Firefly detection device

Abstract

The firefly detection device includes a cumulative relative frequency and cumulative distribution ratio calculation unit (163) that calculates the cumulative relative frequency and cumulative distribution ratio of a feature of partial discharge caused by a conductive foreign object mixed in a metal container filled with insulating gas and in which a high-voltage conductor is installed, a Gini coefficient calculation unit (164) that calculates a Gini coefficient that indicates the degree of unevenness of the feature, and a continuity determination unit (165) that determines the continuity of the firefly state of the conductive foreign object based on the result of comparing the Gini coefficient with a preset threshold value.

Description

[Technical Field]

[0001] The present disclosure relates to a firefly detection device that detects firefly that occurs inside gas-insulated equipment. [Background technology]

[0002] In gas-insulated equipment in which a conductor is placed inside a metal container filled with insulating gas, if a conductive foreign object gets mixed into the metal container, a phenomenon known as firefly may occur in which the conductive foreign object moves inside the metal container when a partial discharge occurs.

[0003] Patent Document 1 discloses a partial discharge diagnostic device that determines that a conductive foreign object is in a firefly state when a partial discharge is detected in which the occurrence pattern of at least one of the time interval of the partial discharge pulse and the amplitude of the partial discharge pulse falls into two types of patterns. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-26650 Summary of the Invention [Problem to be solved by the invention]

[0005] It is known that the behavior of conductive foreign particles in a firefly state changes over time. That is, a conductive foreign particle that begins floating inside a metal container immediately after a firefly occurs will move by jumping along the conductor surface if it remains near the conductor surface, and eventually fall to the bottom of the metal container. Also, if a conductive foreign particle floating inside a metal container does not approach the conductor, it will fall to the bottom of the metal container.

[0006] Although fireflies are transient phenomena that resolve over time, applying a lightning impulse voltage due to a lightning surge while a firefly is occurring can potentially cause insulation breakdown. Therefore, if a firefly occurs in gas-insulated equipment in an active system, and it takes a long time for the firefly condition caused by the conductive foreign object to resolve, measures such as switching to a standby system for power transmission may be necessary. On the other hand, if the firefly condition caused by the conductive foreign object is expected to resolve in a short period of time, and a weather forecast predicts a low possibility of lightning strikes, it is sufficient to simply monitor the situation and there is no need to switch to a standby system. Thus, for efficient operation of gas-insulated equipment, measures must be adjusted depending on the time it takes for the firefly condition caused by the conductive foreign object to resolve.

[0007] The partial discharge diagnostic device disclosed in Patent Document 1 can determine whether a conductive foreign object is in a firefly state, but does not take into consideration the continuity of the firefly state of the conductive foreign object. Therefore, there is a need for a firefly detection device that can determine the continuity of the firefly state of a conductive foreign object.

[0008] The present disclosure has been made in view of the above, and aims to provide a firefly detection device capable of determining the continuity of a firefly state of a conductive foreign object. [Means for solving the problem]

[0009] To solve the above-mentioned problems and achieve the object, a firefly detection device according to the present disclosure includes a cumulative relative frequency and cumulative allocation ratio calculation unit that calculates a cumulative relative frequency and a cumulative allocation ratio of a feature of partial discharge caused by a conductive foreign object mixed in a metal container filled with insulating gas and having a high-voltage conductor installed therein, and a Gini coefficient calculation unit that calculates a Gini coefficient that indicates the degree of unevenness of the feature. The firefly detection device also includes a continuity determination unit that determines the continuity of the firefly state of the conductive foreign object based on a result of comparing the Gini coefficient with a preset threshold. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to obtain an effect of providing a firefly detection device capable of determining the continuity of a firefly state of a conductive foreign object. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the configuration of a firefighting detection device according to a first embodiment. [Figure 2] FIG. 1 is a diagram showing the configuration of a signal processing unit of a firefly detection device according to a first embodiment; [Figure 3] FIG. 10 is a diagram showing an example of a waveform of a signal wave output from an antenna when the firefly detection device according to the first embodiment detects partial discharge. [Figure 4] FIG. 1 is a diagram showing an example of a signal wave output from an antenna when the firefly detection device according to the first embodiment detects partial discharge. [Figure 5] FIG. 1 is a diagram showing an example of a signal wave output from an antenna when the firefly detection device according to the first embodiment detects partial discharge. [Figure 6] FIG. 1 is a diagram showing an example of determining the continuity of a firefly state of a conductive foreign object by the firefly detection device according to the first embodiment; [Figure 7] FIG. 1 is a diagram showing an example of determining the continuity of a firefly state of a conductive foreign object by the firefly detection device according to the first embodiment; [Figure 8] FIG. 1 is a diagram showing an example of determining the continuity of a firefly state of a conductive foreign object by the firefly detection device according to the first embodiment; [Figure 9] FIG. 1 is a diagram showing an example of a hardware configuration of a signal processing unit of a partial discharge detection device according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a firefly detection device according to an embodiment will be described in detail with reference to the drawings.

