Maximum Power Point Tracking Algorithms Research in Terms of Uneven Shading of Solar Panels

Abstract

Power produced by solar power plant (SPP) decreases essentially under conditions of partial or full shading. Uneven shading leads to shift of a maximum power point on the output P-V characteristic and its local peaks appearance. One of the local peaks can be wrongfully taken as the maximum power point (MPP). Thus, the SPP can underproduce electric power. This article observes peculiarities of maximum power point tracking (MPPT) algorithms operation under the circumstances of different shading types. Models developed in Dynamic Simulation Environment SimInTech are presented. Each of the models includes subsystem of SPP connected in series with DC-DC converter and load. DC-DC controller is driven by subsystem of pulse-width modulation (PWM) controller. Models developed in this work differ from each other by algorithm of PWM controller and by types of cloud’s models used for shading simulation above the SPP. Incremental conductance, Voltage based Perturb and Observe and Current based Perturb and Observe algorithms widely used for MPPT are chosen for simulation in this article. Partial shading conditions are simulated for four cases of cloud’s slow motion through the clear sky and for four cases of clearance’s slow motion through the evenly cloudy sky above the SPP. Conditions of wrong maximum power point choice by the algorithms are set out. Analysis of power underproduction is conducted. In the end of the research conclusions about similarity of different algorithms under changing partial shading conditions are presented. Ideas about situations with incorrect algorithm’s operation are stated.