Partial discharge diagnostic device and partial discharge diagnostic method
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- KK TOSHIBA
- Filing Date
- 2024-12-18
- Publication Date
- 2026-06-30
Smart Images
Figure 2026106584000001_ABST
Abstract
Description
Technical Field
[0001] Embodiments of the present invention relate to a partial discharge diagnostic device and a partial discharge diagnostic method.
Background Art
[0002] As a method for diagnosing the deterioration state due to partial discharge of electrical equipment, parameters such as the discharge occurrence frequency n, the discharge charge amount q, and the discharge occurrence phase φ are obtained from the partial discharge signals detected by sensors, electrodes, etc., and based on the distribution of the obtained parameters (for example, φ-q distribution or φ-q-n distribution), a method for diagnosing partial discharge is known.
[0003] In addition, as causes of partial discharge in electrical equipment, voids (voids) existing in insulating materials, insulation breakdown portions (trees) formed in a tree shape in insulating materials, etc. can be mentioned. When the insulating material is burned due to partial discharge, the resin is carbonized. Since the carbonized portion has conductivity, carbonization gradually progresses from the tip of the carbonized portion toward the ground plane due to further partial discharge, and the carbonized portion progresses in a dendritic shape. Hereinafter, the deterioration caused by a tree is also referred to as tree-like deterioration. Tree-like deterioration occurs at the end stage of the deterioration of electrical equipment. When the tree reaches the ground plane of the insulating material, a ground fault occurs, so a technique for detecting tree-like deterioration is required to prevent equipment failure.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Patent Document 2
Patent Document 3
Patent Document 4
Patent Document 5
Summary of the Invention
[0005] The problem that this invention aims to solve is to provide a partial discharge diagnostic device and a partial discharge diagnostic method that can diagnose tree-like deterioration. [Means for solving the problem]
[0006] The partial discharge diagnostic device of this embodiment comprises a pulse group extraction unit and a partial discharge diagnostic unit. The pulse group extraction unit extracts a pulse group, which is a group of pulses generated within a predetermined minute time, from a signal related to a partial discharge generated from the electrical equipment to be diagnosed. When the pulse group is extracted, the partial discharge diagnostic unit determines, based on the history of damage to the electrical equipment, whether the pulse group is due to a tree-like partial discharge. [Brief explanation of the drawing]
[0007] [Figure 1] A schematic diagram showing a configuration for detecting partial discharge from inside a row of boxes using a partial discharge diagnostic device according to the embodiment. [Figure 2] Figure 1 shows the results of the experiment according to the embodiment. [Figure 3] Figure 2 shows the results of the experiment according to the embodiment. [Figure 4] A functional block diagram showing the functional configuration of the partial discharge diagnostic device according to the embodiment. [Figure 5] A flowchart showing the diagnostic process of a partial discharge diagnostic device according to the first embodiment. [Figure 6] A flowchart showing the diagnostic process of a partial discharge diagnostic device according to the second embodiment. [Figure 7] A flowchart showing the diagnostic process of a partial discharge diagnostic device according to the third embodiment. [Figure 8] A flowchart showing the diagnostic process of a partial discharge diagnostic device according to the fourth embodiment. [Modes for carrying out the invention]
[0008] The partial discharge diagnostic device and partial discharge diagnostic method of the embodiment will be described below with reference to the drawings.
[0009] (First Embodiment) Figure 1 is a schematic diagram showing a configuration for detecting partial discharge from inside a row of boxes using a partial discharge diagnostic device 100 of an embodiment. In the first embodiment, it is configured using a plurality of boxes 10 arranged in a row. The plurality of boxes 10 are arranged in a substantially straight line. These boxes 10 are provided with a predetermined power supply system that supplies power to electrical equipment. Each box 10 is a box capable of housing electrical equipment such as switchgears. Each box 10 houses, for example, electrical equipment such as circuit breakers and main circuit conductors. Electrical equipment generates partial discharge due to aging deterioration, etc. Electrodes 110 are fixed to the front of each box 10 so as to be in contact with each other.
[0010] The electrode 110 detects the surface potential of the enclosure 10. The electrode 110 outputs the detected surface potential as an electrical signal to the partial discharge diagnostic device 100. The electrode 110 may be provided in a state that is in semi-permanent contact with the enclosure 10, for example. The electrode 110 may also be in a state that is in temporary contact with the enclosure 10 only while, for example, an inspector or the like is performing the task of determining whether or not there is a partial discharge from the enclosure 10. In the configuration shown in Figure 1, one electrode 110 is provided on the enclosure 10, but multiple electrodes 110 may be provided on one enclosure 10. By providing multiple electrodes 110 on one enclosure 10, the partial discharge diagnostic device 100 can detect the surface potential of the enclosure 10 with higher accuracy. Therefore, the partial discharge diagnostic device 100 can diagnose the condition of electrical equipment with higher accuracy.
