Harmonized Grouping of Renewable and Distributed Generation in the Utility Power Grid

DG position in the utility grid changes greatly from the historical viewpoint of power system engineering. For the secure & safe operation of renewable and distributed generation, the harmonized grouping of DG plants and the careful interconnection of the grouped DG to the existing bulk grid are essentially important. The mandatory requirements for the DG group are the kW-balancing of DG output and local demand, and the voltage regulation in the group. It is necessary to contribute the ancillary service not to give worse disturbances to the exiting utility power grid. Under the support of NEDO grant, the pilot projects of DG grouping have been demonstrated in Japan.