Partial discharge diagnosis device and partial discharge diagnosis method

Abstract

The data capacity required for diagnosis can be reduced.SOLUTION: The partial discharge diagnosis device includes a BGN voltage acquisition unit that acquires a value of a BGN voltage based on a result of measurement of a surface current flowing through metal other than a diagnosis target device in a site where the diagnosis target device is provided, a measured voltage acquisition unit that acquires a value of a measured voltage based on a result of measurement of a surface current of the diagnosis target device, and a waveform cutout unit that cuts out a target voltage waveform in a predetermined time domain based on a time point at which the value of the measured voltage exceeds a threshold value from a measured voltage waveform indicating a temporal change of the value of the measured voltage. The device includes a generation unit for generating φ -q-n data by aggregating φ -q data based on the stored information for each target voltage waveform, and an output unit for outputting information on the φ -q-n data.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a partial discharge diagnostic device and a partial discharge diagnostic method. [Background technology]

[0002] When electrical insulators (insulators) deteriorate over time, bubbles or impurities called voids may form inside the insulator. When voids form, the insulating performance of the insulator decreases, causing partial discharge. Furthermore, if the partial discharge continues and the insulating performance falls below the applied voltage due to the deterioration of the insulator, it can lead to dielectric breakdown, causing significant damage to electrical equipment, etc. Therefore, from the perspective of the safety of electrical equipment and power facilities, it is extremely important to understand (diagnose) the deterioration status of electrical insulators by measuring partial discharge and to avoid dielectric breakdown.

[0003] The more the electrical insulator deteriorates, the greater the charge that accumulates in the voids, and the greater the partial discharge that occurs. Therefore, by measuring partial discharges, it is possible to diagnose the deterioration state of electrical insulators. Patent Document 1 discloses a technique for measuring (diagnosing) partial discharges that uses a φ-qn pattern, in which the horizontal axis represents the voltage phase φ of the power supply and the vertical axis represents the amount of partial discharge charge q, and the number of discharges n is plotted. There is also a diagnostic technique that plots the change in the φ-qn pattern over time t in three dimensions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-161713 Summary of the Invention [Problem to be solved by the invention]

[0005] When measuring partial discharges in power equipment in the field, such as in a substation, the measured voltage includes voltages due to partial discharges as well as external noise. Since voltages generated by partial discharges exhibit damped oscillatory waveforms, by checking the voltage waveform shape, it is possible to determine whether the measured voltage is due to partial discharges or external noise.

[0006] However, because the frequency of partial discharge voltage oscillations is on the order of MHz, checking the partial discharge waveform requires measuring the voltage every nanosecond to microsecond, which poses problems such as a large data storage capacity and time-consuming data processing.

[0007] The present invention has been made in view of the above-mentioned points, and has an object to provide a technique that can reduce the amount of data required for diagnosis. [Means for solving the problem]

[0008] One aspect of the present invention is a partial discharge diagnostic device comprising: a BGN voltage acquisition unit that acquires a BGN voltage value based on the results of measuring the surface current flowing through metal other than the diagnostic target device within the site where the diagnostic target device is installed; a measured voltage acquisition unit that acquires a measured voltage value based on the results of measuring the surface current of the diagnostic target device; a waveform clipping unit that clips a target voltage waveform, which is a measured voltage waveform of a predetermined time domain based on the point at which the measured voltage value exceeds a threshold value set to a value greater than the BGN voltage value, from a measured voltage waveform showing the time change of the measured voltage value; a phase detection unit that detects the phase of the target voltage waveform; a memory control unit that links the phase of the target voltage waveform with voltage information including the maximum value of the target voltage waveform and stores it for each target voltage waveform; a generation unit that generates φ-qn data by aggregating φ-q data based on the stored information for each target voltage waveform; and an output unit that outputs information regarding the φ-qn data.

[0009] In addition, in one aspect of the present invention, the partial discharge diagnostic device further includes a waveform determination unit that determines whether the target voltage waveform is a partial discharge waveform caused by a partial discharge based on the waveform shape of the target voltage waveform cut by the waveform cutting unit, and the generation unit generates φ-qn data based on the φ-q data of the target voltage waveform that has been determined to be the partial discharge waveform by the waveform determination unit.

[0010] In one aspect of the present invention, the storage control unit stores the phase and the maximum value of the target voltage waveform determined to be the partial discharge waveform in association with each other.

[0011] In one aspect of the present invention, the partial discharge diagnostic device further includes a partial discharge diagnostic unit that diagnoses that a partial discharge has occurred when a predetermined percentage or more of the φ-q data among the multiple φ-q data included in the φ-qn data are included in a first phase region from a first phase to a second phase different from the first phase, and in a second phase region from a third phase to a fourth phase different from the third phase, which does not overlap with the first phase region, and the output unit outputs the result of the diagnosis by the partial discharge diagnostic unit.

