KR20220131704A - Apparatus and method for detecting partial discharge of power cables - Google Patents

Abstract

The present invention relates to a device for detecting partial discharge of a cable, comprising: a pair of asymmetric electrodes; a connector including a terminal electrically connected to a conducting wire respectively connected to the pair of asymmetric electrodes; at least one inductor connected in series, parallel, or series-parallel to the pair of asymmetric electrodes and performing impedance matching between a conductor through which a partial discharge signal is transmitted and a control unit; When the output voltage of the pair of asymmetric electrodes becomes greater than or equal to a predetermined voltage level, the instantaneous time, voltage value, and voltage waveform exceeding the set voltage are stored in the internal memory, and then the information stored in the internal memory is transmitted through the internal communication unit. a control unit that transmits to the upper master unit; and a master unit that analyzes the information transmitted from the control unit and calculates a location where the partial discharge occurs.

Description

APPARATUS FOR DETECTING PARTIAL DISCHARGE AND METHOD THEREOF

The present invention relates to an apparatus and method for detecting a partial discharge of a power cable, and more particularly, to detect the location of a partial discharge generated in an HVDC power cable more accurately than before through a clamp-type partial discharge detection sensor. It relates to an apparatus and method for detecting partial discharge of a power cable.

In general, HVDC (High Voltage Direct Current) technology enables long-distance transmission of large-capacity power economically and with less loss than AC transmission, and is a transmission technology that has the advantage of being able to connect with other systems with different frequencies.

HVDC transmission enables large-capacity long-distance power transport, grid linkage between countries, and linkage of different frequencies. As a result, the global demand for HVDC cables is continuously increasing.

As a result, HVDC cables are difficult to detect when a failure occurs due to access restrictions due to underground or subsea installation, and the detection period and recovery time are prolonged, which can lead to huge social costs.

At this time, the main cause of failure of the HVDC cable is partial discharge, which is a local electric discharge phenomenon occurring in the insulation system of the power cable. There is a problem to do.

Therefore, most of the sensors currently used for real-time partial discharge detection of HVDC cables (eg HFCT or metal foil sensors) only detect partial discharges occurring within a certain distance from the attachment location due to the restriction to be attached to the ground wire at the end of the cable or connection part. possible, it is difficult to detect a partial discharge occurring in the entire section of a cable reaching a length of several tens to hundreds of km.

The background technology of the present invention is disclosed in Korean Patent Publication No. 10-2020-0131492 (published on November 24, 2020, a wireless partial discharge position detection system and method).

According to one aspect of the present invention, the present invention was created to solve the above problems, and the position of the partial discharge generated in the HVDC power cable can be detected more accurately than before through a clamp-type partial discharge detection sensor. It is an object of the present invention to provide an apparatus and method for detecting partial discharge of a power cable.

In accordance with an aspect of the present invention, there is provided an apparatus for detecting partial discharge of a power cable, comprising: a pair of asymmetric electrodes; a connector including a terminal electrically connected to a conducting wire respectively connected to the pair of asymmetric electrodes; at least one inductor connected in series, parallel, or series-parallel to the pair of asymmetric electrodes and performing impedance matching between a conductor through which a partial discharge signal is transmitted and a control unit; When the output voltage of the pair of asymmetric electrodes becomes greater than or equal to a predetermined voltage level, the instantaneous time, voltage value, and voltage waveform exceeding the set voltage are stored in the internal memory, and then the information stored in the internal memory is transmitted through the internal communication unit. a control unit that transmits to the upper master unit; and a master unit that analyzes the information transmitted from the control unit and calculates a location where the partial discharge occurs.

In the present invention, when a partial point detection sensor including the pair of asymmetric electrodes, the connector, and the inductor, the control unit is implemented to enable connection of at least one partial discharge detection sensor. .

In the present invention, the clamp for fixing the pair of asymmetric electrodes around the power cable; characterized in that it further comprises.

