Grid-Tied Photovoltaic Array Using Power Electronic Converters with Fuzzy Logic Controller for Maximum Power Point Tracking

Abstract

A simple closed-loop power electronic controller for grid-connected photovoltaic (PV) system using interleaved dual boost (IDB) converter and line commutated inverter (LCI) has been developed for feeding the maximum power to single-phase utility grid. A proportional-integral controller designed using operational amplifier adjusts the duty cycle of the IDB converter to provide the required constant DC voltage to the inverter under varying conditions of PV array. If the PV array output is directly connected to the utility grid through an inverter, a step-up transformer would be required between the inverter and the grid supply. Alternatively the array voltage is to be increased to match with the grid voltage. The introduction of DC-DC converter between PV array and LCI not only eliminates the need for step-up transformer between LCI and the utility grid, but also adds flexibility in the maximum power point tracking algorithm. The fuzzy logic controller, which is designed to vary the firing angle of the inverter to track the maximum power, has been implemented using National Instruments DAQ USB 6009 device and MATLAB tool boxes. The proposed scheme is modelled using MATLAB/PSB and interfaced in real-time for generating the firing pulses to the thyristors in the inverter. The comparison of results obtained from simulation with that of experimental investigation validates the proposed scheme.