JP2023032488A - Partial discharge detection method and partial discharge detection device - Google Patents

Abstract

To provide a partial discharge detection method capable of separating aerial discharge and partial discharge to suitably detect the partial discharge under a condition where the aerial discharge and the partial discharge coexist.SOLUTION: A partial discharge detection method comprises: detecting a transient ground voltage in order to detect the presence or absence of partial discharge in a device installed inside a tank; obtaining two time signals from two TEV sensors, one being a grounded first TEV sensor and the other being an ungrounded second TEV sensor; transforming the two time signals into two frequency signals by Fourier transform; obtaining a frequency signal of a difference component based on the two frequency signals; transforming the frequency signal of the differential component into a time signal of the differential component by inverse Fourier transform; and obtaining a partial discharge signal based on the time signal of the difference component.SELECTED DRAWING: Figure 6

Description

The present invention relates to a partial discharge detection method and a partial discharge detection device for suitably separating air discharge and discharge generated inside a high voltage device (hereinafter sometimes referred to as "partial discharge") in a high voltage device. .

High-voltage devices such as switchboards, switchgears, transformers, and switches are used for a long period of time after being installed, and along with this, aging deterioration such as deterioration of insulation performance (insulation abnormality) occurs. 2. Description of the Related Art It is generally known that partial discharge occurs inside a high-voltage device when insulation performance deteriorates. In particular, if partial discharge occurs repeatedly inside a high-voltage device, it may lead to dielectric breakdown, leading to disasters such as fire. Therefore, it is important to detect partial discharge for safe operation of high voltage equipment.

Background art in such a technical field includes, for example, Japanese Patent Application Laid-Open No. 09-068556 (hereinafter referred to as Patent Document 1) and Japanese Patent Application Laid-Open No. 10-210647 (hereinafter referred to as Patent Document 2).

Patent Literature 1 describes an insulation diagnosis device for electrical equipment that detects electromagnetic waves generated by partial discharge that occurs with insulation abnormality of the electrical equipment and determines insulation abnormality. installed in each phase of the electrical equipment, monitor and compare the output level of the detection means that detects the electromagnetic waves of each phase and the detection means of each phase, and the output level of one or more phases among the multiple phases is the standard and determination means for determining that an insulation abnormality has occurred when the output level exceeds the level and only one phase out of the multiple phases has a uniquely high output level. (See the abstract of Patent Document 1).

In addition, Patent Document 2 describes an insulation abnormality diagnosis device for electrical equipment that determines electromagnetic waves caused by partial discharge and external noise, detects external noise with a noise antenna, and detects external noise in a diagnostic frequency band of 300 to 1000 MHz. A judgment unit that selects a predetermined number of frequencies with less noise, determines these as diagnostic frequencies, uses the detection signal of the diagnostic frequency among the signals detected by the abnormal electromagnetic wave detection antenna during diagnostic processing, and determines the presence or absence of insulation abnormality (See the abstract of Patent Document 2).

Japanese Patent Application Laid-Open No. 09-068556 JP-A-10-210647

Patent Document 1 describes an insulation diagnostic device for electrical equipment that detects electromagnetic waves generated by partial discharge without being affected by external noise. Patent Document 2 describes electromagnetic waves generated by partial discharge and external noise. An insulation abnormality diagnosis device for electrical equipment is described.

However, Patent Literature 1 and Patent Literature 2 disclose a partial discharge detection method and a partial discharge detection method for separating air discharge and partial discharge in a situation where air discharge and partial discharge coexist and suitably detecting partial discharge. No discharge detection device is described.

Accordingly, the present invention provides a partial discharge detection method and a partial discharge detection device that separate the aerial discharge from the partial discharge and suitably detect the partial discharge in a situation where the aerial discharge and the partial discharge coexist. .

