Partial discharge monitoring apparatus and partial discharge monitoring method

Abstract

To provide an apparatus capable of monitoring whether or not partial discharge is occurring in electric power equipment even when no operator is present at a site.SOLUTION: A partial discharge monitoring apparatus comprises a TEV sensor installed on a housing that stores electric power equipment and a processing unit to which a detection voltage sensed by the TEV sensor is inputted via a signal line. The processing unit has a phase analysis part and a determination part. The phase analysis part performs phase analysis on detection voltages inputted from the TEV sensor that exceed a threshold and recognizes an angle interval to which phase angles belong. The determination part identifies a first angle interval with the highest occurrence frequency and determines that partial discharge is occurring when at least one of the following conditions is satisfied: a second angle interval with the next highest occurrence frequency is substantially half a cycle apart in voltage phase from the first angle interval, or the occurrence frequency of any angle interval substantially different from the first angle interval is one-half or less of the occurrence frequency of the first angle interval.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] For substation equipment such as transformers and high-voltage panels, it is important to predict the end of their service life and prevent accidents before they occur. For this reason, preventive maintenance has been proposed, focusing on precursory phenomena that lead to equipment deterioration and accidents in substation equipment and taking measures in advance. One such precursory phenomenon that occurs in substation equipment is partial discharge, which occurs when the insulation function within the equipment deteriorates.

[0003] Partial discharge occurs when defects such as voids exist in the insulators of electric power equipment. Specifically, partial discharge occurs when the voltage applied to the defect exceeds the critical voltage, i.e., spark voltage, due to partial breakdown at the defect. If this partial discharge occurs repeatedly, it may eventually lead to breakdown of the entire insulator, which may cause a power outage due to a ground fault, disrupting power transmission and distribution. However, stopping power transmission and distribution to detect this partial discharge is extremely cumbersome.

[0004] The applicant has previously proposed a technology for detecting partial discharge in an insulator without stopping power transmission and distribution, i.e., while the line is live (see Patent Document 1 below). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6322661 Summary of the Invention [Problem to be solved by the invention]

[0006] The method described in Patent Document 1 involves attaching an ultrasonic sensor to a predetermined location in a cubicle or other enclosure that houses power equipment, analyzing the frequency of the ultrasonic signal received by the ultrasonic sensor, and performing deterioration diagnosis based on information on the frequency that indicates the peak value.

[0007] Generally, deterioration diagnosis of electric power equipment such as cubicles is performed by workers at predetermined intervals, such as every six months or every year. The method of Patent Document 1 is also a technology that assumes that workers will go to the site to perform such periodic diagnosis.

[0008] If it were possible to screen in advance whether or not there is a possibility of partial discharge occurring in electric power equipment, it would be possible to have workers go to only those sites where it is determined that there is a possibility and perform a detailed diagnosis, which would be efficient. However, the method of Patent Document 1 is not suitable for remotely monitoring the occurrence of partial discharge in an unmanned environment.

[0009] In view of the above-mentioned problems, an object of the present invention is to provide a partial discharge monitoring device and a partial discharge monitoring method that can monitor whether or not partial discharge is occurring in electric power equipment even when no workers are present at the site. [Means for solving the problem]

[0010] The partial discharge monitoring device according to the present invention is a device for monitoring whether or not partial discharge occurs in an electric power device, a TEV sensor installed on a wall surface of the electric power device, in a housing that houses the electric power device, or on a wall surface of the housing; a processing unit that is installed inside the housing, on a wall surface of the housing, or in the vicinity of the housing, and to which a detection voltage detected by the TEV sensor is input via a signal line; The processing unit a comparison unit that compares the detected voltage with a predetermined threshold; a phase analysis unit that performs a phase analysis on the detected voltage; a storage unit that records result information relating to the analysis result of the phase analysis unit; a determination unit that determines whether or not a partial discharge has occurred in the electric power device based on the result information, The phase analysis unit a step (a) of performing a phase analysis on the detected voltages input from the TEV sensor that exceed the threshold for a set time from the timing at which the detected voltage exceeds the threshold to identify a phase angle; and (b) outputting, as the result information, information about the angle section to which the phase angle identified in (a) belongs, among a plurality of angle sections obtained by dividing 360° according to a predetermined rule, to the storage unit; The determination unit a step (c) of reading out the result information recorded in the storage unit and identifying a first angle section that is the angle section with the highest occurrence frequency; and (d) determining that partial discharge is occurring in the electric power equipment when at least one of the following conditions is satisfied: a first condition is that the angle interval having the next highest occurrence frequency after the first angle interval is the angle interval that is substantially shifted by half a voltage phase from the first angle interval; and a second condition is that the occurrence frequency of the angle interval that is substantially different from the first angle interval is not more than half the occurrence frequency of the first angle interval.

