Partial discharge monitoring device and partial discharge monitoring method

Abstract

To provide a device capable of monitoring whether or not partial discharge occurs in electric power equipment even when a worker is absent from the site. [Solution] The system includes a TEV sensor installed in a housing that houses electric power equipment, and a processing unit to which the detected voltage detected by the TEV sensor is input via a signal line. The processing unit has a phase analysis unit that performs phase analysis on the detected voltage, and a determination unit. The phase analysis unit performs phase analysis on the detected voltage input from the TEV sensor that exceeds a threshold, and identifies the angle interval to which the phase angle belongs. The determination unit identifies a first angle interval with the highest occurrence frequency, and determines that a partial discharge has occurred if at least one of the following conditions is met: a first condition that the angle interval with the next highest occurrence frequency is substantially shifted by a half cycle of the voltage phase from the first angle interval, and a second condition that the occurrence frequency of angle intervals that are substantially different from the first angle interval is equal to or less than half the occurrence frequency of the first angle interval.

Description

Technical Field

[0001] The present invention relates to a partial discharge monitoring device and a partial discharge monitoring method.

Background Art

[0002] In power receiving and transforming equipment such as transformers and high-voltage switchboards, it is important to predict the lifespan and prevent accidents in advance. For this reason, preventive maintenance has been proposed, which focuses on the precursor phenomena leading to equipment deterioration and accidents occurring in power receiving and transforming equipment and takes countermeasures in advance. One of such precursors occurring in power receiving and transforming equipment is partial discharge that occurs when the insulation function inside the power receiving and transforming equipment deteriorates.

[0003] When there are defects such as voids in the insulator of electrical equipment, partial discharge occurs. Specifically, when the voltage applied to the defect exceeds the critical voltage, that is, the spark voltage, due to partial insulation breakdown in the defect, partial discharge occurs. If this partial discharge is repeated, it may eventually lead to insulation breakdown of the entire insulator, resulting in a situation that may disrupt power transmission and distribution such as a power outage due to a ground fault. On the other hand, stopping power transmission and distribution for detecting this partial discharge is extremely complicated.

[0004] The applicant of the present application has previously proposed a technique for detecting partial discharge of an insulator without stopping power transmission and distribution, that is, in a live state. (See Patent Document 1 below)

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The method described in Patent Document 1 is to attach an ultrasonic sensor to a predetermined location on the housing that houses electrical equipment such as a cubicle, perform frequency analysis on the ultrasonic signal received by the ultrasonic sensor, and perform deterioration diagnosis based on the information of the frequency indicating the peak value.

[0007] For electrical equipment such as cubicles, it is common for workers to go to the site to perform deterioration diagnosis at predetermined intervals such as every six months or every year. The method of Patent Document 1 is also a technology assumed for workers to go to the site to perform diagnostic work such as such regular diagnosis.

[0008] If it is possible to screen in advance whether there is a possibility of partial discharge occurring in the electrical equipment, the worker can go only to the site where it is determined that there is a possibility and perform a detailed diagnosis, so it can be said to be efficient. However, the method of Patent Document 1 is not suitable for remotely monitoring the occurrence of partial discharge in an unmanned state.

[0009] In view of the above problems, an object of the present invention is to provide a partial discharge monitoring device and a partial discharge monitoring method capable of monitoring whether or not partial discharge is occurring in electrical equipment even when a worker is absent from the site.

Means for Solving the Problems

[0010] The partial discharge monitoring device according to the present invention is a device for monitoring whether or not partial discharge is occurring in electrical equipment, a TEV sensor installed on the wall surface of the electrical equipment, inside the housing that houses the electrical equipment, or on the wall surface of the housing, and a processing unit installed inside the housing, on the wall surface of the housing, or in the vicinity of the housing, and into which the detection voltage detected by the TEV sensor is input via a signal line, The processing unit includes a comparison unit that compares the detection voltage with a predetermined threshold value, a phase analysis unit that performs phase analysis on the detection voltage, A storage unit that records result information regarding the analysis result in the phase analysis unit; A determination unit that determines whether partial discharge is occurring in the power equipment based on the result information, and The phase analysis unit Performs step (a) of specifying a phase angle by performing phase analysis on the detected voltage exceeding the threshold value among the detected voltages input from the TEV sensor over a set time from the timing when the detected voltage exceeds the threshold value; Performs step (b) of outputting, as the result information, information regarding the angle interval to which the phase angle specified in step (a) belongs among a plurality of angle intervals obtained by dividing 360° according to a predetermined rule, to the storage unit, and The determination unit Performs step (c) of reading out the result information recorded in the storage unit and specifying a first angle interval that is the angle interval with the highest occurrence frequency; Performs step (d) of determining that partial discharge is occurring in the power equipment when at least one of a first condition that the angle interval with the next highest occurrence frequency after the first angle interval is an angle interval whose voltage phase is substantially shifted by a half cycle from the first angle interval, and a second condition that the occurrence frequency of an angle interval substantially different from the first angle interval is 1 / 2 or less of the occurrence frequency of the first angle interval is satisfied.