In order to solve the above-described problems, the partial discharge detection method of the present invention detects the presence or absence of partial discharge in the equipment installed inside the tank by detecting the transient ground voltage and the first TEV of the ground. Two time signals are obtained from two TEV sensors, one is a sensor and the other is an ungrounded second TEV sensor, the two time signals are converted into two frequency signals by Fourier transform, and the two frequency signals are Based on the signal, a frequency signal of the difference component is obtained, the frequency signal of the difference component is converted into a time signal of the difference component by inverse Fourier transform, and a partial discharge signal is obtained based on the time signal of the difference component. It is characterized by

In addition, the partial discharge detection device of the present invention detects the presence or absence of partial discharge in the equipment inside the tank, and detects a transient ground voltage. Two TEV sensors, which are the second TEV sensors, and two time signals are obtained from the two TEV sensors, the two time signals are converted into two frequency signals by Fourier transform, and based on the two frequency signals A signal detection device that obtains a frequency signal of a differential component, converts the frequency signal of the differential component into a time signal of the differential component by inverse Fourier transform, and acquires a partial discharge signal based on the time signal of the differential component. and.

According to the present invention, there is provided a partial discharge detection method and a partial discharge detection device that separate the aerial discharge and the partial discharge under the condition that the aerial discharge and the partial discharge coexist, and suitably detect the partial discharge. be able to.

Problems, configurations, and effects other than those described above will be clarified by the description of the embodiments below.

FIG. 2 is an explanatory diagram schematically explaining the partial discharge detection device described in Example 1; 4 is an explanatory diagram for explaining detection signals of a TEV sensor 1a and a TEV sensor 1b detected in a tank 4 described in Example 1. FIG. It is an explanatory view explaining a frequency signal by Fourier transform of a detection signal. FIG. 10 is an explanatory diagram for explaining a calculation result obtained by arithmetically processing a frequency signal; FIG. 4 is an explanatory diagram for explaining a time signal obtained by inverse Fourier transform of a calculation result; 4 is an explanatory diagram illustrating the flow of signal processing in the signal detection device 3 described in Embodiment 1. FIG. 4 is an explanatory diagram for explaining calibration data for identifying the charge amount of partial discharge described in Example 1. FIG. FIG. 2 is an explanatory diagram for explaining a metal plate 2 described in Example 1; FIG. 6 is an explanatory diagram schematically illustrating a partial discharge detection device described in Example 2; FIG. 10 is an explanatory view schematically explaining a partial discharge detection device described in Example 3; FIG. 10 is an explanatory diagram schematically illustrating a partial discharge detection device described in Example 4;

An embodiment of the present invention will be described below with reference to the drawings. In addition, in each drawing, substantially the same or similar configuration will be described using the same reference numerals. In each drawing, when the explanation overlaps, the overlapping explanation may be omitted.

First, the partial discharge detection device described in Example 1 will be schematically described.

FIG. 1 is an explanatory view schematically explaining the partial discharge detection device described in Example 1. FIG.

In Example 1, the high voltage device schematically includes a tank 4 having a device for detecting the presence or absence of occurrence of partial discharge 12 inside, and an application wire 13 and a high voltage bushing 6 for the device inside the tank 4. The equipment inside the tank 4 has an insulator 5 and an object 9 to be insulated by the insulator 5 .

One of the objects to be insulated 9 is connected to the high-voltage bushing 6, and the other of the objects to be insulated 9 is grounded.

Equipment inside the tank 4 is supplied with a high voltage from an external power supply 7 via an application line 13 and a high voltage bushing 6 . At this time, air discharge 11 frequently occurs from the high voltage bushing 6 in the air portion of the high voltage bushing 6 .

On the other hand, when the equipment inside the tank 4 is used for a long period of time, the insulator 5 deteriorates with age such as a decrease in insulation performance. That is, voids 10 are generated inside the insulator 5, and the insulation performance of the insulator 5 is deteriorated. When a high voltage is supplied to the equipment inside the tank 4 , partial discharge 12 is generated from the insulator 5 inside the tank 4 due to voids 10 generated inside the insulator 5 .

