Narrowband Damping of Grid-Connected Inverters for Harmonic Resonance Mitigation

Harmonic resonance problems may appear in grid-connected inverter systems due to a mismatch between the power grid impedance and the inverter impedance. Wide band solutions to mitigate resonance problems have been proposed as active and passive damping methods. As an alternative solution, this paper proposes the use of narrowband digital filtering techniques within the DSP of the grid-connected inverter. Due to the selectivity of narrowband digital filtering methods, they avoid the unnecessary deterioration of the inverter regulation functions at frequencies differing from the specific band where the impedance mismatch occurs.