Transformer less Inverter for Low Voltage Grid Connected PV System

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Janardhan Gurram, N. N. V. Surendra Babu, G.N.Srinivas


Harnessing the energy from renewable sources has gained more significance as the conventional sources will not be lasting for upcoming decades. Besides these alternative energy sources are free, the advanced energy conversion mechanisms raising their demand. Out of all the renewable resources photo voltaic (PV) energy conversion is widely used due to its less maintenance, descent efficiency of conversion. Grid  connected PV systems became more popular in the recent years with the advent of sophisticated inverter topologies and conversion techniques. In grid connected PV systems transformer can be eliminated by which space, size of the system can be reduced, and efficiency of the system can be improved. However, by removing transformer, isolation of PV panels and grid is not achieved. If isolation is not achieved, the effect of virtual stary capacitance between PV panels and ground will cause leakage currents due to variation in common mode voltage. A single phase full-bridge/ H- bridge inverter is used and is connected to grid through a LCL filter. Bipolar pulse width modulation is used to eliminate or to suppress leakage current. This paper includes implementation of transformer less inverter for grid connected PV systems using MATLAB/Simulink. It also gives the analysis of various parameters like inverter, grid voltages, currents, and common mode leakage current at various solar irradiance levels.

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