In general, the air discharge 11 and the partial discharge 12 occur at approximately the same timing. Therefore, in the discharge signal detection by a normal antenna, the air discharge signal and the partial discharge signal are superimposed, and only the partial discharge signal is detected. It is difficult to detect.

Therefore, in the first embodiment, two TEV sensors 1 (TEV sensor 1a and TEV sensor 1b) for detecting transient earth voltage (hereinafter referred to as TEV) are used.

A metal plate 2 is installed on each of the TEV sensor 1a and the TEV sensor 1b. The TEV sensor 1a and the TEV sensor 1b each detect and output the surface current induced on the surface of the metal plate 2 as a voltage signal (detection signal).

Both the TEV sensor 1a having the metal plate 2 and the TEV sensor 1b having the metal plate 2 are installed outside (outside) the tank 4, and are installed around the equipment for which partial discharge is to be detected (around the tank 4). be.

A ground wire 8 is connected to the metal plate 2 of the TEV sensor 1a having the metal plate 2, and the metal plate 2 of the TEV sensor 1b having the metal plate 2 is grounded. Do not connect line 8. The ground wire 8 is connected to the ground wire connected to the tank 4 with the other side of the object to be insulated 9 grounded.

That is, the TEV sensor 1a is at ground potential, and the TEV sensor 1b is at floating potential.

The TEV sensor 1a detects a partial discharge signal generated from the insulator 5 via the ground line 8 connecting the metal plate 2 of the TEV sensor 1a to the ground line connected to the tank 4. FIG. At the same time, the TEV sensor 1a detects the air discharge signal as an antenna.

The TEV sensor 1a simultaneously detects the air discharge signal and the partial discharge signal. However, since the air discharge signal reaches the TEV sensor 1a as an electromagnetic wave, it is detected earlier than the partial discharge signal reaching via the ground line 8. FIG.

On the other hand, the TEV sensor 1b detects an air discharge signal propagating in the air as an antenna.

The TEV sensor 1a and the TEV sensor 1b are connected to the signal detection device 3 via the measurement line 14, respectively. Also, the signal detection device 3 is connected to the display device 15 . The signal detection device 3 stores the arrival times and signal strengths of the voltage signals detected by the TEV sensors 1a and 1b. The voltage signal detection timings of the TEV sensor 1a and the TEV sensor 1b are synchronized. The display device 15 also displays FIGS. 2, 3, 4, 5, 7, etc., which will be described later.

Next, detection signals of the TEV sensor 1a and the TEV sensor 1b detected in the tank 4 described in Example 1 will be described.

FIG. 2 is an explanatory diagram for explaining detection signals of the TEV sensor 1a and the TEV sensor 1b detected in the tank 4 described in the first embodiment.

FIG. 2 shows the relationship between time (e.g., microseconds) and signal strength (e.g., mV). is a signal.

The upper part of FIG. 2 shows the detection signal (ungrounded) detected by the TEV sensor 1b, and the lower part of FIG. 2 shows the detection signal (grounded) detected by the TEV sensor 1a.

As shown in FIG. 2, the detection signal (output signal) of the TEV sensor 1a and the detection signal (output signal) of the TEV sensor 1b detected in the tank 4 are different. Since the detection signal of the TEV sensor 1a (lower stage) contains the air discharge signal component and the partial discharge signal component, the signal strength is large, and the detection signal of the TEV sensor 1b (upper stage) contains the air discharge signal component. The signal strength is small because it contains only

The TEV sensor 1a simultaneously detects the air discharge signal and the partial discharge signal. Since the air discharge signal reaches the TEV sensor 1a as an electromagnetic wave, it is detected earlier than the partial discharge signal reaching via the ground line 8. FIG.

Next, a frequency signal obtained by Fourier transform of the detection signal will be described.

FIG. 3 is an explanatory diagram for explaining a frequency signal obtained by Fourier transforming a detection signal.

