy controllers to analyze the performance of instantaneous real active and reactive power (p-q) control strategy for extracting reference currents of shunt active filters (SHAFs) under balanced, unbalanced, and balanced non-sinusoidal conditions. When the supply voltages are balanced and sinusoidal, both controllers converge to the same compensation characteristics. However, if the supply voltages are distorted and/or unbalanced sinusoidal, these controllers result in different degrees of compensation in harmonics. The p-q control strategy with PI controller is unable to yield an adequate solution when source voltages are not ideal. Extensive simulations were carried out with balance, unbalanced, and non-sinusoidal conditions. Simulation results validate the superiority of fuzzy logic controller over PI controller. The three-phase four-wire SHAF system is also implemented on a real-time digital simulator (RTDS hardware) to further verify its effective- ness. The detailed simulation and RTDS hardware results are included. Keywords harmonic compensation, shunt active filter (SHAF), p-q control strategy, PI controller, fuzzy logic controller, real-time digital simulator (RTDS hardware) 1 Introduction Sinusoidal voltage is a conceptual quantity produced by an ideal alternating current (AC) generator built with finely distributed stator and field windings that operate in a uniform magnetic field. Since neither the winding distribution nor the magnetic field are uniform in a working AC machine, voltage waveform distortions are created, and the voltage-time relationship deviates from the pure sine function. The distortion at the point of generation is very small (about 1% to 2%), but nonetheless it exists. Since this is a deviation from a pure sine wave, the deviation is in the form of an episodic function, and by definition, the voltage distortion contains harmonics [1]. When a pure sinusoidal voltage is applied to a certain type of load, the current drawn by the load is proportional to the voltage and impedance and follows the envelope of the voltage waveform. These loads are referred to as linear loads (loads where the voltage and current follow one another without any distortion to their pure sine waves) [2]. Examples of linear loads are resistive heaters, incandescent lamps, and constant speed induction and synchronous motors. In contrast, some loads cause the current to vary disproportionately with the voltage during each half cycle. These loads are defined as nonlinear loads, and the current and voltage have waveforms that are no sinusoidal containing distortions, whereby the 50-Hz waveform has numerous additional waveforms superimposed upon it, creating multiple frequencies within the normal 50-Hz sine wave. The multiple frequencies are harmonics of the fundamental frequency. Examples of nonlinear loads are battery chargers, electronic ballasts, variable frequency drives, and switching mode power supplies. As nonlinear currents flow through a facilities electrical system and the distribution-transmission lines, additional voltage distortions are produced due to the impedance associated with the electrical network. Thus, as electrical power is generated, distributed, and utilized, voltage and current waveform distortions are produced. It is noted that non-sinusoidal current results in many problems for the utility power supply company, such as low power factor, low energy efficiency, electromagnetic interference (EMI), distortion of line voltage, etc. Eminent issues always arise Received March 21, 2011; accepted March 13, 2012 Suresh MIKKILI (✉), A. K. PANDA Department of Electrical Engineering, National Institute of Technology, Rourkela, Orissa 769008, India E-mail: msuresh.ee@gmail.com Front. Electr. Electron. Eng. 2012, 7(4): 427–437 DOI 10.1007/s11460-012-0198-7