[0012] One aspect of the present invention is a partial discharge diagnosis method comprising: a BGN voltage acquisition step for acquiring a BGN voltage value based on the results of measuring a surface current flowing through metal other than the device to be diagnosed within a site where the device to be diagnosed is installed; a measured voltage acquisition step for acquiring a measured voltage value based on the results of measuring the surface current of the device to be diagnosed; a waveform cutting step for cutting out a target voltage waveform, which is a measured voltage waveform of a predetermined time domain based on the point at which the measured voltage value exceeds a threshold value set to a value greater than the BGN voltage value, from a measured voltage waveform showing the time change of the measured voltage value; a phase detection step for detecting the phase of the target voltage waveform; a storage control step for linking the phase of the target voltage waveform with voltage information including the maximum value of the target voltage waveform and storing it for each target voltage waveform; a generation step for generating φ-qn data by aggregating φ-q data based on the stored information for each target voltage waveform; and an output step for outputting information related to the φ-qn data. [Effects of the Invention]

[0013] According to the present invention, the amount of data required for diagnosis can be reduced. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram for explaining an aspect of a partial discharge diagnostic system according to an embodiment; [Figure 2] FIG. 2 is a block diagram for explaining an example of a functional configuration of the partial discharge diagnostic device according to the embodiment. [Figure 3] 10A and 10B are diagrams for explaining an example of a target voltage waveform cut out by a waveform cutting unit; [Figure 4] FIG. 10 is a diagram for explaining an example of φ-qn data. [Figure 5] FIG. 10 is a diagram for explaining an example of diagnosis by a partial discharge diagnosis unit. [Figure 6] 4 is a flowchart illustrating an example of a processing flow of the partial discharge diagnostic device according to the embodiment. [Figure 7]1 is a block diagram showing an example of the internal configuration of a partial discharge diagnostic device according to an embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0015] [Embodiment] A preferred embodiment of a partial discharge diagnostic device and a partial discharge diagnostic method according to the present invention will be described in detail below with reference to the accompanying drawings. In the drawings, identical or similar parts are designated by identical or similar reference numerals. Note that the present invention is not limited to these embodiments and includes various modifications and improvements. In other words, the components described below include those that a person skilled in the art would easily imagine and those that are substantially identical, and the components described below can be combined as appropriate. Furthermore, the present embodiment may include various omissions, substitutions, or modifications of components within the scope of the present invention.

[0016] 1 is a diagram for explaining an aspect of a partial discharge diagnostic system 1 according to an embodiment. The partial discharge diagnostic system 1 includes a first current sensor 2, a second current sensor 3, and a partial discharge diagnostic device 10. The partial discharge diagnostic system 1 diagnoses the deterioration state of the insulators in the device to be diagnosed by diagnosing the presence or absence of partial discharge based on the current flowing on the surface of the device to be diagnosed.

[0017] The diagnosis target device may be an electric device or a power facility, for example, a transformer TR. The diagnosis target device may also be, for example, a high-voltage device, a generator, a switchgear, a cable, etc. A cylindrical insulator (porcelain bushing) is attached to the transformer TR to insulate the transformer TR from the electric wires present in the air and to safely conduct electricity through the electric wires into the transformer TR. Hereinafter, an example will be described in which the partial discharge diagnosis system 1 diagnoses the deterioration state of the insulator inside the porcelain bushing, which is an insulator that insulates the transformer TR from the electric wires.

[0018] The first current sensor 2 measures the current flowing through metals other than the transformer TR, such as steel structures and a transformer TR control panel, in the field where the transformer TR is installed. The first current sensor 2 then measures the current flowing through the surface of the transformer TR, which is generated by partial discharge in the insulator inside the porcelain bushing. Since the first current sensor 2 measures the current flowing through the surface of the transformer TR, the partial discharge diagnosis device 10 can perform partial discharge diagnosis without stopping the use of the transformer TR. The first current sensor 2 is, for example, a surface current sensor, and is detachably attached to the surface of the transformer TR using a magnet or the like. More specifically, the first current sensor 2 may be attached to the wall surface of a tank constituting the transformer TR or near the porcelain bushing attached to the transformer TR, in a position where there is no risk of electric shock during installation. The first current sensor 2 is connected to the partial discharge diagnosis device 10 by wire and transmits a measurement signal to the partial discharge diagnosis device 10. The first current sensor 2 may be, for example, a TEV (Transient Earth Voltage) sensor that non-contactly measures the current flowing on the surface of the transformer TR, or a high-frequency CT (Current Transformer) attached to the ground wire connected to the transformer TR.

[0019] The second current sensor 3 is used to acquire the voltage phase φ of the power supply and measures the current flowing inside the transformer TR. The second current sensor 3 may, for example, measure the current flowing in the wire on the primary side of the transformer TR, or may measure the current flowing in the wire on the secondary side of the transformer TR. The second current sensor 3 may also be attached to, for example, the ground wire of the transformer TR or to a bushing. The second current sensor 3 is connected to the partial discharge diagnostic device 10 by a wire and transmits a measurement signal to the partial discharge diagnostic device 10. The second current sensor 3 may, for example, be a Rogowski coil or the like.