3(a) is the same drawing as FIG. 2, FIG. 3(b) is a drawing (grounded) obtained by Fourier transforming the lower part of FIG. 3(a), and FIG. It is drawing (ungrounded) which carried out the Fourier transform of the upper stage of (a). In addition, FIG.3(b) and FIG.3(c) show the relationship between a frequency (for example, Hz) and signal strength (for example, non-dimensional: energy relative ratio).

The time domain signals of the detection signal (grounded) of the TEV sensor 1a and the detection signal (ungrounded) of the TEV sensor 1b are converted into respective frequency domain signals by Fourier transform. That is, the grounded and ungrounded time signals (detection signals) are converted into grounded and ungrounded frequency signals by Fourier transform.

As shown in FIGS. 3(b) and 3(c), the frequency spectrum (including air discharge signal components and partial discharge signal components) of the TEV sensor 1a at ground potential contains many low frequency components, The frequency spectrum of the floating potential TEV sensor 1b (including only air discharge signal components) contains many high frequency components.

This is because the detection signal of the TEV sensor 1a includes the superimposed air discharge signal and the partial discharge signal, and the detection signal of the TEV sensor 1b includes only the air discharge signal.

In other words, since the detection signal of the TEV sensor 1a is detected via the ground wire 8, when propagating through the ground wire 8, the influence of the ground capacitance of the ground wire 8 causes an effect equivalent to that of a low-pass filter. and the low frequency components increase.

Next, the result of arithmetic processing of the frequency signal will be described.

FIG. 4 is an explanatory diagram for explaining the result of arithmetic processing of the frequency signal.

4(a) is a drawing similar to FIG. 3(b), and FIG. 4(b) is a drawing similar to FIG. 3(c).

Then, based on the grounded frequency spectrum (frequency signal) shown in FIG. 4A and the ungrounded frequency spectrum (frequency signal) shown in FIG. Extract the difference component.

That is, the frequency spectrum of the air discharge is extracted by extracting the AND component (arithmetic processing spectrum of the AND component) from the frequency signals in the two frequency spectra, and the difference component (arithmetic processing spectrum of the differential component) is extracted. to extract the frequency spectrum of the partial discharge.

The calculation of the AND component is a calculation of extracting a small frequency signal by comparing the grounded frequency signal and the ungrounded frequency signal. is subtracted and the absolute value of the subtracted frequency signal is extracted.

Next, a time signal obtained by inverse Fourier transform of the calculation result will be described.

FIG. 5 is an explanatory diagram for explaining a time signal obtained by inverse Fourier transform of the calculation result.

FIG. 5(a) is a drawing similar to FIG. 4(c), and FIG. 5(b) is a drawing similar to FIG. 4(d). FIG. 5(c) is a drawing (air discharge) obtained by inverse Fourier transforming FIG. 5(a), and FIG. 5(d) is a drawing (partial discharge) obtained by inverse Fourier transforming of FIG. 5(b). . In addition, FIG.5(c) and FIG.5(d) show the relationship between time (for example, microseconds) and signal strength (for example, mV).

Thus, the inverse Fourier transform transforms the frequency domain signal into the time domain signal. In other words, each frequency signal of the AND component and the difference component is converted into a time signal of each of the air discharge and the partial discharge by inverse Fourier transform.

Thereby, the time signal of the air discharge and the time signal of the partial discharge are detected.

Then, based on the relationship between the time and signal intensity in partial discharge (FIG. 5(d)), the occurrence of partial discharge 12 in the equipment inside the tank 4 caused by the void 10 generated inside the insulator 5 Presence or absence can be detected. That is, the insulation state of the equipment inside the tank 4 can be grasped.

Next, the flow of signal processing in the signal detection device 3 described in the first embodiment will be described.

FIG. 6 is an explanatory diagram illustrating the flow of signal processing in the signal detection device 3 described in the first embodiment.

(1) In S101, TEV sensor 1a (first TEV sensor) and TEV sensor 1b (second TEV sensor) are used to obtain a grounded detection signal and a non-grounded time signal (a signal of signal strength against time) (Fig. 2).

