Harmonic Reduction of Fuzzy PI Controller Based Three-Phase Seven-Level DCMLI with SVPWM for Grid Connected Photovoltaic System

Abstract

This paper presents a control for a three-phase seven-level diode-clamped multilevel inverter (DCMLI) for grid connected photovoltaic (PV) systems which improves dc link utilization, output voltage quality and avoids the dc link capacitor voltage balancing problem experienced with standard multilevel operation. The maximum power point tracking (MPPT) is capable of extracting maximum power from PV array connected to each DC link voltage level. The MPPT algorithm is solved by fuzzy logic controller (FLC). Space vector pulse width modulation (SVPWM) algorithm uses a simple mapping to generate gate signals for the inverter. A digital proportional integral (PI) current control algorithm is used to remain the current injected into the grid sinusoidal and to achieve high dynamic performance with low total harmonic distortion (THD). The validity of the system is verified through MATLAB/Simulink and the results are compared with three-phase three-level and five-level DCMLI for PV system in terms of THD. Finally, simulation results are presented to verify the effectiveness and accuracy of the proposed system.