[0011] TEV sensors, also known as "transient earth voltage sensors," are sensors that can detect transient changes in potential at grounded points. Ground potential can be detected more stably than ultrasonic signals or electromagnetic signals detected by antennas. Furthermore, the same value is detected no matter where the sensor is installed, as long as the enclosure is grounded. This eliminates the need for workers to go to the site and carry the sensor while searching for an appropriate location to install it.

[0012] The device according to the present invention is equipped with a TEV sensor and a processing unit, and by simply installing both of them on the wall surface of a housing, it is possible to monitor whether partial discharge is occurring in the electric power equipment housed in the housing. More details are as follows.

[0013] When a partial discharge occurs, a potential fluctuation occurs at the discharge location, which in turn causes a transient fluctuation in the ground voltage. Partial discharges occur repeatedly with the same cycle as the equipment voltage and are concentrated at a specific phase, i.e., they are periodic. According to the above-mentioned device, the judgment unit of the processing unit monitors whether at least one of a first condition corresponding to the condition for partial discharges occurring every half cycle of the voltage phase and a second condition corresponding to the condition for partial discharges occurring every cycle of the voltage phase is satisfied. This makes it possible to detect whether partial discharges are occurring in electric power equipment. Therefore, by incorporating a function to notify the occurrence of partial discharges when it is determined that partial discharges are occurring, remote monitoring of electric 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 DC current within a range of 4 mA to 20 mA, which is a standardized instrumentation signal, and outputs the DC current; After the determination unit determines that a partial discharge has occurred 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 the peak value into a current value in the range of 4 mA to 20 mA and output it depending on the height of the held peak value.

[0015] With this configuration, if it is determined that a partial discharge is occurring in the power equipment housed in the enclosure, the analog transmission processing unit outputs a current signal conforming to the standard for standardized instrumentation signals. This makes it possible to incorporate this into existing monitoring systems that monitor information such as the temperature and humidity of other equipment. Furthermore, because the amount of current generated corresponds to the magnitude of the ground voltage, the magnitude of the partial discharge can be roughly grasped.

[0016] As another example, the processing unit may have a communication processing unit that, when the judgment unit determines that partial discharge is occurring in the power equipment, sends information to that effect via email, short message, or the Internet to a staff terminal located away from the installation location of the housing.

[0017] Since the partial discharge monitoring device with the above configuration uses a TEV sensor, it cannot determine which power device is generating the partial discharge when multiple power devices are housed in a housing. Therefore, this device is more suitable for use as a primary screening to determine whether or not it is necessary to go to the site and perform a deterioration diagnosis.

[0018] The step (c) may be a step of identifying the angle section having the highest occurrence frequency and in which the occurrence frequency number exceeds a lower threshold as the first angle section.

[0019] With this configuration, even if the ground potential fluctuates due to noise or the like, erroneous determinations based on the results can be suppressed.

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

[0021] In this case, the k0 and k1 may be natural numbers equal to or less than 50. The values ​​of k0 and k1 may be the same or different.

