A Generalized Framework For Synthesizing Virtual Output Impedance Control Of Grid Integrated Power Electronic Converters

With increased renewable penetration in distribution grids, the harmonic stability issues due to parallel resonance phenomenon are of serious concern. Virtual Output Impedance (VOI) techniques reported in literature modify the effective output impedance to damp the voltage oscillations. However, a generalized framework for the design of VOI of an inverter that considers the grid impedance in real time is not reported. In this paper, a novel generalised framework for synthesizing the VOI loop of grid integrated power converters based on mixed sensitivity H-infinity control is presented. This method relies on real time impedance measurements for the computation of stabilizing VOI loop. This procedure is valid for DC/AC converters and also for DC/DC converters. Proof of concept is provided through impedance based frequency domain analysis.