Time-adjusting adaptive bus protection for shipboard multi-unit power station

With the development of capacity and topology in shipboard power system, parallel running of multiple generators in single power station becomes an important configuration. The traditional protection method, with characteristic of off-line setting, sets the same values for several bus tie breakers. All generators would be step out while short-circuit occurs on bus-bar, which dissatisfies protection demand. A new time-adjusting adaptive bus protection strategy is proposed, which can modify its characteristic automatically according to operation state and fault type of power systems. By detecting three-phase instantaneous currents flowing through bus tie breakers, fault type can be identified and time setting of short delay can be adjusted on-line. The strategy realizes selective protection of bus zone for multi-unit power station, which increases reliability of power supply and system stability. Simulation results of typical instance validate the feasibility and validity to improve protection performance.