ADVANCEMENT IN MULTILEVEL VSI FOR STAND-ALONE SOLAR PV SYSTEM

Multilevel inverter units for stand-alone solar photovoltaic systems are gaining popularity in the present industrial environment. The number of switching devices, total harmonic distortion, number of output levels and number of sources are the governing factors in a multilevel inverter topology. The classical multilevel inverter topologies produce a considerable amount of switching losses due to handful number of switching devices as the number of output levels is increased. Therefore to overcome these drawbacks a multilevel inverter topology to maximize the number of output levels with reduced number of switching devices is opted. The staircase output voltages representing the total number of levels are obtained by the additive and subtractive combination of asymmetrically arranged voltage sources thereby reducing the total number of DC sources required. The reduction of THD and switching losses is done by selecting the suitable PWM technique with low switching frequency. Unlike in the central MPPT architecture, the distributed MPPT architecture is employed for the extraction of maximum power. A multilevel inverter for stand-alone solar PV system incorporating the features like reduced number of switches, reduced number of sources and maximizing the number of output levels with distributed MPPT architecture is designed. By this a better performance compared to the conventional methodology can be attain. The multilevel voltage source inverter with/without distributed MPPT and comparative analysis of the three types of Multicarrier Sinusoidal PWM techniques at low/high carrier wave frequency is modeled and simulation results have been taken. The simulation of the Multilevel VSI for stand-alone solar PV system is done using MATLAB R2014a software.