Design and comparative study of filters for multilevel inverter for grid interface

Concern with power control, power quality or grid connecting application the demand for three-phase pulse width modulation (PWM) inverters has increased in recent years. The use of power converters is very important in maximizing the power transfer from renewable energy sources such as wind, solar, or even a hydrogen-based fuel cell to the utility grid. The inverters are connected to the grid via various topologies of passive filters such as L, L-C or L-C-L. Design and comparative study of L-C and L-C-L filter is presented in this paper for grid interface with Diode-clamped five-level multilevel inverter. The harmonics which is induced by the low switching frequency is reduced by such passive filters and generates a satisfactory level of grid-side current. L-C and L-C-L filters offer a better choice of attenuating switching frequency harmonics. The filter requirements are driven by tight filtering tolerances of standards such as IEEE 519-1992 and IEEE P1547.2-2003. The effectiveness of the proposed algorithm is verified using matlab-simulink.