Partial discharge detection device and partial discharge detection method

Abstract

To provide a partial discharge detection device and a partial discharge detection method which can separate internal partial discharge from external noise under such a situation that the external noise and the internal partial discharge exist in a mixed manner and surely detect the internal partial discharge.SOLUTION: A partial discharge detection device comprises: a transient ground voltage sensor 12 which is provided in a high voltage device and measures the transient ground voltage; partial discharge detection signal selection means 13, 15 which selects a partial discharge detection signal about internal partial discharge in the detection signal output from the transient ground voltage sensor; partial discharge generation detection means 18 which detects a partial discharge generation signal indicating the generation of the internal partial discharge from the selected partial discharge detection signal; partial discharge generation signal holding means 19, 20 which holds the detected partial discharge generation signal; and sampling means 23 which samples the partial discharge generation signal held by the partial discharge generation signal holding means every time a prescribed sampling period comes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a partial discharge detection device for detecting internal partial discharge in high-voltage equipment, and more particularly to a partial discharge detection device and partial discharge detection method for detecting internal partial discharge in high-voltage equipment using a transient ground voltage sensor. [Background technology]

[0002] High-voltage equipment such as distribution boards, switchgears, transformers, and switching devices are used for long periods after installation, which leads to deterioration over time, such as a decline in insulation performance. It is generally known that a decline in the insulation performance of power equipment can lead to internal partial discharges. Repeated discharges (hereinafter referred to as internal partial discharges) within high-voltage equipment constituting power equipment can lead to insulation breakdown, potentially resulting in fires and other disasters. Therefore, accurately detecting internal partial discharges in high-voltage equipment is important for the safe operation of power equipment.

[0003] For example, Japanese Patent Laid-Open Publication No. 09-68556 (Patent Document 1) discloses the following technology for detecting internal partial discharges. Specifically, in a three-phase power facility, output signals from three antennas corresponding to each phase are switched using a channel selector, output to a tuning amplifier, measured as digital data via an A / D converter, and frequency analysis is performed to determine whether or not internal partial discharges have occurred. If an evaluation value (average, etc.) obtained from the measured values ​​is specifically large for only one antenna, it is determined that an insulation abnormality has occurred.

[0004] Furthermore, Japanese Patent Laid-Open Publication No. 10-210647 (Patent Document 2) discloses the following technology for detecting internal partial discharges: Specifically, output signals from three antennas (corresponding to each phase of a three-phase power facility) and a noise antenna are switched using a selector, measured via an amplifier, a tuner, and an A / D converter, frequency analysis is performed to determine whether or not internal partial discharges have occurred, a frequency point where the output level of the noise antenna does not exceed a threshold is determined as the measurement range, and then the outputs of the three antennas are measured within the measurement range, and the presence or absence of internal partial discharges is determined based on the average level of the measured values. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 09-68556 [Patent Document 2] Japanese Patent Application Publication No. 10-210647 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, in order to detect internal partial discharges in high-voltage equipment, it has been proposed to use a transient earth voltage sensor attached to the wall surface inside the high-voltage equipment, for example, a switchboard. However, when using this transient earth voltage sensor to detect internal partial discharges, it is necessary to address the following issues.

[0007] The electromagnetic waves around high-voltage equipment are a mixture of electromagnetic waves caused by internal partial discharges emitted from the surface of insulators inside the equipment or from inside the insulators, and external noise such as electromagnetic waves caused by air discharges generated at parts exposed to the air, such as bushings, and communication waves.To detect internal partial discharges, it is necessary to separate and detect the external noise.

[0008] Furthermore, monitoring devices that monitor the detection signals of transient earth voltage sensors are often configured as one unit with the control devices inside the panel, and the sampling period for internal partial discharges may be set low at a few kHz to suit the monitoring or control device. On the other hand, because the electromagnetic waves caused by internal partial discharges are short-duration signals at a few MHz, there is an issue that if the sampling period is set low, it becomes difficult to reliably detect internal partial discharges.

