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.