Sensor and detection device

Abstract

A problem to be solved by the present invention is to provide a sensor and a detection device having high sensitivity to a partial discharge signal.SOLUTION: According to an embodiment of the invention, the sensor has electrodes and electric wires. The electrode is an electrode of a conductor that is brought into contact with an electrical housing that houses power equipment. The electric wire has a first end connected to the electrode and transmits an electric signal flowing through the electrode.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present invention relate to sensors and detection devices. [Background technology]

[0002] Partial discharge diagnosis of power equipment using TEV (Transient Earth Voltage) sensors is known. Partial discharge deteriorates the insulation of power equipment and leads to equipment failure. Therefore, there is a need to detect partial discharge in the early stages of deterioration of power equipment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-141670 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the TEV sensor has the problem of lower detection sensitivity for partial discharge signals compared to other partial discharge detection methods. The problem that the present invention seeks to solve is to provide a sensor and detection device that is highly sensitive to partial discharge signals. [Means for solving the problem]

[0005] According to an embodiment of the present invention, the sensor includes an electrode and an electric wire, the electrode being a conductive electrode that is in contact with an electrical enclosure that houses an electric power device, and a first end of the electric wire is connected to the electrode and transmits an electrical signal to the electrode.

[0006] According to an embodiment of the present invention, a detection system includes the sensor according to the above aspect and a computing device, and the computing device detects partial discharge in the electric power equipment based on a signal measured by the sensor. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a detection system according to a first embodiment. [Figure 2] FIG. 1 is a schematic diagram showing the configuration of a detection device according to a first embodiment. [Figure 3] FIG. 2 is a plan view showing a surface on which electrodes of the sensor according to the first embodiment are provided. [Figure 4] FIG. 4 is a diagram showing the results of an experiment on the sensor according to the first embodiment. [Figure 5] FIG. 10 is a schematic diagram showing the configuration of a detection device according to a second embodiment. [Figure 6] FIG. 10 is a plan view showing a surface on which electrodes of a sensor according to a third embodiment are provided. [Figure 7] 10A and 10B are diagrams showing the results of a simulation regarding the shape of an electrode according to the embodiment. [Figure 8] 10A and 10B are diagrams showing partial discharge sensitivity test and simulation results according to the embodiment; [Figure 9] 10A and 10B are diagrams showing experimental results regarding the relationship between the position of the electric wire and the sensitivity according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, a sensor and a detection device according to an embodiment will be described with reference to the drawings. (First embodiment) FIG. 1 is a schematic diagram showing the configuration of a detection system according to the first embodiment. The detection system 10 includes a detection device 100 and one or more target electric power devices 200. The detection device 100 of the first embodiment is configured as a single device.

[0009] The target power device 200 comprises an electrical housing 210 and a device body 220. The device body 220 is housed in the grounded electrical housing 210. The device body 220 is a device that may generate partial discharge, such as a power transformer, a gas-insulated switchgear, a generator, an electric motor, or a reactor. The device body 220 is composed of devices such as a circuit breaker, a disconnecting switch, a current transformer, or a voltage transformer. The device body 220 passes high voltage and large current from the outside via a power cable. The device body 220 has a function to cut off the current in the event of an abnormality.

[0010] 2 is a schematic diagram showing the configuration of the detection device 100 according to the first embodiment. The detection device 100 detects the occurrence of partial discharge in the target electric power device 200 and estimates the degradation state of the target electric power device 200.

[0011] The detection device 100 includes a sensor 110 and a computing device 120 (external device). The sensor 110 is attached to an electrical housing 210 of the target power device 200, and measures the potential formed on the surface of the electrical housing 210 via a ground wire and stray capacitance between the sensor 110 and a device main body 220 housed in the electrical housing 210. In other words, the sensor 110 according to the first embodiment is a TEV (Transient Earth Voltage) sensor. The computing device 120 detects and records partial discharges based on the measurement values ​​of the sensor 110. The computing device 120 may be, for example, an oscilloscope.

