Mitigation of Inverter-Grid Harmonic Resonance by Narrow-Band Damping

This paper deals with damping of resonance between grid-connected inverters and the power grid. This paper proposes a narrow-band digital filtering technique to resolve the resonance problem by shaping the inverter output impedance at selected frequencies without affecting the characteristics of the inverter outside the selected frequency range. A frequency-sampling method is used to implement the narrow-band digital filter which allows direct control of the filter´s amplitude and phase response in accordance with damping requirements. The experimental results are presented to demonstrate the performance of the proposed method.