[0020] FIG. 2 is a block diagram illustrating an example of the functional configuration of a partial discharge diagnostic device 10 according to an embodiment. The partial discharge diagnostic device 10 includes, as its components, a BGN voltage acquisition unit 11, a measured voltage acquisition unit 12, a waveform clipping unit 13, a phase detection unit 14, a memory control unit 15, a waveform determination unit 16, a generation unit 17, a partial discharge diagnostic unit 18, an output unit 19, and a memory unit M. Each of these functional units is realized, for example, by using a computer including a central processing unit (CPU) and memory, and software. Each functional unit may also be realized by using an electronic circuit, if necessary. Furthermore, each functional unit does not have to be included in a single device, and the partial discharge diagnostic device 10 may be configured by a plurality of devices. The partial discharge diagnostic device 10 may include, for example, an information processing device such as a personal computer as a component, or may include a measuring device such as an oscilloscope and an information processing device as components.

[0021] The BGN voltage acquisition unit 11 acquires a voltage value resulting from current-voltage conversion of the current measured by the first current sensor 2. The BGN voltage acquisition unit 11 acquires a voltage value based on the results of measuring the surface current flowing through metals other than the transformer TR at the site, when a user of the partial discharge diagnostic device 10 attaches the first current sensor 2 to metals other than the transformer TR. In the following description, the voltage acquired by the BGN voltage acquisition unit 11 may be simply referred to as the BGN voltage. By the BGN voltage acquisition unit 11 acquiring the BGN voltage, the partial discharge diagnostic device 10 acquires a voltage value indicating the background noise (BGN) generated at the site where the transformer TR is installed. Note that background noise is, for example, inverter noise, radio noise, white noise, etc. Because the magnitude of the background noise varies depending on the surrounding environment of the site, the BGN voltage acquisition unit 11 may acquire background noise for each site.

[0022] In order for the BGN voltage acquisition unit 11 to acquire the BGN voltage, i.e., to allow the user to measure the current flowing through metal other than the transformer TR, the partial discharge diagnostic device 10 may, for example, display content urging the user to acquire the BGN voltage on a display or the like, which is a display means (not shown) provided in the partial discharge diagnostic device 10 or the like. The content urging the user to acquire the BGN voltage may, for example, be "We will measure background noise. Please attach a surface current sensor to the transformer control panel." Note that the partial discharge diagnostic device 10 may also display content urging the user to acquire background noise from metal near the transformer TR in order to measure a current of a value similar to the background noise current flowing on the surface of the transformer TR.

[0023] The measured voltage acquisition unit 12, like the BGN voltage acquisition unit 11, acquires a voltage value resulting from current-voltage conversion of the current measured by the first current sensor 2. Unlike the BGN voltage acquisition unit 11, the measured voltage acquisition unit 12 acquires a voltage (hereinafter sometimes referred to as a measured voltage) based on the result of measuring the surface current of the transformer TR.

[0024] For example, the partial discharge diagnostic device 10 may use a display means to display to the user a message urging the user to attach the first current sensor 2 to the transformer TR after acquiring the BGN voltage. The message urging the user to attach the first current sensor 2 to the transformer TR may be, for example, "Background noise measurement has been completed. Please attach a surface current sensor to the equipment to be diagnosed."

[0025] The waveform clipping unit 13 acquires the value of the BGN voltage from the BGN voltage acquisition unit 11. The waveform clipping unit 13 sets a representative value or the like of the acquired BGN voltage as a threshold. The representative value may be, for example, a maximum value or an effective value.

[0026] The waveform clipping unit 13 continuously acquires the measured voltage value from the measured voltage acquisition unit 12. Hereinafter, the continuously acquired data showing the time change of the measured voltage value is referred to as the measured voltage waveform. When the acquired measured voltage value exceeds a set threshold (triggered), the waveform clipping unit 13 clips a voltage waveform of a predetermined time domain based on the point at which the threshold is exceeded (trigger point). The voltage waveform clipped by the waveform clipping unit 13 may be referred to as the target voltage waveform. The predetermined time domain is the time from a point a predetermined time before the trigger point to a point a predetermined time after the trigger point. The predetermined time for acquiring the measured voltage going back from the trigger point and the predetermined time for continuing acquisition from the trigger point may be set, for example, based on a user operation or may be set in advance by a measuring device such as an oscilloscope. The predetermined time for acquiring the measured voltage going back from the trigger point may be, for example, 100 [nsec]. The predetermined time for continuing to acquire the measured voltage after the trigger point may be, for example, 400 [nsec]. Hereinafter, the target voltage waveform acquired retroactively from the trigger point may be referred to as a pre-trigger portion, and the target voltage waveform acquired continuously from the trigger point may be referred to as a post-trigger portion.

