Vacuum Deterioration Estimation Apparatus and Vacuum Deterioration Estimation Method

Abstract

To provide a vacuum deterioration estimation device and a vacuum deterioration estimation method capable of accurately estimating the deterioration of the vacuum degree of a vacuum valve.SOLUTION: A vacuum deterioration estimation device includes a waveform detection unit, a duration identification unit, and an estimation unit. The waveform detection unit detects the waveform of the electromagnetic wave generated from a vacuum valve in one cycle of a power signal. The duration identification unit identifies the duration of a state in which the intensity of an envelope of the electromagnetic wave is equal to or higher than a predetermined threshold value. The estimation unit estimates the deterioration state related to the vacuum deterioration of the vacuum valve on the basis of the identified duration.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to a vacuum deterioration estimation device and a vacuum deterioration estimation method. [Background technology]

[0002] For vacuum valves, which are the main components of circuit breakers and disconnecting switches, maintaining a high degree of vacuum inside the valve is an important factor in maintaining the insulation characteristics. If the degree of vacuum in a vacuum valve decreases, the insulation performance decreases and it becomes impossible to interrupt the current. For this reason, the degree of vacuum is checked periodically to confirm the soundness of the vacuum valve. One method for detecting a decrease in insulation performance is to detect electromagnetic waves generated due to partial discharge. Electromagnetic waves are detected using an electromagnetic wave sensor, but electromagnetic waves such as broadcast waves that propagate through the air are also detected, which can cause misdiagnosis. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-15172 A [Non-patent literature]

[0004] [Non-Patent Document 1] Takuki Okamoto, Masataka Tanaka; "Partial Discharge Cycle Average φ-q Characteristics -Experiments with Six Types of Electrode Shapes-", Transactions of the Institute of Electrical Engineers of Japan, Vol. 102, No. 7, pp. 381-388, 1982. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a vacuum deterioration estimation device and a vacuum deterioration estimation method that can accurately estimate the deterioration of the degree of vacuum in a vacuum valve. [Means for solving the problem]

[0006] The vacuum deterioration estimation device of the embodiment has a waveform detection unit, a duration determination unit, and an estimation unit. The waveform detection unit detects the waveform of an electromagnetic wave generated from a vacuum valve in one period of a power signal. The duration determination unit determines the duration of a state in which the intensity of the envelope of the electromagnetic wave is equal to or greater than a predetermined threshold. The estimation unit estimates a deterioration state related to vacuum deterioration of the vacuum valve based on the determined duration. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a configuration diagram of a switchgear to be monitored for vacuum deterioration according to the first embodiment. [Diagram 2] 1 is a schematic diagram showing a configuration of a vacuum deterioration estimation device 1. FIG. [Diagram 3] FIG. 13 is a diagram showing an example of the relationship between the degree of vacuum of a vacuum valve and the duration of a partial discharge signal. [Figure 4] FIG. 1 is a diagram showing an example of the relationship between the degree of vacuum of a vacuum valve and the main frequency of a partial discharge signal. [Diagram 5] 4 is a diagram showing an example of the relationship between the degree of vacuum of a vacuum valve and the number of pulses generated relating to a main frequency. FIG. [Figure 6] 4 is a flowchart showing the operation of the arithmetic device 15 according to the first embodiment. [Figure 7] FIG. 11 is a schematic diagram showing a configuration of a signal processing device 13 according to a second embodiment. [Figure 8] 13 is a flowchart showing a process of a calculation device 15 according to a second embodiment. [Figure 9] 11 is a diagram showing an example of the relationship between the degree of vacuum of a vacuum valve, the duration of a partial discharge signal, and a first threshold value. FIG. [Figure 10] FIG. 11 is a diagram showing an example of a relationship between a vacuum valve, a main frequency of a partial discharge signal, and a second threshold value. [Figure 11] FIG. 13 is a diagram showing an example of the relationship between a vacuum valve, the number of pulses related to a main frequency, and a third threshold value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, a vacuum deterioration estimation device according to an embodiment will be described with reference to the drawings. (First embodiment) The vacuum deterioration estimation device 1 according to the first embodiment monitors vacuum deterioration associated with a circuit breaker 54 and a disconnecting switch 55 provided in a switchgear 5. FIG. 1 is a configuration diagram of a switchgear that is a target for monitoring vacuum deterioration according to the first embodiment. In FIG. 1, the left side of the page is the front side of the switchgear 5, and the right side of the page is the rear side of the switchgear 5. The switchgear 5 includes a cable head 51, a current transformer 52, a main circuit conductor 53, a circuit breaker 54, a disconnecting switch 55, a movable side connecting conductor 56, an operation mechanism 57, a bus bar 58, and a housing 59.

