Discharge Event Judgment System
Patent Information
- Application Number
- JP2021153843
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2021-04-06
- Filing Date
- 2021-09-22
- Publication Date
- 2025-04-25
- Estimated Expiration
- 2041-09-22
AI Technical Summary
Existing discharge event detection systems inaccurately identify discharge events due to noise interference from equipment like electric drills and hand mixers, leading to false positives.
A discharge event determination system that utilizes a filter unit to extract high-frequency noise, a phase dividing unit to distinguish peak and zero-value time regions, and a calculation unit to determine discharge events by calculating differences between these regions, with thresholds for accurate detection.
Enhances the accuracy of discharge event detection by distinguishing between equipment noise and actual discharge events, allowing for precise identification and estimation of event occurrence.
Smart Images
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Abstract
Description
[Technical Field]
[0001] The present invention relates to a discharge event determination system. [Background technology]
[0002] It is known to extract high-frequency discharge noise superimposed on commercial frequencies using a current sensor or a voltage sensor, as described in Patent Documents 1 and 2. For example, in a typical method for detecting noise from a discharge event, noise is superimposed on the peak value of the commercial frequency in the voltage waveform, and this superimposed noise is detected to determine that a discharge event has occurred.
[0003] More specifically, using a discharge detection unit 100 as shown in FIG. 17, a high-frequency band noise output is extracted by a high-pass filter 111, and the extracted high-frequency band noise output is amplified by an amplifier 112. The amplified noise waveform is then processed by a smoothing unit 113 so that the flow of changes can be tracked. This processing is performed because, when the waveform amplified by the amplifier 112 is examined closely, it appears to be a series of repeated 0s and 1s. Therefore, processing is performed to make it appear as if there are successive 1s by connecting each waveform that cannot be accurately determined (see FIG. 18). The data after this processing is used for determination. Note that a microcomputer, for example, is used as the determination unit 115 that performs the determination. Normally, if the noise level exceeds a threshold for a certain period of time or more, the determination unit 115 determines that there is a discharge. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-184480 [Patent Document 2] Japanese Patent Application Publication No. 2020-134231
[0005] Incidentally, when using certain types of equipment with motors, such as electric drills and hand mixers, noise is constantly superimposed. In such cases, even after filtering, amplification, and smoothing, the waveform to be judged will be similar to that observed when a discharge event occurs (see Figure 19). Therefore, it may be judged as a discharge event even when no discharge event has actually occurred. Summary of the Invention [Problem to be solved by the invention]
[0006] The inventors of the present invention have conducted extensive research into this issue and have attempted to solve it. The problem that the present invention aims to solve is to improve the accuracy of detecting a discharge event and to make it possible to identify the circuit in which the discharge event occurred. [Means for solving the problem]
[0007] In order to solve the above problem, a discharge event determination system is provided that detects the output of noise superimposed on the voltage or current of an electric circuit to which a load is connected, and that includes: a filter unit that extracts an output waveform in a high frequency band; a phase division unit that determines a distinction between a peak time region including the region before and after a peak at the commercial frequency related to the output waveform extracted by the filter unit, and a zero value time region before and after the output at the commercial frequency becomes zero; a calculation unit that calculates the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region; and a determination unit that determines whether the difference calculated by the calculation unit is equal to or greater than a predetermined threshold.
[0008] Furthermore, it is preferable that the calculation unit continuously calculates the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region for a predetermined time, and the determination unit determines that a discharge event has occurred when the state in which the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region is equal to or greater than a threshold value continues for the predetermined time.
[0009] It is also preferable to have a plurality of filter units so that the presence or absence of a discharge event in a plurality of paths can be measured, the calculation unit performs a calculation for a predetermined time to detect the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region for each path, and adds or averages the detected values of the difference over the predetermined time, and the determination unit compares the calculation results for each path to identify the circuit in which the discharge event occurred.
[0010] Furthermore, it is preferable that the phase dividing section is capable of adjusting the times of the peak time region and the zero value time region.