[0027] FIG. 3 is a diagram illustrating an example of a target voltage waveform cut out by the waveform cutout unit 13. In FIG. 3, the vertical axis represents voltage [mV] and the horizontal axis represents time [nsec], showing a target voltage waveform cut out from the measured voltage waveform. The target voltage waveform in FIG. 3 includes a partial discharge waveform PD caused by a partial discharge from 100 [nsec] to 360 [nsec]. The voltage waveform caused by the partial discharge waveform PD becomes a damped oscillatory waveform as the generated current is reflected in the measurement system. By providing a pre-trigger section and a post-trigger section based on the point in time when the threshold is exceeded, the waveform cutout unit 13 can cut out the partial discharge waveform PD caused by a single partial discharge without interruption. In this specification, "cutting" also includes extracting and copying a portion.

[0028] In order to cut out the target voltage waveform, the waveform clipping unit 13 may sequentially store the acquired measured voltage values ​​in the memory unit M. Alternatively, the waveform clipping unit 13 may store measured voltages acquired a predetermined time (e.g., 100 nsec) before the time when a new measured voltage is acquired, and sequentially delete measured voltages acquired more than the predetermined time. The target voltage waveform may be, for example, data on multiple measured voltages acquired in a predetermined time region (pre-trigger portion and post-trigger portion), or may be an image.

[0029] The phase detection unit 14 acquires the target voltage waveform clipped by the waveform clipping unit 13. The phase detection unit 14 also acquires the voltage value resulting from current-voltage conversion of the current measured by the second current sensor 3. The phase detection unit 14 detects the voltage phase of the target voltage waveform based on the voltage acquired by the second current sensor 3 and the target voltage waveform clipped by the waveform clipping unit 13.

[0030] The memory control unit 15 controls the memory unit M. The memory control unit 15 acquires a target voltage waveform from the waveform clipping unit 13. The memory control unit 15 also acquires a value indicating the voltage phase of the target voltage waveform from the phase detection unit 14. The memory control unit 15 identifies the maximum voltage value (hereinafter, “maximum value”) of the target voltage waveform. The memory control unit 15 stores the target voltage waveform, the maximum voltage of the target voltage waveform, and the voltage phase of the target voltage waveform in the memory unit M. By setting the threshold value used by the waveform clipping unit 13 to a value greater than the BGN voltage when clipping the measured voltage, the memory control unit 15 can reduce the possibility of storing a voltage waveform of background noise in the memory unit M as a partial discharge waveform PD. By not storing unnecessary voltage waveforms, maximum values, and voltage phases in the memory unit M by the memory control unit 15, the partial discharge diagnosis device 10 can reduce the amount of data required for processing.

[0031] The memory unit M stores the target voltage waveform clipped by the waveform clipping unit 13, the voltage phase detected by the phase detection unit 14, and the maximum value of the target voltage waveform identified by the memory control unit 15, in accordance with the control of the memory control unit 15. For each target voltage waveform controlled to be stored by the memory control unit 15, the memory unit M stores the target voltage waveform, the maximum value, and the voltage phase in association with each other. In the following description, the associated and stored maximum value and voltage phase may be referred to as φ-q ​​data. Furthermore, the target voltage waveform and the maximum value of the target voltage waveform may be collectively referred to as voltage information. Note that the maximum value may be a voltage value or a value obtained by converting the voltage value into an amount of charge.

[0032] 2 shows an example in which the memory unit M is one storage device, but the present embodiment is not limited to this example, and for example, the memory unit M may be configured with two or more storage devices. Also, while FIG. 2 shows an example in which the target voltage waveform and φ-q data are stored in the memory unit M, the BGN voltage acquired by the BGN voltage acquisition unit 11, the measured voltage acquired by the measured voltage acquisition unit 12, etc. may also be stored.

[0033] The waveform determination unit 16 acquires a target voltage waveform stored in the memory unit M. The waveform determination unit 16 determines whether the acquired target voltage waveform is a partial discharge waveform PD, and therefore whether the partial discharge waveform PD is included. For example, since a partial discharge waveform PD is a damped oscillation waveform, the waveform determination unit 16 determines whether the acquired target voltage waveform is a damped oscillation waveform based on the waveform shape of the target voltage waveform. If the target voltage waveform is a damped oscillation waveform, the waveform determination unit 16 determines that the target voltage waveform is a partial discharge waveform PD. On the other hand, if the target voltage waveform is not a damped oscillation waveform, the waveform determination unit 16 determines that the target voltage waveform is not a partial discharge waveform PD. The waveform determination unit 16 performs the above-mentioned determination for each target voltage waveform stored in the memory unit M.