[0012] The sensor 110 includes one or more electrodes 111, electric wires 112, a bandpass filter circuit 113, a connector 114, a case 115, and a magnet 116. The sensor 110 and the computing device 120 are connected by a coaxial cable 117. The electrode 111 is a conductor formed in a flat plate shape. For example, the electrode 111 may be a stainless steel plate. The electrode 111 may be made of a non-magnetic metal so that the electrode 111 does not absorb the magnetic flux of the magnet 116. The electrode 111 forms part of the outer wall of the case 115. The surface of the electrode 111 facing the outside of the case 115 (i.e., the exposed surface) is called the outer surface, and the surface facing the inside of the case 115 is called the inner surface. The outer surface of the electrode 111 is coated with silver plating, which provides conductivity while preventing corrosion. The inner surface of the electrode 111 and the bandpass filter circuit 113 are connected by an electric wire 112. That is, a first end of the electric wire 112 is connected to the inner surface of the electrode 111, and a second end of the electric wire 112 is connected to an input terminal of the bandpass filter circuit 113.

[0013] The bandpass filter circuit 113 has an input terminal and an output terminal, and extracts a signal of a predetermined frequency band from the electrical signal input to the input terminal and outputs the extracted signal from the output terminal. For example, the bandpass filter circuit 113 according to the first embodiment extracts a signal of a frequency band of 5 MHz to 30 MHz, which is a frequency band in which partial discharge signals are detected. In the example shown in FIG. 2, the bandpass filter circuit 113 is configured by an RLC circuit. Specifically, the bandpass filter circuit 113 includes a coil L, a capacitor C, a resistor R, and a ground line G. A first end of the coil L is connected to an input end of the bandpass filter circuit 113. A first end of the capacitor C is connected to a second end of the coil L. In other words, the coil L and the capacitor C are connected in series. A second end of the capacitor C is connected to an output end of the bandpass filter circuit 113. A second end of the capacitor C is connected to a first end of the resistor R. A second end of the resistor R is connected to the ground line G. The bandpass filter circuit 113 is not limited to that shown in FIG. 2, but the bandpass filter circuit 113 includes the ground line G.

[0014] The connector 114 is a device interface of the sensor 110. The connector 114 according to the first embodiment is a coaxial connector. The connector 114 has a signal line contact 1141 to which the inner conductor (core wire) of the coaxial cable 117 is connected, and a ground contact 1142 to which the outer conductor (shield) is connected. The signal line contact 1141 of the connector 114 is connected to the output end of the bandpass filter circuit 113. The ground contact 1142 of the connector 114 is connected to the ground line G of the bandpass filter circuit 113. In other words, the ground line G of the bandpass filter circuit 113 is at the same potential as the ground of the arithmetic device 120.

[0015] The case 115 is made of an insulator and forms the outer shell of the sensor 110. A portion of the case 115 is made up of the electrode 111. In the example shown in FIG. 2, a recess 1151 into which the electrode 111 fits is provided on one outer surface of the case 115. Hereinafter, on the surface of the case 115 on which the recess 1151 is provided, the portion surrounding the recess 1151 that protrudes relative to the recess 1151 will be referred to as a protrusion 1152. When the electrode 111 fits into the recess 1151 of the case 115, the outer surface of the electrode 111 and the outer surface of the case 115 become flush with each other. The electrode 111 and the recess 1151 are joined by screws or adhesive.

[0016] Magnet 116 is attached to the inner surface of protrusion 1152 of case 115. In Fig. 3, the inner surface of protrusion 1152 is recessed relative to the inner surface of recess 1151. Magnet 116 makes it possible to bring electrode 111 into contact with electrical housing 210 and to fix sensor 110 to electrical housing 210. Note that if electrode 111 is made of a non-magnetic material, magnet 116 may be attached to the inner surface of electrode 111.