[0009] The cable head 51 is provided on the rear side of the switchgear 5. A power cable is connected to one end of the cable head 51 via a current transformer 52. A main circuit conductor 53 is connected to the other end of the cable head 51. The main circuit conductor 53 is covered with insulating resin. A circuit breaker 54 is connected to the main circuit conductor 53. The disconnecting switch 55 is arranged in parallel with the circuit breaker 54. A busbar 58 that connects to an adjacent panel is connected to the disconnecting switch 55.

[0010] The circuit breaker 54 and the disconnector 55 each include a vacuum valve. The vacuum valve has a cylindrical container with an internal vacuum made of alumina magnetic material, and a fixed electrode and a movable electrode are sealed inside the cylindrical container. The movable electrode is connected to the fixed electrode by being pushed in along the axial direction of the vacuum valve, and is disconnected from the fixed electrode by being pulled in the axial direction.

[0011] The fixed electrode of the circuit breaker 54 is connected to the main circuit conductor 53. The fixed electrode of the disconnector 55 is connected to a busbar 58. The movable electrode of the circuit breaker 54 and the movable electrode of the disconnector 55 are connected to each other by a movable-side connecting conductor 56. The movable electrode of the circuit breaker 54 and the movable electrode of the disconnector 55 are connected to a rod extending from an operating mechanism 57. The operating mechanism 57 moves the rod up and down using a control device (not shown), thereby moving the movable electrodes of the circuit breaker 54 and the disconnector 55.

[0012] The housing 59 forms an outer shell of the switchgear 5, and accommodates the cable head 51, the current transformer 52, the main circuit conductor 53, the circuit breaker 54, the disconnecting switch 55, the movable side connecting conductor 56, the operation mechanism 57, and the bus bar 58. The housing 59 is made of metal.

[0013] The vacuum deterioration estimation device 1 detects electromagnetic waves generated from a vacuum valve and estimates the deterioration state of the vacuum valve based on the electromagnetic waves. FIG. 2 is a schematic diagram showing the configuration of the vacuum deterioration estimation device 1. The vacuum deterioration estimation device 1 includes an electromagnetic wave sensor 11, a signal processing device 13, a calculation device 15, and a display device 17. The electromagnetic wave sensor 11 detects electromagnetic waves generated from the vacuum valve, i.e., partial discharge signals. The electromagnetic wave sensor 11 is provided inside a housing 59. Moreover, the electromagnetic wave sensor 11 is preferably provided in the vicinity of the vacuum valve to be monitored. The connection terminal of the electromagnetic wave sensor 11 is drawn out to the outside of the housing 59. The electromagnetic wave sensor 11 is an example of a waveform detection unit.

[0014] The signal processing device 13 is connected to the connection terminal of the electromagnetic wave sensor 11, and performs signal processing on the signal detected by the electromagnetic wave sensor 11 to identify the feature amount of the signal. The signal processing device 13 is formed of hardware such as an oscilloscope. The arithmetic device 15 estimates the deterioration state of the vacuum valve based on the feature amount of the signal identified by the signal processing device 13. The arithmetic device 15 is formed of a computer, for example. The display device 17 displays the result of the estimation of the deterioration state by the signal processing device.

[0015] The signal processing device 13 includes a sampling unit 131, an amplifier 132, a bandpass filter 133, a detection circuit 134, a duration determination unit 135, a frequency conversion unit 136, a frequency determination unit 137, a frequency counter 138, and an output unit 139. The sampling unit 131 cuts out a waveform having a width equivalent to the period of the power signal supplied to the switch gear 5 (for example, 20 milliseconds in the case of a 50 Hz power supply) from the signal output by the electromagnetic wave sensor 11. The amplifier 132 amplifies the waveform cut out by the sampling unit 131 with a predetermined gain. The bandpass filter 133 extracts components of a predetermined frequency band from the amplified waveform. The bandpass filter 133 according to the first embodiment extracts components from, for example, 30 kHz to 10 MHz. The frequency band from 30 kHz to 10 MHz is a frequency band in which a partial discharge signal of a vacuum valve appears.

