Time scale stability analysis of a Hopf bifurcation in a wind–diesel hybrid microgrid

Abstract

Microgrids and modern bulk power systems usually have multiple time scale dynamics, such as slow and fast dynamics. In this study, the stability of a wind–diesel hybrid microgrid is investigated to show a mechanism of system collapse caused by the interaction between fast dynamics of interface converters and slow electromechanical dynamics. This mechanism leads to a Hopf bifurcation of the fast subsystem due to slow changes in the variables of the slow subsystem and is completely understood by decomposing the stability analysis of the microgrid into the stability assessment of two simpler subsystems: the slow and the fast subsystems. The time-scale method proposed in this study for stability analysis of the microgrid extends the existing proposals in the literature and is able to detect this kind of instability scenario, where the interaction between fast and slow subsystems is the cause of collapse, while the existing approaches, such as quasi-steady-state analysis, fail in detecting instability.