Optimal LCL filter design for grid-interfaced distributed power generation system

Abstract

Optimal design of LCL filter for grid connected inverter system is studied. For that, initially normal design is considered. Higher order LCL filters are essential in meeting the interconnection standard requirement for grid-connected voltage source converters. The IEEE 1547-2008 specifications for high-frequency current ripple are used as a major constraint early in the design to ensure that all subsequent optimizations are still compliant with the standards. The LCL filter is designed accordingly and optimal inductance and capacitance values are obtained. Novel small signal model of a three phase grid connected VSI has been derived and its relevant transfer functions have been deduced from it so as to analyze the system for designing a controller and also bode plots have been plotted. Stability Analysis of Grid-Connected Inverters with an LCL Filter Considering Grid Impedance and comparative study between unipolar and bi-polar switching scheme for grid-connected inverter system is also done. Simulation is done in MATLAB SIMULINK environment for feasibility of the study.