[0011] A common grounding busbar 20 is provided at the bottom of the enclosure 10. The grounding busbar 20 is connected to the grounding electrode 30. The enclosure 10 is composed of a front panel, a top panel, a back panel, a bottom panel, and side panels. These front panel, top panel, back panel, bottom panel, and side panels are collectively referred to as the constituent panels of the enclosure 10. In the example shown in Figure 1, the electrode 110 is in contact with and fixed to the front panel, but the electrode 110 may be in contact with and fixed to any of the other constituent panels. The constituent panels are connected to the grounding busbar 20.
[0012] Furthermore, a multi-relay device 120 is provided on the front of the enclosure 10 to display the status of the corresponding electrical equipment. The multi-relay device 120 is a digital relay device that aggregates measurement data from multiple sensors installed on the electrical equipment and records historical data such as the total energizing time of the electrical equipment, voltage waveforms and current waveforms, and the time of surge voltage occurrence.
[0013] In this embodiment, the method for detecting a partial discharge signal is described as detecting the surface potential using the electrode 110, but it is not limited to this. For example, the partial discharge diagnostic device 100 according to another embodiment may detect electromagnetic waves instead of surface potential. In this case, the partial discharge diagnostic device 100 acquires an electrical signal from an antenna instead of the electrode 110. The antenna detects electromagnetic waves. The antenna outputs an electrical signal to the partial discharge diagnostic device 100 based on the detected electromagnetic waves. The partial discharge diagnostic device 100 according to another embodiment may also detect ground current instead of surface potential. In this case, the partial discharge diagnostic device 100 acquires an electrical signal from a sensor such as a high-frequency CT (Current Transformer) instead of the electrode 110. The sensor detects ground current. The sensor outputs an electrical signal to the partial discharge diagnostic device 100 based on the detected ground current. The partial discharge diagnostic device 100 may acquire other signals obtained due to partial discharge of electrical equipment. For example, the partial discharge diagnostic device 100 may acquire signals such as ground potential, electromagnetic waves, ground wire current, vibration, and sound.
[0014] The partial discharge diagnostic device 100 according to the first embodiment diagnoses whether or not tree-like deterioration has occurred in the electrical equipment within the box body 10 based on the electrical signal acquired from the electrode 110. Hereinafter, the reason for being able to diagnose the presence or absence of tree-like deterioration from the electrical signal will be explained.
[0015] FIG. 2 is a first diagram showing the results of an experiment according to the embodiment. The inventor conducted an experiment to verify the difference between partial discharge caused by voids and partial discharge caused by trees. In the experiment, a needle electrode was applied to each of a first insulating resin sample having voids and a second insulating resin sample having trees, and a voltage was applied to the needle electrode to generate partial discharge. An electrical signal was measured from the first insulating resin sample, frequency analysis of the electrical signal was performed, and a spectrogram G1 was created. An electrical signal was measured from the second insulating resin sample, frequency analysis of the electrical signal was performed, and a spectrogram G2 was created. As a result of comparing the spectrogram G1 representing partial discharge caused by voids with the spectrogram G2 representing partial discharge caused by trees, as shown in FIG. 2, in the partial discharge caused by trees, frequency components of 100 MHz or more strongly appear immediately after the occurrence of partial discharge, whereas in the partial discharge caused by voids, almost no frequency components of 100 MHz or more appear.
[0016] FIG. 3 is a second diagram showing the results of an experiment according to an embodiment. Further, the inventor extracted frequency components of 100 MHz or more from the obtained electrical signal to obtain a high-frequency waveform, and compared the high-frequency waveform of partial discharge caused by voids with the high-frequency waveform of partial discharge caused by treeing. As a result, the inventor found that, as shown in FIG. 3, multiple pulses occur within 5 μs in the high-frequency waveform of partial discharge caused by treeing. In particular, the inventor found that two or more pulses occur within 1 μs. When a high electric field is applied to a tree, partial discharge occurs in some of the multiple branches. As a result, the surrounding electric field rises, and partial discharge occurs chain-reaction in another branch portion exceeding the air breakdown electric field. This is considered to be the cause of the continuous occurrence of partial discharge due to treeing. Note that partial discharge caused by voids usually occurs at intervals of several tens of μs to several milliseconds at the timing of the rise or fall of the operating voltage, and multiple pulses do not occur within 5 μs.
