AN IMPROVED SRF- THEORY BASED CONTROLLER APPLIED TO THREE PHASE GRID INTERFACED PV-SYSTEM FOR POWER QUALITY IMPROVEMENT AND ISLANDING DETECTION

摘要

In this paper, a three phase grid connected photovoltaic (PV) system is presented using an improved SRF theory based control technique. The proposed system consists of PV-Module, DC-DC boost converter, voltage source inverter (VSI), smoothing inductor and three phase source as a grid. The reference currents are generated by using modified synchronous reference frame (SRF) theory to control the VSI. A DC-DC boost converter is used for extracting Maximum Power from PV array and the DC link voltage is regulated by using Proportional Integral (PI) controller. The voltage is maintained constant on AC-side at different Irradiation, Temperature and Load conditions. The PV-system acts as a shunt active power filter when there is a non-linear load and the harmonic current is compensated by PV-system, also achieves Unity power factor at grid side. Islanding detection is considered as main task for grid connected PV-system to protect the utility working people from energized lines and the PV-system. In this paper, islanding event is detected and non-critical load is disconnected from PV-system for reliable operation of critical load i.e. local load. The proposed grid connected PV-System is simulated in MATLAB environment.