An active damper for stabilizing power electronics-based AC systems

The mutual interactions between the parallel grid-connected converters coupled through the grid impedance tend to result in a number of stability and power quality challenges. To address them, this paper proposes an active damper concept based on a low-power, high-bandwidth power converter. The basic idea behind this proposal is to dynamically adjust the grid impedance seen from the point of common coupling of the grid-connected converters, such that the potential instabilities and resonance propagation can be effectively mitigated. Simulation and laboratory tests on three parallel grid-connected converters are carried out. The results validate the stabilizing performance of the active damper.