[0013] Embodiment 1 1 is a diagram showing the configuration of a firefighting detection device according to embodiment 1. A firefighting detection device 10 according to embodiment 1 is attached to gas insulated equipment 20.

[0014] Gas-insulated equipment 20 includes a plurality of cylindrical metal containers 21 filled with insulating gas 30, insulating spacers 22 installed between the metal containers 21, and a high-voltage conductor 23 supported by the insulating spacers 22 and arranged across the plurality of metal containers 21. Each metal container 21 is provided with a maintenance hatch 21a.

[0015] The firefly detection device 10 includes an antenna 11 that detects electromagnetic waves 50 generated by partial discharge when a conductive foreign object 40 mixed in the metal container 21 is in a firefly state and outputs a signal wave, a filter 12 that removes noise from the signal wave output by the antenna 11, a signal amplifier 13 that amplifies the signal wave, an analog-to-digital converter 14 that converts the signal wave into digital data and outputs the signal data, a data logger 15 that accumulates the signal data, and a signal processing unit 16 that determines the continuity of the firefly state of the conductive foreign object 40 in the metal container 21 based on the signal data accumulated in the data logger 15. The antenna 11 is inserted into the metal container 21 through a maintenance hatch 21a.

[0016] 2 is a diagram showing the configuration of a signal processing unit of the firefly detection device according to Embodiment 1. The signal processing unit 16 includes a data acquisition unit 161 that acquires signal data from the data logger 15, a signal interval detection unit 162 that detects time intervals of partial discharges based on the signal data, a cumulative relative frequency and cumulative allocation ratio calculation unit 163 that calculates a cumulative allocation ratio corresponding to the cumulative relative frequency of partial discharges, a Gini coefficient calculation unit 164 that calculates a Gini coefficient that indicates the degree of unevenness in time intervals of partial discharges based on the calculation results of the cumulative relative frequency and cumulative allocation ratio calculation unit 163, a continuity determination unit 165 that determines the continuity of the firefly state of the conductive foreign object 40 inside the metal enclosure 21 based on the calculation results of the Gini coefficient calculation unit 164, and a maintenance necessity determination unit 166 that determines whether maintenance of the gas-insulated equipment 20 is necessary.

[0017] 3, 4, and 5 are diagrams showing examples of waveforms of signal waves output from the antenna when the firefly detection device according to the first embodiment detects partial discharge. FIG. 3 shows an example of a waveform of a signal wave immediately after a firefly occurs. FIG. 4 shows an example of a waveform of a signal wave when time has passed since the firefly occurred and conductive foreign object 40 has remained near the surface of high-voltage conductor 23. FIG. 5 shows an example of a waveform of a signal wave when time has passed since conductive foreign object 40 remained near the surface of high-voltage conductor 23. In FIGS. 3, 4, and 5, the horizontal axis represents time, and the vertical axis represents the intensity of the signal wave. Here, a state in which partial discharges occur sporadically immediately after a firefly occurs is referred to as a first state. A state after the first state in which conductive foreign object 40 remains near the surface of high-voltage conductor 23 and sporadic partial discharges and intermittent partial discharges coexist is referred to as a second state. A state after the first and second states in which partial discharges occur intermittently is referred to as a third state.

[0018] In the first state, partial discharge occurs when a conductive foreign object 40 floating inside the metal container 21 approaches the high-voltage conductor 23, and the partial discharge occurs sporadically as shown in Figure 3. Generally, the first state continues for about 20 minutes after the firefly begins.

