Distributed Generator Interconnect Protection Practices

A significant portion of the new generation capacity installed during the next 10 years will be accomplished through the construction of IPP (independent power producer) generating facilities. These facilities can take the form of small dispersed generating (DG) units, or large capacity plants owned and even operated by non-utility personnel. It is forecasted that many of the dispersed generating units will be at smaller industrial and commercial facilities and operating in parallel with the utility system to reduce energy cost through load sharing or "peak shaving." This paper discusses the protection requirements to interconnect these generators to utility systems, as well as methods to reconnect these generators after interconnect protection tripping. The paper also updates the author's previous papers (1997, 2001) on DG interconnection protection. It outlines the specific protection challenges to interconnect distributed generations into utility system at a point not designed to accommodate generation