Comparison of MPPT Techniques on THD Current in a Grid-Connected Photovoltaic System

Abstract

Most comparison studies of MPPT algorithms in the literature are undertaken in terms of their precision, speed, robustness under rapidly changing environmental conditions, etc... In grid-connected photovoltaic (PV) systems, Comparative studies of MPPT methods in terms of THD injected into the network are of significant importance. In this paper, two conventional MPPT methods, perturb and observation (P&O) and incremental conductance (IC), and two advanced MPPT methods, fuzzy logic control (FLC) and Sliding mode control (SMC), were studied and compared in terms of currents injected THD into the grid using MATLAB/Simulink. The grid-connected PV system under consideration is a two-stage unit that includes a classical boost converter and a two-level voltage source inverter. With the FLC and SMC-based MPPT methods, the injected current's THD was 1.34% and 1.99%, respectively. The IC MPPT technique has slightly outperformed the P&O one, with a THD current of 3.48% versus 3.68%. The simulations were run under identical conditions; the superior performance of a particular MPPT technique over others is principally reflected in the dc-link voltage fluctuation.