[0016] The detection circuit 134 performs full-wave rectification and envelope detection of the waveform extracted by the band-pass filter 133. The duration determination unit 135 detects the duration of the envelope waveform generated by the detection circuit 134. That is, the duration determination unit 135 determines the time from when the envelope waveform exceeds a first intensity threshold to when it falls below the first intensity threshold. The first intensity threshold may be, for example, 10% of the maximum intensity of the envelope waveform. In one period of the power signal, one or two partial waveforms that exceed the first intensity and then fall below the first intensity threshold are usually included. When two partial waveforms exist in one period of the power signal, the duration determination unit 135 determines the duration of each partial waveform.

[0017] The frequency conversion unit 136 frequency converts the waveform extracted by the bandpass filter 133 to obtain a frequency domain representation of the waveform. The frequency identification unit 137 identifies a dominant frequency, which is a frequency with the greatest intensity, based on the frequency domain representation generated by the frequency conversion unit 136. The frequency counter 138 counts the number of pulses of the component at the dominant frequency from the waveform extracted by the bandpass filter 133. The output unit 139 outputs data indicating the duration of the envelope waveform, the dominant frequency, and the number of pulses to the calculation device 15. The frequency counter 138 is an example of a signal counting unit.

[0018] The calculation device 15 includes an acquisition unit 151, a relationship storage unit 152, an estimation unit 153, and an output unit 154. The acquisition unit 151 acquires data from the signal processing device 13 indicating the duration of the envelope waveform, the main frequency, and the number of pulses generated.

[0019] The relationship storage unit 152 stores the relationship between the degree of vacuum of the vacuum valve and the duration of the signal, the main frequency, and the number of occurrences of pulses. This is based on the findings of the inventor. That is, the inventor discovered through an experiment on vacuum leakage of the vacuum valve that the duration of the partial discharge signal of the vacuum valve changes depending on the degree of vacuum of the vacuum valve, that there is a correlation between the degree of vacuum of the vacuum valve and the main frequency of the partial discharge signal of the vacuum valve, and that there is a correlation between the degree of vacuum of the vacuum valve and the number of occurrences of pulses related to the main frequency of the partial discharge signal of the vacuum valve.

[0020] FIG. 3 is a diagram showing an example of the relationship between the degree of vacuum of the vacuum valve and the duration of the partial discharge signal. In the example shown in FIG. 3, when the degree of vacuum of the vacuum valve is sufficiently high, the partial discharge signal is not generated, and the duration is short. As the degree of vacuum decreases, the duration increases, and reaches a maximum value t1 in the vicinity of the first degree of vacuum P1. When the degree of vacuum of the vacuum valve exceeds the first degree of vacuum P1, the duration of the partial discharge signal decreases, and reaches a minimum value t2 in the vicinity of the second degree of vacuum P2. When the degree of vacuum of the vacuum valve exceeds the second degree of vacuum P2, the duration of the partial discharge signal increases and approaches the maximum value t1 of the duration.

[0021] FIG. 4 is a diagram showing an example of the relationship between the degree of vacuum in the vacuum valve and the main frequency of the partial discharge signal. In the example shown in FIG. 4, when the degree of vacuum in the vacuum valve is sufficiently high, the main frequency of the partial discharge signal has a value close to the first frequency f1. As the degree of vacuum in the vacuum valve decreases, the main frequency decreases, and the main frequency reaches a minimum value f2 near the second degree of vacuum P2. When the degree of vacuum in the vacuum valve exceeds the second degree of vacuum P2, the main frequency increases and approaches the first frequency f1. However, when the degree of vacuum is equal to or higher than the second degree of vacuum P2 and the degree of vacuum in the vacuum valve is equal to or lower than atmospheric pressure, the main frequency is lower than the first frequency f1.

