Improved modal sensitivity analysis-based method for harmonic resonance analysis

Among the methods used for analysis of harmonic resonance, modal analysis theory and modal sensitivity can be used to illuminate the nature and properties of this phenomenon, and are thus widely applied. In this paper, an improved modal sensitivity-based method is proposed to reliably suppress the harmonic resonance. First, we show that the current resonance analysis schemes that are guided by traditional modal sensitivity are not always robust in some cases. Then, through a theoretical analysis, the roots of the shortcomings of the traditional modal sensitivity are determined. The key factor is that the modal sensitivity of a network component is not always constant but tends to vary with the adjustment of the component parameters. Finally, to quantify this sensitivity variation and improve the robustness of the analysis results, a second-order modal sensitivity and a critical index are proposed. The results of the IEEE 14-bus system and a field case involving high voltage DC (HVDC) systems indicate that the proposed indexes can accurately show the effects of each network component on the resonance, thus are useful in the design of the corresponding analysis scheme.