A module voltage based maximum power point tracking algorithm for photovoltaic arrays under partial shading conditions

摘要

Multiple peaks in the Power vs. Voltage (P-V) characteristics of Photovoltaic (PV) arrays appear due to partial shading. Conventional Maximum Power Point Tracking (MPPT) algorithms fail to track the Global Peak (GP) among the Local Peaks (LP). Special MPPT techniques are applied for tracking the GP under partial shading conditions. Various schemes reported in the literature perform blind scanning of the P-V curve in order to find the GP. This type of scanning takes a long time during which the array is not operated at the MPP. This causes a considerable amount of power loss. In this paper an MPPT algorithm is proposed which quickly tracks the GP of a partially shaded PV array. The algorithm avoids blind and unnecessary scanning of the P-V curve by finding the total number of peaks after tracking the peak nearest to the open circuit voltage (Voc). The tracking process is accelerated through the use of modified versions of the Perturb and Observe (P&O) algorithm.