Stability Enhancement of Three Phase Grid Connected Photovoltaic System Using Partial Feedback Linearization Scheme

Abstract

This project presents a stabilization scheme for a three-phase grid-connected photovoltaic (PV) system to control the current injected into the grid and dc-link voltage to extract maximum power from photovoltaic (PV) units. The scheme is achieved mainly based on the design of a controller using a partial feedback linearizing approach of feedback linearization where the stabilization of the scheme is ensured by considering uncertainties within the PV system mode. The performance of the stability enhancement is evaluated on a three-phase grid-connected PV system in terms of delivering maximum power under changes in atmospheric conditions. In the grid connected PV system the control objectives are met by a strategy using a pulse width modulation (PWM) scheme based on two cascaded control loops. The two cascaded control loops consist of an outer voltage control loop to settle the PV array at the Maximum Power Point (MPP) and an inner current control loop to establish the duty ratio for the generation of a sinusoidal output current which is in phase with the grid voltage.