[0009] An object of the present invention is to provide a partial discharge detection device and a partial discharge detection method that can separate internal partial discharges from external noise and reliably detect internal partial discharges in a situation where external noise and internal partial discharges coexist. [Means for solving the problem]

[0010] The present invention is characterized by a partial discharge detection device comprising: a transient ground voltage sensor provided in a high-voltage device and measuring a transient ground voltage; partial discharge detection signal selection means for selecting a partial discharge detection signal relating to an internal partial discharge from among detection signals output from the transient ground voltage sensor; partial discharge occurrence detection means for detecting a partial discharge occurrence signal indicative of the occurrence of an internal partial discharge from the selected partial discharge detection signal; partial discharge occurrence signal holding means for holding the detected partial discharge occurrence signal; and sampling means for sampling the partial discharge occurrence signal held in the partial discharge occurrence signal holding means at each prescribed sampling period. [Effects of the Invention]

[0011] According to the present invention, in a situation where external noise and internal partial discharges coexist, internal partial discharges can be separated from external noise, and internal partial discharges can be reliably detected. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram showing the configuration of a partial discharge detection device according to a first embodiment of the present invention. [Figure 2]FIG. 2 is an explanatory diagram illustrating a partial discharge signal and an air discharge signal measured by a TEV sensor. [Figure 3] 10A and 10B are explanatory diagrams illustrating signal waveforms of a TEV sensor before and after passing through a low-pass filter. [Figure 4] FIG. 2 is a configuration diagram showing a configuration of a baseline fluctuation suppression circuit. [Figure 5] FIG. 10 is an explanatory diagram illustrating a state in which baseline fluctuations are suppressed. [Figure 6] 10A and 10B are explanatory diagrams showing input and output signals of an integrating circuit and explaining the extension state of the time width of a detection signal. [Figure 7] FIG. 10 is an explanatory diagram for explaining the concept of timing for capturing a partial discharge occurrence signal. [Figure 8] FIG. 4 is a configuration diagram showing the configuration of a partial discharge detection system for detecting partial discharge in a high-voltage device according to a second embodiment of the present invention. [Figure 9] 4 is an explanatory diagram illustrating detection signals of a first TEV sensor and a second TEV sensor. FIG. [Figure 10] FIG. 4 is a block diagram showing the configuration of a partial discharge detection device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The following describes in detail an embodiment of the present invention with reference to the drawings, but the present invention is not limited to the following embodiment and includes various modifications and applications within the technical concept of the present invention. In each drawing, the same components are designated by the same reference numerals, and detailed descriptions of overlapping parts will be omitted. [Example]

[0014] 1 shows the configuration of a partial discharge detection device according to a first embodiment of the present invention. In this embodiment, an example will be described in which a transient earth voltage sensor (hereinafter referred to as a TEV sensor) is used to detect internal partial discharges in a power receiving panel or switchgear, which are high-voltage devices.

[0015] 1, TEV sensor 12 has a function of outputting, as a voltage signal, a surface current induced on the surface of metal wall 11 of a housing constituting a power receiving panel, switchgear, etc. to which TEV sensor 12 is attached. Here, metal wall 11 of the housing is grounded. A detection circuit 10 is connected downstream of TEV sensor 12.

[0016] On the upstream side of the detection circuit 10 are provided high-pass filter 13, which removes external noise components near commercial frequencies, and low-pass filter 15, which removes external noise components due to aerial discharge. Between the high-pass filter 13 and low-pass filter 15, an amplifier 14 with a gain of 1 is provided for the purpose of impedance separation. This eliminates interaction between the high-pass filter 13 and low-pass filter 15. In this way, the high-pass filter 13 to low-pass filter 15 have the function of removing external noise, and this allows a detection signal related to internal partial discharge to be sent to subsequent circuit elements.

