Protection method and protection system of ship's power distribution system

A protection system of ship's power distribution system, when a fault occurs in the feeder preset to be in charge of the third circuit breaker module, the relay of the third circuit breaker module trips the circuit breaker based on a magnitude and a direction of a fault current, and to transmit a power distribution maintenance signal to the relay of the second circuit breaker module. When a fault occurs in the switchboard preset to be in charge of the second circuit breaker module, the relays of the second and third circuit breaker modules trip the circuit breaker based on a magnitude and a direction of a fault current and the relay of the second circuit breaker module transmit a power distribution maintenance signal to the relay of the third circuit breaker module preset based on the magnitude and direction of the fault current.