JP7127625B2 - Partial discharge detector and partial discharge monitoring system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a partial discharge detection device for detecting partial discharge generated in an electrical insulating material provided in an electrical facility by detecting a change in the ground voltage of the electrical facility caused by the partial discharge, and a partial discharge monitoring system provided with the same. .

In electrical insulating materials that insulate high-voltage electricity, the electric field concentrates on defects (defects, voids, etc.) due to aging or damage, and temporary weak discharges, that is, partial short circuits may occur. , this phenomenon is called partial discharge. When partial discharge occurs in an electrically insulating material, the deterioration of the defective portion is accelerated, which may lead to dielectric breakdown.

Therefore, in the maintenance management of electrical equipment that receives high-voltage electricity, the occurrence of partial discharge is regarded as a precursor phenomenon of electrical accidents due to insulation breakdown, and the occurrence of partial discharge is monitored, and the electrical equipment is repaired when partial discharge occurs. The occurrence of electrical accidents is being prevented by taking countermeasures such as refurbishment and renewal.

In order to enable continuous monitoring of partial discharge, for example, Patent Document 1 discloses that waveform data of a discharge detection signal is acquired only when a measured value of the discharge detection signal sampled at a sampling frequency of 1 GHz or higher exceeds a predetermined threshold. A technique is disclosed for reducing the amount of data used for monitoring partial discharge by recording and transferring the data.

However, in the technique disclosed in Patent Document 1, since the discharge detection signal is sampled at a high frequency, if partial discharge occurs frequently in a short period of time, recording and transfer of the waveform data of the discharge detection signal also occur frequently. , the amount of data to be recorded and transferred becomes enormous. Since there are limits to memory capacity and communication speed, if the amount of data becomes enormous, problems will arise in recording and transferring waveform data. Therefore, the technology disclosed in Patent Literature 1 does not necessarily sufficiently solve the problem of enabling continuous monitoring of partial discharge.

JP 2017-219537 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a partial discharge detector and a partial discharge monitoring system that enable continuous monitoring of partial discharges occurring in electrical insulating materials provided in electrical equipment with a simple and inexpensive configuration.

In order to solve the above problems, the partial discharge detection device and the partial discharge monitoring system of the present invention have the following features.

[1] A partial discharge detection device for detecting a partial discharge generated in an electrical insulating material provided in an electrical facility from a change in the ground voltage of the electrical facility caused by the partial discharge, wherein the ground voltage of the electrical facility is A partial discharge detection device comprising: a sensor for measurement; and an analog electronic circuit for outputting a waveform signal of the ground voltage measured by the sensor with a reduced frequency.

[2] The partial discharge detection device according to [1], wherein the analog electronic circuit has an electronic element having a capacitance of 0.001 to 0.1 μF.

[3] The partial discharge detection device according to [2], wherein the electronic element includes a capacitor.

[4] The partial discharge detection device according to [2] or [3], wherein the electronic element includes a diode.

[5] Further comprising a counter that acquires the value of the waveform signal whose frequency has been lowered by the analog electronic circuit at a predetermined cycle and counts the number of times the acquired value exceeds a predetermined threshold. The partial discharge detection device according to any one of [1] to [4].

[6] The partial discharge detection device according to [5], further comprising a communication unit that transfers information on the number of times counted by the counter.

[7] The partial discharge detection device according to [6], wherein the communication unit transfers the information on the number of times by wireless communication.

[8] receiving the information on the number of times transferred from the partial discharge detection device according to [6] or [7] and the communication unit of the partial discharge detection device; A partial discharge monitoring system, comprising: a monitoring terminal for outputting information indicating that equipment needs to be repaired or updated.

According to the partial discharge detection device and the partial discharge monitoring system of the present invention, an analog electronic circuit having a simple configuration including electronic elements such as capacitors and diodes having a capacitance of 0.001 to 0.1 μF, for example, The frequency of the waveform signal of the ground voltage measured by the sensor can be lowered and output.

As a result, changes in the waveform of the ground voltage caused by partial discharge can be captured without performing high-speed sampling, so there is no need to incorporate an expensive high-speed sampling device, and the cost of the partial discharge detection device can be greatly reduced. It is possible to perform continuous monitoring of partial discharge at a large number of locations at a low cost.