[0034] The generating unit 17 acquires information identifying each target voltage waveform that is a partial discharge waveform PD (e.g., a number identifying each target voltage waveform) from the waveform determining unit 16. Furthermore, for each target voltage waveform that is determined to be a partial discharge waveform PD, the generating unit 17 acquires φ-q ​​data associated with the target voltage waveform from the storage unit M. The generating unit 17 generates φ-qn data by aggregating the φ-q data for each target voltage waveform that is a partial discharge waveform PD. FIG. 4 is a diagram for explaining an example of φ-qn data. In FIG. 4, the vertical axis represents voltage [mV] (or charge [q]) and the horizontal axis represents voltage phase [°]. The generating unit 17 may generate the φ-qn data based on information related to each target voltage waveform stored in the storage unit M. In this case, the generation unit 17 may remove, from the generated φ-qn data, information about the target voltage waveform that is determined not to be a partial discharge waveform PD by the waveform determination unit 16. Note that the φ-qn data may be, for example, matrix data or a heat map image.

[0035] The partial discharge diagnosis unit 18 acquires the φ-qn data generated by the generation unit 17. Generally, there is a correlation between the voltage applied to the device under diagnosis and the phase of partial discharge. The partial discharge diagnosis unit 18 diagnoses the presence or absence of partial discharge in the transformer TR based on the distribution of each φ-q data in the acquired φ-qn data. In the following description, the voltage phase region from 0° to 90° is referred to as the first quadrant, the phase region from 90° to 180° is referred to as the second quadrant, the phase region from 180° to 270° is referred to as the third quadrant, and the phase region from 270° to 360° (0°) is referred to as the fourth quadrant.

[0036] FIG. 5 is a diagram illustrating an example of diagnosis by the partial discharge diagnosis unit 18. When partial discharge occurs due to deterioration of the insulators of the high-voltage transformer TR or a bushing, the measured voltage (charge) is concentrated in the first and third quadrants. Therefore, the partial discharge diagnosis unit 18 may diagnose that partial discharge has occurred in the transformer TR or a bushing when the number of φ-q data included in the φ-qn data in the first phase region including the zero crossing in the first quadrant and the second phase region including the zero crossing in the third quadrant is equal to or greater than a predetermined ratio. The first phase region may be a phase region between the first phase (e.g., 330°) and the second phase (e.g., 90°). The second phase region may be a phase region between the third phase (e.g., 150°) and the second phase (e.g., 270°). The first phase region and the second phase region do not overlap each other. The first phase, the second phase, the third phase, and the fourth phase are all different values. The predetermined percentage may be set in advance based on a user operation. On the other hand, if the first phase region and the second phase region do not contain φ-q data of a predetermined percentage or more, that is, if there is no correlation between the measured voltages, the partial discharge diagnosis unit 18 diagnoses that a partial discharge has not occurred in the transformer TR or the bushing. The partial discharge diagnosis unit 18 can diagnose the deterioration state of the insulator by diagnosing whether a partial discharge has occurred.

[0037] Since the correlation between partial discharge and applied voltage differs depending on the type of partial discharge that occurs, the first phase region and the second phase region may be set for each insulator to be diagnosed or each device to be diagnosed. Furthermore, the partial discharge diagnosis unit 18 may identify the correlation between partial discharge and applied voltage from the φ-qn data and diagnose the cause of the partial discharge.

[0038] The output unit 19 outputs information related to the φ-qn data. The information related to the φ-qn data may be, for example, the φ-qn data generated by the generation unit 17 or the results of a diagnosis based on the φ-qn data. The output unit 19 may output the information related to the φ-qn data to a display means (not shown) included in the partial discharge diagnosis device 10, or may output the information related to the φ-qn data to an information processing device other than the partial discharge diagnosis device 10 (for example, a terminal device operated by a user). The user may check the output φ-qn data to diagnose the deterioration status of the insulators included in the transformer TR or the bushing. The user may also view the output diagnosis results to understand the deterioration status of the insulators included in the transformer TR.

[0039] The above description shows an example in which the waveform determination unit 16 determines whether the target voltage waveform stored in the memory unit M is a partial discharge waveform PD. However, the present embodiment is not limited to this example, and the waveform determination unit 16 may determine whether the target voltage waveform is a partial discharge waveform PD before the target voltage waveform is stored in the memory unit M. Specifically, the waveform determination unit 16 may acquire the target voltage waveform clipped by the waveform clipping unit 13 and determine whether the target voltage waveform is a partial discharge waveform PD. Furthermore, the phase detection unit 14 may detect the voltage phase only for the target voltage waveform determined to be a partial discharge waveform PD. Furthermore, the memory control unit 15 may identify a maximum value for the target voltage waveform determined to be a partial discharge waveform PD and store the φ-q data in the memory unit M. If the waveform determination unit 16 determines whether the target voltage waveform is a partial discharge waveform PD before storing information about the target voltage waveform (such as the voltage waveform, maximum value, and voltage phase) in the memory unit M, the memory control unit 15 does not need to store information about the target voltage waveform that is not a partial discharge waveform PD in the memory unit M. When information about a target voltage waveform that is not a partial discharge waveform PD is not stored in the storage unit M, the partial discharge diagnostic device 10 can reduce the amount of data required for processing.

