Successful DG projects: design and build considerations

These four projects are in service in three different utility jurisdictions. They are connected to the distribution lines and a 69 kV customer-owned substation. The need for these facilities varied with each location, and the economic studies showed a good payback for this DG investment. Two of the projects are in southern California and are installed on the process industries distribution delivery point. The goal was reliability and continuity of service when the industrial customers are curtailed during a shortage of energy from the supplying utility. In one case, the use of natural gas for the 2-700 kW diesel generator sets meets the California Emission Standards for cleaner air. The use of numeric protective relays for generator, feeder, and intertie protection reduced the cost for the multifunction protective systems in the customer-owned medium voltage switchgear lineup. An automobile glass manufacturing plant project in Tennessee balanced the electric cost with the cost to generate for the glass process. This interconnection for parallel operation is at the low side of the customer-owned 69/12 kV substation. The supplying utility is a gas and electric utility that buys power wholesale for resale. The fourth project is a combined heat and power installation in the NY City area. It saves the condominium association significant HVAC system costs. The generator is an induction machine driven by a steam turbine and interconnected on the customer´s side of the utility revenue meter. The turbine generator and parallel interconnection are protected by numerical protective systems.