PROTECTIVE RELAY SYSTEM AND PROTECTIVE RELAY DEVICE

Embodiments of the present disclosure provide a protective relay system, a protective relay device, and a time synchronization method which can realize a time synchronization highly precisely between devices. Embodiments of the present disclosure relate to a protective relay system including plural protective relay devices protecting a power system based on electrical quantity data from the power system, and a communication between the protective power devices is performed via a network. The protective relay device includes a clock unit periodically clocking a timing at which sampling is performed on an electrical quantity of the power system, a relay computing unit performing a relay computation based on the electrical quantity data having undergone the sampling and electrical quantity data received via the network, a random-number creating unit creating a random number, and a synchronization-frame processing unit setting a timing of sending a synchronization frame to another protective relay device via the network based on the random number created by the random-number creating unit.