Passivity-Based Controller Design of PCC Voltage Feedforward Active Damping for Grid-Connected Inverters

Abstract

The inherent resonance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$LCL$</tex-math></inline-formula> filter tends to result in the grid-connected inverter system oscillating due to the variation of the grid impedance at the point of common coupling (PCC), so damping needs to be implemented to ensure the asymptotic stability. This article develops a novel and sensorless PCC voltage feedforward active damping (PCCVF-AD) control strategy, which includes a generic controller and a resonant compensation term, and then models the input admittance of current-controlled inverter system. Thereafter, based on the frequency-domain passivity theory, the stability criterion of system is transformed to the real part of the inverter input admittance, thus proposing a well-established PCCVF-AD controller design scheme. The proposed PCCVF-AD is designed to ensure the passivity of inverter input admittance in all frequencies, thereby achieving the plug-and-play capability that the inverter can be connected to the grid regardless of the grid impedance. The presented analysis results are verified by experiments.