[0011] The TEV sensor, also called a "transient earth voltage sensor", is a sensor that can detect changes in transient potential at the grounding point. The ground potential can be stably detected compared with ultrasonic signals and electromagnetic wave signals detected by an antenna. Also, if the housing is in a grounded area, the same value is detected regardless of the installation location. Therefore, during diagnosis, there is no need for an operator to go to the site and search for an appropriate location to install the sensor for diagnosis while holding the sensor.

[0012] The device according to the present invention includes a TEV sensor and a processing unit. By simply installing these on the wall surface of the housing or the like, it is possible to monitor whether partial discharge is occurring in the power equipment housed in the housing. More specifically, it is as follows.

[0013] When partial discharge occurs, potential fluctuations occur at the discharge location, and accordingly, the ground voltage transiently fluctuates. Partial discharge occurs repeatedly at the same cycle as the voltage of the equipment and concentrates at a specific phase, that is, it has periodicity. According to the above device, in the determination unit of the processing unit, it is monitored whether at least one of the first condition corresponding to the condition of partial discharge occurring every half cycle of the voltage phase and the second condition corresponding to the condition of partial discharge occurring every one cycle of the voltage phase is satisfied. Therefore, it is possible to detect whether partial discharge is occurring from the power equipment. For this reason, when it is determined that partial discharge is occurring, by providing a function to notify that fact, remote monitoring of the power equipment becomes possible.

[0014] For example, the processing unit has an analog transmission processing unit that converts the detected voltage detected by the TEV sensor into a direct current within the range of 4 mA to 20 mA, which is a unified signal for instrumentation, and outputs it. After it is determined in the determination unit that partial discharge is occurring in the power equipment, the analog transmission processing unit may hold the peak value of the detected voltage input from the TEV sensor for a predetermined time of 0.1 seconds or more, and convert it into a current value within the range of 4 mA to 20 mA according to the height of the held peak value and output it.

[0015] According to this configuration, when it is determined that the power equipment housed in the housing is generating partial discharge, it is output from the analog transmission processing unit as a current signal suitable for the standard of the unified signal for instrumentation. This makes it possible to incorporate it into an existing monitoring system that monitors information such as the temperature and humidity of other equipment. Furthermore, since a current amount corresponding to the magnitude of the ground voltage is generated, the magnitude of the partial discharge can be roughly grasped.

[0016] As another example, when it is determined in the determination unit that partial discharge is occurring in the power equipment, the processing unit may have a communication processing unit that transmits information to that effect to a person-in-charge terminal at a location away from the installation location of the housing via e-mail, a short message, or the Internet.

[0017] Since the partial discharge monitoring device having the above configuration uses a TEV sensor, when a plurality of power equipment is housed in the housing, it cannot determine which power equipment the partial discharge is occurring from. Therefore, it can be said that this device is more suitable when used as a primary screening for determining whether it is necessary to visit the site for deterioration diagnosis.

[0018] The step (c) may be a step of specifying, as the first angular interval, the angular interval having the highest occurrence frequency and the number of occurrence frequencies exceeding the lower threshold value.

[0019] By configuring in this way, even when the ground potential fluctuates due to noise or the like, false determination based on the same result can be suppressed.

[0020] The first condition corresponds to a condition that a second angular interval having the next highest occurrence frequency after the first angular interval is outside the range of ±k0° sandwiching the first angular interval and is separated from the first angular interval by an angle within the range of (180 - k1)° or more and (180 + k1)° or less, and the numerical values corresponding to k0 and k1 may be changeable.