[0017] FIG. 3 is a plan view showing a surface on which electrodes 111 of sensor 110 according to the first embodiment are provided. In the example shown in FIG. 3, the shape of electrode 111 is an octagon obtained by cutting off the corners of a rectangular parallelepiped. That is, the outer shape of electrode 111 is an octagon having two pairs of parallel long sides and two pairs of parallel short sides, with the short sides and long sides alternately connected. As shown in FIG. 3, recessed portion 1151 of case 115 contacts the outer periphery of electrode 111. Magnet 116 is disposed on the inner surface of protruding portion 1152 of case 115, in a portion surrounded by the short sides of electrode 111 and the side wall of case 115.

[0018] The computing device 120 and the sensor 110 are electrically connected by a coaxial cable 117 . The arithmetic device 120 detects partial discharge in the target electric power device 200 based on the electric signal acquired from the coaxial cable 117. For example, the arithmetic device 120 may extract a partial waveform including a pulse signal from the waveform of the electric signal, and determine whether the pulse signal is caused by a partial discharge based on the peak magnitude (peak value), pulse width, and frequency spectrum of the partial waveform. The arithmetic device 120 may also calculate a ΦQN pattern (Φ is phase, Q is charge amount, and N is frequency) for the partial waveform related to partial discharge, and estimate the degradation state of the target electric power device 200 by integrating the discharge energy generated in the target electric power device 200.

[0019] The arithmetic device 120 includes a processor, a memory, an auxiliary storage device, and the like, which are connected via a bus, and executes programs to realize the above-mentioned functions. Examples of the processor include a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), and a microprocessor. The program may be recorded on a computer-readable recording medium, such as a storage device including a magnetic disk, a magneto-optical disk, an optical disk, or a semiconductor memory. The program may be transmitted via a telecommunications line.

[0020] Note that all or part of the functions of the arithmetic device 120 may be implemented using a custom LSI (Large Scale Integrated Circuit) such as an ASIC (Application Specific Integrated Circuit) or a PLD (Programmable Logic Device). Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). Such integrated circuits are also included in the scope of a processor.

[0021] As shown in Patent Document 1, the electrodes of conventional TEV sensors receive electrical signals from an electrical housing via a dielectric. The dielectric allows specific frequency bands to be filtered out from the electrical signals flowing through the electrical housing, and also cuts out sudden high currents. On the other hand, conventional TEV sensors receive electrical signals via electrostatic coupling via a dielectric, so the level of the received electrical signals is low. This results in a low signal-to-noise ratio (SNR) for external noise.

[0022] In contrast, the sensor 110 according to the first embodiment receives an electric signal by directly contacting the electrode 111 with the electric housing 210 without using a dielectric material, thereby enabling the electric signal to be received with high sensitivity and increasing the signal-to-noise ratio against external noise. Furthermore, the sensor 110 according to the first embodiment includes a bandpass filter circuit 113. This allows the sensor 110 to cut off a specific frequency band from an electrical signal and cut off sudden high currents without including a dielectric.

[0023] The inventors interposed a dielectric FRP (Fiber Reinforced Plastics) plate between the sensor 110 according to the first embodiment and the electrical housing 210. The inventors then measured the output voltage of the sensor 110 while varying the thickness of the FRP plate to investigate the effect of the thickness of the FRP plate on the output of the sensor 110. FIG. 4 shows the results of an experiment using the sensor 110 according to the first embodiment. The graph in FIG. 4 plots the magnitude of the voltage detected by the sensor 110 on the vertical axis and the thickness of the FRP plate on the horizontal axis. The experiment revealed that the thicker the FRP plate, the lower the voltage detected by the sensor 110. This demonstrates that the sensor 110 according to the first embodiment, in which the electrode 111 is in direct contact with the electrical housing 210, can receive electrical signals from the electrical housing 210 with higher sensitivity than a conventional TEV sensor in which the electrode is in contact with the electrical housing 210 via a dielectric such as FRP.