[0011] Furthermore, it is preferable that the phase division unit outputs a phase angle detection pulse for dividing one period into four, and the determination unit is configured to set the times of the peak time region and the zero value time region using the phase angle detection pulse.
[0012] Also, a discharge event determination system that detects the output of noise superimposed on the voltage or current of an electric circuit to which a load is connected includes a filter unit that extracts an output waveform in a high frequency band, a phase division unit that determines a distinction between a peak time region including a region before and after a peak at the commercial frequency related to the output waveform extracted by the filter unit and a zero value time region before and after the output at the commercial frequency becomes zero, a calculation unit that calculates the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region, and a determination unit that determines whether the value calculated by the calculation unit is equal to or greater than a predetermined threshold, and determines the type of discharge event when the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region is equal to or greater than a first threshold, determines whether the output waveform is equal to or greater than a second threshold, and determines the occurrence of a discharge event if the output waveform is equal to or greater than the second threshold.
[0013] In addition, it is preferable that the judgment unit be configured to be able to estimate the location or scale of a discharge event using the phase angle of the peak time region of one of the positive and negative poles and the output of a phase angle different from the other phase angle.
[0014] Furthermore, it is preferable that the judgment unit be configured to be able to estimate the location or scale of a discharge event using "the difference between the output at the timing of the peak time region of one of the positive and negative poles and the output at the timing of the zero value time region immediately before or after the output" and "the difference between the output at the timing of the peak time region of the other of the positive and negative poles and the output at the timing of the zero value time region immediately before or after the output."
[0015] Furthermore, it is preferable that the determination unit is configured to notify an external device that it is unable to determine whether a discharge event has occurred when the output at the timing of the zero value time region is equal to or greater than a third threshold value.
[0016] Furthermore, it is preferable that the determining section is configured to reduce the output waveform extracted by the filter section when the output at the timing of the 0 value time region is equal to or greater than a third threshold value. [Effects of the Invention]
[0017] The present invention makes it possible to improve the accuracy of detecting a discharge event. [Brief explanation of the drawings]
[0018] [Figure 1] 5 is a diagram showing the relationship between a commercial power source, a discharge detection unit, and a load in an embodiment, where (1) to (4) represent the locations where the processes (1) to (4) in FIG. 5 are performed. [Figure 2] FIG. 1 is a conceptual diagram showing that noise is superimposed on a peak at a commercial frequency due to the occurrence of a discharge event. [Figure 3] 10 is a diagram illustrating an example of the relationship between the output timing of a phase angle detection pulse and the peak of a commercial frequency. [Figure 4] 10A and 10B are diagrams showing other examples of phase angle detection pulses. [Figure 5]This diagram shows an example of the processing flow, from capturing a voltage waveform with noise superimposed on it to separating the output into regions. (1) shows the result of extracting the high-frequency output waveform, (2) shows the amplified result, (3) shows the result of processing in the smoothing section, and (4) shows the separation of the output at the timing of the peak time region and the output at the timing of the zero value time region. [Figure 6] This figure shows how the timing at which noise occurs can be determined by comparing the waveform after noise superimposed on the commercial frequency due to a discharge event has been processed by a smoothing section with the commercial frequency. [Figure 7] This figure shows how the timing at which noise occurs can be determined by comparing the waveform after noise superimposed on a commercial frequency due to the use of a specific device has been processed by a smoothing section with the commercial frequency. [Figure 8] This is a diagram showing that the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region is checked multiple times. [Figure 9] This figure shows how the timing of noise occurrence can be determined by comparing the waveform after noise superimposed on the commercial frequency due to a discharge event has been processed by a smoothing section with the commercial frequency. However, noise processing has been performed so that the A' region does not become convex. [Figure 10] 1. FIG. 4 is a diagram showing the relationship between a commercial power source, a discharge detection unit, and a load