Protection method and protection system for sub-synchronous and super-synchronous oscillation in power system

The invention discloses a protection method and a protection system for sub-synchronous and super-synchronous oscillation in a power system. The method comprises the following steps: detecting the voltage and current of sub-synchronous harmonic and/or super-synchronous harmonic of a to-be-detected object; getting the sub-synchronous and/or super-synchronous harmonic complex impedance according to the voltage and current of sub-synchronous harmonic and/or super-synchronous harmonic; judging whether the to-be-detected object is a sub-synchronous excitation source or a super-synchronous excitation source according to the sub-synchronous and/or super-synchronous harmonic complex impedance; and sending an alarm signal or a trip signal if the to-be-detected object is a sub-synchronous excitation source or a super-synchronous excitation source. By using the protection method in the embodiment of the invention, sub-synchronous and/or super-synchronous excitation sources in the power grid can be quickly removed, so as to eliminate the negative impact of sub/super-synchronous oscillation on the power system and better ensure the reliability of the power system.