In the present invention, in the pair of asymmetric electrodes, the sum of the total lengths excluding the distance between the two electrodes becomes the length of the perimeter of the power cable, and the length of one electrode is longer than the length of the other electrode and surrounds the power cable It is characterized in that it is a semi-cylindrical asymmetric electrode.

In the present invention, the pair of asymmetric electrodes is characterized in that it is implemented to surround the outside of the power cable in a form in which the outer surface is surrounded by a clamp.

In the present invention, the pair of asymmetric electrodes is characterized in that it is formed of copper.

In the present invention, as for the pair of asymmetric electrodes, an electrode having a small area or length is connected to a (-) terminal of a connector, and an electrode having a large area or length is connected to a (+) terminal of the connector. do.

In the present invention, the master unit calculates the partial discharge occurrence location based on the time, distance, and speed values of the partial discharge signal arriving from the pair of asymmetric electrodes received through the control unit. do.

)가

인지 체크하고, 상기 N번째와 N+1번째 센서에 도달하는 부분방전 신호의 도착시간 차이가

인 경우, 부분방전은 그 두 센서 사이에서 발생하지 않은 것으로 판단하는 것을 특징으로 한다.In the present invention, the master unit, the difference in arrival time (

)go

It is checked whether the difference in arrival time of the partial discharge signal reaching the Nth and N+1th sensors is

In the case of , it is characterized in that it is determined that the partial discharge has not occurred between the two sensors.

: N번째 센서에 도달하는 부분방전 신호의 도착 시간,here,

: Arrival time of the partial discharge signal reaching the Nth sensor,

: 인접한 두 센서 간의 거리로서, 이미 결정되어 알려진 값이다.

: The distance between two adjacent sensors, which has already been determined and known.

: 부분방전 신호의 속도로서, 케이블의 구조와 매질에 따라 이미 결정되어 알려진 값이다.

: As the speed of the partial discharge signal, it is a known value that has already been determined according to the structure and medium of the cable.

In the present invention, the master unit checks whether a difference between arrival times of the partial discharge signals arriving at the Nth and N+1th sensors is positive, and the partial discharge signals reaching the Nth and N+1th sensors. If the difference in the arrival time of ' is a positive number, it is characterized in that it is determined that the partial discharge occurred on the right side of the N+1th sensor based on the flow of current flowing in the power cable.

In the present invention, when the difference between the arrival times of the partial discharge signals reaching the Nth and N+1th sensors is not positive, the master unit, based on the flow of current flowing in the power cable, the partial discharge is the Nth It is characterized in that it is determined that it occurs on the left side of the sensor.

이 아닌 경우, 부분방전은 N번째와 N+1 번째 센서 사이에서 발생한 것으로 판단하며, 상기 부분방전은 N번째 센서의 위치에서, 수학식(

)을 이용하여 산출한 x 값만큼 오른쪽에 위치에서 발생한 것으로 판단하는 것을 특징으로 한다.In the present invention, the master unit, the difference in the arrival time of the partial discharge signal reaching the N-th and the N+1-th sensor

If not, it is determined that the partial discharge occurred between the Nth and N+1th sensors, and the partial discharge is at the position of the Nth sensor,

) as much as the x value calculated using

In accordance with another aspect of the present invention, there is provided a method for detecting partial discharge of a power cable, comprising: detecting, by a control unit, whether an output voltage of a pair of asymmetric electrodes is equal to or greater than a predetermined voltage level; storing, by the controller, a time, a voltage value, and a voltage waveform at the instant when the output voltage of the pair of asymmetric electrodes exceeds the set voltage in an internal memory; transmitting, by the control unit, the information stored in the internal memory to the upper master unit through the internal communication unit; and calculating, by the master unit, the location where the partial discharge occurs by analyzing the information transmitted from the control unit.