in an embodiment different from the example shown in FIG. [Figure 11] FIG. 10 is a diagram showing an example in which a plurality of detected differences are added together and used for determination. [Figure 12] FIG. 10 is a diagram showing an example in which the difference between area A and area A' is detected and used to estimate the location or scale of occurrence. [Figure 13] FIG. 10 is a diagram showing an example in which "the difference C of AB" and "the difference C' of A'-B'" are used to estimate the scale of an occurrence. [Figure 14] This is a diagram showing an example in which "the difference C' between A' and B'" is used to estimate the scale of an occurrence. Note that "the difference C between AB" is not used to estimate the scale of an occurrence. [Figure 15]FIG. 10 is a diagram showing a state in which a discharge event occurs when a specific device is being used. [Figure 16] FIG. 10 is a diagram illustrating an example of setting a fourth threshold value. [Figure 17] This is a diagram showing an example of a conventional discharge detection unit connected between a commercial power supply and a load, where (1) to (4) represent the parts where processes (1) to (4) in Figures 12 and 13 are performed. [Figure 18] This diagram shows an example of the processing flow using a conventional discharge detection unit, from capturing a voltage waveform superimposed with noise caused by the occurrence of a discharge event to distinguishing the output by region. (1) shows the result of extracting the high-frequency band output waveform, (2) shows the amplified result, (3) shows the result processed by the smoothing section, and (4) shows the distinction between the output at the timing of the peak time region and the output at the timing of the zero value time region. Note that a partial enlargement of (2) is also shown. [Figure 19] This diagram shows an example of the processing flow using a conventional discharge detection unit, from capturing a voltage waveform superimposed with noise caused by the use of a specific device to distinguishing the output by region. (1) shows the result of extracting the output waveform in the high frequency band, (2) shows the result after amplification, (3) shows the result after processing in the smoothing section, and (4) shows the distinction between the output at the timing of the peak time region and the output at the timing of the zero value time region. DETAILED DESCRIPTION OF THE INVENTION
[0019] An embodiment of the invention is described below. The discharge event detection system of this embodiment detects noise output superimposed on the voltage or current of an electrical circuit to which a load 8 is connected. This discharge event detection system includes a filter unit 11 that extracts a high-frequency output waveform; a phase division unit 14 that determines a peak time region, including a region before and after a peak at the commercial frequency of the output waveform extracted by the filter unit 11, and a zero-value time region, including a region before and after the output at the commercial frequency becomes zero; a calculation unit 15 that calculates the difference between the output at the timing of the peak time region and the output at the timing of the zero-value time region; and a determination unit 16 that determines whether the difference calculated by the calculation unit is equal to or greater than a predetermined threshold. This enables improved accuracy in detecting discharge events. While the calculation unit and determination unit are combined into one unit in the example shown in FIG. 1 , they may be separated into separate units.
[0020] Here, an overview of the discharge detection unit 1 used in the discharge event determination system of the embodiment will be described. As shown in Fig. 1, the discharge detection unit 1 is connected between a commercial power supply 91 and a load 8, and the discharge detection unit 1 of the embodiment includes a filter section 11 that passes noise in the high-frequency band and blocks noise in the commercial frequency and low-frequency bands, an amplifier section 12 that amplifies the high-frequency signal that has passed through the filter section 11, a smoothing section 13 that performs preprocessing for determination on the result amplified by the amplifier section 12, a phase division section 14 that identifies the timing at which noise is occurring, and a determination section 15 that performs various determinations.
[0021] The value that passes through this filter unit 11 is amplified several times by the amplifier that is the amplifier unit 12. The amplified value is then processed by the smoothing unit 13, which performs peak hold. The signal processed by the smoothing unit 13 is sent to the phase division unit 14, where it is positioned appropriately. Then, the judgment unit 15 makes a judgment based on the relationship between the value in the region assigned by the phase division unit 14 and the threshold value. Necessary output is made in accordance with the judgment result made by the judgment unit 15. Note that in this embodiment, the judgment is made based on the signal that has been processed by the smoothing unit 13, but it is also possible to make the judgment by the judgment unit 15 without using the smoothing unit 13.
