AFLL Based Control Technique for Grid Interfaced Three Phase PV System

摘要

This work proposes an advanced frequency locked loop (AFLL) based control algorithm for a three phase double stage grid interfaced solar photovoltaic (PV) system. The proposed AFLL based algorithm extracts the fundamental component of the load current (FCI) and improves the system performance during dynamics. The VSC (Voltage Source Converter)of PV system supplies the PV energy to the grid even under the worst situations of DC offset, solar insolation variation, load unbalancing and voltage swell/sag. The VSC switching losses are reduced using adaptive DC link voltage. The proposed system is modeled and simulated in MATLAB for different odd conditions like solar insolation variation, load unbalancing and voltage sag/swell. Tests are conducted on a prototype built in the research laboratory under various odd states like DC offset and voltage swell/sag, insolation change etc. Performance of the system is found satisfactory and THD's of the grid currents are found within limits, as recommended by the IEEE -519 standard.