Dynamics of voltage source converter in a grid connected solar photovoltaic system

This paper emphasises the modelling and control of a voltage source converter (VSC) for three phase grid connected PV system. The transfer functions for inner current control and outer DC link voltage control for VSC are derived. The controllers for VSC are designed based on PI and K factor control methods and the performance of VSC using both the methods are presented with the simulations performed using PSCAD/EMTDC. The design of LC filter to meet the specified THD requirement for grid connected VSC is presented and the corresponding harmonic analysis is performed for different solar radiation conditions. The effectiveness of the proposed controller is illustrated by evaluating the response of PV system for power system voltage sag and swell conditions as well as grid faults.