[0022] In the embodiment, the smoothing unit 13 performs processing to prevent the determination result from being affected by fluctuations in values occurring within a very short, predetermined time period. More specifically, the smoothing unit 13 processes the waveform so that peak values occurring within very close times are connected by a gentle straight line or curve. Note that this very close time period is a time period that is significantly shorter than one cycle (=1 / frequency) of the wave being measured, such as a voltage wave.
[0023] Here, we will explain how noise is superimposed when a specific device such as a hand mixer or an electric drill is used. Specific devices such as a hand mixer or an electric drill continuously affect the waveform while they are in use. For this reason, when processing is performed by the smoothing unit 13, the threshold value may always be exceeded during the time period when the specific device is in use.
[0024] Next, we will explain how noise is superimposed when a discharge event such as tracking, cable breakage, or short circuit occurs. When a discharge event such as tracking, cable breakage, or short circuit occurs, the effect is most noticeable near the peak of the waveform, but there is not much effect near the zero point where the output at commercial frequencies is zero.
[0025] More specifically, as can be seen from Figure 2, when a discharge event such as tracking or a cable break or short occurs, noise appears prominently near the peak of the voltage value, etc. In other words, if one cycle is 360 degrees, noise appears prominently near 90° and 270°. Expressed in terms of time, at a frequency of 60 Hz, one cycle is 1 / 60 seconds, or 16.7 ms, so when a discharge event such as tracking or a cable break or short occurs, noise output appears prominently near 4.2 ms and 12.5 m after the output at the commercial frequency reaches 0.
[0026] On the other hand, in areas where the output at commercial frequencies is 0 (intersections with the 0 point), the noise output is small when a discharge event such as tracking, a cable break, or a short circuit occurs.For this reason, by detecting the difference between the output near the peak of the voltage value, that is, around 90° or 270°, and the output near the intersection with the 0 point, it is possible to accurately determine the occurrence of a discharge event.
[0027] To achieve this, it is conceivable to divide one cycle of voltage waveform information into multiple regions. For example, as shown in Figure 3, it may be divided into four regions. In the example shown in Figure 3, region A has a phase angle of 45 degrees or more and less than 135 degrees, region B has a phase angle of 135 degrees or more and less than 225 degrees, region A' has a phase angle of 225 degrees or more and less than 315 degrees, and region B' has a phase angle of 315 degrees or more and less than 405 degrees. Here, the regions are identified by angle, but it is also possible to identify the regions by other factors such as time.
[0028] The width of this region may be narrowed or set to other values. For this reason, it is preferable that the phase division unit be configured to be able to adjust the times of the peak time region and the zero value time region. It is preferable that the regions A and A' are regions that include the point where the absolute value of the peak is maximum. It is also preferable that the regions B and B' are regions that include the zero point where the output at the commercial frequency becomes zero.
[0029] An attribute is assigned to each divided area in this way, and output values for different attributes are compared and monitored. For example, the average output value within each area is checked, and the average output value of area A is compared with the average output value of area B. In this way, it is possible to determine whether the output is due to a discharge event.
[0030] In this embodiment, to determine each region, a phase angle detection pulse is output from the phase division unit 14, and the output when the pulse is in the on or off state is detected by the determination unit 15. In this way, it is preferable to perform determination by outputting a phase angle detection pulse that is off in the peak time region and on in the zero value time region, and having the determination unit 15 detect the noise output when the phase angle detection pulse is in the on or off state.
[0031] Another example of using a phase angle detection pulse will be described with reference to FIG. 4. FIG. 4(a) shows a case where a phase angle detection pulse is output that is on in the peak time region and off in the zero value time region. FIG. 4(b) shows a case where an instantaneous pulse is applied, outputting an on / off state. FIG. 4(c) shows a case where a pulse is applied only in the positive peak time region, and the time is divided into four regions by calculation: the positive peak time region from pulse detection to 4.2 ms, the zero value time region from 4.2 ms to 8.4 ms and 12.6 ms to 16.7 ms, and the negative peak time region from 8.4 ms to 12.6 ms. In any of the embodiments, by applying a phase angle detection pulse, the determination unit 15 can set the time or phase of the peak time region and the zero value time region of the smoothed output waveform.
