Dispersed generation interconnection-utility perspective

Interconnection of generation to an electric distribution system, which is primarily designed to serve radial loads, must not compromise reliability and quality of supply to customers or safety of public and equipment. This paper presents criteria used by BC Hydro, the third largest utility in Canada, to determine the requirements for interconnecting a generating source to its distribution system. The presented criteria discuss tradeoff involved in specifying the grounding connection of interconnecting transformer or how the size of a distributed generator impacts protection upgrades within the utility system, out-of-step tripping duty on the feeder breaker, and requirement of transfer trip to avoid temporary overvoltages. These criteria are applied consistently and uniformly to minimize cost of interconnection engineering. They are based on sound engineering principles to ensure that interconnection upgrades specified are justifiable and defensible, if necessary, to the utility´s regulator to ensure open access of the grid.