[0017] Resistor R1, capacitor C1, and selector switches 16 and 17 are provided downstream of low-pass filter 15 to suppress baseline fluctuations in the signal from TEV sensor 12. These elements function to suppress baseline fluctuations. Selector switches 16 and 17 consist of output switch 16, which outputs the input signal from low-pass filter 15, and ground switch 17.

[0018] Here, the output switch 16 and the ground switch 17 perform opposite operations when the operation timing arrives, and are operated by a switching signal from a monitoring device 23, which will be described later. When the output switch 16 is in the "on" state, the ground switch 17 is "off", and a partial discharge detection signal is output to the subsequent comparator 18.

[0019] On the other hand, when the output switch 16 is in the "off" state, the ground switch 17 is "on" and the partial discharge detection signal is not output to the comparator 18. When the partial discharge detection signal is not output, the transient ground voltage sensor 12 is in the grounded state and the offset is "0V".

[0020] The operation timing of the changeover switches 16 and 17 may be any cycle, but can also be determined in consideration of the timing of the reset switches 21 and 22, which will be described later. The timing of the reset switches 21 and 22 is synchronized with the sampling cycle of the monitoring device 23.

[0021] The components from the high-pass filter 13 to the changeover switches 16 and 17 function as a "partial discharge detection signal selection means" that selects a partial discharge detection signal related to an internal partial discharge from among the input signals input to the transient earth voltage sensor. Note that the resistor R1, capacitor C1, and changeover switches 16 and 17 can be omitted if not required.

[0022] A comparator 18 is provided after the selector switches 16 and 17, and determines that a partial discharge detection signal equal to or greater than a predetermined threshold is a partial discharge occurrence signal. The comparator 18 functions as a "partial discharge occurrence detection means" that detects a partial discharge occurrence signal indicating the occurrence of an internal partial discharge from the selected partial discharge detection signal.

[0023] When it is determined that a partial discharge occurrence signal has occurred, this partial discharge occurrence signal is output to the downstream integration circuits 19 and 20 each time it occurs. The comparator 18 has a threshold value that can be changed by an external input. This threshold value can be set in advance, for example, at the time of shipment, and in this embodiment it is set at the time of shipment. However, it can also be changed depending on the usage status and environmental conditions of the high-voltage device.

[0024] Integrator circuits 19 and 20 are connected to the rear of the comparator 18. These integrator circuits 19 and 20 are configured in two stages connected in series, and are composed of a first integrator circuit 19 and a subsequent second integrator circuit 20. The first integrator circuit 19 has a function of extending the temporal signal width (time width) of the partial discharge occurrence signal, and the second integrator circuit 20 has a storage function of storing charge based on the partial discharge occurrence signal. These integrator circuits 10 and 20 function as "partial discharge occurrence signal holding means" that holds the partial discharge occurrence signal.

[0025] The first integrating circuit 19 is composed of an operational amplifier OP1 as its main element, resistors R2, R3, R4, and a capacitor C2. The second integrating circuit 20 is composed of an operational amplifier OP2 as its main element, resistors R6, R7, and a capacitor C3. Resistor R5 and capacitor C3 are interposed between the first integrating circuit 19 and the second integrating circuit 20.

[0026] Furthermore, the second integration circuit 20 is provided with a reset switch 21 arranged in parallel with the resistor R6 and a reset switch 22 arranged in parallel with the capacitor C3. The reset switches 21 and 22 are composed of photodiodes. The reset switches 21 and 22 discharge the charge accumulated in the second integration circuit 20, resetting it.

[0027] The amount of charge before being reset indicates the occurrence of internal partial discharge and its intensity. The reset operation of the reset switches 21 and 22 is synchronized with the sampling period of the monitoring device 23, which detects the amount of charge at this time and determines the occurrence of internal partial discharge. These function as "sampling means" that sample the partial discharge occurrence signals held in the integrating circuits 19 and 20.

