Loss of grid protection for an embedded generator

The operation of small or medium sized generation in parallel with the local electric utility supply creates several difficulties for the reliable and safe operation of the power system. These difficulties arise from the generator´s ability to supply power to the network and since it operates independently of the utility´s control system. Here, the authors describe how loss of grid protection is a necessary part of the protection of an embedded generator which operates in parallel with the utility supply. Several techniques have been developed for detecting loss of grid and work is continuing to develop new techniques. Since loss of grid is not a conventional fault condition and in its self does not cause damage, it presents a major challenge to relay designers