Industrial and cogeneration protection problems requiring simulation

The procedures outlined in relay instruction manuals for setting out-of-step, loss-of-excitation, reverse power, external fault, and similar protective relays cover typical situations and may not be appropriate in all circumstances. Cogenerators, small power producers, and industrial generators can face long fault clearing times, high fault levels, lower fault levels, high voltage, and a range of other unusual conditions in the adjoining utility system. Some critical relay applications and the simulations required to select the best settings are outlined for use in such cases. The discussion covers out-of-step protection; loss-of-excitation protection; reverse power protection; overcurrent protection; shaft torques from utility reclosing; load shedding; and self-excitation overvoltages