Laboratory testing of a distributed generator unintentional islanding detection scheme

This paper describes the initial development and testing of an islanding detection scheme in conformance with the IEEE 1547 standard for interconnecting distributed resources with electric power systems. The islanding detection algorithm involves adding a perturbation signal to the throttle of a distributed generator (DG). Deviations in DG electrical frequency caused by the perturbation signal are much smaller when the DG is connected to the grid than when it is in an island. We have performed a subset of the unintentional islanding detection tests required by the IEEE 1547.1 standard using an 85 kW DG powered by a reciprocating engine. The standard requires an island to be detected when the DG and a matching load are simultaneously disconnected from the grid. Preliminary results are promising and we describe the refinements and extensions to the test procedures that will be required to finish demonstrating compliance with the IEEE 1547 standard.