LAUSR

Currently, most utilities require the immediate disconnection of distributed generators in case of unintentional islanding, due to safety and technical reasons. However, there is a trend for allowing the islanded operation of distributed resources under specific conditions, so that the reliability of the energy supply to the consumers can be improved. In this case, the power quality inside the energized island must be assured by the distributed generators’ operators, which means that the transient and steady-state voltage and frequency of the isolated systems must be within acceptable limits. In this context, in this paper we proposed four indices for assessing the technical performance of the islanded operation of distributed generators. The indices are based on power quality issues, and they were proposed by considering the unplanned islanding of a synchronous distributed generator, its transition from the grid-connected mode to the islanded mode and the steady-state operation after a successful islanding. Results have shown the indices application to different operating scenarios, including a load shedding scheme, and they proved to be an interesting tool to technically evaluate the islanded operation of distributed generators, under a power quality perspective.