Computationally Efficient Impedance Scanning Approach for Inverter-based Resources

Impedance-based stability assessment (IBSA) is an effective method to study sub-synchronous control interaction (SSCI) with inverter-based resources (IBRs) in modern power systems. An IBR's required frequency-dependent impedance model can be obtained via the positive sequence scanning method. In this paper, single-sinusoidal signal and multi-sinusoidal signal-based methods for frequency scanning are investigated and evaluated. To benefit from the advantages of both schemes, hybrid scanning is proposed including perturbation signal, amplitude, and frequency segmentation settings. Additionally, a modified quadratic phase shift scheme is proposed for reducing the high magnitudes of multi-sinusoidal signals. All methods are validated and compared using the average value model of a doubly fed induction generator. The guidelines and recommendations are provided for the proper usage of the proposed hybrid scanning in the sub-synchronous frequency range.