Effects of distributed generation (DG) interconnections on protection of distribution feeders

Application of distributed generation (DG) to supply the demand of a diverse customer base has been gaining popularity. Various DG technologies are being integrated into power systems to provide alternatives to energy sources or to improve reliability. In this paper, the effects of DG on system protection have been identified. Changes in system fault duties and associated concerns are presented. Commonly raised issues of relay de-sensitization, Unintentional islanding, series resonance, and ferroresonance are identified, and some methods of their detection are discussed and analyzed. Documented examples of actual cases are presented. Efficient recommendations to protect the distribution feeders against these conditions are proposed.