Online Stability Monitoring of DC Grids Using the Passivity Approach and Impedance Analysis

Proliferation of power electronic converters in smart grids has caused new stability challenges due to dynamic interactions between networks subsystems. In this paper, the concept of dynamic interaction is explained from the impedance point of view and combined with the concept of passivity to provide a sufficient condition for a network instability. An online stability monitoring algorithm is proposed which is based on the broadband DC bus impedance identification. The DC bus impedance is identified by a separate module in a power network. Dynamic interaction, passivity, and the small signal stability are investigated for a notional DC power grid by simulation results.