[0017] Therefore, the partial discharge diagnostic device 100 can diagnose the presence or absence of treeing deterioration by determining the presence or absence of a group of pulses that occur in a short period in the high-frequency waveform. On the other hand, even if there is no treeing deterioration, a group of pulses that occur in a short period may be detected due to external noise. Treeing deterioration is an end-stage deterioration state of electrical equipment, and a diagnostic result indicating that treeing deterioration has occurred promotes the disposal of electrical equipment. Therefore, it is preferable to avoid misdiagnosing as treeing deterioration even though the possibility of treeing deterioration is low. Therefore, the partial discharge diagnostic device 100 according to the first embodiment diagnoses treeing deterioration when a pulse group is detected when the number of years of use (length of use period) of the power equipment is sufficiently long. This is because the probability of treeing deterioration occurring is low when the number of years of use of the power equipment is short, and it is highly likely to be caused by noise. While the power equipment is in use, a voltage is continuously applied to the insulation part. The deterioration of the insulation part progresses due to this voltage. Therefore, it can be said that the number of years of use of the power equipment represents the history of damage to the power equipment.
[0018] Figure 4 is a functional block diagram showing the functional configuration of the partial discharge diagnostic device 100 according to the embodiment. The partial discharge diagnostic device 100 is an information processing device such as a PC, smartphone, or tablet computer. The partial discharge diagnostic device 100 diagnoses the state of the electrical equipment to be diagnosed based on the electrical signals received from the electrode 110. Specifically, the partial discharge diagnostic device 100 diagnoses the degree of partial discharge and the type of power source. The partial discharge diagnostic device 100 includes a communication unit 101, an input unit 102, an output unit 103, an electrical signal storage unit 104, a diagnostic information storage unit 105, and a control unit 106.
[0019] The communication unit 101 is a network interface. The communication unit 101 communicates with external devices via the network.
[0020] The input unit 102 is configured using input devices such as a touch panel, mouse, and keyboard. The input unit 102 may also be an interface for connecting the input devices to the partial discharge diagnostic device 100. In this case, the input unit 102 generates input data from the input signals received by the input devices and inputs it to the partial discharge diagnostic device 100. The input data may be, for example, instruction information indicating an instruction to switch the electrical signal acquired by the partial discharge diagnostic device 100 to another electrode 110.
[0021] The output unit 103 is an output device such as a CRT (Cathode Ray Tube) display, a liquid crystal display, or an organic EL (Electro Luminescence) display. The output unit 103 may also be an interface for connecting the output device to the partial discharge diagnostic device 100. In this case, the output unit 103 generates a video signal from the video data and outputs the video signal to the video output device connected to it.
[0022] The electrical signal storage unit 104 is configured using a storage device such as a magnetic hard disk drive or a semiconductor storage device. The electrical signal storage unit 104 stores the date and time when an electrical signal is acquired by the electrode 110 and the intensity of the electrical signal in association with each other. When the partial discharge diagnostic device 100 acquires electrical signals from multiple electrodes 110, the electrical signal storage unit 104 stores identification information for each electrode 110 in association with the date and time and intensity. The identification information is information used to identify the electrode 110.
[0023] The diagnostic information storage unit 105 is configured using a storage device such as a magnetic hard disk drive or a semiconductor storage device. The diagnostic information storage unit 105 stores multiple historical data. The historical data is information that associates the φ-q distribution of electrical equipment with its degradation state. Details of the historical data will be described later.
[0024] The control unit 106 controls the operation of each part of the partial discharge diagnostic device 100. The control unit 106 is executed by a device equipped with a processor such as a CPU (Central Processing Unit) and RAM (Random Access Memory). By executing a partial discharge diagnostic program, the control unit 106 functions as an electrical signal acquisition unit 161, a filter unit 162, a pulse identification unit 163, a pulse group extraction unit 164, an acquisition unit 165, and a partial discharge diagnostic unit 166.
[0025] The electrical signal acquisition unit 161 acquires electrical signals from the electrodes 110. The electrical signal acquisition unit 161 acquires a time series of the intensity of the electrical signals, i.e., the signal waveform. The electrical signal acquisition unit 161 records the waveform data representing the signal waveform in the electrical signal storage unit 104, associating it with the time the waveform data was acquired. If the partial discharge diagnostic device 100 has multiple electrodes 110, the electrical signal acquisition unit 161 records the waveform data, the acquisition time, and the identification information of the electrodes 110 in the electrical signal storage unit 104, associating them.
[0026] The filter unit 162 removes low-frequency noise contained in the signal waveform acquired by the electrical signal acquisition unit 161 to obtain a high-frequency signal waveform. The filter unit 162 may be a high-pass filter that allows the frequency band containing the partial discharge signal to pass through. The inventors have found through the above experiments that, as shown in Figure 2, extracting signal components of 100 MHz or higher is effective in capturing pulses of partial discharge caused by trees.
[0027] The pulse identification unit 163 identifies the generation timing and generation intensity of pulses related to partial discharge based on the high-frequency signal waveform obtained by the filter unit 162. For example, the pulse identification unit 163 extracts a portion of the high-frequency signal waveform in which the absolute value of the intensity exceeds a threshold, identifies the timing at which this portion is at its maximum or minimum as the pulse generation timing, and identifies the intensity at that timing as the pulse generation intensity.
