PSO based Optimal Operation of a Cascaded Grid Connected Three Phase Solar PV Inverter

In order to commercialize & utilize the PV energy properly, connect it to the grid is a more viable option. Therefore, the study of grid-connected solar PV generation system has gained wide attention. Optimizing output power from a solar photovoltaic module and simultaneous reduction in the harmonics in the line current is of special attention because the efficiency of the solar PV cell is quite low. The conventional line-commutated inverter (commonly used in grid-connected inverter) introduces line current of square-shaped which contains the higher-order harmonics and causes heating of the core of the transformer. The thyristors/SCR based switches have low switching losses and their power handling capability and reliability increases in comparison to the MOSFET/IGBT switches. Nevertheless, for PWM applications, the traditional thyristor-based forced commutated inverters are not appropriate due to the issue of commutation circuits. In this work, a three-phase cascaded full bridge inverter (Rectifier operating in inversion mode) topology has been utilized to produce the seven levels in the input grid current, which is closer to a sinusoidal wave and hence has lower total harmonic distortion (THD). The modular nature of cascaded bridge type configuration is suitable for grid connected solar PV inverter. The results of the proposed scheme have been verified successfully in the MATLAB Simulink environment. The performance of the cascaded configuration is tested for THD in line current, power factor and power transfer capability (PV to the grid). The enhanced performance is obtained by applying a metaheuristic algorithm and meticulous selection of performance parameter.