[0022] The second condition corresponds to the condition that the occurrence frequency of the angle section corresponding to the outside of the range of ±k2° that surrounds the first angle section is less than or equal to half the occurrence frequency of the first angle section, 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 is characterized in that it uses the partial discharge monitoring device having the above-described configuration to monitor whether or not a partial discharge is occurring in the electric power equipment when no workers are present near the housing that houses the electric power equipment. [Effects of the Invention]

[0025] According to the partial discharge monitoring device and partial discharge monitoring method of the present invention, it is possible to monitor whether or not partial discharge is occurring in electric power equipment even when no workers are present at the site. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a diagram schematically illustrating a state in which a partial discharge monitoring device according to an embodiment is used to monitor whether or not a partial discharge occurs in an electric power device. [Figure 2] 1 is a functional block diagram illustrating a configuration of a partial discharge monitoring device according to an embodiment of the present invention; [Figure 3] 1 is a flowchart illustrating an example of a partial discharge determination process performed by a partial discharge monitoring device according to an embodiment. [Figure 4] 10 is a graph schematically showing an example of a direct current Io output from an analog transmission processing unit 38. [Figure 5] 4 is a graph schematically showing an example of a waveform of a detection voltage Vi output from a TEV sensor 1. [Figure 6] 1 is a graph showing a schematic representation of the detected voltage Vi output from the TEV sensor 1 in relation to the sampling period of the central monitoring system. [Figure 7]10 is a schematic graph for explaining a method of generating a DC current Io output from an analog transmission processing unit 38 in accordance with the sampling period of the central monitoring system. DETAILED DESCRIPTION OF THE INVENTION

[0027] Embodiments of a partial discharge monitoring device and a partial discharge monitoring method according to the present invention will be described below with reference to the accompanying drawings. Note that the drawings are all schematic representations, and the dimensional ratios and number of elements in the drawings do not necessarily correspond to the actual dimensional ratios and number of elements.

[0028] Fig. 1 is a diagram schematically showing a state in which a partial discharge monitoring device according to this embodiment is used to monitor whether or not a partial discharge occurs in an electric power device. Fig. 2 is a functional block diagram schematically showing the configuration of the partial discharge monitoring device according to this 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 transient fluctuations in the ground potential. In the example shown in FIG. 1, the electric power equipment to be monitored is a transformer 4 in a cubicle 3, and the TEV sensor 1 is attached to a wall surface 9 of the cubicle 3. Note that electric power equipment that can be monitored by the partial discharge monitoring device 10 according to the present invention includes, in addition to the transformer 4, switches, circuit breakers, bushings, etc.

[0030] Since the wall surface 9 of the cubicle 3 normally exhibits ground potential, transient ground voltage can be detected by attaching the TEV sensor 1 to this location. From this perspective, the location where the TEV sensor 1 is attached is not limited to the wall surface 9 outside the cubicle 3, but may be any location near the transformer 4 where ground potential is ensured. For example, the TEV sensor 1 may be attached to the wall surface inside the cubicle 3, or may be attached to 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 via a signal line 5, and receives as input a transient ground voltage (hereinafter referred to as a "detected voltage Vi") detected by the TEV sensor 1. As shown in FIG. 2, the processing unit 2 includes a signal input receiving 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 wall surface 9 outside 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 is a position where it can be connected to the TEV sensor 1 via a signal line 5. That is, the attachment position of the processing unit 2 may be inside the cubicle 3 or near the outside of the cubicle 3. However, from the viewpoint of preventing the processing unit 2 from being inadvertently touched by a third party, it is preferable that the processing unit 2 be fixed to the wall surface of the cubicle 3 or housed inside the cubicle 3.

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

[0034] In this 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 process procedure executed by the partial discharge monitoring device 10. Below, the function of each element provided in the processing unit 2 will be explained with reference to the flowchart in Fig. 3. In the following explanation, the step numbers in Fig. 3 will be referred to as appropriate.

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

[0037] The comparator 32 is a circuit that compares the detected voltage Vi from the TEV sensor 1 with a reference threshold voltage Vth. The comparator 32 is provided so that if the detected voltage Vi is noise, the process of determining whether or not a partial discharge has occurred is not performed. In other words, the threshold voltage is set to the lowest value that exceeds the noise level and that may occur if a partial discharge has occurred. This threshold voltage may be adjustable as appropriate.

[0038] When the comparison unit 32 detects 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 about the analysis result is recorded in the storage unit 34 (step #3). More specifically, the angle section corresponding to the phase angle at which the detected voltage Vi appears is recorded in the storage unit 34. Note that when the detected voltage Vi is equal to or less than the threshold voltage Vth (No in step #2), steps #1 and #2 are repeated.