[0028] The pulse group extraction unit 164 extracts pulse groups that may be caused by treeing from a plurality of pulses identified by the pulse identification unit 163. Specifically, the pulse group extraction unit 164 extracts consecutive pulse groups with an interval of 5 μs or less as pulse groups that may be caused by treeing. Alternatively, the pulse group extraction unit 164 extracts multiple pulses contained within a time range of 5 μs as pulse groups that may be caused by treeing. More specifically, the pulse group extraction unit 164 extracts two or more pulses as pulse groups that may be caused by treeing if there are two or more pulses extracted by the pulse identification unit 163 in each partial waveform obtained by dividing the high-frequency signal waveform obtained by the filter unit 162 into 5 μs intervals. Individual pulses that are not extracted as part of a pulse group may, for example, be pulses generated due to voids.
[0029] The acquisition unit 165 acquires historical data from the multi-relay device 120. The historical data recorded by the multi-relay device 120 includes information such as the date and time of the initial power-on of the electrical equipment and the total power-on time of the electrical equipment. The difference between the date and time of the initial power-on of the electrical equipment and the current date and time, as well as the total power-on time of the electrical equipment, represent the length of the electrical equipment's usage period.
[0030] The partial discharge diagnostic unit 166 diagnoses whether or not treey degradation has occurred based on the extraction results of the pulse group extraction unit 164. Specifically, the partial discharge diagnostic unit 166 diagnoses that treey degradation has occurred in electrical equipment when the pulse group extraction unit 164 extracts more than a predetermined number of pulse groups, and the length of the service life of the electrical equipment, determined from the history data acquired by the acquisition unit 165, exceeds a predetermined threshold (for example, the recommended replacement period indicated by the Electrical Safety Association). If the electrical equipment is a switchgear, the recommended replacement period is about 15 years. The number of pulses extracted that serves as the threshold for determining whether or not treey degradation has occurred may be one or multiple. If the partial discharge diagnostic unit 166 determines that treey degradation has occurred, it causes the output unit 103 to output an alarm indicating that treey degradation has occurred. Examples of such alarms include notifications indicating severe degradation, such as that the electrical equipment is nearing the end of its lifespan, that there is a high probability of failure of the electrical equipment or internal components, or that replacement is being urged. The alarm may be sent in the form of an email to a pre-designated maintenance worker's email address, displayed on the display of a remote monitoring device (not shown) for remote monitoring by the maintenance worker, or made by voice. If the partial discharge diagnostic unit 166 determines that no treey degradation has occurred, it diagnoses the degree of degradation of the electrical equipment based on the φ-q distribution generated from the extracted pulses and the actual data related to voidy discharge stored in the diagnostic information storage unit 105.
[0031] Here, we will explain the actual data stored in the diagnostic information storage unit 105. The diagnostic information storage unit 105 stores actual data related to void discharge. The actual data related to void discharge is data that associates the φ-q distribution of pulses caused by partial discharge from electrical equipment whose deterioration state is known with the deterioration state of the electrical equipment. The partial discharge diagnostic unit 166 compares the φ-q distribution of the electrical equipment to be diagnosed with the φ-q distribution related to historical data, identifies the degradation state corresponding to the closest φ-q distribution, and diagnoses the degradation state of the electrical equipment to be diagnosed. For example, the partial discharge diagnostic unit 166 may identify the degradation state using a trained model that has been trained using historical data related to void discharge as a training dataset. In this case, the trained model is trained using the φ-q distribution related to historical data as an input sample and the degradation state as an output sample. Furthermore, for example, the partial discharge diagnostic unit 166 may diagnose a high probability of failure when the average value of the voltage phase φ falls within a predetermined range, or when the average value of the discharge charge amount q exceeds a threshold.
[0032] Figure 5 is a flowchart showing the diagnostic process of the partial discharge diagnostic device 100 according to the first embodiment. The electrical signal acquisition unit 161 of the partial discharge diagnostic device 100 acquires electrical signals from the electrodes 110 while the power equipment is in operation, and records waveform data representing the signal waveform of the electrical signals in the electrical signal storage unit 104 in association with time. As a result, waveform data is accumulated in the electrical signal storage unit 104.
