Abstract

This paper presents the design of a hybrid type-2 fuzzy logic (T2FL) / proportional-integral (PI) controller proposed to solve harmonic and balancing problems in the output voltage of a single-phase three-wire inverter system. The inverter system consists of a converter circuit with three legs and an auxiliary LC filter, and a voltage-based feedback control algorithm including a differential-mode and common-mode controllers. In this algorithm, a T2FL controller and a PI controller whose gain coefficients are optimized by particle swarm optimization (PSO) algorithm are used as the differential-mode controller and common-mode controller, respectively. To evaluate the effects on system performance of the proposed hybrid controller, the inverter is also controlled using traditional PI/PI controller and hybrid type-1 fuzzy logic (T1FL) / PI controller. Simulation results show that the hybrid T2FL/PI controlled inverter has faster dynamic response in the case of step load changes, and gives a better sinusoidal alternating current(AC) output voltage and a lower neutral line voltage under unbalanced linear and non-linear load conditions than the both conventional PI/PI and hybrid T1FL/PI controlled inverters.

Key words: Proportional-integral controller, type-1 fuzzy logic controller, type-2 fuzzy logic controller, hybrid controller, particle swarm optimization algorithm, single phase three-wire inverter.

Abbreviation

PI, Proportional-integral; T2FL, type-2 fuzzy logic; PSO, particle swarm optimization; T1FL, type-1 fuzzy logic; AC, alternating current; UPS, uninterruptible power supply; BESS, battery energy storage system; GA, genetic algorithm; DC, direct current; PWM, pulse width modulation; NB, negative big; NS, negative small; Z, zero; PS, positive small; PB, positive big; NVB, negative very big; NM, negative medium; PM, positive medium; PVB, positive very big; COS, center of set; IAE, integrated absolute error; ITSE, integrated of time weight square error; ISE, integrated of squared error; VS, voltage sags.