[0028] Next, the operation of the detection circuit 10 shown in Fig. 1 will be described with reference to Fig. 2 to Fig. 7. Fig. 2 shows the partial discharge signal and air discharge signal of the high-voltage device output from the TEV sensor 12, Fig. 3 shows the waveform of the detection signal of the TEV sensor 12 before and after passing through a low-pass filter, Fig. 4 shows the configuration of a baseline fluctuation prevention circuit, Fig. 5 shows the baseline fluctuation suppression state, Fig. 6 shows a comparison of the time widths of the input signal and output signal by the integration circuit, and Fig. 7 shows the concept of the detection timing of the detection device.

[0029] First, Figure 2 (A) shows the partial discharge detection signal inside the housing of the high-voltage equipment measured by the TEV sensor 12, and (B) shows the air discharge detection signal outside the housing of the high-voltage equipment. The high-frequency components are the same frequency, 80 MHz for internal partial discharges and 90 MHz for air discharges, but the frequency components of the envelope components of the high-frequency vibration are 4 MHz for internal partial discharges and 10 MHz for air discharges, a difference of about 2.5 times. Therefore, by distinguishing between the envelope frequency components, it is possible to select internal partial discharges.

[0030] In the case of an air discharge, the air discharge reaches the housing directly as electromagnetic waves, and the surface current induced on the surface of the housing is detected by the TEV sensor 12. In contrast, in the case of an internal partial discharge inside the housing, the electromagnetic waves of the internal partial discharge induce a surface current inside the housing, which leaks from the bushing or the like and propagates outside the housing to be detected by the TEV sensor 12. In addition to this, a ground current component that flows into the housing via the housing's ground wire is also detected by the TEV sensor 12. This ground current component is a relatively low frequency component.

[0031] Therefore, first, to remove external noise near commercial frequencies, the detection signal from the TEV sensor 12 is passed through a high-pass filter 13 with a cutoff frequency of several tens of kHz, thereby removing external noise components in the low frequency band. Next, to separate internal partial discharges from air discharges, the signal is passed through a low-pass filter 15 with a cutoff frequency of 7 MHz to 9 MHz, thereby cutting out the envelope frequency components of air discharges and selecting and extracting the partial discharge detection signal.

[0032] As a result, the signal waveform of the TEV sensor 12 retains the envelope component of the partial discharge signal, as shown in Figure 3. The upper part of Figure 3 shows the partial discharge signal inside the housing of the high-voltage device measured by the TEV sensor 12, and the lower part shows the envelope component signal that has passed through the low-pass filter 15. The cutoff frequencies of the high-pass filter 13 and the low-pass filter 15 vary depending on the usage situation and environmental conditions in which the high-voltage device is installed. It is preferable to use filters with variable cutoff frequencies. This makes it possible to change the cutoff frequencies as needed and improve detection accuracy.

[0033] In this embodiment, in order to prevent fluctuations in the baseline of the partial discharge detection signal, a baseline voltage fluctuation suppression circuit 24, which is composed of a resistor R1, a capacitor C1, and changeover switches 16 and 17 as shown in Fig. 4, is provided after the low-pass filter 15. This baseline suppression circuit 24 has the function of suppressing voltage fluctuations in the baseline.

[0034] The output switch 16, which outputs a partial discharge detection signal, and the ground switch 17 are changeover switches; when the output switch 16 is in the "on" state, the ground switch 17 is "off" at the timing when the partial discharge detection signal is to be output, and when the output switch 16 is in the "off" state, the ground switch 17 is "on" at the timing when the partial discharge detection signal is not to be output. As a result, the TEV sensor 12 side is in the grounded state, and the offset becomes "0V."

[0035] The operation of the baseline voltage fluctuation suppression circuit 24, which suppresses such baseline fluctuations, is shown in Figure 5. Figure 5 (A) shows the partial discharge detection signal on the input side (a) of resistor R1 before passing through the baseline suppression circuit 24, and shows the influence of baseline voltage fluctuations.