[0019] In the second state, conductive foreign matter 40 resides near the surface of high-voltage conductor 23, and conductive foreign matter 40 repeatedly generates partial discharges while adhering to and detaching from high-voltage conductor 23. As conductive foreign matter 40 residing near the surface of high-voltage conductor 23 repeatedly generates partial discharges, the degree of non-uniformity of the time intervals between partial discharges in the second state is smaller than the degree of non-uniformity of the time intervals between partial discharges in the first state, as shown in Fig. 4. Generally, the second state begins about 20 minutes after the start of the firefly and continues until about two hours have passed since the start of the firefly.

[0020] The frequency with which the conductive foreign object 40 generates partial discharges varies depending on the shape of the conductive foreign object 40. For example, a conductive foreign object 40 with a pointed shape generates partial discharges intermittently while it resides near the surface of the high-voltage conductor 23. On the other hand, a conductive foreign object 40 without a pointed shape does not generate partial discharges intermittently while it resides near the surface of the high-voltage conductor 23, but generates a single partial discharge when the distance between the conductive foreign object 40 and the high-voltage conductor 23 becomes equal to or less than a certain value. Therefore, partial discharges generated by a conductive foreign object 40 with a pointed shape have a higher signal strength and occur less frequently than partial discharges generated by a conductive foreign object 40 with a pointed shape. For this reason, sporadic partial discharges and intermittent partial discharges coexist in the second state.

[0021] Furthermore, conductive foreign objects 40 that do not have sharp parts are less likely to be attracted back to the high-voltage conductor 23 after releasing charge due to partial discharge, and tend to fall to the bottom of the metal container 21 more easily than conductive foreign objects 40 that have sharp parts. For this reason, the proportion of conductive foreign objects 40 that do not have sharp parts among the conductive foreign objects 40 that remain in the firefly state decreases over time.

[0022] In the third state, the proportion of conductive foreign objects 40 without sharp edges among the conductive foreign objects 40 maintaining the firefly state is lower than in the second state. Therefore, as shown in FIG. 5, the degree of non-uniformity of the time intervals of partial discharges in the third state is smaller than the degree of non-uniformity of the time intervals of partial discharges in the second state. Generally, the third state begins about two hours after the onset of the firefly and continues until about 20 hours have passed since the onset of the firefly. In other words, all of the conductive foreign objects 40 fall to the bottom of the metal container 21 about 20 hours after the onset of the firefly.

[0023] 6, 7, and 8 are diagrams illustrating an example of determination of the continuity of the firefly state of a conductive foreign object by the firefly detection device according to the first embodiment. FIG. 6 illustrates an example of determination of the continuity of the firefly state of a conductive foreign object 40 in a first state. FIG. 7 illustrates an example of determination of the continuity of the firefly state of a conductive foreign object 40 in a second state. FIG. 8 illustrates an example of determination of the continuity of the firefly state of a conductive foreign object 40 in a third state. In FIGS. 6, 7, and 8, the horizontal axis represents the cumulative frequency of the partial discharge time intervals, and the vertical axis represents the cumulative allocation ratio of the partial discharge time intervals. In FIGS. 6, 7, and 8, the solid line represents the Lorenz curve L(F) of the partial discharge time intervals, and the dotted line represents the uniform distribution line Lpe. The Lorenz curve L(F) is a curve that represents the relationship between the cumulative relative frequency and the cumulative allocation ratio, and is calculated based on the cumulative relative frequency and the output of the cumulative allocation ratio calculation unit 163. The bias in the time intervals of partial discharges is greatest in the first state, followed by the second state, and smallest in the third state. Therefore, the area enclosed by the Lorenz curve L(F) and the uniform distribution line Lpe is greatest in the first state shown in Figure 6, followed by the second state, and smallest in the third state.

[0024] The Gini coefficient is an index that indicates the degree of data inequality, with a larger value indicating greater inequality in the data. The Gini coefficient can be expressed as the ratio of the area enclosed by the Lorenz curve L(F) and the equal distribution line Lpe to the area of ​​the region below the equal distribution line Lpe. The Gini coefficient calculation unit 164 calculates the Lorenz curve L(F) based on the calculation results of the cumulative relative frequency and cumulative allocation ratio calculation unit 163, and further calculates the Gini coefficient Gini by the following formula (1):

[0025]

number

[0026] In the examples shown in Figures 6, 7, and 8, the Gini coefficient Gini calculated by the Gini coefficient calculation unit 164 is 0.70 in the first state, 0.39 in the second state, and 0.25 in the third state.