[0032] Next, a more specific example will be shown for explanation. In this example, regions are defined so that one period is equally divided into four, with region A having a phase angle of 45 degrees or more and less than 135 degrees, region B having a phase angle of 135 degrees or more and less than 225 degrees, region A' having a phase angle of 225 degrees or more and less than 315 degrees, and region B' having a phase angle of 315 degrees or more and less than 405 degrees.
[0033] As can be seen from Figures 1 and 5, this example involves the following steps: "(1) High-frequency noise is extracted by filter unit 11," "(2) the high-frequency noise is amplified by amplifier unit 12," "(3) each noise waveform group is smoothed by smoother unit 13," and "(4) one period of the waveform is divided into four on the time axis."
[0034] Next, the determination unit 15 makes a determination. In this example, to make the determination, the determination unit 15 performs a calculation to subtract the "average value of the region B, which is a time region of zero positive values," from the "average value of the region A, which is a time region of peak positive values." Note that the calculation may also be performed to subtract the "average value of the region B', which is a time region of zero negative values," from the "average value of the region A', which is a time region of peak negative values." Alternatively, both of these may be performed.
[0035] In the example shown in Figure 6, where noise due to a discharge event is detected, the peak time region is convex and the zero value time region is approximately zero. Therefore, if the "average value of region B, the positive zero value time region," is subtracted from the "average value of region A, the positive peak time region," the result is greater than the threshold. Similarly, if the "average value of region A', the negative peak time region," is subtracted from the "average value of region B', the negative zero value time region," the result is greater than the threshold. The calculated value is "average value of region A - approximately zero," or "approximately the average value of region A." Note that this threshold can be set arbitrarily, but in the present invention, it is preferably set to the output level that determines a discharge event. In this case, the type of discharge event is detected, which determines whether it is noise caused by the device or a discharge event such as tracking, a cable break, or a short circuit, and the occurrence of a discharge event is detected simultaneously.
[0036] On the other hand, when a specific device such as an electric drill is used, the detection result will be as shown in Figure 7, and if you perform a calculation such that the "average value of region B, which is the time region of zero positive values," is subtracted from the "average value of region A, which is the time region of peak positive values," you will get a value that is smaller than the threshold. Similarly, if you perform a calculation such that the "average value of region B', which is the time region of zero negative values," is subtracted from the "average value of region A', which is the time region of peak negative values," you will get a value that is smaller than the threshold. More specifically, the "average value of region A - average value of region B" will be "approximately 0."
[0037] As can be seen from this example, by setting a threshold value to an appropriate value and determining whether the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region is greater than or equal to the predetermined threshold, it is possible to distinguish between noise caused by the use of a specific device and noise caused by a discharge event.
[0038] To improve the accuracy of such a determination, it is preferable to determine that a discharge event has occurred when a state in which the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region is equal to or greater than a threshold value continues for a predetermined period of time. When a discharge event has occurred, as shown in FIG. 8 , the result that the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region is equal to or greater than a predetermined threshold value continues repeatedly. Therefore, it is sufficient to determine that a discharge event has occurred when such a state occurs a specific number of times within a specific period of time. Of course, other means may also be used. To achieve this, in the discharge event determination system of the embodiment, the calculation unit 15 continuously calculates the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region for a predetermined period of time.
[0039] In the example shown in Fig. 6 above, both "area A, which is a peak time area of positive values" and "area A', which is a peak time area of negative values" can be used as elements of the judgment, but as can be seen from Fig. 9, it is not necessary to use both as elements of the judgment. In the example shown in Fig. 9, "area A, which is a peak time area of positive values" can be used as an element of the judgment, but "area A', which is a peak time area of negative values" cannot be used as an element of the judgment. In such a case, the judgment can be made using only those elements that can be used as elements of the judgment.