[0036] 5(B) shows the partial discharge detection signal on the output side (b) of the output switch 16 after passing through the baseline voltage fluctuation suppression circuit 24, where the influence of baseline voltage fluctuations is suppressed. Here, (C) shows the timing of the ground switch 17, where the partial discharge detection signal is input to the downstream comparator 18 when the ground switch is "off" (and conversely, when the output switch 16 is "on").

[0037] The comparator 18 compares the partial discharge detection signal with a predetermined threshold value. The predetermined threshold value is a threshold value for determining whether an internal partial discharge has occurred, and if the predetermined threshold value is exceeded, it is considered that an internal partial discharge has occurred. The partial discharge occurrence detection signal, which the comparator 18 has recognized as indicating the occurrence of an internal partial discharge, is input to the first integration circuit 19. Here, the strength of the partial discharge signal to be determined may change depending on the usage status of the high-voltage device, environmental conditions, etc., and therefore it is preferable that the threshold value setting of the comparator 18 is adjustable.

[0038] The partial discharge occurrence signal output by the comparator 18 is input to the subsequent integrating circuits 19 and 20, which expand the temporal signal width (time width). As described above, the integrating circuits 19 and 20 are configured in two stages connected in series.

[0039] The time width of the partial discharge occurrence signal is then expanded by the first-stage integrating circuit 19. The values ​​of the resistors R2, R3, and R4 and the capacitor C2 connected to the operational amplifier OP1 are set so that this time width can be sampled within the sampling period and bandwidth of the monitoring device 23.

[0040] The results of the simulation are shown in Figure 6. For example, when an input signal with a time width of 125 ns was input to the input side of the integrator circuit 19, an output signal with a time width of 400 μs was output from the output side after passing through the integrator circuit 19. As such, it can be seen that the time width of the partial discharge occurrence signal from the comparator 18 is expanded so as to correspond to the sampling period.

[0041] Next, the second-stage integrating circuit 20 accumulates the charge due to the partial discharge occurrence signal. The intensity of the internal partial discharge can be determined based on the amount of this accumulated charge. The amount of accumulated charge is then captured by the monitoring device 23 as an output value of the internal partial discharge. The monitoring device 23 determines the intensity of the internal partial discharge based on the magnitude of this captured output value.

[0042] After the output value is captured, a reset signal is input from the monitoring device 23 to the second integration circuit 20, and the reset switches 12 and 13 are turned "on" to discharge the electric charge. In this way, by synchronizing the period of the reset signal with the sampling period of the monitoring device 23, it is possible to improve the detection accuracy.

[0043] FIG. 7 illustrates the concept of timing for taking in the charges accumulated by the integrating circuits 19 and 20.

[0044] At the falling edge of the reset signal from the monitoring device 23, the output switch 16 is turned "on" and the ground switch 17 is turned "off", thereby inputting a partial discharge occurrence signal to the integrating circuits 19 and 20. Then, a signal acquisition period is set over a predetermined time, and this state is maintained to accumulate charge based on the partial discharge occurrence signal. When the signal acquisition period ends, the output switch 16 is changed to "off" and the grounding switch 17 is changed to "on". At this time, the charge accumulated in the second integrating circuit 20 is held.

[0045] Next, the accumulated charge is captured in response to the arrival of a reset signal from the monitoring device 23. In this case, the accumulated charge is captured at the rising edge of the reset signal, and the accumulated charge is discharged at the falling edge, and this process is repeated. With this operation, an output value based on the partial discharge occurrence signal is input to the monitoring device 23 at a sampling period of several kHz, and the presence or absence of an internal partial discharge can be reliably detected by the monitoring device installed in the high-voltage equipment, without using measuring equipment such as a high-speed oscilloscope. [Example]

[0046] Next, a second embodiment of the present invention will be described. The second embodiment is characterized in that a second TEV sensor for detecting aerial discharge is provided.

[0047] 8, high-voltage device 25 is provided with electrodes 26 and 27, with insulating material 28 disposed between the electrodes. A first TEV sensor 12 is provided in the housing of high-voltage device 25 and is connected to monitoring device 23 via transmission line 29. High-voltage device 25 is connected to power supply 32 via bushing 30 and application line 31.

