DIGITAL PROTECTIVE RELAY DEVICE ABNORMALITY MONITORING DEVICE AND ABNORMALITY MONITORING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a simple abnormality monitoring device and abnormality monitoring method capable of reducing erroneous detection of abnormality of a digital protective relay device.SOLUTION: An abnormality monitoring device comprises: a harmonic generation circuit for generating a harmonic signal; a harmonic generation control unit for controlling whether to generate either harmonic signal of first and second harmonic signals that have the same frequency and phases differing by a half period; an adding unit for superposing the harmonic signal on an electric signal to generate a harmonic superposition signal; a digital filter unit for extracting a frequency component whose frequency is the same as that of the harmonic signal from the harmonic superposition signal having passed through an analog signal processing unit; a harmonic monitoring unit for determining whether or not the extracted frequency component satisfies a setting condition; and a device abnormality determination unit for determining the existence of abnormality in the analog signal processing unit on the basis of a result of the determination by the harmonic monitoring unit. The harmonic generation control unit performs control of making the harmonic generation circuit generate the second harmonic signal, depending on a result of determination by the harmonic monitoring unit in the case of selecting the first harmonic signal as the harmonic signal.SELECTED DRAWING: Figure 1