Device for detecting partial discharge in power equipment using radiated electromagnetic wave

• US 20030214307A1
• Filed: 03/20/2003
• Published: 11/20/2003
• Est. Priority Date: 03/29/2002
• Status: Abandoned Application

• Current Assignee: Power System Diagnosis Tech., Inc.
• Original Assignee: Power System Diagnosis Tech., Inc.
• Inventors: Kang, Chang-Won, Choi, Gil-Soo
• Application Number:
  US10/392,532
• Publication Number:
  US 20030214307A1
• Time in Patent Office: Days
• US Class Current: 324/536
• CPC Class Codes: G01R 31/1254 of gas-insulated power appliances or vacuum gaps testing switches G01R31/327; detecting electrical or mechanical defects in encased switchgear H02B13/065
• CPC Class Codes: G01R 31/1272 of cable, line or wire insulation, e.g. using partial discharge measurements locating faults in cables G01R31/083
• CPC Class Codes: H01H 33/26 Means for detecting the presence of an arc or other discharge
• CPC Class Codes: H02H 1/0015 Using arc detectors

Abstract

Disclosed is a device for detecting a partial discharge of power equipment. EM (electromagnetic wave) sensors detect EM signals from a partial discharge in a metal clad switchgear, a power cable, and a GIS. EM detectors amplify the signals from the sensors, and output only noise-removed IF signals. A pulse generator integrates the IF-processed EM to compare the integrated value with a previous value, and outputs a pulse according to a partial discharge. An EM level processor compares the IF-processed EM with reference voltages to output EM pulses of a plurality of levels. A waveform shaper shapes the pulses. A controller calculates the average number of pulses per 1 cycle by counting the partial discharge pulses for a predetermined time, receives the waveform-shaped pulses to calculate the partial discharge amount, and transmits the calculated amount, combined with the average number, to an external monitoring system.

Claims

1. A device for detecting a partial discharge of power equipment, the device comprising:

a plurality of electromagnetic wave detection sensors, respectively, for detecting electromagnetic wave signals radiated from a partial discharge in a metal clad switchgear, a power cable, and a Gas Insulator Switchgear (GIS);

a plurality of electromagnetic wave detectors for amplifying the signals outputted from the detection sensors, and then outputting only electromagnetic wave signals of intermediate frequency, from which noise is removed;

a pulse generator for integrating an intermediate-frequency-processed electromagnetic wave outputted from one of the electromagnetic wave detectors, comparing the integrated value with a value before the integration, and outputting a pulse according to a partial discharge based on the compared result;

an electromagnetic-wave level processor for comparing the intermediate-frequency-processed electromagnetic wave with each of a plurality of reference voltages, and outputting electromagnetic wave pulses representing a plurality of levels based on the compared result;

a waveform shaper for shaping and outputting a waveform of the pulse according to the partial discharge and a waveform of the electromagnetic wave pulses representing the plurality of levels; and

a controller for calculating an average number of pulses per 1 cycle by counting the waveform-shaped pulses according to the partial discharge for a predetermined time, receiving an input of the waveform-shaped electromagnetic wave pulses representing the plurality of levels to calculate a partial discharge amount in predetermined units, and transmitting the calculated partial discharge amount, combined with the average number of pulses, to an external monitoring system through a communication module.

2. The device as set forth in claim 1, wherein each of the electromagnetic wave detection sensor for metal clad switchgears and the electromagnetic wave detection sensor for power cables detects only an electromagnetic wave signal in a band of 30 MHz.

3. The device as set forth in claim 2, wherein the electromagnetic wave detection sensor for power cables includes:

a cable connection section whose one side has a curved surface matching a surface of the power cable;

a helical-type antenna inserted in the cable connection section; and

a holder mounted on the cable connection section, the holder having an end on which a BNC connector is formed, the holder including therein an amplifying circuit connected to the BNC connector and the antenna.

4. The device as set forth in claim 3, wherein a groove is defined on an outer surface of the holder so that one end of a pole including a knob formed at its top can be screwed into the groove.

5. The device as set forth in claim 2, wherein the electromagnetic wave detection sensor for power cables includes:

a cable connection section whose one side has a curved surface matching a surface of the power cable;

a helical-type antenna inserted in the cable connection section;

a holder mounted on the cable connection section, the holder including therein a first photoelectric converter connected to the antenna; and

a knob coupled to the holder, the knob having an end on which a BNC connector is formed, the knob including therein a second photoelectric converter coupled between an end of the BNC connector and an optical transmission medium connected to an output end of the first photoelectric converter.

6. The device as set forth in claim 1, wherein the electromagnetic wave detection sensor for GIS is a band-type electromagnetic-wave detection sensor having two ends of pattern antenna type which can be fixedly coupled to each other by a coupling member, and detects only an electromagnetic wave signal in a band of 423 MHz.

7. The device as set forth in claim 1, wherein each of the electromagnetic wave detectors includes at least:

a RF amplifier for synchronizing and amplifying only an electromagnetic wave signal in a band of 30 MHz or 423 MHz, among electromagnetic waves in a wide frequency band radiated by a partial discharge, through a resonance circuit, and then outputting the amplified signal;

an IF processor for modulating the RF-amplified electromagnetic wave signal into a signal of an intermediate frequency of 500 KHz through a plurality of intermediate frequency transformer circuits, and outputting the modulated signal; and

a noise filter for performing a full wave rectification of the intermediate-frequency-processed IF signal to output only an electromagnetic wave signal from which noise is removed.