[0033] When the partial discharge diagnostic device 100 starts the diagnostic process according to instructions from the administrator, the filter unit 162 extracts high-frequency signal waveforms related to frequency components of 100 MHz or higher from the waveform data recorded in the electrical signal storage unit 104 (step S1). The pulse group extraction unit 164 generates multiple partial waveforms (partial signals) by dividing the extracted high-frequency signal waveform into 5 μs intervals (step S2). The pulse identification unit 163 identifies the generation timing and generation intensity of pulses related to partial discharge for each partial waveform (step S3). The pulse group extraction unit 164 extracts pulse groups consisting of two or more pulses included in one partial waveform. As a result, the pulse group extraction unit 164 classifies the multiple pulses identified in step S3 into single pulses and pulse groups (step S4). In addition, the acquisition unit 165 acquires history data of electrical equipment from the multi-relay device 120 (step S5).
[0034] In step S4, the partial discharge diagnostic unit 166 determines whether the pulse group extraction unit 164 has extracted a pulse group exceeding a threshold (step S6). If the partial discharge diagnostic unit 166 determines that a pulse group exceeding a threshold has been extracted (step S6: YES), it calculates the length of the electrical equipment's service life from the history data acquired in step S5 and determines whether the length of the service life exceeds a predetermined recommended replacement period (step S7).
[0035] If no pulse group exceeding the threshold is extracted (Step S6: NO), or if the length of the electrical equipment's service life does not exceed the recommended replacement period (Step S7: NO), it is highly likely that the extracted pulse group was caused by noise. In this case, the partial discharge diagnostic unit 166 generates a φ-q distribution based on the pulses classified as individual pulses in Step S4 (Step S8). The partial discharge diagnostic unit 166 diagnoses the deterioration state of the power equipment based on the generated φ-q distribution and the actual data related to void discharge stored in the diagnostic information storage unit 105 (Step S9). The partial discharge diagnostic unit 166 outputs the diagnosis result of the power equipment's deterioration state to the output unit 103 (Step S10).
[0036] On the other hand, if a group of pulses exceeding a threshold is extracted, and the length of the electrical equipment's service life exceeds the recommended replacement period (Step S7: YES), it is highly likely that the extracted group of pulses is caused by treey degradation. In this case, the partial discharge diagnostic unit 166 causes the output unit 103 to output an alarm indicating that treey degradation has occurred (Step S11).
[0037] Thus, the partial discharge diagnostic unit 166 of the partial discharge diagnostic device 100 according to the first embodiment extracts a group of pulses, which are multiple pulses generated within a minute time, and determines that the pulse group is due to treey discharge when the length of the usage period exceeds a predetermined threshold. In other words, when some kind of deterioration has occurred in the insulating part due to a long period of use, the partial discharge diagnostic unit 166 can estimate that the pulse group is due to treey deterioration and not noise, because a pulse group that may be caused by treey deterioration has been detected. As a result, the partial discharge diagnostic device 100 according to the first embodiment can diagnose treey deterioration. Furthermore, if the partial discharge diagnostic device 100 detects tree-like deterioration, it may provide information indicating severe deterioration and prompting early maintenance.
[0038] (Second embodiment) In the first embodiment, the partial discharge diagnostic device 100 diagnoses that the electrical equipment is suffering from treey deterioration when a group of pulses is detected after the power equipment has been in use for a sufficiently long period, in order to avoid misdiagnosis of treey deterioration. In the second embodiment, the partial discharge diagnostic device 100 diagnoses that the electrical equipment is suffering from treey deterioration when a group of pulses is detected after a surge voltage has occurred in the past, in order to avoid misdiagnosis of treey deterioration. This is because the occurrence of a surge voltage can cause carbonization of the insulating part of the electrical equipment, and treey deterioration can occur with the carbonized part as the end. Therefore, the history of surge voltage occurrence can be said to represent the history of damage to the power equipment.
[0039] Figure 6 is a flowchart showing the diagnostic process of the partial discharge diagnostic device 100 according to the second embodiment. The electrical signal acquisition unit 161 of the partial discharge diagnostic device 100 acquires electrical signals from the electrodes 110 while the power equipment is in operation, and records waveform data representing the signal waveform of the electrical signals in the electrical signal storage unit 104 in association with time. As a result, waveform data is accumulated in the electrical signal storage unit 104.
[0040] When the partial discharge diagnostic device 100 starts the diagnostic process in accordance with instructions from the administrator, the partial discharge diagnostic device 100 performs the processes from step S1 to step S5 in the same manner as in the first embodiment. The history data acquired by the acquisition unit 165 in step S5 includes information such as the time of surge voltage occurrence.
[0041] In step S4, the partial discharge diagnostic unit 166 of the partial discharge diagnostic device 100 according to the second embodiment determines whether the pulse group extraction unit 164 has extracted a pulse group exceeding a threshold (step S6). If the partial discharge diagnostic unit 166 according to the second embodiment determines that a pulse group exceeding a threshold has been extracted (step S6: YES), it performs the determination in step S21 instead of step S7 according to the first embodiment. That is, the partial discharge diagnostic unit 166 calculates the number of surge voltage occurrences in the electrical equipment from the history data acquired in step S5 and determines whether the number of surge voltage occurrences is equal to or greater than a predetermined threshold (step S21). The threshold may be 1 or a number of 2 or more.
