KR20170061750A - Partial discharge measuring device - Google Patents

Abstract

The partial discharge measuring apparatus according to an embodiment of the present invention may include a first optical CT (Current Transformer) for measuring a power transfer current flowing through a conductor, a partial discharge current measurement using a power transfer current measured in the first optical CT And a light source for outputting the polarized light to the second light CT and the first light CT and the second light CT, wherein a change in the polarization angle of the light due to the power transfer current is removed from the current measured in the second light CT, The partial discharge current is measured by extracting the change in polarization angle due to the pure partial discharge current.

Description

[0001] PARTIAL DISCHARGE MEASURING DEVICE [0002]

The present invention relates to a partial discharge measuring apparatus.

In general, a partial discharge may occur due to an abnormality in the insulation of a high voltage device such as a gas insulated switchgear (GIS).

Conventionally, a UHF partial discharge diagnosis system for discriminating the presence or absence of discharge by using a UHF sensor for detecting an electromagnetic wave pulse signal in the UHF (Ultra High Frequency) band or a partial discharge current diagnosis system using a partial discharge current conducted to the ground through a GIS ground line A HFCT (High Frequency Current Transformer) partial discharge diagnosis system is used to measure the partial discharge, which determines the presence or absence of discharge after detection by the CT of the HF region installed on the ground line.

However, in the case of the UHF partial discharge diagnosis system, it is difficult to measure in the case of the deteriorated insulator, and the measured power (dBm) of the UHF band electromagnetic wave signal can not be expressed by the discharge amount (pC) .

In the case of the HFCT partial discharge diagnosis system, since the GIS ground line is exposed to the outside of the GIS, noise can be easily introduced. Therefore, it is unsuitable for the environment of the actual substation because it is vulnerable to noise. So that it is difficult to measure a pure discharge signal.

The following Patent Document 1 relates to a partial discharge signal detecting apparatus for a power facility, but fails to provide a solution to the above-mentioned problem.

Korean Patent Publication No. 10-2013-0028545

Disclosure of the Invention The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method of detecting a partial discharge by using CT for measuring electric power transmission current and CT for detecting partial discharge current having high sensitivity, Provided is a partial discharge measuring apparatus capable of measuring a partial discharge current by removing a change in the polarization angle of light due to a power electric power transfer current in a CT for current measurement and extracting a change in the angle of view by a pure partial discharge signal.

A partial discharge measuring apparatus according to an embodiment of the present invention includes a first optical CT for measuring a power electric power transfer current flowing through a conductor, And a light source for outputting the polarized light to the first light CT and the second light CT, wherein a change in the polarization of the light due to the power electric power transfer current at a current measured in the second light CT is represented by And the partial discharge current is measured by extracting the polarization angle change by the pure partial discharge current.

In one embodiment, the first light CT includes a first optical fiber that receives the polarized light at one end thereof, a first optical fiber wound on the conductor a first number of times, and a second optical fiber that polarizes light output to the other end of the first optical fiber, 1 polarizer, and a first optical meter for measuring light output from the first polarizer and outputting a first optical output.

In one embodiment, the second light CT includes a second optical fiber that receives the polarized light at one end and is wound a second number of times to the conductor, a second optical fiber that outputs a first axial component output and a second axial component output at the first optical output A second polarizer that adjusts the polarization axis according to the first axis component output and the second axis component output and polarizes the light output to the other end of the second optical fiber to the adjusted polarization axis, And a signal processing unit for calculating a partial discharge current based on the second light output.

Here, the extracting unit may include a converter for extracting a first axis component output of the first light output and a phase shifter for extracting a phase of the first axis component output by 90 degrees to extract a second axis component output .

The extracting unit may further include a low-pass filter that extracts components of the same frequency band as the power transmission current of the conductor at the first light output, and outputs the components to the converter.

In one embodiment, the second number may be greater than the first number.

In one embodiment, the Verdet constant of the second optical fiber may be greater than the Verdet constant of the first optical fiber.

According to the embodiment of the present invention, by using the light CT for measuring the power electric power transfer current and the light CT for measuring the partial discharge current with high sensitivity, It is possible to precisely measure the partial discharge current and the partial discharge amount by extracting the change in the flat angle of light by the pure partial discharge signal.

In addition, unlike HFCT, optical CT is installed in the GIS, so the possibility of influx of external noise is low, and the response speed to current is very fast as 10 ^-9 seconds, so that signals from DC to UHF band can be captured well.

1 is a block diagram illustrating a partial discharge measuring apparatus according to an embodiment of the present invention.
FIG. 2 is a configuration diagram for explaining an embodiment of the first light CT and the second light CT shown in FIG. 1. FIG.
3 is a block diagram for explaining an embodiment of the extracting unit shown in FIG.
FIG. 4 is a diagram illustrating a polarization angle of light output from the second light beam CT shown in FIG. 2. Referring to FIG.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

In the drawings referred to in the present invention, elements having substantially the same configuration and function will be denoted by the same reference numerals, and the shapes and sizes of the elements and the like in the drawings may be exaggerated for clarity.