[0021] In this case, k0 and k1 may be natural numbers of 50 or less. Note that the values of k0 and k1 may be the same or different.

[0022] The second condition corresponds to a condition that the occurrence frequency of the angle interval corresponding to the outside of the range of ±k2° sandwiching the first angle interval is 1 / 2 or less of the occurrence frequency of the first angle interval, and the numerical value corresponding to k2 may be changeable.

[0023] In this case, k2 may be a natural number of 20 or less.

[0024] The partial discharge monitoring method according to the present invention uses the partial discharge monitoring device having the above configuration, and monitors whether or not partial discharge is occurring in the power equipment when no operator is present in the vicinity of the housing that houses the power equipment.

Effect of the Invention

[0025] According to the partial discharge monitoring device and the partial discharge monitoring method of the present invention, it is possible to monitor whether or not partial discharge is occurring in the power equipment even when the operator is not present at the site.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiment for Carrying Out the Invention

[0027] Embodiments of the partial discharge monitoring device and the partial discharge monitoring method according to the present invention will be described below with appropriate reference to the drawings. Note that each of the following drawings is schematically shown, and the dimensional ratios and the number of elements on the drawings do not necessarily match the actual dimensional ratios and the number of elements.

[0028] FIG. 1 is a drawing schematically showing a state of monitoring whether or not partial discharge is occurring in an electric power apparatus using the partial discharge monitoring device of the present embodiment. FIG. 2 is a functional block diagram schematically showing the configuration of the partial discharge monitoring device of the present embodiment.

[0029] The partial discharge monitoring device 10 includes a TEV sensor 1 and a processing unit 2. The TEV sensor 1 is a sensor that detects a transient change in the ground potential. In the example shown in FIG. 1, the electric power apparatus to be monitored is a transformer 4 in a cubicle 3, and the TEV sensor 1 is attached to the wall surface 9 of the cubicle 3. Note that examples of the electric power apparatus that can be monitored by the partial discharge monitoring device 10 according to the present invention include, in addition to the transformer 4, a switch, a circuit breaker, a bushing, and the like.

[0030] Since the wall surface 9 of the cubicle 3 normally shows the ground potential, by attaching the TEV sensor 1 to this location, a transient ground voltage can be detected. From this viewpoint, the attachment location of the TEV sensor 1 is not limited to the outer wall surface 9 of the cubicle 3, and may be any location near the transformer 4 where the ground potential is ensured. For example, the attachment location of the TEV sensor 1 may be the inner wall surface of the cubicle 3, or may be a predetermined position inside the cubicle 3 that is electrically connected to the wall surface.

[0031] The processing unit 2 is connected to the TEV sensor 1 by the signal line 5, and the transient ground voltage detected by the TEV sensor 1 (hereinafter referred to as "detected voltage Vi") is input. As shown in FIG. 2, the processing unit 2 includes a signal input reception unit 21, a determination processing unit 22, and an output processing unit 23.

[0032] In the example shown in FIG. 1, the processing unit 2 is attached to the outer wall surface 9 of the cubicle 3, similar to the TEV sensor 1. However, the attachment position of the processing unit 2 is not limited as long as it can be connected to the TEV sensor 1 by the signal line 5. That is, the attachment position of the processing unit 2 may be inside the cubicle 3 or in the vicinity outside the cubicle 3. However, from the viewpoint of avoiding accidental contact by a third party, it is preferable that the processing unit 2 is fixed to the wall surface of the cubicle 3 or housed inside the cubicle 3.

[0033] The signal input reception unit 21 shown in FIG. 2 is an interface that receives the input of the detected voltage Vi from the TEV sensor 1. For example, when the signal line 5 is a coaxial cable, the signal input reception unit 21 corresponds to the cable jack.

[0034] In the present embodiment, the determination processing unit 22 includes a clock unit 31, a comparison unit 32, a phase analysis unit 33, a storage unit 34, and a determination unit 35. The output processing unit 23 includes an analog transmission processing unit 38 and a communication processing unit 39.

[0035] FIG. 3 is a flowchart showing an example of a partial discharge determination processing procedure executed by the partial discharge monitoring device 10. Hereinafter, with reference to the flowchart of FIG. 3, the functions of each element included in the processing unit 2 will be described. In the following description, the step numbers in FIG. 3 are appropriately referred to.

