DAMAGE DETECTION METHOD FOR LINE IN RESONANT GROUNDED THREE-PHASE NETWORK Russian patent published in 2014 - IPC H02H3/16 

FIELD: electricity.

SUBSTANCE: invention is related to protective relaying of electrical networks under voltage of 6-35 kV with the compensated neutral and is intended for selective damage detection for the line among other network lines when single phase-to-ground fault (SPG fault) occurs. According to the method zero-sequence currents and current of the compensating reactor are measured simultaneously for the protected network lines by means of current sensors with identical amplitude-frequency response. Then the first harmonic is filtered in the obtained results and amplitude-frequency spectrum for the measured current harmonics and amplitude-frequency spectrum for the compensating reactor current are obtained. The amplitude-frequency spectra are compared for all line currents with current spectrum of the reactor, and when amplitude-frequency spectrum for one of the protected network lines coincides with amplitude-frequency spectrum of the compensating reactor current in regard to a group of harmonics specific for the reactor current, damage in the line is recorded.

EFFECT: selective protection of electrical networks from SPG fault and reliable detection of the damaged line among other lines.

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