An Improved Single-Phase Transformerless Inverter Topology for Grid Connected PV System with Reactive Power Control

Abstract

This proposed model deals with a three-phase two-stage grid tied SPV (solar photo-voltaic) system. The first stage is a boost converter, which serves the purpose of MPPT (maximum power point tracking) and feeding the extracted solar energy to the DC link of the PV inverter, whereas the second stage is a two-level VSC (voltage source converter) serving as PV inverter which feeds power from a boost converter into the grid. The versatile DC voltage control helps in the decrease switching power losses.  The dc voltage is regulated using a PI controller when various control algorithms are used for load compensation. In this work, a FUZZY logic based supervisory method is proposed to improve transient performance of the dc link. The FUZZY logic based supervisor varies the proportional and integral gains of the PI controller during the transient period immediately after a load change. A considerable reduction in the error in dc link voltage during load change compared to a normal PI controller is obtained. The performance of the proposed strategy is proved using detailed simulation studies.