[0040] Furthermore, if the waveform determination unit 16 determines whether or not the target voltage waveform is a partial discharge waveform PD before storing information about the target voltage waveform (such as the voltage waveform, maximum value, and voltage phase) in the memory unit M, all of the φ-q data stored in the memory unit M will be data caused by partial discharge. Therefore, it is not necessary to determine again whether or not the φ-q data stored in the memory unit M is data caused by partial discharge, and there is no need to store the target voltage waveform in the memory unit M. If the target voltage waveform is not stored in the memory unit M, the partial discharge diagnostic device 10 can reduce the amount of data required for processing.

[0041] Note that the above description shows an example in which the storage control unit 15 identifies the maximum value of the target voltage waveform. However, this embodiment is not limited to this example. The maximum value of the target voltage waveform may be identified by the generation unit 17. In this case, the storage control unit 15 may associate the target voltage waveform with the voltage phase of the target voltage waveform and store them in the storage unit M. Furthermore, the voltage information may include the target voltage waveform, but may not include information indicating the maximum value of the target voltage waveform.

[0042] Although the above description shows an example in which the BGN voltage and the measured voltage are acquired using one first current sensor 2, the present embodiment is not limited to this example. The partial discharge diagnostic system 1 may include a first current sensor 2 that acquires the BGN voltage and a first current sensor 2 that acquires the measured voltage, which are separate and independent from each other.

[0043] Fig. 6 is a flowchart for explaining an example of the processing flow of the partial discharge diagnostic device 10 according to the embodiment. The processing flow shown in Fig. 6 is merely an example, and the processing flow of the partial discharge diagnostic device 10 is not limited to this example.

[0044] (Step S101) The first current sensor 2 is attached to a metal other than the diagnosis target device at a site where the diagnosis target device, such as a steel structure or a transformer control panel, is installed. The partial discharge diagnostic device 10 acquires a voltage waveform of background noise at the site from the first current sensor 2. The partial discharge diagnostic device 10 sets a threshold based on the acquired voltage waveform of the background noise. Thereafter, the partial discharge diagnostic device 10 displays to the user a message indicating that the background noise measurement has been completed.

[0045] (Step S102) The first current sensor 2 is attached near the porcelain insulator tube of the transformer TR, which is the device to be diagnosed. The partial discharge diagnostic device 10 acquires a measured voltage waveform flowing on the surface of the transformer TR from the first current sensor 2. When the measured voltage exceeds a threshold, the partial discharge diagnostic device 10 extracts from the measured voltage waveform a voltage waveform (target voltage waveform) within a predetermined range based on the point at which the measured voltage exceeded a threshold. The partial discharge diagnostic device 10 also acquires a voltage phase φ from the current flowing inside the transformer TR from the second current sensor 3, thereby detecting the voltage phase between the voltage and the target voltage waveform.

[0046] (Step S103) The partial discharge diagnostic device 10 associates the cut-out target voltage waveform with the voltage phase and stores (preserves) them in the storage unit M. Note that the measured voltage waveform does not have to be stored.

[0047] (Step S104) The partial discharge diagnostic device 10 continues to acquire the measured voltage waveform for a specified number of times or for a specified time. The specified number may be, for example, the number of measured voltage data to be acquired. The specified time may be, for example, the time for acquiring the measured voltage waveform or the number of cycles (periods).

[0048] (Step S105) When the measured voltage waveform has been acquired the specified number of times or for the specified time (Step S104; Yes), the partial discharge diagnostic device 10 reads the data of the target voltage waveform and its voltage phase stored in the memory unit M.

[0049] (Step S106) The partial discharge diagnostic device 10 identifies the maximum value of the read target voltage waveform. The partial discharge diagnostic device 10 also converts the identified maximum voltage value [mV] into an electric charge amount [q].

[0050] (Step S107) The partial discharge diagnostic device 10 writes φ-q ​​data, which associates the charge amount [q] with the voltage phase [φ] for each target voltage waveform, into an aggregated file. The aggregated file may be stored in the storage unit M or in a storage unit separate from the storage unit M.

[0051] (Step S108) The partial discharge diagnostic device 10 repeatedly performs a process of creating φ-q data for each target voltage waveform stored in the storage unit M and writing the data into the aggregated file.

[0052] (Step S109) When writing to the aggregated file is completed for all target voltage waveforms (Step S108; Yes), the partial discharge diagnostic device 10 reads the aggregated file.

[0053] (Step S110) The partial discharge diagnostic device 10 generates a φ-qn image (characteristic diagram) from the φ-qn data into which the φ-q data has been aggregated. Note that the aggregated file may also aggregate φ-q data of voltage [mV] instead of charge [q]. When the φ-q data is voltage [mV], the partial discharge diagnostic device 10 may convert the voltage to charge before generating the φ-qn image, or may generate the φ-qn image using the voltage as is.

