JP7155327B2 - Partial discharge detection method - Google Patents

Description

An embodiment of the present invention relates to a partial discharge detection method for detecting with high sensitivity partial discharge occurring in power equipment.

2. Description of the Related Art Conventionally, in a power device such as a switchgear in which a circuit breaker and the like are housed in a box, there has been known one in which a plurality of partial discharge sensors are attached to the box to identify the position where partial discharge occurs. A partial discharge sensor detects a signal by a partial discharge pulse propagating through a stray capacitance, and can specify a three-dimensional position from the difference in arrival time (see, for example, Patent Document 1).

On the other hand, in a switchgear in which electrical members such as main circuit conductors are molded with an insulating material, a plurality of electrodes are provided on the surface of the ground layer to detect the surface potential. , a method of detecting partial discharge by subtracting the surface potential of the measurement electrode from the reference electrode to obtain a potential difference is known (see, for example, Patent Document 2).

Also, a pair of electrodes for detecting the surface potential is prepared, one electrode is attached to the surface of the ground layer and the other electrode is arranged so as not to be in contact with the ground layer. is known (see, for example, Patent Document 3).

These partial discharge detectors have a single structure of a box and a molded member, and are intended to improve the identification and detection sensitivity of the generation position of the partial discharge generated inside. Here, in a switchgear, a plurality of boxes are often arranged side by side in order to constitute a complicated electric power system. Switchgears connected side by side are connected to other electric power systems and are connected to power equipment such as power converters and motors, so complex noise (BGN) is generated, penetrates, and is superimposed on the power supply. . In the switchgears arranged side by side in this way, there is a limit to the noise removal capability for noise with different frequency components and power, and detection of partial discharge, which is a weak signal, has been difficult. For this reason, there has been a demand for a method capable of detecting, with high sensitivity, partial discharges in row-mounted switchgears, which are susceptible to intrusion of complex noise.

JP 2011-149896 A JP 2012-220209 A JP 2012-220208 A

The problem to be solved by the present invention is that it is possible to detect partial discharge in units of boxes with high sensitivity in row-mounted switchgears that are connected to various power supply systems and electric power devices and are superimposed with large noise. An object of the present invention is to provide a partial discharge detection method.

In order to solve the above problems, the partial discharge detection method of the embodiment includes a first box housing an electric device and a grounding bus of the first box housing the electric device and commonly connected to a ground bus. In a state where an insulating member is provided between the n-th box, the surface potential is detected by the first electrode for contact-fixing to the first box, and contact-fixing to the n-th box. A surface potential is detected by an n-th electrode for detecting the surface potential, and occurrence of partial discharge is determined based on a potential difference obtained by subtracting the surface potential detected from the first electrode and the n-th electrode. do.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram which shows the structure of the partial discharge detection apparatus used for Example 1 of this invention. 1 is a diagram for explaining the circuit configuration of a partial discharge detection device used in Example 1 of the present invention; FIG. FIG. 4 is a diagram for explaining noise removal of the partial discharge detection device used in Example 1 of the present invention; The figure explaining the circuit structure of the partial discharge detection apparatus used for Example 2 of this invention. The figure explaining the circuit structure of the partial discharge detection apparatus used for Example 3 of this invention. The schematic diagram which shows the structure of the partial discharge detection apparatus used for Example 4 of this invention.

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

First, a partial discharge detection device used in Example 1 of the present invention will be described with reference to FIGS. 1 to 3. FIG. FIG. 1 is a schematic diagram showing the configuration of the partial discharge detection device used in Example 1 of the present invention, FIG. 2 is a diagram illustrating the circuit configuration of the partial discharge detection device used in Example 1 of the present invention, and FIG. 3 is a diagram for explaining noise removal of the partial discharge detection device used in Example 1 of the present invention; FIG.

As shown in FIG. 1, a plurality of first to n-th boxes 1a to 1n containing electrical equipment such as circuit breakers and main circuit conductors are arranged substantially linearly to form a predetermined power supply system. . First to n-th electrodes 2a to 2n for detecting surface potential are fixed in contact with the first to n-th boxes 1a to 1n. Outputs of the first to n-th electrodes 2a to 2n are input to a partial discharge determining device 3 for extracting weak signals. A common ground bus line 4 is arranged under the first to n-th boxes 1a to 1n and connected to a ground electrode 5. As shown in FIG. The first to n-th electrodes 2a to 2n detect surface potentials detected via stray capacitances formed between the electrical equipment housed therein. Here, each of the first to n-th boxes 1a to 1n is composed of a front panel, a ceiling panel, a back panel, a floor panel, and a side panel, and any one of the first to n-th boxes is provided on the plate surface. are fixed in contact with each other. For this reason, the front panel, ceiling panel, rear panel, floor panel, and side panel are each referred to as component panels that form the box. The component plates are connected to the ground busbar 4 .