[0027] The continuity determination unit 165 determines that the firefly state of the conductive foreign object 40 is in the first state when the Gini coefficient, which indicates the degree of non-uniformity of the time intervals between partial discharges, is greater than a predetermined first threshold. The continuity determination unit 165 also determines that the firefly state of the conductive foreign object 40 is in the third state when the Gini coefficient, which indicates the degree of non-uniformity of the time intervals between partial discharges, is equal to or less than a predetermined second threshold. The continuity determination unit 165 also determines that the firefly state of the conductive foreign object 40 is in the second state when the Gini coefficient, which indicates the degree of non-uniformity of the time intervals between partial discharges, is equal to or less than the predetermined first threshold and greater than the predetermined second threshold. In the above example, by setting the first threshold to 0.50 and the second threshold to 0.30 in advance, the continuity determination unit 165 can determine the continuity of the firefly state of the conductive foreign object 40 based on the Gini coefficient, which indicates the degree of non-uniformity of the time intervals between partial discharges.

[0028] The maintenance necessity determination unit 166 determines that maintenance of the gas-insulated equipment 20 is unnecessary if the Gini coefficient becomes zero based on the results of multiple determinations of the firefly state of the conductive foreign object 40, and determines that maintenance of the gas-insulated equipment 20 is necessary if a predetermined first time has elapsed while the firefly state of the conductive foreign object 40 remains in the first state, or if the Gini coefficient does not become zero even after a predetermined second time has elapsed since the firefly state of the conductive foreign object 40 occurred.

[0029] As described above, the firefly detection device 10 according to the first embodiment can determine the continuation of the firefly state of the conductive foreign object 40. Therefore, the manager of the gas-insulated equipment 20 can perform maintenance of the gas-insulated equipment 20 based on the determination result of the firefly detection device 10, depending on how long the firefly state of the conductive foreign object 40 will continue. For example, if the firefly state of the conductive foreign object 40 is determined to be the first state, the firefly state of the conductive foreign object 40 is predicted to continue for more than half a day. Therefore, the manager of the gas-insulated equipment 20 can take measures to prevent a ground fault from occurring, such as switching the power transmission system to a standby system. Furthermore, if the firefly state of the conductive foreign object 40 is determined to be the third state, the manager of the gas-insulated equipment 20 can take measures, such as continuing power transmission by the gas-insulated equipment 20 while monitoring the situation, based on the determination that the conductive foreign object 40, which has a shape without sharp parts and has a high partial discharge signal strength, has already fallen to the bottom of the metal container 21.

[0030] Furthermore, the firefly detection device 10 according to the first embodiment can also predict the duration of the firefly state of the conductive foreign object 40 based on the results of multiple determinations of the firefly state of the conductive foreign object 40. For example, as described above, the second state begins approximately 20 minutes after the firefly phenomenon begins and continues until approximately two hours have passed since the firefly phenomenon began. Therefore, by identifying the timing of the transition from the first state to the second state based on the results of multiple determinations of the firefly state of the conductive foreign object 40, it becomes possible to predict the time required for the firefly state of the conductive foreign object 40 to be resolved.

[0031] Furthermore, as described above, a firefly is essentially a transient phenomenon, and the firefly state of conductive foreign object 40 will disappear over time. However, there are cases where, for some reason, it takes a long time for the firefly state of conductive foreign object 40 to disappear, or the firefly state of conductive foreign object 40 does not disappear even after time has passed. In such cases, maintenance of gas-insulated equipment 20, such as removing conductive foreign object 40 from metal container 21, is required. In firefly detection device 10 according to embodiment 1, maintenance necessity determination unit 166 can determine whether maintenance of gas-insulated equipment 20 is required based on multiple determination results of the firefly state of conductive foreign object 40. Therefore, a manager of gas-insulated equipment 20 can perform maintenance of gas-insulated equipment 20 based on the determination result of maintenance necessity determination unit 166.