[0054] (Step S110) The partial discharge diagnostic device 10 stores the generated φ-qn image in the storage unit M or the like.

[0055] (Step S111) The partial discharge diagnostic device 10 diagnoses whether the waveform is a partial discharge waveform based on whether the φ-q data shown in the φ-qn image is distributed concentratedly in the first phase region and the second phase region and whether each target voltage waveform is a damped oscillation waveform.

[0056] (Step S112) The partial discharge diagnostic device 10 creates a report file based on the diagnostic results. The report file may include information including, for example, diagnostic results such as the presence or absence of partial discharge, the deterioration state of insulators provided in the transformer TR or bushing, or the need for replacing the insulators, on-site measurement conditions, and the generated φ-qn image.

[0057] (Step S113) The partial discharge diagnostic device 10 displays the measurement conditions indicated in the created report file to the user, who can analyze the diagnostic results by referring to the measurement conditions.

[0058] (Step S114) The partial discharge diagnostic device 10 displays the results shown in the created report and the φ-qn image diagnosis to the user. Based on the diagnostic results, the user can understand the deterioration status of the insulators provided in the transformer TR and bushings and determine the need for replacement.

[0059] In the above description, an example is shown in which the determination of whether the target voltage waveform is a damped oscillation waveform is performed in step S112, but the present embodiment is not limited to this example. Whether the target voltage waveform is a damped oscillation waveform may be determined, for example, after the target voltage waveform is cut out from the measured voltage waveform in step S102.

[0060] [Summary of the embodiment] According to the above-described embodiment, the partial discharge diagnostic device 10 includes a BGN voltage acquisition unit 11 that acquires the value of the BGN voltage based on the results of measuring the surface current flowing through metal other than the device to be diagnosed in the field where the transformer TR or bushing is installed; a measured voltage acquisition unit 12 that acquires the value of the measured voltage based on the results of measuring the surface current of the transformer TR; a waveform clipping unit 13 that clips out a target voltage waveform, which is a measured voltage waveform of a predetermined time domain based on the point at which the threshold is exceeded, from the measured voltage waveform that shows the change in the value of the measured voltage over time when the value of the measured voltage exceeds a threshold set to a value greater than the value of the BGN voltage; a phase detection unit 14 that detects the voltage phase (sometimes simply referred to as phase) of the target voltage waveform; a memory control unit 15 that links the voltage phase of the target voltage waveform with voltage information including the maximum value of the target voltage waveform and stores it in a memory unit M for each target voltage waveform; a generation unit 17 that generates φ-qn data by aggregating φ-q data based on the stored information for each target voltage waveform; and an output unit 19 that outputs information regarding the φ-qn data. The partial discharge diagnostic device 10 according to this embodiment extracts a target voltage waveform, which is a waveform exceeding the BGN voltage, from a measured voltage waveform to generate φ-qn data. Therefore, the partial discharge diagnostic device 10 does not use the measured voltage waveform to generate the φ-qn data, but uses the target voltage waveform, which is a part of the measured voltage waveform, to generate the φ-qn data, thereby reducing the amount of data required for diagnosis.

[0061] Moreover, according to the above-described embodiment, the partial discharge diagnostic device 10 further includes a waveform determination unit 16 that determines whether or not the target voltage waveform is a partial discharge waveform PD caused by partial discharge, based on the waveform shape of the target voltage waveform clipped by the waveform clipping unit 13. Furthermore, the generation unit 17 generates φ-qn data based on the φ-q data of the target voltage waveform that has been determined to be a partial discharge waveform by the waveform determination unit 16. This makes it possible to prevent a voltage that occurs due to sudden noise and is larger than the BGN voltage from being aggregated into the φ-qn data.

[0062] Furthermore, according to the above-described embodiment, the memory control unit 15 associates and stores the voltage phase and maximum value of the target voltage waveform determined to be a partial discharge waveform. That is, the waveform determination unit 16 determines whether the target voltage waveform is a partial discharge waveform PD while information about the target voltage waveform is being stored in the memory unit M. This eliminates the need to store the target voltage waveform as is in the memory unit M, allowing the partial discharge diagnostic device 10 to reduce the required data capacity.