Then, the value of the waveform signal whose frequency has been lowered by the analog electronic circuit is sampled at a low frequency, the number of times the acquired value of the waveform signal exceeds a predetermined threshold is counted, and the information on this number of times is transferred to the outside. used to monitor partial discharge. Therefore, compared to the case where the frequency of the waveform signal is not lowered by the analog electronic circuit, the amount of data transferred from the partial discharge detection device to the outside is greatly suppressed, and the continuous monitoring of partial discharge can be performed inexpensively and reliably. be able to.

1 is a block diagram showing the configuration of an example of the partial discharge detection device and partial discharge monitoring system of the present invention; FIG. 4 is a graph showing an example of transient changes in the ground voltage of electrical equipment due to partial discharge occurring in an electrical insulating material provided in the electrical equipment; FIG. 4 is a graph showing ground voltage waveform signals before and after being processed by the partial discharge detection apparatus of the present invention; FIG. 4 is a graph showing an example of a ground voltage waveform signal processed by the partial discharge detection device of the present invention and a count of the number of times this waveform signal exceeds a predetermined threshold;

Embodiments of the partial discharge detection device and the partial discharge monitoring system of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a partial discharge detection device 10 and a partial discharge monitoring system 1 of this embodiment.

A partial discharge detection device 10 of the present embodiment detects partial discharge of an electrical insulating material provided in a transformer 51 and a switchboard 52 of a substation, which are electrical equipment to which high-voltage electricity is applied. Specifically, when a defect due to aged deterioration or damage occurs in the electrical insulating material provided in the transformer 51 and the switchboard 52, and a partial discharge occurs due to the concentration of the electric field of high-voltage electricity at the defect site, Due to this partial discharge, the ground voltage of transformer 51 and switchboard 52 changes. The partial discharge detection device 10 measures this ground voltage and detects the occurrence of partial discharge by measuring changes in the ground voltage.

As shown in FIG. 1, the partial discharge detection device 10 includes a TEV (Transient Earth Voltage) sensor (sensor) 11 that measures the ground voltage of a transformer 51 and a switchboard 52, and an analog electronic circuit 12 connected to the TEV sensor 11. , a microcontroller (counter) 16 that processes the signal output from the analog electronic circuit 12, a wireless module (communication section) 17 that transfers the signal processed by the microcontroller 16 to the outside by wireless communication, and the microcontroller 16 and a battery 18 that serves as a power source for the wireless module 17 .

Further, the partial discharge monitoring system 1 of the present embodiment includes the partial discharge detection device 10 and a personal computer (monitoring terminal) 20. The personal computer 20 receives a signal transferred from the partial discharge detection device 10. information indicating that the transformer 51 and switchboard 52 need to be repaired or updated.

The TEV sensor 11 is fixed to the housings of the transformer 51 and switchboard 52 by built-in magnets. Since the housings of the transformer 51 and the switchboard 52 are grounded, the ground voltage can be measured by the TEV sensor 11 fixed to this housing. The TEV sensor 11 measures the ground voltage at a sampling frequency of 1 GHz, for example.

FIG. 2 shows an example of a ground voltage waveform signal measured by the TEV sensor 11 when the ground voltage changes due to partial discharge. As indicated by the width of the double-headed arrow in FIG. 2, the occurrence of partial discharge appears as a short-wavelength (high-frequency) waveform of 100 nsec level in the ground voltage waveform signal.

The analog electronic circuit 12 lowers the frequency of the waveform signal of the ground voltage measured by the TEV sensor 11 (dulls the waveform) and outputs it. , down to the frequency of 100 μsec level and output. As shown in FIG. 1, the analog electronic circuit 12 is configured by connecting a bandpass filter 13, a diode 14, and a capacitor 15 in series.

First, the band-pass filter 13 removes noise from the waveform signal by passing only frequency components of, for example, 10 to 33 MHz out of the waveform signal of the ground voltage measured by the TEV sensor 11 .

The waveform signal from which noise has been removed by the bandpass filter 13 passes through the diode 14 and is half-wave rectified. Partial discharge occurs at the upper and lower peaks of the AC power supply cycle (for example, 60 Hz or 50 Hz). be reduced to one-half.

