Harmonic Resonance Mitigation and Impedance Stability Improvement of Converter-Based Resources in Active Distribution Grids

This paper discusses the stability issues of the converter-based resources due to the interaction with an active grid that comprises converter-based loads. The dynamics of the converter based loads modify the grid impedance characteristics from passive to active. The impedance-based stability criterion is employed to evaluate the stability of the converter-based resources that are integrated into an active grid. The results reveal that, unlike a passive grid, the impedance stability of converter-based resources cannot be guaranteed with an active grid. As a result, to maintain the overall system’s stability, preventive measures should be implemented in converter-based resources. To suppress the resonances, two distinct damping approaches, the filter-based approach and the state feedback-based approach, are used. However, the state feedback-based approach offers superior performance and a more straightforward design; the filter-based approach is more practical. Simulation results are provided for verifying the theoretical analysis.