[0036] The signal input reception unit 21 receives the input of the detected voltage Vi from the TEV sensor 1 (step #1).

[0037] The comparison unit 32 is a circuit that compares the detected voltage Vi from the TEV sensor 1 with a reference threshold voltage Vth. The comparison unit 32 is provided to prevent the determination process of the presence or absence of partial discharge from being performed when the detected voltage Vi is noise. That is, as the threshold voltage, a value exceeding the noise level and being the lowest value that may occur if partial discharge occurs is set. This threshold voltage may be adjusted as appropriate.

[0038] In the comparison unit 32, when it is detected that the detected voltage Vi from the TEV sensor 1 exceeds the reference threshold voltage Vth (Yes in step #2), the phase analysis unit 33 performs a phase analysis of the detected voltage Vi, and information regarding the analysis result is recorded in the storage unit 34 (step #3). More specifically, an angular range corresponding to the phase angle at which the detected voltage Vi appears is recorded in the storage unit 34. When the detected voltage Vi is equal to or lower than the threshold voltage Vth (No in step #2), steps #1 to #2 are continuously repeated.

[0039] The phase analysis unit 33 is a functional means that recognizes the temporal change of the detected voltage Vi and performs a phase analysis. For example, it is an analyzer capable of performing intensity analysis for each phase angle. The phase analysis unit 33 specifies the phase angle corresponding to the detected voltage Vi.

[0040] The phase analysis unit 33 further determines the angular range to which the specified phase angle belongs. An example of the angular range is shown in Table 1.

[0041]

Table 1

[0042] In the example of Table 1, the case where 360° is divided into 128 angular intervals is shown. For example, when the phase analysis unit 33 determines that the phase angle of the detected voltage Vi is 3.0°, it is specified that the angular interval to which the detected voltage Vi belongs is interval 2. Note that the number of divisions is not limited to 128, but from the viewpoint of ensuring a certain accuracy, the angular range for specifying each angular interval is preferably within 5°, more preferably within 4°, and particularly preferably within 3°. In the example of Table 1, the angular range for specifying each angular interval is set to approximately 2.8°.

[0043] The information regarding the angular interval thus specified is recorded in the storage unit 34. The storage unit 34 is a storage area such as a flash memory.

[0044] Steps #1 to #3 above are executed until a predetermined set time elapses after it is first detected that the detected voltage Vi from the TEV sensor 1 exceeds the reference threshold voltage Vth. As a result, information regarding the phase of the detected voltage Vi that exceeds the threshold voltage Vth, that is, information regarding the angular interval, is successively recorded in the storage unit 34 until the set time elapses. In this way, the information regarding the angular interval recorded in the storage unit 34 corresponds to the "result information".

[0045] When the set time elapses after it is first detected that the detected voltage Vi from the TEV sensor 1 exceeds the reference threshold voltage Vth (Yes in step #4), in the determination unit 35, based on the result information recorded in the storage unit 34, the first angular interval Φ1, which is the angular interval with the highest occurrence frequency, is extracted (step #5). The determination unit 35 is, for example, an arithmetic processor such as a CPU or an MPU.

[0046] Here, the set time may be recorded in the storage unit 34 in advance. Also, the set time may be configured to be changeable from the outside as appropriate. An example of the set time is 10 seconds. Whether the set time has elapsed is detected by the clock unit 31. The clock unit 31 is a means capable of measuring the elapsed time since a predetermined condition was satisfied. The clock unit 31 may be a general-purpose clock or a device that realizes a clock-equivalent function.

[0047] When the determination unit 35 extracts the first angle range Φ1, it determines whether at least one of the first condition S1 and the second condition S2 is satisfied according to the following steps #6 and #7.

[0048] The determination unit 35 reads out the result information recorded in the storage unit 34 and determines the second angle range Φ2 with the next highest occurrence frequency after the first angle range Φ1. Then, it is determined whether this second angle range Φ2 is outside the range of ±k0° sandwiching the first angle range and is an angle range in which the voltage phase is substantially shifted by a half cycle from the first angle range Φ1. The establishment condition of this determination corresponds to the first condition S1.

