Electric Distribution Protection Problems Associated with the Interconnection of small, disperesed Generation Devices

This paper discusses the results of simulating three potential protection problems associated with the interconnection of rotating-type, small dispersed storage and generation (DSG) devices to the electric distribution system. These simulations were performed as part of a study to address the-adequacy of the electric utility industry´s present protection practices and hardware for distribution systems with DSG. The simulations considered phenomena such as the effect of dispersed generati, on infeed on the coordination of fuses, resonance of an isolated section of feeder with a three-phase DSG device, and the islanding of a DSG device on an isolated feeder. The phenomena were simulated for a 12. 47 kV feeder with DSG. A digital computer program was used to calculate the transient currents and voltages produced on the feeder for the three types of phehomena. Results of the simulations indicate that these are concerns which should be considered by electric utilities in the connection of dispersed generation sources to the electric distribution system.