INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING Int. J. Adapt. Control Signal Process. 2016; 30:809–823 Published online 2 November 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/acs.2637 Fuzzy logic controller for three-level shunt active filter compensating harmonics and reactive power Salem Saidi * ,† , Rabeh Abbassi and Souad Chebbi Laboratory of Technologies of Information and Communication and Electrical Engineering (LaTICE), National Higher School of Engineers of Tunis (ENSIT), University of Tunis, B.P.56-1008 Bab Menara, Tunis, Tunisia SUMMARY In this paper, the use of a three-level inverter as a shunt active power filter is carried out, taking advantage of the benefits of multi-level inverter, namely, the reduction both in the overall switching losses and in total harmonic distortion. The main focus of this article is to investigate the potentialities of the inverter employed as shunt active power filter on the compensation of the reactive power and the mitigation of harmonics drawn from a nonlinear load and unbalanced sources. The most previously reported three-level inverter-based shunt active power filters have been controlled and monitored through conventional controllers, which require a complicated mathematical model. In order to overcome this problem, an extended intelligent controller is proposed for a three-level shunt active power filter. The aim of the proposed fuzzy logic control algorithm is to improve the behavior of voltage across the floating capacitors in steady/dynamic states and to minimize the switches commutations by taking into account the references of the harmonic currents injected in the network. The proposed control strategy has been simulated, and the obtained results prove that it is very successful. Copyright © 2015 John Wiley & Sons, Ltd. Received 30 July 2013; Revised 12 September 2015; Accepted 24 September 2015 KEY WORDS: Harmonics; fuzzy logic control; reactive power; instantaneous reactive power theory (P-Q theory); shunt active filter; power quality; imbricated cells inverter; space vector pulse width modulation 1. INTRODUCTION In order to interface with the electrical network, modern power electronics uses diode power rec- tifiers or thyristor converters that absorb deformed and non-sinusoidal currents [1–3], which lead to an increase in harmonic injection in the network and a lower power factor [4–6]. This behavior causes voltage distortion that affects other loads connected at the same point of common coupling [7]. Besides, these negative effects disrupt the network that supplies nonlinear loads by harmonic current injection. The proliferation of harmonics causes voltage deformation, malfunction and fail- ures of sensitive equipments, additional losses and heating in the electrical equipments, perturbing torque, vibrations, and noise in motors. The simplest method to remove the harmonics and improve the electric power quality is to use passive filters tuned around the frequencies, such as 5th-order, 7th-order, 11th-order, or 13th-order harmonics [8]. This solution is simple, reliable, and economical [9, 10]. Nevertheless, the use of the passive filters has many disadvantages, such as weight, volume, frequency tuning, and risk of resonance problems, which decrease more the flexibility and reliabil- ity of the filter devices [11, 12]. However, thanks to recent advances in semiconductor technology, power electronics has helped to design a new filter structure called active power filters (APFs). This *Correspondence to: Salem Saidi, Laboratory of Technologies of Information and Communication and Electrical Engi- neering (LaTICE), National Higher School of Engineers of Tunis (ENSIT), University of Tunis, B.P.56-1008 Bab Menara, Tunis, Tunisia. † E-mail: saidi_salem@ymail.com Copyright © 2015 John Wiley & Sons, Ltd.