Instantaneous Active and Reactive Power Control Using Direct Power Control Strategy for Multilevel Multistring Inverter Fed Photovoltaic System

Abstract

This paper presents the Direct Power Control (DPC) strategy for Multilevel Multistring Inverter fed Photovoltaic (PV) system to control the instantaneous active and reactive power. The proposed system consists of PV strings, boost converter and three phase three level cascaded H-bridge (CHB) inverter. In multistring topology, each PV string is connected to the dc/dc converter and the distributed MPPT control algorithm is connected to the central inverter. The Space Vector Modulation (SVM) based DPC approach is used to obtain the constant switching frequency and reduced power ripple. The detailed model of the proposed system is developed in Matlab to evaluate the performance. A laboratory based prototype of the proposed system is developed to realize the system in real time. dSPACE DS1103 is used as the control interface to perform the real time implementation (RTI). Power Quality Analyser (PQ-Box 200) is used to analyse the system parameters like voltage, current and Total Harmonic Distortion (THD) of inverter. The effectiveness of the proposed system has been validated with the help of simulation and the experimental results.