Modified Modular Multilevel Inverter topology for Photovoltaic Applications

Abstract

Solar power plant replaces the conventional power generation due to the development of recent technologies and climate change. So, there is a need for appropriate inverter topology for integrating solar Photovoltaic system with the grid. Multilevel Inverter (MLI) is suitable for power transformation, which overcomes the limitations of square wave inverter such as Harmonic distortion, higher voltage stress and Electro Magnetic Interference (EMI). This paper proposes a seventeen-level modified asymmetrical inverter topology to convert DC power which consists of solar photovoltaics, fuel cell or battery to AC power for industrial and domestic loads. The proposed topology composes of nine IGBT semiconductor devices, one bidirectional switch and four asymmetrical solar PV System to produce seventeen level staircase type waveform and it is identical to sinusoidal shape. The pulse for the switches is produced by Nearest Voltage Level (NVL) algorithm which shows higher efficiency and reliability compared to other PWM techniques at the higher levels. The proposed topology for Solar PV system is validated by simulating in MATLAB/Simulink and harmonic spectrum of output current and voltage are analyzed. The Total Harmonic Distortion (THD) of current (I) is 0.35 % and voltage (V) is 1.33 % which follow IEEE519 standards.