Grid Connected PV Plant with Fuzzy Logic PQ Regulator-based Grid Following Inverter

Abstract

Integration of PV plant into an existing grid is very complex task as the grid operates on three phase AC and the PVs generate power in DC. The PV DC power need to be maximum extracted and convert to three phase AC using a P&O MPPT based boost converter and six switch inverters respectively. In this paper the six-switch inverter is operated by a PQ based GFL control structure rather than the conventional SRF controller. The reason for using PQ based GFL controller is for attaining control over active and reactive power injection from the PV plant. In traditional SRF controller this cannot be achieved as it has no exchange of reactive power and complete active power from PV plant is injected to the grid. However, the PQ based GFL controller has conventional PI regulator for generating the reference current from the active and reactive powers comparison. This leads to under damping of the inverter creating higher oscillations, settling time, harmonics and peak overshoots in powers and voltages. In order to reduce these power quality issues the PI regulator is replaced with Fuzzy Logic regulator with high resolution. The update to the PQ based GFL controller with Fuzzy Logic regulator reduces oscillations, settling time, harmonics and peak overshoots in power and voltages. This paper includes the analysis of the proposed system with comparative graphical representations determining the better system using MATLAB software.