[0049] The first condition S1 is a condition corresponding to whether the second angle range Φ2 is an angle range substantially different from the first angle range Φ1 and is separated from the first angle range Φ1 by an angle within the range of (180 - k1)° or more and (180 + k1)° or less. Here, the values of k0 and k1 are typically positive numbers of 50 or less, and more typically positive numbers of 40 or less. These values of k0 and k1 are recorded in the storage unit 34 in advance and may be configured to be changeable from the outside as appropriate. Note that the value of k1 may be adopted as the value of k0.

[0050] The fact that the first condition S1 is satisfied means that a transient ground voltage (detected voltage Vi) greater than the noise level, as confirmed from cubicle 3, occurs every half cycle of the voltage phase. In such a case, there is a high possibility that partial discharge has occurred in the transformer 4 within cubicle 3. Therefore, when the determination unit 35 confirms that the first condition S1 is satisfied (Yes in step #6), it determines that partial discharge has occurred in the transformer 4 within cubicle 3 (step #8).

[0051] The determination unit 35 further reads out the result information recorded in the storage unit 34 and determines whether the occurrence frequency of the voltage phase of the transient ground voltage (detected voltage Vi) occurs substantially only within the first angular interval Φ1. The establishment condition of this determination corresponds to the second condition S2.

[0052] The second condition S2 corresponds to whether the occurrence frequency of the voltage phase of the transient ground voltage (detected voltage Vi) belonging to an angular interval corresponding to the outside of the range of ±k2° sandwiching the first angular interval Φ1, that is, an angular interval that can be regarded as substantially outside the first angular interval Φ1, is 1 / 2 or less of the occurrence frequency of the voltage phase of the transient ground voltage (detected voltage Vi) belonging to the first angular interval Φ1. Here, the value of k2 is typically a positive number of 20 or less, and more typically a positive number of 10 or less. The value of k2 is recorded in the storage unit 34 in advance and may be configured to be changeable from the outside as appropriate. The reason for setting the value of k2 is to consider that the phases corresponding to the angular intervals in the range of ±k2° sandwiching the first angular interval Φ1 are in the same phase as the first angular interval Φ1.

[0053] The fact that the second condition S2 is satisfied means that a transient ground voltage (detected voltage Vi) greater than the noise level, as confirmed from cubicle 3, occurs every cycle of the voltage phase. In such a case, there is a high possibility that partial discharge has occurred in the transformer 4 within cubicle 3. Therefore, when the determination unit 35 confirms that the second condition S2 is satisfied (Yes in step #7), it determines that partial discharge has occurred in the transformer 4 within cubicle 3 (step #8).

[0054] On the other hand, when the determination unit 35 confirms that neither the first condition S1 nor the second condition S2 is satisfied (both No in steps #6 and #7), the detection voltage Vi received in a magnitude exceeding the threshold voltage Vth is determined to be noise (step #10).

[0055] Note that in FIG. 3, it is described that step #7 is executed when step #6 is No, but this is just an example. For example, the execution order of step #6 and step #7 may be reversed, or even if one of step #6 and step #7 is Yes, the other step may also be executed.

[0056] In step #8, when it is determined in the determination unit 35 that partial discharge has occurred in the transformer 4 in the cubicle 3, output processing to that effect is executed in the output processing unit 23 (step #9).

[0057] The processing unit 2 of the present embodiment shown in FIG. 2 has an analog transmission processing unit 38 and a communication processing unit 39 as the output processing unit 23.

[0058] The analog transmission processing unit 38 is a circuit that converts the detection voltage Vi input from the TEV sensor 1 into a direct current Io within the range of 4 mA to 20 mA, which is a unified signal for instrumentation defined by the IEC (International Electrotechnical Commission), and outputs it. As shown in FIGS. 1 and 2, the processing unit 2 is connected with a transmission signal line 6 for outputting the direct current Io. This transmission signal line 6 is connected to a standardized central monitoring system into which instrumentation signals of other facilities are input.

[0059] FIG. 4 is a graph schematically showing an example of the direct current Io output from the analog transmission processing unit 38. When partial discharge occurs in the transformer 4 in the cubicle 3, it is assumed that the TEV sensor 1 continuously outputs a detection voltage Vi whose magnitude is derived from the partial discharge. The analog transmission processing unit 38 converts it into a direct current Io within the range of 4 mA to 20 mA according to the magnitude of the detection voltage Vi and outputs it to the transmission signal line 6. Thereby, on the central monitoring system side, it can be confirmed that there may be partial discharge in the transformer 4 in the cubicle 3. That is, even when there is no operator in the cubicle 3, by checking the central monitoring system, it is possible to remotely recognize that there may be partial discharge in the transformer 4 in the cubicle 3.