Next, the circuit configuration of the partial discharge determining device 3 will be described with reference to FIG. As shown in FIG. 2, the partial discharge determination device 3 includes a subtraction processing unit 6 to which the outputs of the first to n-th electrodes 2a to 2n are input, a determination unit 7 to which the output of the subtraction processing unit 6 is connected, a determination It is composed of a display section 8 to which the output of the section 7 is connected.

Next, a method for determining partial discharge will be described with reference to FIGS. 3(a) to 3(c). As shown in FIG. 3(a), for example, when a partial discharge occurs in the first box 1a, the first electrode 2a is affected by attenuating partial discharge as shown in the upper row and noise as shown in the lower row. The surface potential of the superimposed random vibration waveform is detected. In the second to n-th electrodes 2b to 2n, as shown in FIG. 3(b), the partial discharge propagated from the first box 1a is small, and the noise is of the same magnitude. To detect. When these are subtracted by the subtraction processing unit 6 to obtain the potential difference, the noise is removed and only the partial discharge is extracted as shown in FIG. 3(c). Since the component plates of the first to n-th boxes 1a to 1n are connected to the ground bus 4, the same level of noise is detected in all the component plates, and partial discharge is caused only in the box. It will be greatly detected.

These processes are performed between the first to n-th electrodes 2a to 2n, and when a predetermined potential difference is detected by the determination unit 7, the place of occurrence is identified and displayed on the display unit 8. FIG. In the determination unit 7, thresholds are set for the peak value of the potential difference, the duration, the frequency of occurrence, and the like, and partial discharge is determined to occur when any of the thresholds is exceeded. Note that the discharge energy calculated by multiplying the peak value, the duration, and the frequency of occurrence may be used. Further, since partial discharge is often intermittent discharge, malfunction can be prevented by judging occurrence of partial discharge when potential difference is detected several times in the judging section 7 .

As a result, the occurrence of partial discharge can be detected for each box in the switchgear in which the first to n-th boxes 1a to 1n are arranged side by side. In the switchgear, other power systems and power equipment that easily generate noise are connected, and complex and large noise with different frequency components and power is superimposed on the main circuit. The noise superimposed on the entire 1st to n-th boxes 1a to 1n can be reliably removed. If the partial discharge generation box is identified, separate it from the other boxes and use a general partial discharge measuring instrument to find the point of occurrence and replace the parts or replace the entire box. can be done.

According to the partial discharge detection method of the first embodiment, the first to n-th electrodes 2a to 2n are fixed in contact with the constituent plates of the plurality of first to n-th boxes 1a to 1n arranged in rows, respectively, These outputs are subtracted by the subtraction processing unit 6 of the partial discharge determination device 3, and the noise superimposed on the main circuit is removed in units of boxes, so even complex and large noise with different frequency components and power can be reliably removed. and can detect partial discharge with high sensitivity.

In the above-described first embodiment, the switchgears arranged side by side are explained using the first to n-th boxes 1a to 1n. In a switch gear in which a plurality of molded members are connected, the first to n-th electrodes 2a to 2n are attached to the ground layer of each molded member, and the subtraction processing unit 6 subtracts each molded member to obtain a large Noise can be removed.

Next, a partial discharge detection device used in Example 2 of the present invention will be described with reference to FIG. FIG. 4 is a diagram for explaining the circuit configuration of the partial discharge detection device used in Example 2 of the present invention. The second embodiment differs from the first embodiment in that the signals of partial discharge are averaged. In FIG. 4, the same reference numerals are assigned to the same components as in the first embodiment, and detailed description thereof will be omitted.

As shown in FIG. 4 , the partial discharge determination device 3 is provided with an averaging processing unit 9 and the output thereof is input to the subtraction processing unit 6 . Since the averaging processing unit 9 performs averaging processing for several times, it is possible to suppress sudden events and improve detection sensitivity.

According to the partial discharge detection method of the second embodiment, in addition to the effects of the first embodiment, the detection sensitivity of partial discharge can be improved.

Next, a partial discharge detection device used in Example 3 of the present invention will be described with reference to FIG. FIG. 5 is a diagram for explaining the circuit configuration of the partial discharge detection device used in Example 3 of the present invention. The third embodiment differs from the second embodiment in that the partial discharge signal is subjected to wavelet transform for frequency conversion. In FIG. 5, the same components as those of the apparatus used in Example 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 5, a wavelet transform unit 10 is connected between the subtraction processing unit 6 and the determination unit 7 . In the wavelet transform unit 10, when a high result is obtained at a frequency of 1 to 20 MHz, it is determined that the partial discharge is from the insulator.

According to the partial discharge detection method of the third embodiment, in addition to the effect of the second embodiment, partial discharge can be reliably detected by wavelet transform.