[0063] FIG. 7 is a block diagram showing an example of the internal configuration of the partial discharge diagnostic apparatus 10 according to the embodiment. At least some of the functions of the partial discharge diagnostic apparatus 10 can be implemented using a computer. As shown in the figure, the computer includes a central processing unit 901, a RAM 902, an input / output port 903, input / output devices 904 and 905, and a bus 906. The computer itself can be implemented using existing technology. The central processing unit 901 executes instructions contained in a program read from the RAM 902 or the like. In accordance with the instructions, the central processing unit 901 writes data to the RAM 902, reads data from the RAM 902, and performs arithmetic and logical operations. The RAM 902 stores data and programs. Each element included in the RAM 902 has an address and can be accessed using the address. RAM is an abbreviation for "random access memory." The input / output port 903 is a port through which the central processing unit 901 exchanges data with external input / output devices. The input / output devices 904 and 905 are input / output devices. The input / output devices 904 and 905 exchange data with the central processing unit 901 via the input / output port 903. The bus 906 is a common communication path used within the computer. For example, the central processing unit 901 reads and writes data from and to the RAM 902 via the bus 906. Also, for example, the central processing unit 901 accesses the input / output port via the bus 906. Furthermore, all or part of the functional units provided in the partial discharge diagnostic device 10 may be realized using hardware such as an ASIC, a PLD, or an FPGA. Furthermore, all or part of the functional units may be realized by a combination of software and hardware.

[0064] Note that all or part of the functions of each unit of the partial discharge diagnostic device 10 in the above-described embodiment may be realized by recording a program for realizing these functions on a computer-readable recording medium, and reading and executing the program recorded on the recording medium into a computer system. Note that the term "computer system" here includes hardware such as an OS and peripheral devices.

[0065] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design modifications can be made without departing from the spirit of the present invention. Furthermore, the configurations described in the above-described embodiments and examples can be combined. [Explanation of symbols]

[0066] 1...Partial discharge diagnostic system, 2...First current sensor, 3...Second current sensor, TR...Transformer, 10...Partial discharge diagnostic device, 11...BGN voltage acquisition unit, 12...Measured voltage acquisition unit, 13...Waveform cutting unit, 14...Phase detection unit, 15...Memory control unit, 16...Waveform determination unit, 17...Generation unit, 18...Partial discharge diagnostic unit, 19...Output unit, M...Memory unit

Claims

1. a BGN voltage acquisition unit that acquires a BGN voltage value based on a result of measuring a surface current flowing through a metal other than the diagnosis target device in a site where the diagnosis target device is installed; a measured voltage acquisition unit that acquires a measured voltage value based on a result of measuring a surface current of the device to be diagnosed; a waveform clipping unit that, when the value of the measured voltage exceeds a threshold value set to a value greater than the value of the BGN voltage, clips a target voltage waveform, which is a measured voltage waveform in a predetermined time domain based on the point in time when the value of the measured voltage exceeds the threshold value, from a measured voltage waveform showing a time change of the value of the measured voltage; a phase detection unit that detects the phase of the target voltage waveform; a storage control unit that associates the phase of the target voltage waveform with voltage information including a maximum value of the target voltage waveform and stores the associated information for each target voltage waveform; a generating unit that generates φ-qn data by aggregating φ-q data based on stored information for each of the target voltage waveforms; an output unit that outputs information related to the φ-qn data; A partial discharge diagnostic device comprising:

2. a waveform determination unit that determines whether the target voltage waveform is a partial discharge waveform caused by a partial discharge based on the waveform shape of the target voltage waveform cut out by the waveform cutting unit, the generation unit generates φ-q-n data based on φ-q data of the target voltage waveform determined by the waveform determination unit to be the partial discharge waveform. The partial discharge diagnostic device according to claim 1 .

3. the storage control unit associates the phase and the maximum value of the target voltage waveform determined to be the partial discharge waveform with each other and stores the associated data. The partial discharge diagnostic device according to claim 2.

4. a partial discharge diagnosis unit that diagnoses that a partial discharge has occurred when a predetermined proportion or more of the φ-q data among the plurality of φ-q data included in the φ-q-n data are included in a first phase region from a first phase to a second phase different from the first phase, and in a second phase region from a third phase to a fourth phase different from the third phase, the second phase region not overlapping with the first phase region, the output unit outputs the result of the diagnosis by the partial discharge diagnosis unit. The partial discharge diagnostic device according to any one of claims 1 to 3.

5. a BGN voltage acquisition step of acquiring a BGN voltage value based on a result of measuring a surface current flowing through a metal other than the diagnosis target device in a site where the diagnosis target device is installed; a measured voltage acquisition step of acquiring a measured voltage value based on a result of measuring a surface current of the device to be diagnosed; a waveform cutting step of cutting out a target voltage waveform, which is a measured voltage waveform in a predetermined time domain based on the point in time when the measured voltage value exceeds a threshold value set to a value greater than the BGN voltage value, from a measured voltage waveform showing a time change of the measured voltage value; and a phase detection step of detecting a phase of the target voltage waveform; a storage control step of associating the phase of the target voltage waveform with voltage information including a maximum value of the target voltage waveform and storing the information for each target voltage waveform; a generating step of generating φ-qn data by aggregating φ-q data based on the stored information for each of the target voltage waveforms; an output step of outputting information about the φ-qn data; A partial discharge diagnostic method comprising:

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