Relay protection method and device against LC parallel circuit detuning faults

摘要

A relay protection method against LC parallel circuit detuning faults comprises the steps of: a relay protection device samples a current of a parallel LC, that is, a reactor and a capacitor, and samples a total current flowing through the whole LC; convert the current of the reactor into a current of an equivalent capacitor; calculate amplitudes of the current of the equivalent capacitor and a current of a realistic capacitor, and calculate an amplitude of the total current flowing through the LC; calculate a current amplitude ratio of the equivalent capacitor to the realistic capacitor; and when the amplitude of the total current flowing through the LC is large enough, send an alarm signal or a trip signal by delay and output an idle contact of a trip relay if the current ratio exceeds a preset upper and lower limit range. Also provided is a corresponding relay protection device. The relay protection method and device against LC parallel circuit detuning faults can improve stability of calculation results of a current ratio, and raise sensitivity and rapidity of protection.