Analysis of the Passivity Characteristics of Synchronous Generators and Converter-Interfaced Systems for Grid Interaction Studies

•Feasibility of passivity as a grid-connectivity criterion is analysed.•Passivity of synchronous generators and converter-interfaced generation explored.•Generalized inferences from analytical models validated using frequency scanning.•Passivity compliance feasible for higher frequency models.•Low frequency models inherently non-passive due to steady-state control strategies. The concept of passivity has been used previously by researchers for avoiding adverse interactions between converter-interfaced devices and the lightly damped oscillatory modes of the electrical network (“grid resonances”). The earlier approaches for achieving this objective involve passivating specific devices like voltage source converters around the resonant frequencies of the network. However, the applicability of passivity for the stability analysis of a wider class of devices and a wider spectrum of transients has not been explored in depth so far. To address this issue, theoretical investigations pertaining to the generalized application of passivity to grid-interaction analysis have been carried out in this paper. The investigations cover aspects like the preservation of passivity under transformations, passivity characteristics of low and high frequency models of synchronous generators and converter-interfaced devices, and the effect of typical real and reactive power control strategies. The results of the investigations are illustrated using case studies. The application of the frequency scanning technique for numerical passivity evaluation of complex, converter-interfaced devices is also presented. The prospects for the practical application of passivity as a generalized grid connectivity criterion are analysed in the light of the presented results.