[0022] FIG. 5 is a diagram showing an example of the relationship between the degree of vacuum of the vacuum valve and the number of pulses generated according to the main frequency. In the example shown in FIG. 5, when the degree of vacuum of the vacuum valve is sufficiently high, no partial discharge signal is generated, and the number of pulses generated is also small. As the degree of vacuum decreases, the number of pulses generated increases, and the number of pulses generated reaches a maximum value n1 near the first degree of vacuum P1. When the degree of vacuum of the vacuum valve exceeds the first degree of vacuum P1, the number of pulses generated decreases, and the number of pulses generated reaches a minimum value n2 near the second degree of vacuum P2. When the degree of vacuum of the vacuum valve exceeds the second degree of vacuum P2, the number of pulses generated increases and approaches the maximum value n1 of the number of pulses generated.

[0023] As shown in Figs. 3 and 5, the duration of the partial discharge signal and the number of pulses are maximum in the vicinity of the first vacuum P1. On the other hand, the vacuum at which the duration of the partial discharge signal is maximum does not necessarily coincide with the vacuum at which the number of pulses is maximum. Similarly, as shown in Figs. 3, 4 and 5, the duration of the partial discharge signal, the main frequency and the number of pulses are minimum in the vicinity of the second vacuum P2. On the other hand, the vacuum at which the duration of the partial discharge signal is minimum, the vacuum at which the main frequency is minimum and the vacuum at which the number of pulses is minimum do not necessarily coincide with each other. Note that the relationships shown in Figs. 3 to 5 are merely the results obtained by measuring a specific vacuum valve, and these relationships may change depending on the design of the vacuum valve. For example, the relationships between the first vacuum P1 and the second vacuum P2 and the maximum and minimum values ​​may be different in other vacuum valves.

[0024] The estimation unit 153 identifies a vacuum degree value corresponding to the duration acquired by the acquisition unit 151, a vacuum degree value corresponding to the main frequency, and a vacuum degree value corresponding to the number of pulses generated, based on the data stored in the relationship storage unit 152. When each vacuum degree value coincides within a predetermined error range (e.g., ±10%), the estimation unit 153 estimates the average value of the identified vacuum degree values ​​as the vacuum degree of the vacuum valve. When the estimated vacuum degree is less than a predetermined threshold, the estimation unit determines that the vacuum valve is normal, and when the estimated vacuum degree is equal to or greater than the predetermined threshold, the estimation unit determines that a vacuum leak has occurred in the vacuum valve. The output unit 154 outputs a display signal indicating the estimation result of the estimation unit 153 to the display device 17. The determination result of whether or not a vacuum leak has occurred and the vacuum degree are both examples of a deterioration state related to vacuum deterioration.

[0025] 6 is a flowchart showing the operation of the arithmetic device 15 according to the first embodiment. The signal processing device 13 extracts the electromagnetic waves detected by the electromagnetic wave sensor 11 by the period of the power signal, and identifies the duration, main frequency, and number of pulses of the electromagnetic waves. The acquisition unit 151 of the arithmetic device 15 acquires data indicating the duration, main frequency, and number of pulses of the electromagnetic waves from the signal processing device 13 (step S1).

[0026] The estimation unit 153 refers to the data stored in the relationship storage unit 152 and identifies the corresponding degree of vacuum from the duration of the electromagnetic wave (step S2). When the electromagnetic wave has multiple partial signals, the estimation unit 153 identifies the value of the degree of vacuum for each duration. The estimation unit 153 refers to the data stored in the relationship storage unit 152 and identifies the corresponding degree of vacuum from the main frequency of the electromagnetic wave (step S3). The estimation unit 153 refers to the data stored in the relationship storage unit 152 and identifies the corresponding degree of vacuum from the number of pulses generated (step S4).

[0027] The estimation unit 153 judges whether each vacuum degree value identified in steps S2, S3, and S4 falls within a predetermined error range (step S5). When there are two or more vacuum degree values ​​corresponding to the feature amount of the electromagnetic wave, the estimation unit 153 judges whether at least one of the multiple vacuum degree values ​​corresponding to one feature amount falls within an error range with respect to the vacuum degree values ​​corresponding to the other feature amounts. When each vacuum degree value does not fall within the predetermined error range (step S5: NO), the estimation unit 153 judges that the detected electromagnetic wave contains noise other than a partial discharge signal. The calculation device 15 returns the process to step S1 and performs processing based on the electromagnetic wave newly detected from the electromagnetic wave sensor 11.

