A Potential Island Formation Identification Scheme Supported by PMU Measurements

An island formation identification scheme utilizing both phasor measurement unit (PMU) measurements and supervisory control and data acquisition (SCADA) information, in conjunction with an analytical method, is developed and presented. The motivation for this work came from the investigation of the islanding event in the Entergy, Louisiana power system in 2008. During Hurricane Gustav in September of 2008, 14 transmission lines were lost which led to the formation of a large electrical island containing much of Baton Rouge and New Orleans. This work proposes a method for identifying any specific area of the transmission system that is vulnerable to islanding as the result of losing a system branch. PMU measurements are then utilized to verify SCADA reports that a system branch has been lost. The proposed identification scheme is called the one line remaining (OLR) algorithm. The proposed algorithm identifies potential island formations based on the criteria that a single bus, or a number of buses, are connected to the rest of the system by only a single branch as a direct result of a branch outage. The OLR algorithm is detailed and applied to several small test systems to motivate and validate the approach. The OLR algorithm is then applied to a large Entergy test system for the Gustav islanding event and correctly identifies the last tie line that was lost and created the island.