[0032] In the above description, the continuation of the firefly state of the conductive foreign object 40 is determined based on the degree of non-uniformity of the time intervals of the partial discharges, but the continuation of the firefly state of the conductive foreign object 40 may also be determined based on the degree of non-uniformity of a characteristic quantity of the partial discharges other than the time intervals. For example, the firefly detection device 10 may determine the firefly state of the conductive foreign object 40 based on the degree of non-uniformity of the signal strength of the partial discharges.

[0033] Next, a description will be given of the hardware configuration of the signal processing unit 16 of the partial discharge detection device according to embodiment 1. Fig. 9 is a diagram showing an example of the hardware configuration of the signal processing unit of the partial discharge detection device according to embodiment 1.

[0034] The signal processing unit 16 is realized by a processor 91 that executes various processes, a memory 92 serving as a main memory, and a storage device 93 that stores information. The processor 91 may be a computing device such as an arithmetic unit, a microprocessor, a microcomputer, a central processing unit (CPU), or a digital signal processor (DSP). The memory 92 may be a semiconductor memory such as a random access memory (RAM), a flash memory, an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM). The storage device 93 stores a program for executing a process for determining the continuity of the firefly state of the conductive foreign object 40. The processor 91 reads the program stored in the storage device 93 into the memory 92 and executes it. The processor 91 reads the program stored in the storage device 93 into the memory 92 and executes it, thereby realizing the functions of the signal processing unit 16.

[0035] The configurations shown in the above embodiments are merely examples of the content, and may be combined with other known technologies, and parts of the configurations may be omitted or modified as long as they do not deviate from the gist of the invention. [Explanation of symbols]

[0036] 10 Firefly detection device, 11 Antenna, 12 Filter, 13 Signal amplifier, 14 Analog-digital converter, 15 Data logger, 16 Signal processing unit, 20 Gas insulated equipment, 21 Metal container, 21a Maintenance hatch, 22 Insulating spacer, 23 High voltage conductor, 30 Insulating gas, 40 Conductive foreign object, 50 Electromagnetic wave, 91 Processor, 92 Memory, 93 Storage device, 161 Data acquisition unit, 162 Signal interval detection unit, 163 Cumulative relative frequency and cumulative allocation ratio calculation unit, 164 Gini coefficient calculation unit, 165 Continuity determination unit, 166 Maintenance necessity determination unit.

Claims

1. a cumulative relative frequency and cumulative allocation ratio calculation unit that calculates a cumulative relative frequency and a cumulative allocation ratio of a feature quantity of partial discharge caused by a conductive foreign object mixed in a metal container filled with insulating gas and in which a high-voltage conductor is installed; a Gini coefficient calculation unit that calculates a Gini coefficient indicating the degree of unevenness of the feature amount; a continuity determination unit that determines the continuity of the firefly state of the conductive foreign object based on a comparison result between the Gini coefficient and a preset threshold value.

2. 2. The firefly detection device according to claim 1, wherein the characteristic amount is a time interval between the partial discharges.

3. the threshold values ​​include a first threshold value and a second threshold value that is smaller than the first threshold value; The continuity determination unit If the Gini coefficient is greater than the first threshold value, the firefly state of the conductive foreign object is determined to be a first state in which the partial discharge occurs sporadically; When the Gini coefficient is equal to or less than the first threshold value and greater than the second threshold value, the firefly state of the conductive foreign object is determined to be a second state which is a state subsequent to the first state and in which sporadic partial discharges and intermittent partial discharges coexist, The firefly detection device according to claim 1 or 2, characterized in that, when the Gini coefficient is equal to or less than the second threshold value, the firefly state of the conductive foreign object is determined to be a third state, which is a state subsequent to the first state and the second state and in which the partial discharge occurs intermittently.

4. 4. The firefly detection device according to claim 3, wherein the continuity determination unit predicts the duration of the firefly state of the conductive foreign object based on a plurality of determination results of the firefly state of the conductive foreign object.

5. The firefly detection device according to claim 4, further comprising a maintenance necessity determination unit that determines that maintenance of the gas-insulated equipment having the metal container is unnecessary if the Gini coefficient becomes zero based on multiple determination results of the firefly state of the conductive foreign object, and determines that maintenance of the gas-insulated equipment is necessary if a predetermined first time has elapsed while the firefly state of the conductive foreign object remains in the first state, or if a predetermined second time has elapsed since the firefly state of the conductive foreign object occurred and the Gini coefficient does not become zero.

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