[0028] If each vacuum degree value falls within a predetermined error range (step S5: YES), the estimation unit 153 calculates the average value of each vacuum degree determined in steps S2, S3, and S4 (step S6). The estimation unit 153 determines whether the average value of the vacuum degree is equal to or greater than a predetermined threshold (step S7). If the average value of the vacuum degree is equal to or greater than the threshold (step S7: YES), the estimation unit 153 determines that a vacuum leak has occurred in the vacuum valve (step S8). On the other hand, if the average value of the vacuum degree is less than the threshold (step S7: NO), the estimation unit 153 determines that the vacuum valve is normal (step S9). The output unit 154 outputs a display signal indicating the determination result of the estimation unit 153 to the display device 17 (step S10).

[0029] In this way, the vacuum deterioration estimation device 1 according to the first embodiment detects the waveform of the electromagnetic waves generated from the vacuum valve in one period of the power signal, and estimates the degree of vacuum of the vacuum valve based on the duration of the state in which the intensity of the envelope of the electromagnetic waves is equal to or greater than a predetermined threshold. Based on the inventor's knowledge that there is a correlation between the duration of the electromagnetic waves and the degree of vacuum of the vacuum valve, the vacuum deterioration estimation device 1 can appropriately estimate the deterioration state related to the vacuum leak of the vacuum valve.

[0030] Furthermore, the vacuum deterioration estimation device 1 according to the first embodiment estimates the deterioration state of the vacuum valve based on the main frequency, which is the frequency at which the component strength in the electromagnetic wave is greatest, and the occurrence frequency of pulses related to the main frequency. This makes it possible to estimate the deterioration state related to vacuum leakage more accurately than estimating the degree of vacuum based only on the duration. Note that the vacuum deterioration estimation device 1 according to other embodiments may estimate the deterioration state of the vacuum valve based on the main frequency and duration, without using the occurrence frequency of pulses related to the main frequency.

[0031] The vacuum deterioration estimation device 1 estimates the deterioration state of the vacuum valve when the conditions that the corresponding vacuum degree is within a certain error range for all of the duration, main frequency, and occurrence frequency are satisfied. This makes it possible to prevent erroneous determination of the deterioration state of the vacuum valve due to noise mixed in with the electromagnetic waves.

[0032] The vacuum deterioration estimation device 1 extracts the frequency band in which the partial discharge signal of the vacuum valve appears by the bandpass filter 133, and estimates the deterioration state of the vacuum valve based on the duration of the electromagnetic waves related to the extracted band. This makes it possible to reduce the influence of noise mixed in the electromagnetic waves.

[0033] Second Embodiment The vacuum deterioration estimation device 1 according to the second embodiment estimates a deterioration state related to vacuum deterioration of a vacuum valve, as well as a deterioration state related to other causes. The vacuum deterioration estimation device 1 according to the second embodiment differs from the first embodiment in the configuration of the signal processing device 13 and the calculation contents of the calculation device 15. Examples of deterioration related to other causes include the presence of air bubbles in the insulating resin covering the main circuit conductor 53 and peeling of the insulating resin.

[0034] 7 is a schematic diagram showing the configuration of a signal processing device 13 according to the second embodiment. The signal processing device 13 according to the second embodiment further includes a bandpass filter 140, a detection circuit 141, a partial signal identification unit 142, a frequency conversion unit 143, and a frequency identification unit 144 in addition to the configuration of the first embodiment.

[0035] The bandpass filter 140 extracts components related to a frequency band higher than that of the bandpass filter 133 from the waveform amplified by the amplifier 132. The bandpass filter 140 according to the second embodiment extracts components from, for example, 10 MHz to 100 MHz. The frequency band from 10 MHz to 100 MHz is a frequency band related to discharges due to reasons other than vacuum deterioration. Hereinafter, the frequency band extracted by the bandpass filter 133 will be referred to as the first frequency band, and the frequency band extracted by the bandpass filter 140 will be referred to as the second frequency band.

[0036] The detection circuit 141 performs full-wave rectification and envelope detection of the waveform extracted by the band-pass filter 140. The partial signal identification unit 142 identifies a partial signal from when the envelope waveform generated by the detection circuit 141 exceeds a first intensity threshold to when it falls below the first intensity threshold.