[0040] In the above example, the determination of whether noise is caused by the device and the determination of whether a discharge event has occurred are made at the same time, but these may be made at different times. For example, it is preferable to determine whether the output waveform is equal to or greater than a second threshold when the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region is equal to or greater than a first threshold, and to determine that a discharge event has occurred when the output waveform is equal to or greater than the second threshold.
[0041] This allows for situations where the detected noise is not noise caused by the equipment, but does not necessarily need to be determined as a discharge event and the breaker tripped. For example, if the value calculated by subtracting the output at the timing of the zero-value time region from the output at the timing of the peak time region is equal to or greater than the first threshold, it is determined whether the output at the timing of the peak time region is equal to or greater than the second threshold. In this case, the first threshold is used to estimate the cause of the noise, and the second threshold is used to determine whether to perform a specific output, such as tripping the breaker. In the example shown in FIG. 10, to enable this, the output output from the determination unit 15 is temporarily input back into the determination unit 15. Note that in this embodiment, the type of discharge event is detected using the first threshold, and then the occurrence of a discharge event is detected using the second threshold, but the order of determination may be arbitrary.
[0042] However, in cases where a single large noise occurs, it may not be possible to make an appropriate judgment by simply looking at the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region. Therefore, it is preferable that the calculation unit performs calculations to detect the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region for each path for a predetermined time, and then adds or averages the detected differences over the predetermined time. If the judgment unit compares the calculation results for each path obtained thereby and identifies the circuit of the discharge event, it can handle such irregular situations.
[0043] In the example shown in Figure 11, discharge detection units 1 are formed in multiple circuits to be measured, and the measurement data of the filter section 11 of each discharge detection unit 1 is added or averaged to determine the difference detection values over a predetermined period of time divided by a phase division section, and the results are compared to determine the path on which the discharge event occurred.
[0044] In this embodiment, the determination is made by adding or averaging the difference between the output at the timing of the peak time region in the positive range of the commercial frequency and the output at the timing of the zero value time region, but the determination may also be made by adding or averaging the difference between the output at the timing of the peak time region in the negative range of the commercial frequency and the output at the timing of the zero value time region, or by adding or averaging the difference between the output at the timing of the peak time region in the positive and negative range of the commercial frequency and the output at the timing of the zero value time region. Furthermore, the phase dividing section 14 may be formed for each electric discharge detection unit 1, or a single phase dividing section 14 may be used to collect measurement data from all circuits and divide it all at once.
[0045] Incidentally, the noise caused by a discharge event is most pronounced in the peak time region (region A, region A') that includes the region before and after the peak of the commercial frequency. Also, whether the noise caused by a discharge event appears in the peak time region (region A) that includes the region before and after the peak of the positive commercial frequency, or in the peak time region (region A') that includes the region before and after the peak of the negative commercial frequency, depends on whether the wiring (plug) of the device of load 8 is connected to the positive or negative side. Therefore, when determining whether a discharge event has occurred, the determination can be made based on the side with the larger output.
[0046] However, depending on the level of the discharge event that has occurred, a waveform may be output in the other peak region (for example, the region of negative values A') on the polarity side different from the one peak region (for example, the region of positive values A) on the side that determines whether or not a discharge event has occurred. This occurs when the scale of the discharge event is large or when the location where the discharge event has occurred is close to the discharge detection unit 1. In other words, the scale and location of the discharge can be inferred from the output status on the polarity side different from the side that is used to determine whether or not a discharge event has occurred.
[0047] Therefore, it is preferable that the determination unit 15 be able to estimate the location or scale of a discharge event using the output of the phase angle of one of the positive and negative peak time regions and a phase angle different from the one phase angle. More specifically, it is preferable that the determination unit 15 be able to estimate the location or scale of a discharge event using the output of one phase angle used in determining whether a discharge event has occurred and the other phase angle different from the one phase angle.