(2) In S102, the time signal of the detection signal (grounded) of the TEV sensor 1a is converted into a frequency signal by Fourier transform, and the time signal of the detection signal (ungrounded) of the TEV sensor 1b is converted into a frequency signal by Fourier transform. Convert to a signal (a signal of signal strength against frequency) (see FIG. 3).

(3) In S103, arithmetic processing is performed based on the grounded frequency signal and the ungrounded frequency signal to acquire the frequency signal of the AND component and the frequency signal of the difference component (see FIG. 4). That is, the common signal component (AND component) of the two frequency signals is defined as the air discharge component, and the remaining signal component (difference component) of the two frequency signals is defined as the partial discharge component.

(4) In S104, the AND component frequency signal is converted into an AND component time signal by inverse Fourier transform, and the differential component frequency signal is converted into a differential component time signal by inverse Fourier transform (FIG. 5). reference).

(5) In S105, an air discharge signal is obtained based on the AND component time signal, and a partial discharge signal is obtained based on the difference component time signal (see FIG. 5).

As described above, the partial discharge detection method described in the first embodiment is installed around the tank 4 to detect the presence or absence of the partial discharge 12 in the equipment installed inside the tank 4, and the transient ground voltage is applied. Two time signals are obtained from two TEV sensors 1, one is a grounded TEV sensor 1a (first TEV sensor) and the other is an ungrounded TEV sensor 1b (second TEV sensor), and these The two time signals are transformed into two frequency signals by Fourier transform, the frequency signal of the difference component is obtained based on these two frequency signals, and the frequency signal of the difference component is transformed into the difference by inverse Fourier transform. A partial discharge signal is obtained based on the difference component time signal.

Further, the partial discharge detection device described in the first embodiment is installed around the tank 4 to detect the presence or absence of the partial discharge 12 in the equipment installed inside the tank 4, and detects the transient ground voltage. , two TEV sensors 1, one grounded TEV sensor 1a (first TEV sensor) and the other ungrounded TEV sensor 1b (second TEV sensor), and from the two TEV sensors 1, two time signals These two time signals are converted into two frequency signals by Fourier transform, based on these two frequency signals, a differential component frequency signal is obtained, and this differential component frequency signal is converted into an inverse and a signal detection device 3 for converting into a differential component time signal by Fourier transform and obtaining a partial discharge signal based on the differential component time signal.

As a result, the air discharge signal and the partial discharge signal are detected, and the presence or absence of the partial discharge 12 occurring in the equipment inside the tank 4 can be detected. Then, based on the partial discharge signal, the insulation state of the equipment inside the tank 4 can be grasped.

As described above, according to the first embodiment, when the partial discharge 12 is detected, the air discharge 11 (including external noise of electromagnetic waves such as radio waves) generated in a portion exposed to the air such as the high voltage bushing 6 is detected. is superimposed on the partial discharge 12 generated in the equipment to be detected, but only this partial discharge 12 can be detected.

Moreover, according to the first embodiment, when the TEV sensor 1 is used to detect the partial discharge 12, there is no need to select a predetermined number of frequencies, and there is no need to determine the diagnosis frequency, and only the partial discharge 12 is detected. can do.

That is, according to Example 1, two TEV sensors 1, one grounded and one ungrounded, are used, and the output signals from these two TEV sensors 1 are signal-processed to generate an air discharge 11 and a partial discharge 12. It is possible to separate the aerial discharge 11 and the partial discharge 12 in a situation where both of

Next, calibration data for identifying the charge amount of partial discharge described in Example 1 will be described.

FIG. 7 is an explanatory diagram for explaining calibration data for identifying the charge amount of partial discharge described in the first embodiment.

Here, the magnitude of the detected charge amount of the partial discharge 12 is identified.

First, calibration data is acquired in order to identify the magnitude of the detected charge amount of the partial discharge 12 .

In the calibration data shown in FIG. 7, the horizontal axis is the detected signal strength (mV), and the vertical axis is the calibration signal strength (pC).