1 is a block diagram illustrating a partial discharge measuring apparatus according to an embodiment of the present invention.

Referring to FIG. 1, a partial discharge measuring apparatus 10 according to an embodiment of the present invention may include a first optical CT (Current Transformer) 100, a second optical CT 200, and a light source 300 .

The first optical CT 100 and the second optical CT 200 can measure the current flowing through the conductor 1 by detecting a change in the polarization that is input from the light source 300. [ Here, the conductor 1 may be a central conductor of a GIS (Gas Insulated Switchgear).

Specifically, the first and second optical CTs 100 and 200 utilize the Faraday effect, which is a magneto-optic phenomenon. By virtue of the magneto-optic effect of the magnetic field formed by the current flowing in the conductor 1, The current can be measured by measuring the change in the polarization angle (polarization axis rotation of polarized light) passing through the first and second optical CTs 100 and 200.

Here, the first optical CT 100 can measure the power transfer current flowing through the conductor 1, and the second optical CT 200 can measure the power transfer current flowing through the conductor 1 using the power transfer current measured in the first optical CT 100, The current can be measured.

Specifically, the second optical CT 200 eliminates the polarization angle change of light due to the power transfer current measured by the first optical CT 100 from the current measured by the second optical CT 200, The partial discharge current can be measured by extracting the change in the polarization angle by the current.

The first optical CT 100 and the second optical CT 200 will be described in more detail below with reference to FIGS. 2 to 4. FIG.

FIG. 2 is a configuration diagram for explaining an embodiment of the first light CT and the second light CT shown in FIG. 1, FIG. 3 is a configuration diagram for explaining an embodiment of the extracting unit shown in FIG. 2, FIG. 4 is a diagram illustrating a polarization angle of light output from the second light beam CT shown in FIG. 2. Referring to FIG.

Referring to FIG. 2, a first optical CT 100 according to an embodiment of the present invention may include a first optical fiber 110, a first polarizer 120, and a first optical meter 130.

The first optical fiber 110 can be wound on the conductor 1 for a first number of times to measure a power transfer current flowing through the conductor 1 and receive polarized light from the light source 300 at one end. The polarizing angle of the polarized light passing through the first optical fiber 110 can be rotated at a predetermined angle by the magnetic field formed by the current flowing through the conductor 1. Here, the rotated polarization angle may be proportional to the number of turns of the first optical fiber 110 (the first number of times) and the magnitude of the current flowing in the conductor 1.

Here, the relationship between the polarization angle? 1 by the first optical fiber 110 and the magnitude of the electric power transmission current It flowing through the conductor 1 can be represented by the following equation (1).

Equation 1

Herein,? 1 denotes a polarization angle of the first optical fiber 110, n1 denotes a first number of times, and Vc1 denotes a Verdet constant of the first optical fiber 110.

The first polarizer 120 may polarize light output from the other end of the first optical fiber 110 to a first axis (e.g., the x-axis) and output the polarized light to the optical meter 130.

The first optical meter 130 can measure the light output from the first polarizer 120 and output the first optical output. Here, the first light output can be calculated by the following equation (2).

(2)

Here, k1 represents the gain of the first optical meter 130. [

Here, the magnitude of the electric power transfer current It flowing through the conductor 1 can be obtained using Equations (1) and (2), which can be calculated by the following Equation (3).

(3)

A second optical fiber 200 according to an embodiment of the present invention includes a second optical fiber 210, an extraction unit 220, a second polarizer 230, a second optical meter 240, and a signal processing unit 250 can do.

The second optical fiber 210 can be wound on the conductor 1 a second number of times to measure the partial discharge current flowing through the conductor 1 and can receive polarized light from the light source 300 at one end.

Here, the electric power transmission current flowing through the central conductor of the GIS may be 60 Hz. When a partial discharge occurs, the partial discharge current, which is a short pulse signal, may be combined with the electric power transfer current and flow to the center conductor. The second optical fiber 210 may have a larger Verdet constant than the first optical fiber 110 to measure a partial discharge current having a smaller magnitude than the power transfer current.

The number of turns of the second optical fiber 210 (the second number of times) may be larger than the number of turns of the first optical fiber 110 (the first number) in order to measure the partial discharge current having a smaller size than the power transfer current.

When the same polarized light is input to the first and second optical fibers 110 and 210 in one light source 300, the ratio of the polarization angle θ2 by the second optical fiber 210 and the polarization angle θ1 by the first optical fiber 110 (d) can be expressed by the following equation (4).

Equation 4.

Here, Vc1 is a Verdet constant of the first optical fiber 110, Vc2 is a Verdet constant of the second optical fiber 210, n1 is a first number, and n2 is a second number.