[0042] If no pulse group exceeding the threshold is extracted (step S6: NO), or if the number of surge voltage occurrences is less than the threshold (step S21: NO), it is highly likely that the extracted pulse group was caused by noise. In this case, the partial discharge diagnostic device 100 outputs the diagnostic result of the deterioration state of the power equipment to the output unit 103 in the same procedure as steps S8 to S10 of the first embodiment.
[0043] On the other hand, if a group of pulses exceeding the threshold is extracted and the number of surge voltage occurrences is greater than or equal to the threshold (step S21: YES), it is highly likely that the extracted group of pulses was caused by treeability degradation. In this case, the partial discharge diagnostic unit 166 causes the output unit 103 to output an alarm indicating that treeability degradation has occurred (step S11).
[0044] Thus, the partial discharge diagnostic unit 166 of the partial discharge diagnostic device 100 according to the second embodiment determines that a pulse group is due to treey discharge when a pulse group consisting of multiple pulses generated within a minute time is extracted and the number of surge voltage occurrences exceeds a predetermined threshold. In other words, when deterioration has occurred in the insulation part due to past surge voltage occurrences, the partial discharge diagnostic unit 166 can estimate that the pulse group is due to treey deterioration and not noise, because a pulse group that may be caused by treey deterioration has been detected. As a result, the partial discharge diagnostic device 100 according to the second embodiment can diagnose treey deterioration. Note that the partial discharge diagnostic device 100 according to the second embodiment determines the presence or absence of surge voltage based on historical data acquired from the multi-relay device 120, but is not limited to this. The partial discharge diagnostic device 100 according to other embodiments may determine the presence or absence of surge voltage by analyzing waveform data stored in the electrical signal storage unit 104. In this case, the partial discharge diagnostic device 100 may issue an alarm as moderate deterioration information before a surge voltage occurs and exceeds a threshold, and then issue an alarm as severe deterioration information when it is determined to be treey. An example of moderate deterioration information would be an alarm stating, "A surge voltage has been detected. This may affect the equipment. Maintenance is recommended." An example of severe deterioration information would be an alarm stating, "Treey discharge has been detected. There is a high possibility of failure. Early inspection is recommended." Thus, the partial discharge diagnostic device 100 may provide different alarm information depending on the deterioration state.
[0045] (Third embodiment) The partial discharge diagnostic device 100 according to the third embodiment diagnoses that the electrical equipment is undergoing treey deterioration when a pulse group is detected, after a certain amount of damage has been accumulated due to past partial discharges, in order to avoid misdiagnosis of treey deterioration. This is because partial discharges can accelerate the deterioration of the insulating parts of the electrical equipment, and this progression of deterioration may lead to treey deterioration. The larger the charge amount of the partial discharge, the more likely the deterioration is to progress. Therefore, the accumulation of charge amounts from partial discharges can be said to represent the history of damage to the power equipment.
[0046] Figure 7 is a flowchart showing the diagnostic process of the partial discharge diagnostic device 100 according to the third embodiment. The electrical signal acquisition unit 161 of the partial discharge diagnostic device 100 acquires electrical signals from the electrodes 110 while the power equipment is in operation, and records waveform data representing the signal waveform of the electrical signals in the electrical signal storage unit 104 in association with time. As a result, waveform data is accumulated in the electrical signal storage unit 104.
[0047] When the partial discharge diagnostic device 100 starts the diagnostic process in accordance with instructions from the administrator, the partial discharge diagnostic device 100 performs the processing from step S1 to step S4 in the same manner as in the first embodiment. In the third embodiment, the partial discharge diagnostic unit 166 generates a φ-q distribution based on the pulses classified as individual pulses in step S4 (step S8). From the generated φ-q distribution, the partial discharge diagnostic unit 166 calculates the cumulative value of the charge amount due to partial discharge included in the waveform data recorded in the electrical signal storage unit 104 (step S41).
[0048] Next, in step S4, the partial discharge diagnostic unit 166 determines whether the pulse group extraction unit 164 has extracted a pulse group exceeding a threshold (step S6). If the partial discharge diagnostic unit 166 according to the third embodiment determines that a pulse group exceeding a threshold has been extracted (step S6: YES), it determines whether the cumulative value of the charge amount obtained in step S41 is equal to or greater than a predetermined threshold (step S42).
[0049] If no pulse group exceeding the threshold is extracted (Step S6: NO), or if the cumulative value of the charge is less than the threshold (Step S42: NO), it is highly likely that the extracted pulse group was caused by noise. In this case, the partial discharge diagnostic device 100 diagnoses the deterioration state of the power equipment based on the φ-q distribution generated in Step S8 and the actual data related to void discharge stored in the diagnostic information storage unit 105 (Step S9). The partial discharge diagnostic unit 166 outputs the diagnosis result of the deterioration state of the power equipment to the output unit 103 (Step S10).
