PROJECT TITLE:

Grid-Current-Feedback Active Damping for LCL Resonance in GridConnected Voltage Source Converters -2015

ABSTRACT:

This paper investigates active damping of LCL-filter resonance during a grid-connected voltage-supply converter with solely grid-current feedback control. Basic analysis within the s-domain shows that the proposed damping technique with a negative high-pass filter along its damping path is like adding a virtual impedance across the grid-side inductance. This added impedance is a lot of exactly represented by a series RL branch in parallel with a negative inductance. The negative inductance helps to mitigate part lag caused by time delays found in a very digitally controlled system. The mitigation of section-lag, in turn, helps to shrink the region of nonminimum-phase behavior caused by negative virtual resistance inserted unintentionally by most digitally implemented active damping techniques. The presented high-pass-filtered active damping technique with a single grid-current feedback loop is so a additional effective technique, whose systematic style within the z-domain has been developed during this paper. For verification, experimental testing has been performed with results obtained matching the theoretical expectations closely.