This calibration data is acquired by the following procedure.
(1) First, a discharge generator or a signal generator with a known amount of discharge charge is connected to the device in advance to generate a discharge or a signal.
(2) Next, the TEV sensor 1a and the TEV sensor 1b are used to obtain a grounded detection signal and a non-grounded time signal. Then, the partial discharge signal is obtained according to the signal processing flow described above.
(3) This is performed with several types of discharge charge amounts to obtain a characteristic curve (calibration data) between the detected signal intensity and the calibrated signal intensity.
(4) Then, using this calibration data, based on the signal intensity (detection signal intensity) of the partial discharge 12 at a certain time, identify the magnitude of the detected charge amount (calibration signal intensity) of the partial discharge 12 do.

Thereby, the magnitude of the detected charge amount of the partial discharge 12 can be identified.

Next, the metal plate 2 described in Example 1 will be described.

FIG. 8 is an explanatory diagram illustrating the metal plate 2 described in Example 1. FIG.

Here, the shape of the metal plate 2 made of, for example, aluminum or stainless steel, which is installed in the TEV sensor 1a and the TEV sensor 1b, is the shape of a bow-tie antenna. That is, the metal plate 2 is composed of two isosceles triangular plates having the same shape, and is installed so that the vertical angles of the respective isosceles triangular plates face each other.

In addition, since the air discharge 11 is often in the GHz band, it is preferable to set the antenna length and the antenna opening angle so that the center frequency in the frequency characteristics of the bowtie antenna is in the GHz band. It is preferable to set the length to 10 cm or more and the antenna opening angle to 30 degrees or more. In Example 1, the antenna length is 10 cm and the antenna opening angle is 30 degrees.

As a result, the frequency characteristics can be wideband, and the reception sensitivity can be improved.

Next, the partial discharge detection device described in Example 2 will be schematically described.

FIG. 9 is an explanatory view schematically explaining the partial discharge detection device described in Example 2. FIG.

In Example 2, the TEV sensor 1a is installed directly on the metal portion of the side surface of the tank 4 . Thereby, the same effects as those of the first embodiment can be obtained.

A partial discharge 12, which is a radial electromagnetic wave generated inside the tank 4, is induced in the metal portion of the wall surface of the tank 4 to generate a surface current.

Then, according to the second embodiment, the signal intensity of the partial discharge can be increased by detecting the surface current induced in this metal portion.

In addition, in Example 2, the metal plate 3 is not installed on the TEV sensor 1a.

Next, the partial discharge detection device described in Example 3 will be schematically described.

FIG. 10 is an explanatory view schematically explaining the partial discharge detection device described in Example 3. FIG.

In Example 3, three TEV sensors 1a are directly installed at three locations on the metal portion of the side surface of the tank 4 . Thereby, the same effects as those of the first embodiment can be obtained.

Also, the three positions to be installed on the metal part of the side surface of the tank 4 are separated from each other. Specifically, for example, one is installed at the side of the tank 4 , one at the upper end of the side facing the side of the tank 4 , and one at the lower end of the side facing the side of the tank 4 .

When the TEV sensors 1a are installed at three positions separated from each other, the arrival times of the electromagnetic waves of the partial discharge 12 are different. Then, the arrival times of the first waves of the detection signals of the three TEV sensors 1a are compared.

The shorter the distance from the partial discharge source to the TEV sensor 1a, the faster this arrival time.

Further, since the speed of the electromagnetic wave of the partial discharge 12 is constant, the distance between the partial discharge source and each TEV sensor 1a can be obtained from the arrival time of the electromagnetic wave of the partial discharge 12 at each TEV sensor 1a. can be done.

According to the third embodiment, since the TEV sensors 1a are installed at three positions, the position of the partial discharge source can be specified. In other words, the distance from each TEV sensor 1a to the partial discharge source is defined as a radius, and can be indicated by a circle centered on each TEV sensor 1a. The overlapping portion of the circles is the position of the partial discharge source .

