A single-phase two-stage grid interfaced SPV system with adjustable DC link voltage for VSC under non ideal grid conditions

Abstract

This paper deals with single phase grid interfaced SPV (Solar Photo Voltaic) system. A two stage power circuit topology is used in the presented work, in which the first stage is a boost converter, which serves the purpose of MPPT (Maximum Power Point Tracking) and the second stage is a PV inverter which serves the purpose of feeding extracted energy into the grid. A feed-forward term for solar contribution is used to improve the dynamic response. The PV inverter DC link voltage is continuously adjusted according to PCC (Point of Common Coupling) voltage, which in turn helps in reduction of power losses. A PI (Proportional Integral) controller is used to regulate the DC link voltage to desired reference voltage. The system is modeled and simulated on MATLAB based platform. A wide range of simulation results are shown to demonstrate all features of proposed system. The system is tested considering realistic non ideal grid conditions. The proposed system is advantageous in cases of frequent and sustained grid voltage variations (such is the case of far radial ends of Indian grid). The performance of proposed system is found satisfactory for wide variation of grid voltage. The THD (Total Harmonics Distortion) of grid current has been found well under IEEE-519 standard.