[0048] Furthermore, an external antenna 33 made of metal is provided around the periphery of the high-voltage device 25, and a second TEV sensor 34 is attached to this. The second TEV sensor 34 is also connected to the monitoring device 23 by a transmission line 29. Note that an electromagnetic wave Em1 due to an internal partial discharge is emitted from the insulator 28, and an electromagnetic wave EM2 due to an air discharge is emitted from the bushing 30. The electromagnetic wave Em1 is measured by the first TEV sensor 12, and the electromagnetic wave Em2 is measured by the second TEV sensor 34.

[0049] Figure 9 shows the detection signals of the first TEV sensor 12 and the second TEV sensor 34 when an internal partial discharge occurs. Figure 9 (A) shows the signal waveform of the first TEV sensor 12, and (B) shows the signal waveform of the second TEV sensor 34. When a minute signal of, for example, about 20 pC is generated due to an internal partial discharge from the insulator 28 of the high-voltage device 25, the first TEV sensor 12 detects a signal due to a surface current caused by electromagnetic waves that reach the housing directly. On the other hand, the second TEV sensor 34 does not detect a signal due to an internal partial discharge. Therefore, the occurrence of an internal partial discharge can be detected from these behaviors.

[0050] The detection circuit of the second embodiment is shown in Fig. 10. The circuit configuration on the side of the first TEV sensor 12 is the same as that of the first embodiment, so a description thereof will be omitted.

[0051] The detection device on the side of the second TEV sensor 34 also has substantially the same circuit configuration as that shown in the first embodiment, from the high-pass filter 13 to the part before the comparator 18.

[0052] Specifically, there is provided a high-pass filter 35 that removes external noise components near the commercial frequency, and a low-pass filter 37 that removes external noise components. The low-pass filter 15 on the side of the first TEV sensor 12 has a cutoff frequency that passes envelope components of the detection signal based on internal partial discharges and air discharges. The low-pass filter 37 on the side of the second TEV sensor 34 has a cutoff frequency that passes envelope components of the detection signal based on air discharges.

[0053] Furthermore, a 1x gain amplifier 36 is provided between the high-pass filter 35 and the low-pass filter 37 for the purpose of impedance isolation, thereby eliminating any interaction between the high-pass filter 35 and the low-pass filter 37.

[0054] Resistor R1, capacitor C1, and selector switches 38 and 39 are provided downstream of low-pass filter 37 to suppress baseline voltage fluctuations in the signal from second TEV sensor 34. These circuit elements function to suppress baseline voltage fluctuations. Selector switches 38 and 39 are composed of output switch 38, which outputs the input signal from low-pass filter 37, and ground switch 39.

[0055] Here, the output switch 38 and the ground switch 37 perform opposite operations when the operation timing arrives, and are operated by a switching signal from the monitoring device 23, which will be described later. When the output switch 38 is in the "on" state, the ground switch 39 is "off," and an aerial discharge detection signal is output to the comparator 18 in the subsequent stage.

[0056] On the other hand, when the output switch 38 is in the "off" state, the grounding switch 39 is "on" and the aerial discharge detection signal is not output to the comparator 18. When the aerial discharge detection signal is not output, the second TEV sensor 34 is in the grounded state and the offset is "0 V."

[0057] 10, the inputs to the comparator 18 are the partial discharge detection signal from the first TEV sensor 12 and the air discharge detection signal from the second TEV sensor 34. When only the partial discharge detection signal from the first TEV sensor 12 exceeds the threshold, it is output to the downstream integration circuits 19 and 20 as an internal partial discharge.