[0024] As described above, the sensor 110 according to the first embodiment includes a conductive electrode 111 that is brought into contact with the electrical housing 210 that houses the target power device 200, and an electric wire 112 that has a first end connected to the electrode 111 and transmits an electric signal that flows through the electrode 111. The sensor 110 can sensitively receive an electric signal from the electrical housing 210 by bringing the electrode 111 into contact with the electrical housing 210.

[0025] The sensor 110 according to the first embodiment also includes a bandpass filter circuit 113 having an input terminal connected to the second end of the electric wire 112. This allows the sensor 110 to selectively receive signals in a frequency band that includes pulse signals related to partial discharge.

[0026] Furthermore, the sensor 110 according to the first embodiment includes a connector 114 having a first end connected to the output end of the bandpass filter circuit 113 and configured to connect a coaxial cable 117 for transmitting a bandpass signal to the computing device 120. A signal line contact 1141 of the connector 114 is connected to the output end of the bandpass filter circuit 113, and a ground contact 1142 of the connector 114 is connected to the ground line G of the bandpass filter circuit 113. This allows the sensor 110 to receive an electrical signal from the electrical housing 210 with the ground of the computing device 120 as the reference.

[0027] (Second embodiment) The sensor 110 according to the first embodiment is fixed to the electrical housing 210 by a magnet 116. The sensor 110 according to the second embodiment is fixed to the electrical housing 210 by a means different from the magnet 116.

[0028] 5 is a schematic diagram showing the configuration of a detection device 100 according to the second embodiment. A sensor 110 according to the second embodiment includes a conductive double-sided tape 118 instead of a magnet 116. The conductive double-sided tape 118 is attached to the outer surface of a case 115 on which an electrode 111 is provided. The conductive double-sided tape 118 is formed by applying a conductive adhesive to both sides of a conductive sheet such as copper foil. In other words, the conductive adhesive is applied to the outer surface of the electrode 111 according to the second embodiment. The sensor 110 according to the second embodiment can be fixed to the electrical housing 210 by means of conductive double-sided tape 118.

[0029] Note that sensor 110 according to another embodiment may have a conductive adhesive applied to the outer surface of electrode 111 instead of conductive double-sided tape 118 .

[0030] (Third embodiment) FIG. 6 is a plan view showing a surface on which electrodes 111 of a sensor 110 according to the third embodiment are provided. In the example shown in FIG. 6, the shape of the electrode 111 is rectangular. For example, the shape of the electrode 111 may be a rectangle measuring 100 mm x 10 mm. That is, the outer shape of the electrode 111 has two pairs of long sides that are parallel to each other and two pairs of short sides that are parallel to each other. The configuration other than the shape of the electrode 111 may be the same as that of the first or second embodiment. As in the third embodiment, partial discharge signals can be detected with high sensitivity by forming the electrode 111 into a rectangular shape with a width of 20 mm or less. The width of the electrode 111 may be, for example, 5 mm or more and 20 mm or less.

[0031] 7 is a diagram showing the results of a simulation regarding the shape of the electrode according to the embodiment. The inventors performed a simulation of the time change in the distribution of an electric signal when a partial discharge signal occurs, using electrodes of various shapes. In the simulation, the time change in the distribution of an electric signal when a partial discharge signal occurs was simulated for electrodes of a star-shaped regular pentagon inscribed in a circle with a diameter of 105 mm, a circle with a diameter of 100 mm, a rectangle with a size of 100 mm x 10 mm, and a square with a size of 50 mm x 50 mm. In the simulation, the electrode thickness was set to 5 mm, and the partial discharge signal was approximated by a Gaussian pulse traveling in a direction perpendicular to the electrode 111.

[0032] As shown in FIG. 7, it can be seen that partial discharge signals flow easily to the edges of the electrode 111 and less easily through the center of the electrode 111. This is thought to be due to the skin effect. As shown in FIG. 7, it can be seen that current flows more easily within a range of 20 mm from the edge of the electrode 110 than near the center. In this case, it can be seen that in a rectangular electrode with a width of 10 mm, which is shorter than 20 mm as shown in FIG. 7, current flows more easily even in the center, and sensitivity is good. FIG. 8 shows the results of a partial discharge sensitivity test and simulation according to the embodiment. The results of FIG. 8 also show that the sensitivity of the rectangular electrode is better than that of star-shaped regular pentagonal, circular, and square electrodes.