Here, the polarization angle &thetas; 2 by the second optical fiber 210 may include a polarization angle &thetas; 2t by a power transfer current and a polarization angle &thetas; 2p by a discharge current as shown in FIG.

The extraction unit 220 extracts the first axis component output P1x and the second axis component output P1y from the first optical output P1 output from the first optical meter 130 and outputs the first axis component output P1x and the second axis component output P1y to the second polarizer 230, .

In one embodiment, the extractor 220 may include a converter 222, a phase shifter 224, and a low-pass filter, as in FIG.

The converter 222 can extract the first axis component output (e.g., x axis component output, P1x) of the first light output P1.

The phase shifter 224 can extract the second axis component output (e.g., the y axis component output, P1y) by shifting the first axis component output P1x extracted from the converter 222 by 90 degrees.

The extracted first and second axis component outputs P1x and P1y may be input in the x and y axes, respectively, to adjust the polarization axis of the second polarizer 230.

In one embodiment, the first and second axis component outputs P1x and P1y can be calculated by the following equations (5) and (6).

Equation (5)

≪ / RTI >

The low pass filter 226 can extract the component of the same frequency band as the power transmission current It of the conductor 1 from the first light output Px and output it to the converter 222. Here, in the case of the central conductor of the GIS, only the frequency of the power transfer current It and the harmonic band thereof can be passed.

The second polarizer 230 may be a polarization axis variable polarizer capable of adjusting a polarization axis according to an applied voltage. In one embodiment, the polarization axis of the second polarizer 230 can be adjusted according to the first axis component output P1x and the second axis component output P1y extracted by the extraction unit 220. [

More specifically, the first axis component output P1x input from the converter 222 can be input to the x axis of the second polarizer 230 and the second axis component output P1y input from the phase shifter 224 May be input to the y-axis of the second polarizer 230.

Thus, when the first axis component output P1x and the second axis component output P1y are input to the second polarizer 230 in the x and y axes, the polarization axis of the second polarizer 230 is perpendicular to? 2t . ≪ / RTI >

Accordingly, the second light output P2 measured by the second optical meter 240 may be an output value of a pure partial discharge current obtained by removing a power transfer current component.

In one embodiment, the second light output P2 can be calculated by the following equation (7).

Equation (7)

The signal processing unit 250 may calculate the partial discharge current and the discharge amount using the second light output P2 measured by the second optical meter 240. [

In one embodiment, the partial discharge current Ip and the discharge amount Q can be calculated by the following equations (8) and (9).

Equation (8)

Equation (9)

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the particular forms disclosed. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1: Conductor
10: Partial discharge measuring device
100: first optical CT
110: first optical fiber
120: first polarizer
130: first optical meter
200: second optical CT
210: second optical fiber
220:
230: 2nd polarizer
240: second optical meter
250: Signal processor

Claims (7)

A first optical CT (Current Transformer) for measuring a power transfer current flowing in a conductor;
A second light CT for measuring a partial discharge current using the electric power transfer current measured in the first light CT; And
A light source for outputting the polarized light to the first light CT and the second light CT; ≪ / RTI >
A partial discharge measuring device for measuring a partial discharge current by removing a change in the polarization angle of light caused by the power transfer current from a current measured in the second optical CT and extracting a polarization change due to a pure partial discharge current.
The apparatus according to claim 1, wherein the first light (CT)
A first optical fiber receiving the polarized light at one end and being wound on the conductor a first number of times;
A first polarizer for polarizing light output to the other end of the first optical fiber to a first axis; And
A first optical meter for measuring light output from the first polarizer and outputting a first optical output;
And the partial discharge measuring device.
3. The apparatus of claim 2, wherein the second light (CT)
A second optical fiber receiving the polarized light at one end and being wound on the conductor a second number of times;
An extraction unit for extracting a first axis component output and a second axis component output from the first light output;
A second polarizer that adjusts the polarization axis according to the first axis component output and the second axis component output and polarizes the light output to the other end of the second optical fiber to the adjusted polarization axis;
A second optical meter for measuring light output from the second polarizer and outputting a second optical output; And
A signal processing unit for calculating a partial discharge current based on the second light output;
And the partial discharge measuring device.
The image processing apparatus according to claim 3,
A converter for extracting a first axis component output of the first light output; And
A phase shifter for shifting the phase of the first axis component output by 90 degrees and extracting the second axis component output as a second axis component output;
And the partial discharge measuring device.
The apparatus of claim 4,
A low pass filter for extracting components of the same frequency band as the power transmission current of the conductor from the first optical output and outputting the components to the converter; Further comprising:
The method of claim 3,
Wherein the second number is larger than the first number.
The method of claim 3,
Wherein a Verdet constant of the second optical fiber is larger than a Verdet constant of the first optical fiber.

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