Next, a partial discharge detection device used in Example 4 of the present invention will be described with reference to FIG. FIG. 6 is a schematic diagram showing the configuration of a partial discharge detection device used in Example 4 of the present invention. It should be noted that the device used in the fourth embodiment differs from the first embodiment in that the panels are insulated. In FIG. 6, the same components as those of the apparatus used in Example 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 6, between the first box 1a and the second box 1b, between the second box 1b and the third box 1c, between the third box 1c and the n-th box 1n. Insulating members 11a, 11b, 11c, and 11n are provided between the so-called boxes. The insulating members 11a, 11b, 11c, and 11n may be insulating sheets, insulating thin plates, insulating coatings applied to the first to n-th boxes 1a to 1n, and the like. It shall have a thickness that can withstand a potential difference of

As a result, the ground potentials of the first to n-th boxes 1a to 1n are electrically independent, and the potential difference due to partial discharge can be reliably detected by the boxes. For example, when a partial discharge occurs in the first box 1a, the ground current shunting to the second box 1b and beyond is interrupted by the insulating member 11a, and the surface potential is reliably detected by the first electrode 2a. be able to.

In addition, in the first to n-th boxes 1a to 1n of the apparatus used in Example 1, the constituent plates are generally painted to insulate between the boxes, or the boxes are insulated from each other, or high resistance is generated due to delicate contact. Insulating members 11a, 11b, 11c, and 11n can be eliminated if they are connected and can prevent shunting of the ground current.

According to the partial discharge detection method of the fourth embodiment, in addition to the effect of the third embodiment, it is possible to reliably detect partial discharges in the first to n-th boxes 1a to 1n.

According to the embodiment as described above, an electrode for detecting a surface potential is attached to each of the constituent plates of a plurality of boxes arranged side by side, and these outputs are subtracted from each other to obtain the potential difference. Therefore, it is possible to reliably remove large noise in units of boxes, and to detect the partial discharge of a weak signal with high sensitivity.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

1a to 1n 1st to nth boxes 2a to 2n 1st to nth electrodes 3 partial discharge determination device 4 ground bus 6 subtraction processing unit 7 determination unit 9 averaging processing unit 10 wavelet

Claims (7)

In a state in which an insulating member is provided between the first box housing the electric equipment and the n-th box housing the electric equipment and commonly connected to the grounding bus of the first box ,
A surface potential is detected by a first electrode for contact fixing to the first box,
Detecting the surface potential by the n-th electrode for contacting and fixing to the n-th box ,
A method for detecting partial discharge, wherein occurrence of partial discharge is determined based on a potential difference obtained by subtracting the surface potentials detected by the first electrode and the n-th electrode . A surface potential is detected by a first electrode for contacting and fixing to a first box housing an electrical device,
The surface potential is detected by the n-th electrode for contacting and fixing to the n-th box that houses the electrical equipment and is commonly connected to the ground bus of the first box,
A method for detecting partial discharge, comprising: averaging the surface potentials detected by the first electrode and the n-th electrode several times, respectively, and then determining the occurrence of partial discharge based on the subtracted potential difference. . A surface potential is detected by a first electrode for contacting and fixing to a first box housing an electrical device,
The surface potential is detected by the n-th electrode for contacting and fixing to the n-th box that houses the electrical equipment and is commonly connected to the ground bus of the first box,
A method for detecting partial discharge, comprising performing wavelet processing for frequency-converting a potential difference obtained by subtracting the surface potential detected by the first electrode and the n-th electrode, and determining occurrence of partial discharge. A surface potential is detected by a first electrode for contacting and fixing to a first box housing an electrical device,
An n-th box housing electrical equipment and commonly connected to the grounding busbar of the first box
Detecting the surface potential by the nth electrode for contact fixing to
A method for detecting partial discharge, wherein when a potential difference obtained by subtracting the surface potentials detected by the first electrode and the n-th electrode exceeds a threshold value several times, it is determined that partial discharge has occurred. A surface potential is detected by a first electrode for contacting and fixing to a first ground layer provided on the surface of the first mold member,
detecting a surface potential by means of an n-th electrode provided on the surface of the n-th mold member and for fixing in contact with the n-th ground layer commonly connected to the ground bus of the first ground layer;
A method for detecting partial discharge, comprising: averaging the surface potentials detected by the first electrode and the n-th electrode several times, respectively, and then determining the occurrence of partial discharge based on the subtracted potential difference. . A surface potential is detected by a first electrode for contacting and fixing to a first ground layer provided on the surface of the first mold member,
detecting a surface potential by means of an n-th electrode provided on the surface of the n-th mold member and for fixing in contact with the n-th ground layer commonly connected to the ground bus of the first ground layer;
A method for detecting partial discharge, characterized by performing wavelet processing for frequency conversion on a potential difference obtained by subtracting the surface potential detected by the first electrode and the n-th electrode to determine the occurrence of partial discharge. A surface potential is detected by a first electrode for contacting and fixing to a first ground layer provided on the surface of the first mold member,
Detecting the surface potential of an nth electrode provided on the surface of the nth mold member and for contact fixing to the nth ground layer commonly connected to the ground bus of the first ground layer;
A method for detecting partial discharge, wherein the occurrence of partial discharge is determined when a potential difference obtained by subtracting the surface potential detected between the first electrode and the n-th electrode exceeds a threshold value several times.

Images