Fault recorder in power system has always been known as "power black box". It is the basic tool for fault analysis in power system. It plays a key role in correctly judging the action behavior of relay protection and safety automatic device, determining the cause of fault, troubleshooting in time and restoring normal operation.

        Fault recorder has become an important basis for analyzing system faults. Staff need to analyze and study the system oscillation. The power system may cause system oscillation due to dynamic stability failure, static stability failure, non synchronous closing failure to pull into synchronization and generator loss of excitation. When the system oscillates, although the instruments in the power plant or substation have swing reflection, they can not leave specific data, let alone display the change law of some parameters.

        The oscillogram of fault recording device can provide the whole process of system oscillation from generation, out of step, synchronous oscillation, asynchronous oscillation and resynchronization, as well as the characteristics and variation law of oscillation period, current, voltage and other parameters. Therefore, the use of recording data can help analyze and study the system oscillation problem, so as to determine the treatment method, shorten the oscillation time, realize rapid resynchronization and quell the oscillation as soon as possible. At the same time, the analysis and research of system oscillation process can provide a basis for designing and improving relay protection devices.