[0048] Specifically, for example, the difference between area A and area A' may be detected, and the determination unit 15 may specify the location and scale of the occurrence based on the magnitude of the difference (see FIG. 12). It is also preferable to store determination conditions in the determination unit 15 or a storage unit, etc., and make a determination by comparing the conditions. Note that even if the outputs of area A and area A' are similar and it is not clear which output is due to a discharge event, it is possible to determine the location and scale of the occurrence by comparing them.
[0049] Although it is difficult to measure the distance precisely using the methods described above, if the distance can be roughly estimated and communicated to the user, it will be easier for the user to respond to the discharge event. Furthermore, being able to estimate the scale of the occurrence, such as the intensity, can provide the user with a guide for determining the urgency. For example, if the alarm output is changed according to the determined intensity, it will be possible to prompt the user to make a quick decision when the scale of the occurrence is large. The level of the occurrence scale may also be displayed on an indicator provided on the surface of the discharge detection unit 1.
[0050] In the above example, the difference between the A region and the A' region was simply detected and used to estimate the location or scale of the discharge. However, it is also possible to estimate the location or scale of the discharge event using the difference between the output at the timing of one of the positive and negative peak time regions and the output at the timing of the zero value time region immediately before or after the output, and the difference between the output at the timing of the other of the positive and negative peak time regions and the output at the timing of the zero value time region immediately before or after the output. More specifically, the location and scale of the discharge event can be estimated from the difference C between A and B and the difference C' between A' and B'. For example, after determining that a discharge event has occurred, the location or scale of the discharge event can be estimated by checking the sum or average value of "C01, C02, C03, C04, ..." over a predetermined time period and determining whether it exceeds a predetermined value (see FIG. 13).
[0051] In this case, a threshold different from the "threshold" used to determine whether a discharge event has occurred may be used to make the determination. Furthermore, the predetermined time used to estimate the location or scale of the discharge event may be the same as the "predetermined time" used to determine whether a discharge event has occurred, or may be a different predetermined time.
[0052] Furthermore, the location and scale of the occurrence can be estimated from the "difference C' of A'-B'" without using the "difference C of AB." For example, after determining that a discharge event has occurred using the "difference C of AB (C01, etc.)," the location or scale of the occurrence can be estimated by checking the sum or average value of "C02, C04, C06, C08, ..." over a predetermined time period and determining whether it exceeds a predetermined value (see FIG. 14).
[0053] As can be seen from these examples, when determining whether a discharge event has occurred, it is preferable to use the "difference between the output at the timing of one peak time region and the output at the timing of the zero value time region," and when estimating the location or scale of the discharge event, to use the "difference between the output at the timing of a peak time region different from the output at the timing of one peak time region and the output at the timing of the zero value time region."
[0054] 15 shows another example of a case where the output at the timing of the zero value time region becomes large due to the use of a particular device such as a hand mixer or an electric drill. In this example, even though a discharge event occurs, when the difference between the output at the timing of the peak time region different from the output at the timing of one of the peak time regions is calculated, it does not exceed the first threshold.
[0055] To deal with such cases, it is preferable to set a third threshold. It is preferable to set a third threshold and, if the output at the timing of the zero-value time region is equal to or greater than the third threshold, notify that a discharge event cannot be determined. Furthermore, if there is an output exceeding the third threshold, it is preferable for the determination unit 15 to reduce the sensitivity and decrease the output waveform. The first threshold can be determined by decreasing the amplification factor of the amplifier unit 12, which amplifies the high-frequency wave that has passed through the filter unit 11. In this case, the output waveform is decreased to equal to or less than the third threshold.
[0056] In the example shown in Fig. 16, a fourth threshold is set. If the sensitivity is left lowered when use of a specific device that outputs noise is finished, there is a risk that the detection range will become narrower or noise caused by discharge will not be detected. However, since a fourth threshold is set, after exceeding the third threshold, the sensitivity is lowered to or below the third threshold, and if the output at the timing of the zero value time region subsequently falls below the fourth threshold, which is set lower than the third threshold, the sensitivity can be controlled to return to the original setting.