)가

인지 체크하고, 상기 N번째와 N+1번째 센서에 도달하는 부분방전 신호의 도착시간 차이가

인 경우, 부분방전은 그 두 센서 사이에서 발생하지 않은 것으로 판단하는 것을 특징으로 한다.In the present invention, the master unit, the difference in arrival time (

)go

It is checked whether the difference in arrival time of the partial discharge signal reaching the Nth and N+1th sensors is

In the case of , it is characterized in that it is determined that the partial discharge has not occurred between the two sensors.

: N번째 센서에 도달하는 부분방전 신호의 도착 시간,here,

: Arrival time of the partial discharge signal reaching the Nth sensor,

: 인접한 두 센서 간의 거리로서, 이미 결정되어 알려진 값이다.

: The distance between two adjacent sensors, which has already been determined and known.

: 부분방전 신호의 속도로서, 케이블의 구조와 매질에 따라 이미 결정되어 알려진 값이다.

: As the speed of the partial discharge signal, it is a known value that has already been determined according to the structure and medium of the cable.

In the present invention, the master unit checks whether a difference between arrival times of the partial discharge signals arriving at the Nth and N+1th sensors is positive, and the partial discharge signals reaching the Nth and N+1th sensors. If the difference in the arrival time of ' is a positive number, it is characterized in that it is determined that the partial discharge occurred on the right side of the N+1th sensor based on the flow of current flowing in the power cable.

In the present invention, when the difference between the arrival times of the partial discharge signals reaching the Nth and N+1th sensors is not positive, the master unit, based on the flow of current flowing in the power cable, the partial discharge is the Nth It is characterized in that it is determined that it occurs on the left side of the sensor.

이 아닌 경우, 부분방전은 N번째와 N+1 번째 센서 사이에서 발생한 것으로 판단하며, 상기 부분방전은 N번째 센서의 위치에서, 수학식(

)을 이용하여 산출한 x 값만큼 오른쪽에 위치에서 발생한 것으로 판단하는 것을 특징으로 한다.In the present invention, the master unit, the difference in the arrival time of the partial discharge signal reaching the N-th and the N+1-th sensor

If not, it is determined that the partial discharge occurred between the Nth and N+1th sensors, and the partial discharge is at the position of the Nth sensor,

) as much as the x value calculated using

According to one aspect of the present invention, the present invention enables a position of a partial discharge generated in an HVDC power cable to be detected more accurately than before through a clamp-type partial discharge detection sensor.

1 is an exemplary view showing a schematic configuration of a partial discharge detection apparatus of a power cable according to an embodiment of the present invention.
Figure 2 is a flow chart for explaining the partial discharge detection method of the power cable according to an embodiment of the present invention.

Hereinafter, an embodiment of an apparatus and method for detecting partial discharge of a power cable according to the present invention will be described with reference to the accompanying drawings.

In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, definitions of these terms should be made based on the content throughout this specification.

1 is an exemplary diagram showing a schematic configuration of an apparatus for detecting partial discharge of a power cable according to an embodiment of the present invention.

As shown in Figure 1, the partial discharge detection apparatus of the power cable according to the present embodiment, a pair of asymmetric electrodes (110, 120), a connector (130), inductors (140, 150), a control unit (160), and a master unit 170 .

The pair of asymmetric electrodes 110 and 120, the sum of the lengths of the two electrodes (ie, the total length excluding the distance between the two electrodes) is almost the length of the circumference (ie, arc) of the power cable (eg, HVDC cable) , and the length of one electrode is longer than the length of the other electrode, and the asymmetric electrode (ie, electrodes of different lengths) in a semi-cylindrical shape (ie, the enclosing shape of the power cable) is spaced at a certain distance from the power cable (eg, HVDC). It is configured in the form of enclosing the outer anticorrosive layer (protective layer) of the cable).

In order for the asymmetric electrode (ie, electrodes of different lengths) to surround the external anticorrosive layer (protective layer) of the power cable (eg, HVDC cable), using a clamp to surround the outer surface of the asymmetric electrode (110, 120) It can be implemented in the form

Here, the pair of asymmetric electrodes 110 and 120 is preferably a copper electrode, but is not limited thereto and may be replaced with another metal.