[0060] As an example, when the detection voltage Vi is 10 mV or less, the analog transmission processing unit 38 generates a direct current Io of 4 mA, and when the detection voltage Vi is 900 mV or more, it generates a direct current Io of 20 mA. When the detection voltage Vi is within the range of 10 mV to 900 mV, it generates and outputs a direct current Io obtained by proportional distribution according to the magnitude of the detection voltage Vi.

[0061] Note that the detection voltage Vi output from the TEV sensor 1 is a signal that is confirmed over an extremely short time (for example, on the order of microseconds to several hundred microseconds). In other words, as schematically shown in FIG. 5, the time Ta during which the detection voltage Vi is confirmed is an extremely short time. On the other hand, as schematically shown in FIG. 6, the sampling period Ts applied in the central monitoring system to which the instrumentation signals of other facilities are input is at most about 0.1 second. Therefore, even if an attempt is made to directly convert the detection voltage Vi into a current signal, there may be cases where it cannot be sampled.

[0062] Therefore, as shown in FIG. 7, the analog transmission processing unit 38 holds the peak value of the detection voltage Vi output from the TEV sensor 1 for a predetermined time Ta of 0.1 second or more, and then converts it into a current value at a timing synchronized with the sampling period Ts applied in the central monitoring system. Thereby, the information of the monitoring result obtained by the present invention can be added to the central monitoring system into which the instrumentation signals of other existing facilities are input.

[0063] The communication processing unit 39 is a functional means for transmitting an e-mail, a short message, a chat, etc. to the terminal of the person in charge using a telecommunication line 7 such as Internet communication. That is, in step #8, when it is determined in the determination unit 35 that partial discharge has occurred in the transformer 4 in the cubicle 3, notification information to that effect is created by the communication processing unit 39 and notified to the terminal of the person in charge (for example, a computer or a smartphone). Thereby, even when there is no operator in the cubicle 3, it is possible to remotely recognize that partial discharge may have occurred in the transformer 4 in the cubicle 3.

[0064] Note that the output processing unit 23 may be configured to include only one of the analog transmission processing unit 38 and the communication processing unit 39.

[0065] [Another Embodiment] Hereinafter, another embodiment will be described.

[0066] 〈1〉 In step #5, the determination unit 35 may determine that the detection voltage Vi input from the TEV sensor 1 is a voltage signal derived from noise when the frequency of occurrence in the angular interval with the highest frequency of occurrence is equal to or less than a predetermined lower threshold value. In this case, steps #6 to #7 may not be executed, and after step #10, it may return to step #1 again.

[0067] The information regarding the lower threshold value related to this frequency of occurrence may be recorded in the storage unit 34 in advance, or may be configured to be changeable from the outside as appropriate. An example of the lower threshold value is three times.

[0068] <2>In the example shown in FIG. 1, a case where a plurality of transformers 4 are housed in the cubicle 3 is shown. However, the number of power equipment represented by the transformer 4 housed in the housing represented by the cubicle 3 may be single. In this case, the TEV sensor 1 may be attached to the wall surface of the transformer 4.

[0069] <3>When the output processing unit 23 has the analog transmission processing unit 38, it may always output the direct current Io to the central monitoring system via the transmission signal line 6 regardless of the determination result in the determination unit 35. However, in this case, when the occurrence of partial discharge is not detected by the determination unit 35, the output processing unit 23 may output a direct current Io of 4 mA.