[0050] On the other hand, if a group of pulses exceeding the threshold is extracted and the cumulative value of the charge amount is greater than or equal to the threshold (step S42: YES), it is highly likely that the extracted group of pulses was caused by treey degradation. In this case, the partial discharge diagnostic unit 166 causes the output unit 103 to output an alarm indicating that treey degradation has occurred (step S11).
[0051] Thus, the partial discharge diagnostic unit 166 of the partial discharge diagnostic device 100 according to the third embodiment determines that a pulse group is due to treey discharge when a pulse group consisting of multiple pulses generated within a minute time exceeds a predetermined threshold, and the cumulative value of the charge amount related to the partial discharge exceeds a predetermined threshold. In other words, when deterioration has occurred in the insulating part due to past partial discharge, the partial discharge diagnostic unit 166 can estimate that the pulse group is due to treey deterioration rather than noise, because a pulse group that may be caused by treey deterioration has been detected. As a result, the partial discharge diagnostic device 100 according to the third embodiment can diagnose treey deterioration.
[0052] (Fourth embodiment) In the fourth embodiment, the partial discharge diagnostic device 100 diagnoses that the electrical equipment is experiencing treey deterioration when a pulse group is detected, after a certain amount of damage has been accumulated due to past partial discharges, in order to avoid misdiagnosis of treey deterioration. This is because partial discharges can accelerate the deterioration of the insulating parts of the electrical equipment, and this progression of deterioration may lead to treey deterioration. In the fourth embodiment, the progression of deterioration is estimated using the diagnostic results based on void discharge. Therefore, the diagnostic results based on void discharge can be said to represent the history of damage to the power equipment.
[0053] Figure 8 is a flowchart showing the diagnostic process of the partial discharge diagnostic device 100 according to the fourth embodiment. The electrical signal acquisition unit 161 of the partial discharge diagnostic device 100 acquires electrical signals from the electrodes 110 while the power equipment is in operation, and records waveform data representing the signal waveform of the electrical signals in the electrical signal storage unit 104 in association with time. As a result, waveform data is accumulated in the electrical signal storage unit 104.
[0054] When the partial discharge diagnostic device 100 starts the diagnostic process in accordance with instructions from the administrator, the partial discharge diagnostic device 100 performs the processes from step S1 to step S4 in the same manner as in the first embodiment. Next, the partial discharge diagnostic device 100 estimates the deterioration state of the power equipment from the pulses related to void discharge in the same manner as in steps S8 to S9 of the first embodiment.
[0055] Next, in step S4, the partial discharge diagnostic unit 166 determines whether the pulse group extraction unit 164 has extracted a pulse group exceeding a threshold (step S6). If the partial discharge diagnostic unit 166 according to the fourth embodiment determines that a pulse group exceeding a threshold has been extracted (step S6: YES), it determines whether the degradation state estimated in step S9 is above a predetermined level (step S61).
[0056] If no pulse group exceeding the threshold is extracted (step S6: NO), or if the degradation state is below a predetermined level (step S61: NO), it is highly likely that the extracted pulse group was caused by noise. In this case, the partial discharge diagnostic device 100 outputs the diagnostic result obtained in step S9 to the output unit 103 (step S10).
[0057] On the other hand, if a group of pulses exceeding a threshold is extracted and the degradation state is above a predetermined level (step S61: YES), it is highly likely that the extracted group of pulses was caused by treey degradation. In this case, the partial discharge diagnostic unit 166 causes the output unit 103 to output an alarm indicating that treey degradation has occurred (step S11).
[0058] Thus, the partial discharge diagnostic unit 166 of the partial discharge diagnostic device 100 according to the fourth embodiment extracts a group of pulses, which are multiple pulses generated within a minute time, and determines that the pulse group is due to treey discharge when the degradation state due to void discharge in step S10 exceeds a predetermined level. When degradation has occurred in the insulating part due to past void discharge, the detection of a pulse group that may be due to treey degradation allows it to be estimated that the pulse group is due to treey degradation and not noise. As a result, the partial discharge diagnostic device 100 according to the fourth embodiment can diagnose treey degradation. In this case, the partial discharge diagnostic device 100 may issue an alarm as mild deterioration information before the deterioration state due to void discharge exceeds a predetermined level, and then issue an alarm as severe deterioration information when it is determined to be treey discharge. An example of mild deterioration information would be an alarm stating, "Partial discharge has been detected. Maintenance is recommended." An example of severe deterioration information would be an alarm stating, "Treey discharge has been detected. There is a high possibility of failure. Early inspection is recommended." Thus, the partial discharge diagnostic device 100 may provide different alarm information depending on the deterioration state.