For example, an area of the pair of asymmetric electrodes 110 and 120 may be 34 cm ² , 18 cm ² , respectively, and an interval between the electrodes may be 1 cm. However, it is not intended to limit the area of the electrode and the interval between the electrodes, and the area of the electrode and the interval between the electrodes may be changed. However, there is an advantage that the sensitivity increases as the area of the electrode increases.

The connector 130 includes terminals electrically connected to conductive wires respectively connected to the pair of asymmetric electrodes 110 and 120 .

For example, the electrode 120 having a small area (or length) may be connected to a (-) electrode of the connector 130 , and the electrode 110 having a large area (or length) may be connected to a (+) electrode of the connector 130 . .

In addition, the connector 130 may use a connector (eg, BNC, SMA, etc.) of a form that can be connected to a common coaxial RF cable.

The inductors 140 and 150 are connected in series, parallel, or series-parallel with the pair of asymmetric electrodes 110 and 120, and partial discharge through impedance matching between the conductor through which the partial discharge signal is transmitted and the controller 160 Prevents signal loss.

Here, the clamp is made of an insulator, and the inner diameter corresponds to the outer diameter of the power cable to which the sensor (ie, a pair of asymmetric electrodes for detecting partial discharge) is to be mounted, and the pair of asymmetric electrodes ( 110, 120) are attached. That is, the clamp serves to fix the pair of asymmetric electrodes 110 and 120 around the power cable.

When the output voltage of the partial discharge detection sensor (ie, a pair of asymmetric electrodes) exceeds a predetermined voltage level, the control unit 160 stores the instantaneous time, voltage value, and voltage waveform that exceeds the set voltage in an internal memory (not shown). ) is stored in

In addition, the control unit 160 transmits the information stored in the internal memory (not shown) (eg, the instantaneous time exceeding the set voltage, voltage value, voltage waveform, etc.) to the upper master unit 170 through the internal communication unit (not shown). (e.g. server).

Here, when a partial point detection sensor including the pair of asymmetric electrodes 110 and 120, the connector 130, and the inductors 140 and 150, the control unit 160 detects at least one partial discharge It may be implemented so that the connection of the sensor is possible.

The master unit 170 analyzes the information transmitted from the control unit 160 (eg, the instantaneous time exceeding the set voltage, voltage value, voltage waveform, etc.) to calculate the presence or absence of partial discharge and the location where the partial discharge occurred. do.

For example, when a partial discharge occurs in the insulation of the power cable, a high-frequency electromagnetic pulse is propagated along the conductor and the metal shielding layer of the power cable, so that near the point where the partial discharge occurs, the high-frequency electromagnetic pulse is uniform along the entire circumference of the metal shielding layer It does not propagate as much as possible, but propagates along some areas of the metal shielding layer. That is, the distribution of the circumferential component (?) of the high-frequency electromagnetic pulse at a specific position (z) in the metal shielding layer is not uniform.

Accordingly, when a high-frequency electromagnetic pulse propagating along a partial region of the metal shielding layer passes through a semi-cylindrical asymmetric electrode with a pair of arc lengths different as in the configuration of the sensor (ie, a pair of asymmetric electrodes), the two electrodes have capacitance. Voltages of different magnitudes are induced through sexual coupling.

For example, when the high-frequency electromagnetic pulse propagates through the metal shielding layer corresponding to the arc range of the first electrode 110 , the voltage induced in the first electrode 110 and the voltage of the second electrode 120 are different from each other. induced, and it is detected by the device according to the present embodiment.

At this time, as the distance at which the high-frequency electromagnetic pulse generated by the partial discharge propagates along the metal shielding layer increases, the distribution of the high-frequency electromagnetic pulse within the metal shielding layer becomes more uniform. That is, as the propagation distance z increases (longer), the range of the arc in which the high-frequency electromagnetic pulse is distributed becomes wider, and when propagating a sufficiently long distance, the uniform high-frequency electromagnetic pulse is distributed and propagated along the entire circumference of the metal shielding layer.