Although the three TEV sensors 1a are installed at three locations in the third embodiment, three or more TEV sensors 1a may be installed at three locations or more.

In addition, in Example 3, the metal plate 3 is not installed on the three TEV sensors 1a.

Next, the partial discharge detection device described in Example 4 will be schematically described.

FIG. 11 is an explanatory view schematically explaining the partial discharge detection device described in Example 4. FIG.

In Example 4, a changeover switch 16 is installed on the metal plate 2 installed on the TEV sensor 1 . One end of the changeover switch 16 is connected to the metal plate 2, the other end of the changeover switch 16 is connected to the ground wire 8, and the TEV sensor 1 is grounded (ON) or ungrounded (OFF) by turning the changeover switch 16 ON or OFF. ) and . In other words, the two TEV sensors 1 are realized with one TEV sensor 1 by the changeover switch 16 installed on the metal plate 2 . Thereby, the same effects as those of the first embodiment can be obtained.

Further, according to the fourth embodiment, it is possible to switch between grounding and non-grounding with one TEV sensor, and obtain grounded and non-grounded detection signals. That is, when the changeover switch 16 is grounded, the partial discharge signal and the air discharge signal are obtained, and when the changeover switch 16 is not grounded, only the air discharge signal is obtained.

In addition, the present invention is not limited to the following examples, and includes various modifications. For example, the embodiments described below are specifically described in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described.

Also, part of the configuration of one embodiment can be replaced with part of the configuration of another embodiment. Moreover, the configuration of another embodiment can be added to the configuration of one embodiment. Also, a part of the configuration of each embodiment can be deleted, a part of another configuration can be added, and a part of another configuration can be substituted.

Reference Signs List 1 TEV sensor 2 Metal plate 3 Signal detection device 4 Tank 5 Insulator 6 High voltage bushing 7 External power supply 8 Ground wire 9 Object to be insulated 10 Void 11 Air discharge 12 Partial discharge 13 ... application line 14 ... measurement line 15 ... display device 16 ... changeover switch

Claims (7)

In order to detect the presence or absence of partial discharge in the equipment installed inside the tank, two sensors are used to detect the transient ground voltage, one being the grounded first TEV sensor and the other being the ungrounded second TEV sensor. Obtaining two time signals from a TEV sensor, converting the two time signals into two frequency signals by Fourier transform, obtaining a frequency signal of a difference component based on the two frequency signals, 1. A partial discharge detection method, comprising converting a frequency signal of a difference component into a time signal of a difference component by inverse Fourier transform, and acquiring a partial discharge signal based on the time signal of the difference component. The partial discharge detection method according to claim 1,
A method for detecting partial discharge, characterized in that a metal plate is placed on at least a second ungrounded TEV sensor. A partial discharge detection method according to claim 2,
A method for detecting partial discharge, wherein the shape of the metal plate is a shape of a bow-tie antenna. The partial discharge detection method according to claim 1,
A partial discharge detection method, wherein the first TEV sensor is directly installed on a metal part of the side surface of the tank. A partial discharge detection method according to claim 4,
At least three or more of the first TEV sensors are installed, the distance between the partial discharge generation source and each first TEV sensor is obtained from the arrival time of the partial discharge in each of the first TEV sensors, and the partial discharge generation source is obtained. A partial discharge detection method characterized by identifying a position. A partial discharge detection method according to claim 2,
A partial discharge detection method, wherein the two TEV sensors are realized by a changeover switch installed on the metal plate. Two TEV sensors, one grounded first TEV sensor and the other ungrounded second TEV sensor, for detecting the presence or absence of partial discharge in the equipment inside the tank, for detecting transient ground voltages; ,
Two time signals are obtained from the two TEV sensors, the two time signals are converted into two frequency signals by Fourier transform, and a differential component frequency signal is obtained based on the two frequency signals. a signal detection device for converting the frequency signal of the differential component into a time signal of the differential component by inverse Fourier transform, and obtaining a partial discharge signal based on the time signal of the differential component;
A partial discharge detection device comprising:

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