The waveform signal half-wave rectified by diode 14 further passes through capacitor 15 . Capacitor 15 has a capacitance within the range of 0.001 to 0.1 μF, and this capacitance allows the short-wavelength (high-frequency) waveform at the 100 nsec level to change the frequency up to the 100 μsec level. be lowered.

In FIG. 3, examples of waveform signals before and after passing through diode 14 and capacitor 15 are shown in thin and thick lines, respectively. As shown in FIG. 3, when the waveform signal passes through the diode 14 and the capacitor 15, the 100 nsec level short wavelength (high frequency) acicular waveform is transformed into a triangular waveform having a 100 μsec level wavelength with a suppressed peak. It can be seen that it is converted into a waveform.

If the analog electronic circuit 12 as a whole has a capacitance within the range of 0.001 to 0.1 μF, the 100 nsec level high frequency waveform can be converted into a 100 μsec level frequency waveform. The electronic circuit 12 may not necessarily be provided with the capacitor 15 .

For example, a diode has a certain capacitance, but if the capacitance is within the range of 0.001 to 0.1 μF, the diode can also function as a capacitor and the capacitor can be omitted. For example, a 0.01 μF silicon diode or the like can be suitably used as the diode having the function of lowering the frequency of the waveform signal of the measured ground voltage and outputting it.

Also, if the analog electronic circuit 12 has a capacitance within the range of 0.001 to 0.1 μF, the analog electronic circuit 12 may not necessarily be provided with a diode for rectification.

The waveform signal, whose frequency has been reduced to the 100 μsec level by diode 14 and capacitor 15 , is input to microcontroller 16 connected to analog electronics 12 . The microcontroller 16 acquires the value of the waveform signal at a sampling frequency of 20 kHz, which is twice 100 μsec (=10 kHz), and counts the number of times the acquired value exceeds a predetermined threshold. Information on the number of times is transferred by wireless communication from the wireless module 17 connected to the microcontroller 16 to the personal computer 20 installed in the substation.

4(a) to 4(c) show the waveform of the ground voltage measured by the TEV sensor 11, the waveform of the ground voltage whose frequency has been lowered by the analog electronic circuit 12, and the number of times counted by the microcontroller 16, respectively. Schematically. It can be seen that the amount of data is greatly reduced as the process progresses from FIG. 4(a) to FIG. 4(c).

The microcontroller 16 and wireless module 17 can be configured at extremely low cost by setting a general-purpose microcontroller equipped with a wireless communication function using a programming language. With a sampling frequency of about 20 kHz, measurement can be performed using the functions of a general-purpose microcontroller, so there is no need to incorporate an expensive high-speed sampling device into the partial discharge detection device 10 .

As a general-purpose microcontroller equipped with a wireless communication function, for example, switch science company "ESP-WROOM-02 development board" can be used. As a programming language, for example, "Arduino Sketch" ("Arduino" is a registered trademark) can be used.

In this embodiment, the microcontroller 16 is program-controlled so that it is activated every 4 hours, measures the waveform signal for 5 minutes once activated, and is in a sleep state except during measurement. As a result, the operation time of the microcontroller 16 and the wireless module 17 is reduced to 30 minutes per day, so the battery 18 lasts longer and the frequency of replacing the battery 18 of the partial discharge detection device 10 can be reduced. .

Then, the personal computer 20 receives the information on the number of times transferred from the wireless module 17 of the partial discharge detection device 10, and based on the information on the number of times, determines whether the transformer 51 and the switchboard 52 need to be repaired or updated. judge. When it is determined that the transformer 51 and the switchboard 52 need to be repaired or updated, information indicating that the repair or update is required is output in the form of a screen display, an alarm sound, or the like.

According to the partial discharge detection device 10 and the partial discharge monitoring system 1 of this embodiment, a large cost reduction effect can be obtained as follows.

First, it is assumed that a substation is provided with a total of four banks of transformers 51 (three banks plus one spare bank), and seven switchboards 52 are connected to each transformer 51 . Assuming that each transformer 51 is equipped with two partial discharge detection devices 10 and each switchboard is equipped with two partial discharge detection devices 10, a total of 64 partial discharge detection devices 10 are installed per substation.
In the detection device, the value of the waveform signal is acquired at a sampling frequency of 1 GHz (10 ⁹ /sec), and if the size of each acquired value is 2 bytes (65536 signal levels), a total of 64 The amount of data transferred from the partial discharge detector to the personal computer per second is calculated as follows.