Therefore, if a pair of asymmetric electrodes with different arc lengths are used as in the present embodiment, even if the high-frequency electromagnetic pulse propagates a sufficient distance and the distribution of the circumferential component becomes uniform, the width (length) of the electrodes is different, so that each electrode has a different size. There is a characteristic that the voltage of the voltage is induced and can be detected.

Accordingly, the master unit 170 calculates the location of the partial discharge based on the time and voltage value at which the partial discharge signal arrives at the two sensors (a pair of asymmetric electrodes) adjacent to the point where the partial discharge occurs.

2 is a flowchart for explaining a method for detecting partial discharge of a power cable according to an embodiment of the present invention. Based on the time, distance, and speed at which the discharge signal arrives, the location of the partial discharge is calculated.

2 is a flowchart illustrating a method of detecting a partial discharge occurrence position using a plurality of (N+1) partial discharge sensor arrays arranged at regular intervals.

)가

인지 체크한다(S101).2, the difference in arrival time of the partial discharge signal reaching the Nth and N+1th sensors (

)go

It is checked whether it is (S101).

인 경우(S101의 예), 부분방전은 그 두 센서 사이에서 발생하지 않은 것을 의미한다.The difference in arrival time of the partial discharge signal reaching the Nth and N+1th sensors is

(Yes in S101), it means that partial discharge does not occur between the two sensors.

Then, it is checked whether a difference between the arrival times of the partial discharge signals arriving at the Nth and N+1th sensors is a positive number (S102).

When the difference between the arrival times of the partial discharge signals arriving at the N-th and N+1-th sensors is a positive number (Yes in S102), it means that the partial discharge occurs on the right side of the N+1-th sensor.

Accordingly, it is necessary to check the difference in arrival times of the N+1th and N+2th sensors. Therefore, the value of N is increased by 1 until the condition of S101 is false (S103).

If the difference between the arrival times of the partial discharge signals arriving at the Nth and N+1th sensors is not a positive number (No in S102), that is, arrivals of the partial discharge signals arriving at the Nth and N+1th sensors. If the time difference is negative (No in S102), it means that the partial discharge occurs on the left side of the N-th sensor.

For reference, the right or left side of the sensor is based on the current flowing through the power cable.

Accordingly, it is necessary to check the difference in arrival time between the N-1 th sensor and the N th sensor. Therefore, the value of N is decreased by 1 until the condition of S101 is false (S104).

이 아닌 경우(S101의 아니오), 부분방전은 N번째와 N+1 번째 센서 사이에서 발생한 것을 의미한다(S105).On the other hand, the difference in arrival time of the partial discharge signal reaching the Nth and N+1th sensors is

If not (No in S101), it means that the partial discharge has occurred between the N-th and N+1-th sensors (S105).

)을 이용하여 산출한 x 값만큼 오른쪽에 위치에서 발생한 것(

)을 의미한다(S106).At this time, the partial discharge is at the position of the N-th sensor, in the above step S105, the equation (

) that occurred at the position on the right as much as the x value calculated using (

) means (S106).

: N번째 센서에 도달하는 부분방전 신호의 도착 시간,here,

: Arrival time of the partial discharge signal reaching the Nth sensor,

: 인접한 두 센서 간의 거리로서, 이미 결정되어 알려진 값이다.

: The distance between two adjacent sensors, which has already been determined and known.

: 부분방전 신호의 속도로서, 케이블의 구조와 매질에 따라 이미 결정되어 알려진 값이다.

: As the speed of the partial discharge signal, it is a known value that has already been determined according to the structure and medium of the cable.