[0039] The phase analysis unit 33 is a functional means for recognizing temporal changes in the detected voltage Vi and performing phase analysis, and is, for example, an analyzer that can perform intensity analysis for each phase angle. The phase analysis unit 33 identifies the phase angle corresponding to the detected voltage Vi.

[0040] The phase analysis unit 33 further determines the angle interval to which the identified phase angle belongs. Table 1 shows examples of angle intervals.

[0041] [Table 1]

[0042] The example in Table 1 shows a case where 360° is divided into 128 angle intervals. For example, if the phase analysis unit 33 determines that the phase angle of the detected voltage Vi is 3.0°, the angle interval to which the detected voltage Vi belongs is identified as interval 2. The number of divisions is not limited to 128, but from the perspective of ensuring a certain level of accuracy, the angle range specifying each angle interval is preferably within 5°, more preferably within 4°, and particularly preferably within 3°. In the example in Table 1, the angle range specifying each angle interval is set to approximately 2.8°.

[0043] Information relating to the angle interval thus identified is recorded in the storage unit 34. The storage unit 34 is a storage area such as a flash memory.

[0044] The above steps #1 to #3 are executed from the time when it is first detected that the detected voltage Vi from the TEV sensor 1 exceeds the reference threshold voltage Vth until a predetermined set time has elapsed. As a result, information about the phase of the detected voltage Vi that has exceeded the threshold voltage Vth, i.e., information about the angle interval, is successively recorded in the storage unit 34 until the set time has elapsed. In this way, the information about the angle interval recorded in the storage unit 34 corresponds to "result information."

[0045] When a set time has elapsed since it was first detected that the detected voltage Vi from the TEV sensor 1 exceeds the reference threshold voltage Vth (Yes in step #4), the determination unit 35 extracts the first angle interval Φ1, which is the angle interval with the highest occurrence frequency, based on the result information recorded in the storage unit 34 (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 advance in the storage unit 34. The set time may also be configured to be changeable externally as needed. 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 after a predetermined condition is met. The clock unit 31 may be a general-purpose clock or a device that achieves the same function as a clock.

[0047] After extracting the first angle interval Φ1, the determination unit 35 determines whether or not at least one of the first condition S1 and the second condition S2 is satisfied in the following steps #6 and #7.

[0048] The determination unit 35 reads the result information stored in the storage unit 34 and determines a second angle interval Φ2 that has the second highest occurrence frequency after the first angle interval Φ1. The determination unit 35 then determines whether the second angle interval Φ2 is outside the range of ±k0° that includes the first angle interval and is an angle interval whose voltage phase is substantially shifted by half a cycle from the first angle interval Φ1. The condition for this determination to be satisfied corresponds to the first condition S1.

[0049] The first condition S1 corresponds to whether the second angle interval Φ2 is an angle interval substantially different from the first angle interval Φ1 and is separated from the first angle interval Φ1 by an angle in the range of (180-k1) degrees or more and (180+k1) degrees or less. Here, the values ​​of k0 and k1 are typically positive numbers of 50 or less, more typically positive numbers of 40 or less. The values ​​of k0 and k1 are pre-stored in the storage unit 34 and may be configured to be externally changeable as appropriate. The value of k1 may be used as the value of k0.

[0050] The fact that the first condition S1 is met means that a transient ground voltage (detected voltage Vi) exceeding the noise level is observed from the cubicle 3 and is generated every half cycle of the voltage phase. In such a case, there is a high possibility that a partial discharge is occurring in the transformer 4 in the cubicle 3. Therefore, when the determination unit 35 confirms that the first condition S1 is met (Yes in step #6), it determines that a partial discharge is occurring in the transformer 4 in the 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 (detection voltage Vi) occurs substantially only within the first angle interval Φ1. The condition for establishing this determination corresponds to the second condition S2.

[0052] The second condition S2 is a condition corresponding to whether the occurrence frequency of the voltage phase of the transient ground voltage (detected voltage Vi) in an angle interval corresponding to an angle interval outside the range of ±k2° including the first angle interval Φ1, i.e., an angle interval that can be substantially considered to be other than the first angle interval Φ1, is equal to or less than half the occurrence frequency of the voltage phase of the transient ground voltage (detected voltage Vi) in the first angle interval Φ1. Here, the value of k2 is typically a positive number equal to or less than 20, more typically a positive number equal to or less than 10. The value of k2 is pre-stored in the storage unit 34 and may be configured to be externally changeable as appropriate. The value of k2 is set so that the phase corresponding to the angle interval in the range of ±k2° including the first angle interval Φ1 is considered to be the same phase as the first angle interval Φ1.