[0070] <4>The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for better understanding of the present invention, and are not necessarily limited to those having all the configurations described. The scope of the present invention is indicated by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

Explanation of Reference Numerals

[0071] 1: TEV sensor 2: Processing unit 3: Cubicle 4: Transformer 5: Signal line 6: Transmission signal line 7: Telecommunication line 9: Wall surface 10: Partial discharge monitoring device 21: Signal input reception unit 22: Determination processing unit 23: Output processing unit 31: Clock unit 32: Comparison unit 33: Phase analysis unit 34: Storage unit 35: Determination Unit 38: Analog Transmission Processing Unit 39: Communication Processing Unit

Claims

1. A partial discharge monitoring device for monitoring whether partial discharge is occurring in an electrical apparatus, comprising: a TEV sensor installed on the wall surface of the electrical apparatus, inside the housing that houses the electrical apparatus, or on the wall surface of the housing; a processing unit installed inside the housing, on the wall surface of the housing, or in the vicinity of the housing, to which the detection voltage detected by the TEV sensor is input via a signal line; the processing unit includes: a comparison unit that compares the detection voltage with a predetermined threshold value; a phase analysis unit that performs phase analysis on the detection voltage; a storage unit that records result information regarding the analysis result in the phase analysis unit; a determination unit that determines whether partial discharge is occurring in the electrical apparatus based on the result information; the phase analysis unit: performs step (a) of specifying a phase angle by performing phase analysis on the detection voltage exceeding the threshold value among the detection voltages input from the TEV sensor over a set time period from the timing when the detection voltage exceeds the threshold value; performs step (b) of outputting, as the result information, information regarding the angle interval to which the phase angle specified in step (a) belongs among a plurality of angle intervals obtained by dividing 360° according to a predetermined rule, to the storage unit; the determination unit: performs step (c) of reading out the result information recorded in the storage unit and specifying a first angle interval that is the angle interval with the highest occurrence frequency; performs step (d) of determining that partial discharge is occurring in the electrical apparatus when at least one of a first condition that the angle interval with the next highest occurrence frequency after the first angle interval is an angle interval whose voltage phase is substantially shifted by a half cycle from the first angle interval, and a second condition that the occurrence frequency of the angle interval substantially different from the first angle interval is equal to or less than 1 / 2 of the occurrence frequency of the first angle interval, is satisfied. The partial discharge monitoring device is characterized by the above.

2. The partial discharge monitoring device according to claim 1, wherein step (c) is a step of specifying, as the first angle interval, the angle interval having the highest occurrence frequency and the number of occurrence times exceeding a lower threshold value.

3. The first condition corresponds to a condition that the second angle interval with the next highest occurrence frequency after the first angle interval is outside the range of ±k0° sandwiching the first angle interval and is separated from the first angle interval by an angle within the range of (180 - k1)° or more and (180 + k1)° or less. The partial discharge monitoring device according to claim 1, characterized in that the numerical values corresponding to the k0 and the k1 are changeable.

4. The partial discharge monitoring device according to claim 3, characterized in that the k1 is a positive number of 50 or less.

5. The second condition corresponds to a condition that the occurrence frequency of the angle interval corresponding to the outside of the range of ±k2° sandwiching the first angle interval is 1 / 2 or less of the occurrence frequency of the first angle interval. The partial discharge monitoring device according to claim 1, characterized in that the numerical value corresponding to the k2 is changeable.

6. The partial discharge monitoring device according to claim 3, characterized in that the k2 is a positive number of 20 or less.

7. The processing unit has an analog transmission processing unit that converts the detection voltage detected by the TEV sensor into a direct current within the range of 4 mA to 20 mA, which is a unified signal for instrumentation, and outputs it. The analog transmission processing unit holds the peak value of the detection voltage input from the TEV sensor for a predetermined time of 0.1 seconds or more after it is determined in the determination unit that partial discharge has occurred in the power equipment, and according to the height of the held peak value, converts it into a current value within the range of 4 mA to 20 mA and outputs it. The partial discharge monitoring device according to any one of claims 1 to 6.

8. The processing unit has a communication processing unit that, when it is determined in the determination unit that partial discharge has occurred in the power equipment, transmits information to that effect to a person-in-charge terminal at a position away from the installation location of the housing through e-mail or the Internet. The partial discharge monitoring device according to any one of claims 1 to 6.

9. A partial discharge monitoring method, characterized in that the partial discharge monitoring device according to claim 7 is used to monitor whether partial discharge is occurring in the power equipment when there is no operator in the vicinity of the housing that houses the power equipment.

10. A partial discharge monitoring method, characterized in that the partial discharge monitoring device according to claim 8 is used to monitor whether partial discharge is occurring in the power equipment when there is no operator in the vicinity of the housing that houses the power equipment.

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