: 부분방전 발생 위치,

: Location of partial discharge,

: N 번째 센서의 위치,

: the position of the Nth sensor,

: N 번째 센서로 부터의 거리,

: distance from the Nth sensor,

As described above, in this embodiment, when the control unit 160 to which a plurality of sensors (ie, a sensor composed of a plurality of asymmetric electrodes) is connected detects a partial discharge signal and transmits it to the master unit 170, the master unit ( 170), a partial discharge occurrence location is calculated based on the time, distance, and speed values at which the partial discharge signal arrives.

Accordingly, the present embodiment can be easily installed regardless of the position of the cable non-invasively without structural deformation of the power cable, and has the effect of accurately measuring the location of the partial discharge. In addition, the present embodiment can replace the existing HFCT sensor, and since it is inexpensive and light, a large number of sensors can be installed over the entire transmission line, so that the location of the partial discharge can be detected more accurately.

As described above, the present invention has been described with reference to the embodiment shown in the drawings, but this is merely an example, and various modifications and equivalent other embodiments are possible therefrom by those skilled in the art. will understand the point. Therefore, the technical protection scope of the present invention should be defined by the following claims. Implementations described herein may also be implemented as, for example, a method or process, an apparatus, a software program, a data stream, or a signal. Although discussed only in the context of a single form of implementation (eg, discussed only as a method), implementations of the discussed features may also be implemented in other forms (eg, as an apparatus or program). The apparatus may be implemented in suitable hardware, software and firmware, and the like. A method may be implemented in an apparatus such as, for example, a processor, which generally refers to a computer, a microprocessor, a processing device, including an integrated circuit or programmable logic device, or the like. Processors also include communication devices such as computers, cell phones, portable/personal digital assistants (“PDA”) and other devices that facilitate communication of information between end-users.

110, 120: a pair of asymmetric electrodes
130: connector
140, 150: inductor
160: control unit
170: master unit

Claims (17)

a pair of asymmetric electrodes;
a connector including a terminal electrically connected to a conducting wire respectively connected to the pair of asymmetric electrodes;
at least one inductor connected in series, parallel, or series-parallel to the pair of asymmetric electrodes and performing impedance matching between a conductor through which a partial discharge signal is transmitted and a control unit;
When the output voltage of the pair of asymmetric electrodes becomes greater than or equal to a predetermined voltage level, the instantaneous time, voltage value, and voltage waveform exceeding the set voltage are stored in the internal memory, and then the information stored in the internal memory is transmitted through the internal communication unit. a control unit that transmits to the upper master unit; and
and a master unit that analyzes the information transmitted from the control unit and calculates a location where the partial discharge occurs.
The method of claim 1,
When it is called a partial point detection sensor including the pair of asymmetric electrodes, the connector, and the inductor,
The control unit is a partial discharge detection device of the power cable, characterized in that implemented to enable the connection of at least one partial discharge detection sensor.
The method of claim 1,
The device for detecting partial discharge of a power cable further comprising a; clamp for fixing the pair of asymmetric electrodes to the circumference of the power cable.
According to claim 1, wherein the pair of asymmetric electrodes,
The sum of the total lengths excluding the distance between the two electrodes becomes the length of the circumference of the power cable, the length of one electrode is longer than the length of the other electrode, and the power cable is a semi-cylindrical asymmetric electrode surrounding the power cable of partial discharge detection device.
According to claim 1, wherein the pair of asymmetric electrodes,
Partial discharge detection device of the power cable, characterized in that implemented to surround the outside of the power cable in a form in which the outer surface is surrounded by a clamp.
According to claim 1, wherein the pair of asymmetric electrodes,
Partial discharge detection device of the power cable, characterized in that formed of copper.
According to claim 1, wherein the pair of asymmetric electrodes,
An electrode with a small area or length is connected to the (-) terminal of the connector,
The partial discharge detection device of the power cable, characterized in that the electrode having a large area or length is connected to the (+) terminal of the connector.
According to claim 1, wherein the master unit,
Partial discharge detection apparatus of a power cable, characterized in that for calculating the partial discharge occurrence location based on the time, distance, and speed values of the partial discharge signal arrives from the pair of asymmetric electrodes received through the control unit.
The method of claim 8, wherein the master unit,
The difference in arrival time of the partial discharge signal arriving at the Nth and N+1th sensors (

)go

It is checked whether the difference in arrival time of the partial discharge signal reaching the Nth and N+1th sensors is

If , the partial discharge detection device of the power cable, characterized in that it is determined that the partial discharge does not occur between the two sensors.
here,

: Arrival time of the partial discharge signal reaching the Nth sensor,

: The distance between two adjacent sensors, which has already been determined and known.

