RELAY PROTECTION METHOD AND APPARATUS 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 after a setting time delay if the current ratio exceeds a preset upper and lower limit range. Also provided is a corresponding relay protection device.

主权项

1. A relay protection method against LC parallel circuit detuning faults, comprising:
(1) sampling, by a relay protection device, a current of a parallel reactor, sampling a current of a parallel capacitor, and sampling a total current flowing through the LC parallel circuit; (2) converting the current of the reactor into a current of an equivalent capacitor; (3) calculating amplitudes of the current of the equivalent capacitor and a current of a realistic capacitor and calculating an amplitude of the current flowing through the LC parallel circuit; (4) calculating a current amplitude ratio of the equivalent capacitor to the realistic capacitor; and (5) when the amplitude of the total current flowing through the LC parallel circuit is large enough, sending an alarm signal or a trip after a setting time delay if the current amplitude ratio exceeds a preset upper and lower limit range.