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Efficient Utilization of Solar Energy under Partial Shading Conditions Using a Novel MPPT Technique

AswathyKanth

Vastly growing concerns on energy sustainability and security have introduced significant research efforts on the penetration of Renewable Energy Sources (RES) into present electric power system. Photovoltaic (PV) energy is the most important RES since it is clean, pollution free, and inexhaustible. The efficiency of a photovoltaic (PV) array is greatly influenced by shading conditions. The PV arrays get shadowed, completely or partially, by the passing clouds, neighboring buildings and towers, trees, and utility and telephone poles. Under partially shaded conditions, the PV exhibits non convex characteristics with multiple peaks. Extraction of maximum power from PV array under partial shading condition is possible using Maximum Power Point Tracking (MPPT).The technique of MPPT can be achieved either by distributed MPPT (DMPPT) which acts on the voltages of PV modules or by centralized MPPT (CMPPT) which acts on the input voltage of inverter. But both DMPPT as well as CMPPT has its own advantages and disadvantages. This paper details the study of a novel MPPT which is a combination of both C&D MPPTs and can overcome the disadvantages of DMPPT as well as CMPPT enhanced PV system. In this paper, DMPPT is achieved with the use of sub-module integrated converters(subMIC) which gives an efficiency of 98% for a mismatch of not less than 25%.And CMPPT is achieved using 2 conventional MPPT techniques-perturb & observe and incremental conductance MPPT. A 3-module PV series string with novel MPPT was simulated under mismatched solar irradiation conditions using MATLAB Simulink