[0059] As described above, the partial discharge diagnostic device 100 according to the embodiment performs the following processing. The pulse group extraction unit 164 extracts a pulse group, which is a group of pulses generated within a predetermined minute time, from the signal related to the partial discharge generated from the electrical equipment to be diagnosed. When a pulse group is extracted, the partial discharge diagnostic device 166 determines whether the pulse group is due to treey partial discharge based on the history of damage to the electrical equipment. In this way, the partial discharge diagnostic device 100 can diagnose treey degradation while preventing misdiagnosis due to noise by using the pulse group and the history of damage to the electrical equipment.
[0060] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.
[0061] For example, the partial discharge diagnostic device 100 according to the above embodiment diagnoses power receiving and distribution equipment such as switchgears housed in the enclosure 10, but is not limited to this. For example, the partial discharge diagnostic device 100 according to another embodiment may diagnose other electrical equipment such as electrical equipment having molded coils (molded transformers, rotating machines, generators, motors, etc.). In this case as well, the partial discharge diagnostic device 100 can diagnose the condition of the electrical equipment by attaching electrodes 110 to the grounded portion of the enclosure in which the electrical equipment to be diagnosed is housed. [Explanation of symbols]
[0062] 10... Enclosure 100... Partial discharge diagnostic device 101... Communication unit 102... Input unit 103... Output unit 104... Electrical signal storage unit 105... Diagnostic information storage unit 106... Control unit 110... Electrode 120... Multi-relay device 161... Electrical signal acquisition unit 162... Filter unit 163... Pulse identification unit 164... Pulse group extraction unit 165... Acquisition unit 166... Partial discharge diagnostic unit 20... Grounding bus 30... Grounding electrode
Claims
1. A pulse group extraction unit extracts a pulse group, which consists of multiple pulses generated within a predetermined minute time, from a signal related to partial discharge generated from the electrical equipment to be diagnosed. A partial discharge diagnostic unit determines, based on the history of damage to the electrical equipment, whether the pulse group is due to a tree-like partial discharge when the pulse group is extracted, A partial discharge diagnostic device equipped with the following features.
2. The damage history is the length of time the electrical equipment has been in use, The partial discharge diagnostic unit determines that the pulse group is due to tree-type discharge when the pulse group is extracted and the length of the usage period exceeds a predetermined threshold. The partial discharge diagnostic device according to claim 1.
3. The damage history is the number of times a surge voltage occurred in the electrical equipment, The partial discharge diagnostic unit determines that the pulse group is due to tree-type discharge when the pulse group is extracted and the number of surge voltage occurrences exceeds a predetermined threshold. The partial discharge diagnostic device according to claim 1.
4. The damage history is the cumulative value of the amount of charge related to the partial discharge that occurred in the electrical equipment, The partial discharge diagnostic unit determines that the pulse group is a tree-type discharge when the pulse group is extracted and the cumulative value of the charge amount related to the partial discharge exceeds a predetermined threshold. The partial discharge diagnostic device according to claim 1.
5. The partial discharge diagnostic unit estimates the deterioration state of the electrical equipment as a damage history based on pulses related to voidy partial discharges included in the signal relating to partial discharge generated from the electrical equipment. The partial discharge diagnostic unit determines that the pulse group is due to tree-type discharge when the pulse group is extracted and the estimated degradation state exceeds a predetermined degree of degradation. The partial discharge diagnostic device according to claim 1.
6. An acquisition unit that acquires information representing the history of damage to the electrical equipment from a digital relay device installed in the electrical equipment. A partial discharge diagnostic device according to claim 1, comprising:
7. The pulse group extraction unit extracts the pulse group consisting of two or more pulses that occurred within 5 microseconds. The partial discharge diagnostic device according to claim 1.
8. The pulse group extraction unit extracts the partial signals for each minute time interval from the signal relating to the partial discharge, and if there are two or more pulses in the partial signal, it extracts those two or more pulses as the pulse group. The partial discharge diagnostic device according to claim 7.
9. The steps include: extracting a group of pulses, which are multiple pulses generated within a predetermined minute time, from a signal related to partial discharge generated from the electrical equipment to be diagnosed; If the pulse group is extracted, the step of determining whether the pulse group is due to a tree-like partial discharge based on the history of damage to the electrical equipment, A partial discharge diagnostic method comprising the following features.
10. The steps include: extracting a group of pulses, which are multiple pulses generated within a predetermined minute time, from a signal related to partial discharge generated from the electrical equipment to be diagnosed; If the aforementioned pulse group is extracted, the step of issuing a second alarm in a different manner from the first alarm which is issued based on the history of damage to the electrical equipment, A method for notifying deterioration of electrical equipment equipped with [a specific feature / feature].