MPPT technique based on perturb and observe method for pv systems under partial shading conditions

Abstract

This paper presents implementation of a maximum power point (MPP) tracking system with a novel algorithm to track the global MPP (GMPP) of solar PV system under partial shading conditions. Due to partial shading caused by clouds, trees and buildings on the solar panel, MPP tracking algorithm becomes more complex because of the presence of multiple peaks in the power- voltage characteristics. When PV array is uniformly illuminated there is only one MPP, while in the partial shading conditions multiple MPPs formed. Many algorithms track the local MPP(LMPP) instead of global MPP (GMPP) and this cause PV system to become low efficient. Therefore, a novel algorithm based on Perturb and Observe (P&O) technique is proposed. Algorithm consists of two main parts, scanning of power voltage characteristics for the maximum power among power values at some defined voltages, and P&O algorithm is run near the maximum power to track the exact GMPP. The proposed method was validated in a simulation study and an experimental study. From the experimental results 84.90% MPP tracking efficiency has realized.