: As the speed of the partial discharge signal, it is a known value that has already been determined according to the structure and medium of the cable.
The method of claim 9, wherein the master unit,
It is checked whether the difference in arrival times of the partial discharge signals arriving at the Nth and N+1th sensors is a positive number, and when the difference in arrival times of the partial discharge signals arriving at the Nth and N+1th sensors is positive, Partial discharge detection device of a power cable, characterized in that it is determined that the partial discharge occurred on the right side of the N+1th sensor based on the flow of current flowing in the power cable.
The method of claim 9, wherein the master unit,
If the difference between the arrival times of the partial discharge signals arriving at the Nth and N+1th sensors is not a positive number, it is determined that the partial discharge occurred on the left side of the Nth sensor based on the flow of current flowing in the power cable. A device for detecting partial discharge of power cables.
The method of claim 9, wherein the master unit,
The difference in arrival time of the partial discharge signal reaching the Nth and N+1th sensors is

If not, it is determined that the partial discharge occurred between the Nth and N+1th sensors, and the partial discharge is at the position of the Nth sensor,

), the partial discharge detection device of the power cable, characterized in that it is determined that the x value calculated by using the position on the right side.
detecting, by the controller, whether the output voltage of the pair of asymmetric electrodes is equal to or greater than a predetermined voltage level;
storing, by the controller, a time, a voltage value, and a voltage waveform at the instant when the output voltage of the pair of asymmetric electrodes exceeds the set voltage in an internal memory;
transmitting, by the control unit, the information stored in the internal memory to the upper master unit through the internal communication unit; and
and calculating, by the master unit, the location where the partial discharge has occurred by analyzing the information transmitted from the control unit.
The method of claim 13, wherein the master unit,
The difference in arrival time of the partial discharge signal arriving at the Nth and N+1th sensors (

)go

It is checked whether the difference in arrival time of the partial discharge signal reaching the Nth and N+1th sensors is

, the partial discharge detection method of the power cable, characterized in that it is determined that the partial discharge does not occur between the two sensors.
here,

: Arrival time of the partial discharge signal reaching the Nth sensor,

: The distance between two adjacent sensors, which has already been determined and known.

: As the speed of the partial discharge signal, it is a known value that has already been determined according to the structure and medium of the cable.
15. The method of claim 14, wherein the master unit,
It is checked whether the difference in arrival times of the partial discharge signals arriving at the Nth and N+1th sensors is a positive number, and when the difference in arrival times of the partial discharge signals arriving at the Nth and N+1th sensors is positive, Partial discharge detection method of a power cable, characterized in that it is determined that the partial discharge occurred on the right side of the N+1th sensor based on the flow of current flowing in the power cable.
15. The method of claim 14, wherein the master unit,
If the difference between the arrival times of the partial discharge signals arriving at the Nth and N+1th sensors is not a positive number, it is determined that the partial discharge occurred on the left side of the Nth sensor based on the flow of current flowing in the power cable. A method for detecting partial discharge of a power cable with
15. The method of claim 14, wherein the master unit,
The difference in arrival time of the partial discharge signal reaching the Nth and N+1th sensors is

If not, it is determined that the partial discharge occurred between the Nth and N+1th sensors, and the partial discharge is at the position of the Nth sensor,

), a partial discharge detection method of a power cable, characterized in that it is determined that the x value calculated by using the x value is determined to have occurred in the right position.

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