Identification of Power Islands via Event-Triggered Decaying Current Injection by Inverter Networks

Conventional islanding detection methods only determine whether an Inverter-Based Resource (IBR) is islanded to activate anti-islanding protection. In order to form microgrids for sustainable power islands, it is critical to identify the boundaries of islands such that the IBRs in the same island could be coordinated by microgrid secondary control. This paper proposes an islanding identification method that can agilely determine the boundaries of power islands following islanding events. A controlled low-frequency decaying current is injected into the grid via the dq frame current controllers of IBRs, and the Estimation of Signal Parameters via Rotational Invariance Technique (ESPRIT) method is used to extract signals from measurements at the terminals of other IBRs. If the signal injected by an IBR is observed at the terminal of another IBR, it is determined that they are electrically connected, i.e., operated in the same island. The proposed method minimizes the impact on power quality and grid operation with the event-triggered and rapidly decaying signal injection mechanisms. The proposed framework is verified in the IEEE 13-node test feeder.