Protection of dispersed storage and generation units against islanding

This paper deals with islanding protection which is the most important protection requirement of dispersed storage and generation units (DSGs). A power based digital algorithm has been developed for the protection of DSG units against islanding. Computer simulation results show that, in addition to effectively detecting the islanding, the new algorithm trips for the load changes that occur during the islanding operation but remains unstable for the load fluctuations while the DSG unit is operating in parallel with the utility network. The algorithm also detects the condition when the utility supply is reconnected to the power island while the two supplies are out of phase