[0057] While the present invention has been described above using the embodiments as examples, the present invention is not limited to the above embodiments and can be embodied in various forms. For example, it is possible to detect noise superimposed on current rather than noise superimposed on voltage. [Explanation of symbols]
[0058] 1 Discharge detection unit 8 Load 11 Filter section 12 Amplification section 13 Smooth section 14 Phase division section 15 Arithmetic unit and judgment unit
Claims
1. A discharge event determination system that detects a noise output superimposed on a voltage or current of an electric line to which a load is connected, a filter unit that extracts an output waveform in a high frequency band; a phase dividing unit that determines a peak time region including a region before and after a peak in the commercial frequency of the output waveform extracted by the filter unit, and a zero value time region before and after the output of the commercial frequency becomes zero; a calculation unit that calculates a difference between an output at a timing in a peak time region and an output at a timing in a zero value time region; a determination unit that determines whether the difference calculated by the calculation unit is equal to or greater than a predetermined threshold; A discharge event determination system comprising:
2. the calculation unit continuously calculates the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region for a predetermined time period; The discharge event determination system according to claim 1, wherein the determination unit determines that a discharge event has occurred when a state in which the difference between the output at the timing of the peak time region and the output at the timing of the zero value time region is greater than or equal to a threshold value continues for a predetermined period of time.
3. A plurality of the filter units are provided, and it is possible to measure the presence or absence of discharge events in a plurality of paths; the calculation unit performs a calculation for a predetermined time to detect a difference between an output at a timing in a peak time region and an output at a timing in a zero value time region for each path, and adds or averages the detected values of the difference for the predetermined time; The discharge event determination system according to claim 1 , wherein the determination unit compares the calculation results of each path to identify the circuit in which the discharge event occurs.
4. 4. The discharge event determination system according to claim 1, wherein the phase dividing unit is capable of adjusting the times of the peak time region and the zero value time region.
5. The phase division unit outputs a phase angle detection pulse for dividing one period into four, 2. The discharge event determination system according to claim 1, wherein the determination unit sets the times of the peak time region and the zero value time region based on the phase angle detection pulse.
6. A discharge event determination system that detects a noise output superimposed on a voltage or current of an electric line to which a load is connected, a filter unit that extracts an output waveform in a high frequency band; a phase dividing unit that determines a peak time region including a region before and after a peak in the commercial frequency of the output waveform extracted by the filter unit, and a zero value time region before and after the output of the commercial frequency becomes zero; a calculation unit that calculates a difference between an output at a timing in a peak time region and an output at a timing in a zero value time region; a determination unit that determines whether the value calculated by the calculation unit is equal to or greater than a predetermined threshold; Equipped with the determination unit determines the type of discharge event when a difference between the output at the timing of the peak time region and the output at the timing of the zero value time region is equal to or greater than a first threshold; The discharge event determination system determines whether the output waveform is equal to or greater than a second threshold, and determines that a discharge event has occurred if the output waveform is equal to or greater than the second threshold.
7. The discharge event determination system according to claim 1 or 6, wherein the determination unit is capable of estimating the location or scale of the discharge event using an output of a phase angle of a peak time region of one of the positive and negative poles and a phase angle different from the other phase angle.
8. The determination unit is The difference between the output at the timing of the peak time region of one of the positive and negative poles and the output at the timing of the zero value time region immediately before or after the output; The difference between the output at the timing of the peak time region of the other of the positive and negative polarities and the output at the timing of the zero value time region immediately before or after the output; The discharge event determination system according to claim 7, wherein the location or scale of the discharge event can be estimated using the above.
9. 2. The discharge event determination system according to claim 1, wherein the determination unit notifies an external device that a discharge event cannot be determined when the output at the timing of the zero value time region is equal to or greater than a third threshold value.
10. 10. The discharge event determination system according to claim 1, wherein the determination unit reduces the output waveform extracted by the filter unit when the output at the timing of the zero value time region is equal to or greater than a third threshold value.