[0037] The frequency conversion unit 143 obtains a frequency domain representation of the waveform by frequency converting the waveform extracted by the bandpass filter 140. The frequency identification unit 144 identifies a dominant frequency, which is a frequency with the strongest intensity, based on the frequency domain representation generated by the frequency conversion unit 143.

[0038] The calculation device 15 according to the second embodiment performs a process of determining a deterioration state related to a cause other than vacuum deterioration in addition to the process shown in Fig. 6. Fig. 8 is a flowchart showing the process of the calculation device 15 according to the second embodiment. The process shown in Fig. 8 may be performed in parallel with the process shown in Fig. 6, or may be performed before or after the process shown in Fig. 6.

[0039] The acquiring unit 151 acquires data indicating the waveform, main frequency, and number of pulse occurrences of the partial signal of the electromagnetic wave related to the second frequency band, and the main frequency related to the first frequency band from the signal processing device 13 (step S21).

[0040] The estimation unit 153 determines whether the intensity of the main frequency component related to the second frequency band is greater than the intensity of the main frequency component related to the first frequency band (step S22). That is, the estimation unit 153 determines whether the main frequency in the frequency band including the first frequency band and the second frequency band is 10 MHz or more. If the intensity of the main frequency component related to the second frequency band is equal to or less than the intensity of the main frequency component related to the first frequency band (step S22: NO), the estimation unit 153 determines that there is no degradation related to reasons other than vacuum degradation, and ends the process.

[0041] On the other hand, if the intensity of the main frequency component related to the second frequency band is greater than the intensity of the main frequency component related to the first frequency band (step S22: YES), the estimation unit 153 determines whether or not there are two partial signals in the second frequency band (step S23). That is, it determines whether or not the components of the second frequency band of the electromagnetic wave include a component related to a frequency twice that of the power signal. If only one partial signal exists in the second frequency band (step S23: NO), the estimation unit 153 determines that there is no degradation related to reasons other than vacuum degradation, and ends the process.

[0042] On the other hand, if two partial signals are present in the second frequency band (step S23: YES), the estimation unit 153 determines that there is deterioration related to a cause other than vacuum deterioration. The estimation unit 153 extracts feature quantities of each of the two partial signals (step S24). Specifically, the estimation unit 153 extracts the number of pulses generated, the detected voltage value, and the pulse generation phase of each of the two partial signals. The estimation unit 153 compares the type of deterioration previously identified by an experiment or the like and the distribution of the pulse generation number ratio, the detected voltage value ratio, and the pulse generation phase of each of the partial signals with the identified feature quantities, and estimates the type of deterioration (step S25). The output unit 154 outputs a display signal indicating the determination result of the estimation unit 153 to the display device 17 (step S26).

[0043] (Third embodiment) The vacuum deterioration estimation device 1 according to the first and second embodiments can appropriately determine the deterioration when deterioration occurs in one of the vacuum valves included in the switch gear 5. On the other hand, when deterioration with different degrees of vacuum occurs in two or more vacuum valves, partial discharge signals with different characteristics are generated from each vacuum valve, and the electromagnetic waves measured by the electromagnetic wave sensor 11 contain different partial discharge signals. Therefore, the vacuum deterioration estimation device 1 according to the first and second embodiments may not be able to appropriately determine the deterioration. In contrast, the vacuum deterioration estimation device 1 according to the third embodiment appropriately detects the deterioration even when deterioration occurs in two or more vacuum valves included in the switch gear 5.

[0044] The vacuum deterioration estimation device 1 according to the third embodiment differs from the first embodiment in the processing of the signal processing device 13 and the calculation device 15. The frequency identification unit 137 of the signal processing device 13 according to the third embodiment identifies one or more main frequencies. For example, the frequency identification unit 137 identifies, as the main frequency, a peak frequency having an intensity equal to or greater than a predetermined value among the frequencies of the peaks included in the frequency domain representation of the waveform generated by the frequency conversion unit 136. The detection circuit 134 of the signal processing device 13 identifies an envelope of a component related to a frequency band in the vicinity of each main frequency identified by the frequency identification unit 137. The duration identification unit 135 identifies the duration of each main frequency component. The frequency counter 138 measures the number of pulses generated for each main frequency identified by the frequency identification unit 137.