[0058] On the other hand, in the case of an aerial discharge, the housing of the high-voltage device 25 also functions as an antenna, so that if the aerial discharge detection signal from the first TEV sensor 12 and the aerial discharge detection signal from the second TEV sensor 34 simultaneously exceed the threshold, the signal is determined to be due to an aerial discharge and is not output to the downstream integration circuits 19 and 20. This makes it possible to distinguish between internal partial discharges and aerial discharges, and to confirm partial discharges with the monitoring device 23.

[0059] The features of the second embodiment shown in FIG. 10 can be summarized as follows.

[0060] the high-voltage equipment side discharge detection signal selection means for selecting a discharge detection signal relating to an internal partial discharge and an air discharge from among the detection signals output from the first transient ground voltage sensor; the second transient ground voltage sensor for detecting an air discharge from an external antenna located outside the high-voltage equipment; the external antenna side discharge detection signal selection means for selecting a discharge detection signal relating to an air discharge from among the detection signals output from the second transient ground voltage sensor; partial discharge occurrence detection means for receiving the discharge detection signal from the external antenna side discharge detection signal selection means and the discharge detection signal from the high-voltage equipment side discharge detection signal selection means and detecting the occurrence of an internal partial discharge from a combination of the discharge detection signal from the external antenna side discharge detection signal selection means and the discharge detection signal from the high-voltage equipment side discharge detection signal selection means; discharge occurrence signal holding means for holding the detected partial discharge occurrence signal; and sampling means for sampling the partial discharge occurrence signal held in the discharge occurrence signal holding means at each predetermined sampling period. [Example]

[0061] Furthermore, the detection circuits in the first and second embodiments can be implemented using a field programmable gate array (FPGA) and analog elements, which simplifies the change of circuit constants and allows circuit parameters to be set to suit the environment without changing elements on the board.

[0062] As described above, the present invention is characterized by a partial discharge detection device comprising: a transient ground voltage sensor that is provided in a high-voltage device and measures a transient ground voltage; partial discharge detection signal selection means that selects a partial discharge detection signal related to an internal partial discharge from the detection signals output from the transient ground voltage sensor; partial discharge occurrence detection means that detects a partial discharge occurrence signal that indicates the occurrence of an internal partial discharge from the selected partial discharge detection signal; partial discharge occurrence signal holding means that holds the detected partial discharge occurrence signal; and sampling means that samples the partial discharge occurrence signal held in the partial discharge occurrence signal holding means every time a predetermined sampling period arrives.

[0063] According to this, in a situation where external noise and internal partial discharges coexist, internal partial discharges can be separated from external noise, and internal partial discharges can be reliably detected.

[0064] The present invention is not limited to the above-described embodiments, but includes various modifications. The above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace other configurations with respect to the configuration of each embodiment. [Explanation of symbols]

[0065] 10...detection device, 11...metal wall, 12...transient earth voltage (TEV) sensor, 13...high-pass filter, 14...amplifier, 15...low-pass filter, 16...output switch, 17...ground switch, 18...comparator, 19...first integrator circuit, 20...second integrator circuit, 21...reset switch, 22...reset switch, 23...monitoring device

Claims

1. a transient ground voltage sensor provided in the high voltage device for measuring a transient ground voltage; a partial discharge detection signal selection means for selecting a partial discharge detection signal relating to an internal partial discharge by removing external noise components near commercial frequencies and external noise components due to air discharge from the detection signals output from the transient ground voltage sensor; a partial discharge occurrence detection means for detecting a partial discharge occurrence signal indicating the occurrence of an internal partial discharge from the selected partial discharge detection signal; a partial discharge occurrence signal holding means having an extension function for integrating the detected partial discharge occurrence signal to extend the temporal signal width, and an accumulation function for integrating and accumulating charge based on the extended partial discharge occurrence signal, and for holding the accumulated charge amount as the partial discharge occurrence signal; a sampling means for sampling the partial discharge occurrence signal held in the partial discharge occurrence signal holding means at each predetermined sampling period, The partial discharge detection signal selection means is composed of a filtering means, and the filtering means comprises: a high-pass filter that removes external noise near the commercial frequency from the detection signal from the transient ground voltage sensor; a low-pass filter connected to the high-pass filter and configured to remove external noise due to air discharge; The low-pass filter has a cutoff frequency equal to the envelope component of the frequency components of the detection signal from the high-pass filter. A partial discharge detection device characterized by:

