Comparative Study of a Photovoltaic System Connected to a Three-Phase Grid by Using PI or Fuzzy Logic Controllers

Abstract

This work presents a comparative study for a photovoltaic system connected to a three-phase grid through a three-phase inverter controlled by a fuzzy logic controller or through a proportional-integral (PI) controller. The innovative aspect of this article consists of the elaboration of two models in MATLAB–Simulink for the photovoltaic system consisting of 40 photovoltaic panels and of the control algorithms of the three-phase inverter for each type of controller. The comparative analysis of the results obtained through simulation has established that the use of the fuzzy logic controller (for controlling the three-phase inverter) leads to transferring to the alternative current (AC) grid an electric power of 6.5 kW, whilst the use of the PI type controller leads to transferring to the AC grid an electric power of 4.6 kW under the same value of the intensity of solar radiation. The total harmonic distortion (THD) of the voltage resulting after the filtering circuit has a lower value in case of using the fuzzy logic controller than in case of using the PI controller. Through the usage of the fuzzy logic controller for controlling the inverter, an increase in quantity and quality of the electric energy introduced to an AC grid from a photovoltaic system was noticed, compared to the usage of a PI controller.