[0045] The estimation unit 153 of the calculation device 15 executes the process shown in Fig. 6 for each main frequency identified by the signal processing device 13. This allows the vacuum deterioration estimation device 1 to appropriately detect deterioration even when deterioration occurs in two or more vacuum valves among the vacuum valves provided in the switchgear 5.

[0046] (Fourth embodiment) In the vacuum deterioration estimation device 1 according to the first to third embodiments, the estimation unit 153 calculates the degree of vacuum in the vacuum valve and determines the presence or absence of deterioration related to vacuum leakage based on the result of the calculation of the degree of vacuum. In contrast, the vacuum deterioration estimation device 1 according to the fourth embodiment determines the presence or absence of deterioration related to vacuum leakage without calculating the degree of vacuum.

[0047] The vacuum deterioration estimation device 1 according to the fourth embodiment differs from the first embodiment in the operation of the calculation device 15. The estimation unit 153 of the calculation device 15 according to the fourth embodiment estimates that no vacuum leak has occurred when the duration of the waveform is equal to or less than a first threshold, the main frequency is equal to or greater than a second threshold, and the number of pulses generated is equal to or less than a third threshold. On the other hand, the estimation unit 153 estimates that a vacuum leak has occurred when the duration of the waveform is longer than the first threshold, the main frequency is smaller than the second threshold, and the number of pulses generated is less than the third threshold.

[0048] The reason why the presence or absence of deterioration related to vacuum leakage can be determined by judging the above threshold value will be explained below. Fig. 9 is a diagram showing an example of the relationship between the degree of vacuum of a vacuum valve, the duration of a partial discharge signal, and the first threshold. The degree of vacuum that is the standard for determining whether or not there is vacuum deterioration is set as a vacuum threshold Pth. The vacuum threshold Pth is a lower vacuum than the first vacuum P1 and the second vacuum P2. As shown in Fig. 9, it can be seen that the first threshold th1, which is the duration corresponding to the vacuum threshold Pth, is smaller than the minimum value t2 of the duration, and when the degree of vacuum exceeds the vacuum threshold Pth, the duration is always larger than the first threshold th2.

[0049] Figure 10 is a diagram showing an example of the relationship between the vacuum valve, the main frequency of the partial discharge signal, and the second threshold. As shown in Figure 10, when the degree of vacuum exceeds the vacuum threshold Pth, the main frequency is always smaller than the second threshold th2. Note that when the degree of vacuum in the vacuum valve exceeds the second vacuum P2, the main frequency approaches the first frequency f1, but when the degree of vacuum is equal to or lower than atmospheric pressure, the main frequency is always lower than the second threshold th2 as shown in Figure 10.

[0050] Fig. 11 is a diagram showing an example of the relationship between the number of pulses generated for the vacuum valve and the main frequency and the third threshold value. As shown in Fig. 11, the third threshold value th3, which is the duration corresponding to the vacuum threshold value Pth, is smaller than the minimum value n2 of the number of pulses generated, and when the vacuum exceeds the vacuum threshold value Pth, it can be seen that the number of pulses generated is always larger than the third threshold value th3.

[0051] In this way, by setting the first threshold th1 to a value smaller than the minimum value t2, the second threshold th2 to a value close to the first frequency, and the third threshold th3 to a value smaller than the minimum value n2, the vacuum deterioration estimation device 1 can determine the presence or absence of deterioration related to vacuum leakage without calculating the degree of vacuum.

[0052] According to at least one of the embodiments described above, the vacuum deterioration estimation device 1 has a waveform detection unit that detects the waveform of the electromagnetic wave generated from the vacuum valve during one period of the power signal, a duration acquisition unit that acquires the duration of the state in which the intensity of the envelope of the electromagnetic wave is above a predetermined threshold, and an estimation unit that estimates the deterioration state related to vacuum deterioration of the vacuum valve based on the acquired duration, thereby enabling the vacuum deterioration estimation device 1 to accurately estimate the deterioration of the vacuum degree of the vacuum valve.

[0053] The arithmetic device 15 includes a processor, a memory, an auxiliary storage device, and the like, which are connected via a bus, and functions as a device including an acquisition unit 151, a relationship storage unit 152, an estimation unit 153, and an output unit 154 by executing a deterioration estimation program. Examples of the processor include a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), and a microprocessor. The deterioration estimation program may be recorded in a computer-readable recording medium. The computer-readable recording medium is, for example, a storage device such as a magnetic disk, a magneto-optical disk, an optical disk, a semiconductor memory, etc. The deterioration estimation program may be transmitted via a telecommunication line. All or part of the functions of the degradation estimation may be realized 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 example of a processor.

