A new microprocessor based islanding protection algorithm for dispersed storage and generation units

The ability to detect when dispersed storage and generation (DSG) units become islanded from the main source of generation enables the DSG to be quickly disconnected from the utility network and for that network to be rebuilt in a safe and orderly manner. The new islanding protection algorithm described in the paper has been developed to be part of an integrated protection package to cover all the protection requirements of a DSG. A selection of the results obtained from extensive laboratory and field tests are presented and show that the algorithm reliably trips for islanding conditions within 120 milliseconds, trips for load fluctuations should the DSG be operating independent of the main source of supply and restrains for single phase faults close to the DSG