The load shedding scheme design for an integrated steelmaking cogeneration facility

This paper develops the coordination of a load-shedding scheme for a large industrial customer with several cogenerator units. A detailed description of each design procedure is included. The loads are tripped by the underfrequency relays, to prevent the power system from collapse when the plant becomes isolated, due to a utility service outage. Different system fault cases have been selected to derive the proper formulation of a load-shedding scheme, according to the historical operation records. The key factors, such as frequency settings, number of load-shedding steps, size and location of the loads to be tripped, relay time delay, and the coordination with the generator protection scheme, were examined through the simulation of the transient stability program. The proper load-shedding scheme has been designed, and the related hardware has been installed in the plant, to keep the system from blackout when the disturbance occurs.