[0033] (Fourth embodiment) In the sensor 110 according to the fourth embodiment, an electric wire 112 is connected to an end of an electrode 111. Specifically, the electric wire 112 is connected to an end of the inner surface of the electrode 111 (the surface facing the inside of the case 115). The configuration other than the attachment position of the electric wire 112 may be the same as that of the third embodiment. By connecting the electric wire 112 to the end of the electrode 111 as in the fourth embodiment, partial discharge signals can be detected with high sensitivity.

[0034] Fig. 9 is a diagram showing experimental results regarding the relationship between the position of an electric wire and sensitivity according to the embodiment. In the experiment shown in Fig. 9, partial discharge signals were measured using a sensor 110 in which an electric wire 112 was attached to the center of a rectangular electrode 111 measuring 100 mm x 10 mm, as in the third embodiment, and a sensor 110 in which an electric wire 112 was attached to an end of a rectangular electrode 111 measuring 100 mm x 10 mm, as in the fourth embodiment. As a result, as shown in Fig. 9, it was found that when the electric wire 112 was attached to the end of the electrode 111, sensitivity was higher than when the electric wire 112 was attached to the center of the electrode 111. This is because, as can be seen from Fig. 7, current caused by the partial discharge signal, which is a pulse signal, tends to flow to the end of the electrode 111.

[0035] According to at least one of the embodiments described above, a sensor and a detection device having high sensitivity to partial discharge signals can be provided by having a conductor electrode that is brought into contact with an electrical housing that houses electric power equipment, and an electric wire whose first end is connected to the electrode and that transmits an electric signal that flows through the electrode.

[0036] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [Explanation of symbols]

[0037] 10...Detection system 100...Detection device 110...Sensor 111...Electrode 112...Electric wire 113...Band-pass filter circuit 114...Connector 1141...Signal line contact 1142...Ground contact 115...Case 1151...Concave portion 1152...Convex portion 116...Magnet 117...Coaxial cable 118...Conductive double-sided tape 120...Calculating device 200...Target power equipment 210...Electrical housing 220...Equipment body

Claims

1. a conductive electrode that contacts an electrical enclosure that houses the power device; an electric wire having a first end connected to the electrode and transmitting an electric signal flowing through the electrode; A sensor comprising:

2. a bandpass filter circuit having an input terminal connected to the second end of the electric wire; the bandpass filter circuit extracts a predetermined frequency band from the electrical signal input to the input terminal and outputs a bandpass signal from the output terminal; The sensor of claim 1 .

3. a connector having a first end connected to the output end of the bandpass filter circuit and configured to connect a cable for transmitting the bandpass signal to an external device; the connector has a signal line contact and a ground contact; the output terminal of the bandpass filter circuit is connected to the signal line contact of the connector; the ground of the bandpass filter circuit is connected to the ground contact of the connector; The sensor of claim 2 .

4. a case for housing the bandpass filter circuit; The electrode forms a part of the outer wall of the case. The sensor of claim 2 .

5. The sensor according to claim 4 , further comprising a magnet provided on the same surface of the case as the electrodes.

6. The electrode is configured in a flat plate shape, A conductive adhesive is attached to the surface of the electrode that contacts the electrical housing. The sensor of claim 1 .

7. The electrode has a rectangular shape. The sensor of claim 1 .

8. The width of the electrode is 20 mm or less. The sensor of claim 1 .

9. the first end of the wire is connected to an end of the electrode; The sensor of claim 1 .

10. The sensor according to any one of claims 1 to 9; a computing device that detects partial discharge of the electric power equipment based on the signal measured by the sensor; A detection device comprising:

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