Systematic design of grid-current-based active damping for grid-connected LCL filters

This work investigates the using of high-pass filter (HPF) of the grid current to actively damp the resonance in grid-connected LCL filters. A new form for such HPF is deduced. Using this form, a systematic co-design procedures for the HPF along with the fundamental current regulator are presented to achieve pre-specified behavior. This behavior includes avoiding the non-minimum phase behavior along with achieving pre-specified requirements of fundamental loop gain and crossover frequency. Numerical example along with the experimental work are introduced at different resonant frequencies.