2. In the partial discharge detection device according to claim 1, An amplifier with a gain of 1 is disposed between the high-pass filter and the low-pass filter. A partial discharge detection device characterized by:

3. In the partial discharge detection device according to claim 1, The partial discharge occurrence detection means is a comparator, and the comparator comprises: The partial discharge detection signal from the low-pass filter is compared with a predetermined threshold value, and when the partial discharge detection signal exceeds the threshold value, it is determined that an internal partial discharge has occurred, and the partial discharge occurrence signal is output. A partial discharge detection device characterized by:

4. In the partial discharge detection device according to claim 3, A baseline voltage fluctuation suppression circuit is provided between the low-pass filter and the comparator to suppress baseline voltage fluctuations. A partial discharge detection device characterized by:

5. In the partial discharge detection device according to claim 3, the partial discharge occurrence signal holding means is composed of a first integrating circuit and a second integrating circuit connected in series, the first integration circuit is connected to the comparator and has an extension function for extending a temporal signal width of the partial discharge occurrence signal from the comparator; The second integration circuit connected to the first integration circuit has the accumulation function of accumulating the charge based on the partial discharge occurrence signal. A partial discharge detection device characterized by:

6. In the partial discharge detection device according to claim 5, the sampling means is a monitoring device that monitors the occurrence of partial discharge, The monitoring device acquires the amount of charge accumulated in the second integration circuit in synchronization with the sampling period, and when the amount of charge is acquired, the monitoring device discharges the charge accumulated in the second integration circuit. A partial discharge detection device characterized by:

7. In the partial discharge detection device according to claim 6, The second integration circuit includes a reset switch for discharging the accumulated charge, and the charge is discharged by the reset switch in accordance with the sampling period. A partial discharge detection device characterized by:

8. In the partial discharge detection device according to claim 7, The partial discharge detection device according to claim 1, wherein the reset switch of the second integration circuit is composed of a photodiode.

9. In the partial discharge detection device according to claim 3, The threshold value of the comparator can be changed externally. A partial discharge detection device characterized by:

10. A first transient ground voltage sensor provided in a high voltage device for measuring a transient ground voltage; a high-voltage device-side discharge detection signal selection means for passing envelope components of the detection signals output from the first transient ground voltage sensor that are based on internal partial discharges and air discharges, and selecting discharge detection signals related to internal partial discharges and air discharges; a second transient ground voltage sensor provided on an external antenna located outside the high voltage device for detecting air discharge; an external antenna side discharge detection signal selection means for passing an envelope component of the detection signal based on an aerial discharge among the detection signals output from the second transient ground voltage sensor, and selecting the discharge detection signal related to the aerial discharge; partial discharge occurrence detection means, which receives the discharge detection signal from the external antenna side discharge detection signal selection means and the discharge detection signal from the high voltage device side discharge detection signal selection means, and detects the occurrence of an internal partial discharge as a partial discharge occurrence signal from a combination of the discharge detection signal from the external antenna side discharge detection signal selection means and the discharge detection signal from the high voltage device side discharge detection signal selection means; a discharge occurrence signal holding means having an extension function for integrating the detected partial discharge occurrence signal to extend a temporal signal width, and an accumulation function for integrating and accumulating charge based on the extended partial discharge occurrence signal, and for holding the accumulated charge amount as the partial discharge occurrence signal; a sampling means for sampling the partial discharge occurrence signal held in the discharge occurrence signal holding means at each predetermined sampling period; A partial discharge detection device characterized by:

11. The partial discharge detection device according to claim 10, The partial discharge occurrence detection means determines that a partial discharge has occurred when only the partial discharge occurrence signal is detected. A partial discharge detection device characterized by:

Images