[0053] The fact that the second condition S2 is satisfied means that a transient ground voltage (detected voltage Vi) exceeding the noise level is observed from the cubicle 3 and is generated for every voltage phase cycle. In such a case, there is a high possibility that a partial discharge is occurring in the transformer 4 in the cubicle 3. Therefore, when the determination unit 35 confirms that the second condition S2 is satisfied (Yes in step #7), it determines that a partial discharge is occurring in the transformer 4 in the cubicle 3 (step #8).

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

[0055] 3, step #7 is executed when step #6 is No, but this is just an example. For example, the order of execution of steps #6 and #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, if the determining unit 35 determines that a partial discharge has occurred in the transformer 4 in the cubicle 3, the output processing unit 23 executes an output process to that effect (step #9).

[0057] The processing unit 2 of this 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 detected voltage Vi input from the TEV sensor 1 into a DC current Io within the range of 4 mA to 20 mA, which is a standardized instrumentation signal established by the IEC (International Electrotechnical Commission), and outputs the converted current. As shown in Figures 1 and 2, the processing unit 2 is connected to a transmission signal line 6 for outputting the DC current Io. This transmission signal line 6 is connected to a standardized central monitoring system to which instrumentation signals from other equipment are input.

[0059] FIG. 4 is a graph schematically illustrating an example of a DC current Io output from the analog transmission processing unit 38. When a 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 having a magnitude resulting from the partial discharge. The analog transmission processing unit 38 converts the detection voltage Vi into a DC current Io in 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. This allows the central monitoring system to determine whether a partial discharge may be occurring in the transformer 4 in the cubicle 3. In other words, even when no worker is present in the cubicle 3, it is possible to remotely determine whether a partial discharge may be occurring in the transformer 4 in the cubicle 3 by checking the central monitoring system.

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

[0061] The detected voltage Vi output from the TEV sensor 1 is a signal that is observed over an extremely short period of time (for example, on the order of microseconds to several hundred microseconds). In other words, as shown schematically in FIG. 5, the time Ta during which the detected voltage Vi is observed is extremely short. On the other hand, as shown schematically in FIG. 6, the sampling period Ts used in a central monitoring system to which instrumentation signals from other equipment are input is at most about 0.1 seconds. Therefore, even if an attempt is made to convert the detected voltage Vi directly into a current signal, sampling may not be possible.

[0062] 7, the analog transmission processing unit 38 holds the peak value of the detected voltage Vi output from the TEV sensor 1 for a predetermined time Ta of 0.1 seconds or more, and then converts it into a current value at a timing synchronized with the sampling period Ts used in the central monitoring system. This makes it possible to upload information about the monitoring results obtained by the present invention to an existing central monitoring system to which instrumentation signals from other equipment are input.

[0063] The communication processing unit 39 is a functional means for sending e-mails, short messages, chats, etc. to the terminal of the person in charge using the telecommunications line 7 such as the Internet. That is, in step #8, when the determination unit 35 determines that a partial discharge has occurred in the transformer 4 in the cubicle 3, the communication processing unit 39 creates notification information to that effect and notifies the terminal of the person in charge (for example, a computer or smartphone). This makes it possible to recognize, from a central monitoring system remotely, that a partial discharge may have occurred in the transformer 4 in the cubicle 3, even when no worker is present in the cubicle 3.

[0064] 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] Another embodiment will be described below.

[0066] <1> In step #5, if the occurrence frequency in the angle section with the highest occurrence frequency is equal to or less than a predetermined lower threshold, the determination unit 35 may determine that the detected voltage Vi input from the TEV sensor 1 is a voltage signal derived from noise. In this case, steps #6 to #7 may not be executed, and the process may go through step #10 and return to step #1 again.

[0067] The information regarding the lower limit threshold for the occurrence frequency may be stored in advance in the storage unit 34, or may be configured to be externally changeable as appropriate. An example of the lower limit threshold is three times.