[0054] Although some 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 gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as the scope of the invention and its equivalents described in the claims. For example, the vacuum deterioration estimation device 1 includes a signal processing device 13 and a calculation device 15, but a part or all of the configuration of the signal processing device 13 may be realized by the calculation device 15. In addition, the vacuum deterioration estimation device 1 according to another embodiment may estimate the deterioration of a vacuum valve provided in a device other than the switchgear 5. In addition, the vacuum deterioration estimation device 1 according to another embodiment may be built into the switchgear 5. [Explanation of symbols]

[0055] 1... Vacuum deterioration estimation device 11... Electromagnetic wave sensor 13... Signal processing device 131... Sampling unit 132... Amplifier 133... Bandpass filter 134... Detection circuit 135... Duration determination unit 136... Frequency conversion unit 137... Frequency determination unit 138... Frequency counter 139... Output unit 15... Calculation device 151... Acquisition unit 152... Relationship memory unit 153... Estimation unit 154... Output unit 17... Display device 5... Switchgear 51... Cable head 52... Current transformer 53... Main circuit conductor 54... Circuit breaker 55... Disconnector 56... Movable side connecting conductor 57... Operation mechanism 58... Busbar 59... Housing

Claims

1. a waveform detection unit that detects the waveform of an electromagnetic wave generated from the vacuum valve in one period of the power signal; a duration determination unit that determines a duration of a state in which the intensity of the envelope of the electromagnetic wave is equal to or greater than a predetermined threshold; an estimation unit that estimates a deterioration state related to vacuum deterioration of the vacuum valve based on the identified duration; A vacuum deterioration estimation device comprising:

2. A frequency identification unit is further provided to identify a main frequency, which is a frequency at which a component has the greatest intensity in the electromagnetic wave, The estimation unit estimates a deterioration state of the vacuum valve based on the identified duration and the identified dominant frequency. The vacuum deterioration estimation device according to claim 1 .

3. a signal counting unit that identifies an occurrence frequency of pulses having a predetermined intensity or more in a frequency component related to the main frequency, The estimation unit estimates a deterioration state of the vacuum valve based on the identified duration, the main frequency, and the occurrence frequency. The vacuum deterioration estimation device according to claim 2 .

4. The estimation unit identifies a deterioration state indicated by the identified duration, the dominant frequency, and the occurrence frequency based on a relationship between the deterioration state of the vacuum valve and the duration, the dominant frequency, and the occurrence frequency of electromagnetic waves that has been obtained in advance. The vacuum deterioration estimation device according to claim 3 .

5. The estimation unit estimates a deterioration state of the vacuum valve when the identified duration, the main frequency, and the occurrence frequency all satisfy predetermined conditions. The vacuum deterioration estimation device according to claim 3 or 4.

6. a filter for extracting from the electromagnetic waves a first frequency band in which electromagnetic waves caused by partial discharge of the vacuum valve appear; The vacuum deterioration estimation device according to claim 1 , wherein the duration specifying unit specifies a duration of the electromagnetic waves related to the first frequency band.

7. The estimation unit estimates that a partial discharge related to a reason other than vacuum deterioration is occurring when the main frequency is 10 MHz or more and there are two partial signals whose intensities are equal to or greater than a predetermined threshold in an envelope of a component related to a frequency band of 10 MHz or more of the electromagnetic wave. The vacuum deterioration estimation device according to any one of claims 2 to 5.

8. When the main frequency is 10 MHz or more and two partial signals having intensities equal to or greater than a predetermined threshold are present in an envelope of a component of the electromagnetic wave related to a frequency band of 10 MHz or more, the estimation unit estimates the deterioration state by comparing the two partial signals. The vacuum deterioration estimation device according to claim 7.

9. detecting a waveform of an electromagnetic wave generated from the vacuum valve during one period of the power signal; determining a duration of a state in which the intensity of the envelope of the electromagnetic wave is equal to or greater than a predetermined threshold; estimating a deterioration state related to vacuum deterioration of the vacuum valve based on the identified duration; A vacuum deterioration estimation method comprising:

Images