Robust Active Damping Control for LCL-Type Shunt Active Power Filters

A dual-loop current control is discussed for LCL -type shunt active power filters (APFs), where inverter-side feedback and point of common coupling (PCC) voltage feedforward both provide damping (AD) effects resonance. However, two ADs are equivalently applied to different elements filter with narrow boundaries, which causes less robustness against grid impedance variation. Hence, this paper has presented a comprehensive approach strengthen the system On basis phase compensated resonant unit, delay-compensation scheme firstly proposed extend boundary up almost Nyquist frequency ( $f_{s}/2$ ). Theory analysis considering PCC indicates that can keep robust when initial resonance falls between notation="LaTeX">$f_{s}/3$ extended boundary. Moreover, typical weighted proportional-resonant suggested prevent high-frequency units from inducing instability under large impedance. We finally validate effectiveness through experiments.