[0068] <2> In the example shown in Figure 1, multiple transformers 4 are housed in the cubicle 3. However, the number of power devices, such as the transformer 4, housed in a housing, such as the cubicle 3, may be just one. In this case, the TEV sensor 1 may be attached to the wall of the transformer 4.

[0069] <3> When the output processing unit 23 has the analog transmission processing unit 38, it may be configured to always output the DC current Io to the central monitoring system via the transmission signal line 6 regardless of the determination result of the determination unit 35. However, in this case, if the determination unit 35 does not detect the occurrence of partial discharge, the output processing unit 23 may be configured to output the DC 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 to provide a better understanding of the present invention, and the present invention is not necessarily limited to those having all of the configurations described. The scope of the present invention is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

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

Claims

1. A partial discharge monitoring device for monitoring whether or not partial discharge occurs in electric power equipment, a TEV sensor installed on a wall surface of the electric power device, in a housing that houses the electric power device, or on a wall surface of the housing; a processing unit that is installed inside the housing, on a wall surface of the housing, or in the vicinity of the housing, and to which a detection voltage detected by the TEV sensor is input via a signal line; The processing unit a comparison unit that compares the detected voltage with a predetermined threshold; a phase analysis unit that performs a phase analysis on the detected voltage; a storage unit that records result information relating to the analysis result of the phase analysis unit; a determination unit that determines whether or not a partial discharge has occurred in the electric power device based on the result information, The phase analysis unit a step (a) of performing a phase analysis on the detected voltages that exceed the threshold among the detected voltages input from the TEV sensor for a set time from the timing when the detected voltage exceeds the threshold, to identify a phase angle; and (b) outputting, as the result information, information about an angle section to which the phase angle identified in (a) belongs, among a plurality of angle sections obtained by dividing 360° according to a predetermined rule, to the storage unit; The determination unit a step (c) of reading out the result information recorded in the storage unit and identifying a first angle section that is the angle section with the highest occurrence frequency; and (d) determining that a partial discharge is occurring in the electric power equipment when at least one of the following conditions is satisfied: a first condition that the angle interval next to the first angle interval is an angle interval that is substantially shifted by a half voltage phase from the first angle interval; and a second condition that the occurrence frequency of the angle interval that is substantially different from the first angle interval is equal to or less than half the occurrence frequency of the first angle interval.

2. 2. The partial discharge monitoring device according to claim 1, wherein step (c) is a step of identifying, as the first angle section, the angle section in which the occurrence frequency is highest and in which the number of occurrence frequencies exceeds a lower threshold value.

3. the first condition corresponds to a condition in which a second angle interval having a second highest occurrence frequency after the first angle interval is outside a range of ±k0° that sandwiches the first angle interval, and is separated from the first angle interval by an angle that is within a range of (180−k1)° or more and (180+k1)° or less; 2. The partial discharge monitoring device according to claim 1, wherein the values ​​corresponding to k0 and k1 are changeable.

4. 4. The partial discharge monitoring device according to claim 3, wherein k1 is a positive number equal to or less than 50.

5. the second condition corresponds to a condition that the occurrence frequency of the angle section corresponding to the outside of a range of ±k2° that sandwiches the first angle section is equal to or less than ½ of the occurrence frequency of the first angle section, 2. The partial discharge monitoring device according to claim 1, wherein the value corresponding to k2 is changeable.

6. 4. The partial discharge monitoring device according to claim 3, wherein k2 is a positive number equal to or less than 20.

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

8. The partial discharge monitoring device according to any one of claims 1 to 6, characterized in that the processing unit has a communication processing unit that, when the determination unit determines that a partial discharge has occurred in the electric power equipment, transmits information to that effect via email or the Internet to a staff terminal located away from where the housing is installed.

9. 10. A partial discharge monitoring method, comprising: using the partial discharge monitoring device according to claim 7; and monitoring whether or not a partial discharge is occurring in the electric power equipment when no worker is present near the housing that houses the electric power equipment.

10. 9. A partial discharge monitoring method, comprising: using the partial discharge monitoring device according to claim 8; and monitoring whether or not a partial discharge is occurring in the electric power equipment when no worker is present near the housing that houses the electric power equipment.

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