(10 ⁹ /sec) x 2 bytes x 64 = 128 GB/sec
On the other hand, in the partial discharge detection device 10 of the present embodiment, the microcontroller 16 acquires the waveform signal value at a sampling frequency of 20 kHz (20×10 ³ /sec), and the waveform signal is output from the analog electronic circuit 12 Assuming that the size of each acquired value is also suppressed to 1 byte (256 levels of signal levels) because the peak is suppressed by , the total of 64 partial discharge detection devices in one substation can be sent to the personal computer 20 in 1 second. The amount of data transferred is calculated as follows.

(20×10 ³ /sec)×1Byte×64=1.28MB/sec
Thus, according to the partial discharge detection device 10 and the partial discharge monitoring system 1 of the present invention, the amount of data processed and transferred per unit time is reduced to about 1/100,000 of that of the conventional partial discharge detection device. , the amount of data can be greatly reduced, so that the continuous monitoring of partial discharge can be reliably performed without causing any trouble in data recording or transfer.

In addition, since the conventional partial discharge detection device acquires discharge signals at a high sampling frequency of 1 GHz, it incorporates an expensive sampling device, which is expensive (for example, about 300,000 to 1,000,000 yen per 10 partial discharge detection devices). )Met.

In contrast, the partial discharge detector 10 of the present invention reduces the frequency of the measured ground voltage waveform signal in advance by the analog electronic circuit 12 having a simple configuration, and then detects the value of the discharge signal at a low sampling frequency. Therefore, as described above, a simple electronic device and a general-purpose microcontroller can be combined and configured at low cost (for example, about 15,000 to 20,000 yen per 10 partial discharge detection devices).

Thus, the partial discharge detection device 10 of the present invention can reduce the cost of the device to one tenth or less of that of the conventional partial discharge detection device.

Assuming that a plant such as an ironworks has 80 substations in the premises, the number of partial discharge detection devices 10 required in the entire premises is 64×80=approximately 5000 pieces. Since the cost of such a large number of partial discharge detection devices 10 can be reduced to 1/10, it can be seen that a significant cost reduction effect can be obtained in continuous monitoring of partial discharges at a large number of locations.

1 partial discharge monitoring system 10 partial discharge detector 11 sensor (TEV sensor)
12 analog electronic circuit 13 bandpass filter 14 electronic element (diode)
15 electronic device (capacitor)
16 counter (microcontroller)
17 communication unit (wireless module)
18 battery 20 monitoring terminal (personal computer)
51 Electrical equipment (transformers)
52 Electrical equipment (distribution board)

Claims (6)

A partial discharge detection device for detecting a partial discharge generated in an electrical insulating material provided in an electrical facility from a change in the ground voltage of the electrical facility caused by the partial discharge,
a sensor fixed to a grounded enclosure of the electrical equipment and measuring the ground voltage of the electrical equipment;
The waveform signal of the ground voltage measured by the sensor is input, the circuit as a whole has a capacitance of 0.001 to 0.1 μF, and the frequency of the waveform signal of the ground voltage is lowered by the capacitance . an analog electronic circuit for output;
a counter that acquires the value of the waveform signal whose frequency has been lowered by the analog electronic circuit at a cycle that is twice the lowered frequency, and counts the number of times that the acquired value exceeds a predetermined threshold. A partial discharge detection device characterized by: 2. The partial discharge detection device of claim 1 , wherein the analog electronic circuitry includes a capacitor. 3. A partial discharge detection device according to claim 1 or 2 , wherein the analog electronic circuit comprises a diode. 4. The partial discharge detection device according to any one of claims 1 to 3, further comprising a communication unit that transfers information on the number of times counted by the counter. 5. The partial discharge detection device according to claim 4 , wherein the communication unit transfers the information on the number of times by wireless communication. a partial discharge detection device according to claim 4 or 5 ;
a monitoring terminal that receives the information on the number of times transferred from the communication unit of the partial discharge detection device, and outputs information indicating that the electrical equipment needs to be repaired or updated based on the information on the number of times; A partial discharge monitoring system comprising:

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