JP5530966B2 - Method and apparatus for testing insulation performance of gas insulation equipment - Google Patents

Description

  The present invention relates to an insulation performance test method and apparatus for gas insulation equipment, and more particularly, a simple and efficient insulation performance test method and apparatus for verifying insulation performance of gas insulation equipment in the atmosphere without enclosing insulation gas. About.

Gas-insulated equipment such as gas-insulated switchgears, gas-insulated busbars, and gas-insulated transformers that constitute gas-insulated substation equipment has an electrical conductor portion (also referred to as a charging portion) in a sealed metal container such as an epoxy resin. It is formed by being supported by an insulating material and filled with an insulating gas (generally SF ₆ gas). Thereby, a gas insulation apparatus has high dielectric strength, and is formed compactly. The withstand voltage value for evaluating the insulation performance of gas-insulated equipment is determined for each voltage class according to various standards (for example, IEC standards (Standard of the International Electrotechnical Committee) and JEC standards (Electrical Standards Committee Standards Standards)). Have been commercialized to satisfy them. In addition, a withstand voltage test is performed after assembly to verify that the insulation performance is satisfied.

  On the other hand, if a metal foreign object is present in the gas insulation device, the insulation performance is greatly reduced. Therefore, great care is taken to prevent the foreign material from entering the gas insulation device during assembly. However, if a foreign substance such as a metal is left in the metal container, a partial discharge is generated from the part of the foreign substance, and if left unattended, a dielectric breakdown occurs. Therefore, conventionally, in order to quickly detect partial discharge, electromagnetic waves generated by partial discharge are received by an antenna installed in a metal container to detect partial discharge (Patent Document 1).

  On the other hand, in the insulation performance test of gas insulation equipment, after the assembly of gas insulation equipment is usually completed at the manufacturing plant, the inside of the metal container is evacuated and the insulation gas is sealed, and the test voltage is applied to the high voltage conductor in the metal container. This is done by applying electricity. If the result of the insulation performance test is satisfactory, the insulating gas in the metal container is recovered, and then a dry gas such as nitrogen gas is sealed in the metal container and shipped to an installation location or the like. If insulation abnormality such as partial discharge is detected as a result of the insulation performance test, after collecting the insulating gas in the metal container, open the metal container in the atmosphere, remove the cause defect, and again Repeat the same procedure to perform the insulation performance test.

By the way, SF ₆ gas is designated as a global warming gas, and is restricted from leaking into the atmosphere or being released. Therefore, when the gas insulation device is opened for some reason, it is necessary to collect SF ₆ gas so as not to leak. The SF ₆ gas recovery work is carried out with careful and controlled work procedures, and the release of air is suppressed by introducing equipment with high recovery efficiency. Therefore, in an insulation performance test conducted by filling SF ₆ gas, there is a problem that work efficiency is lowered if there is an insulation abnormality.

  Therefore, in Patent Document 2, gas insulation equipment is installed in a test tank, and instead of the insulation gas, dry pressurized air having insulation performance equivalent to that of the insulation gas is sealed in the tank to provide insulation. It has been proposed to perform performance tests. According to this, since the dry pressurized air in the tank can be released to the atmosphere as it is, the tank can be opened as many times as necessary, so that there is an advantage that the work of the insulation performance test can be made efficient.

WO98 / 53334 JP 2001-194409 A

  However, according to Patent Document 2, since a test tank, an air compressor, and a drier that accommodate gas insulating devices or parts are required, the test equipment is increased in size, and it takes time to generate and dry compressed air. There is a problem that it takes.

  The problem to be solved by the present invention is to enable verification of insulating performance equivalent to insulating gas in a gas insulating device in the atmosphere.

The inventors of the present invention diligently conducted research to enable an insulation performance test equivalent to an insulation gas in the atmosphere for gas insulation equipment. As a result, a gas-insulated device having normal insulation performance has a sufficiently low test voltage (for example, 1/10 of the SF ₆ gas) compared to the dielectric breakdown (FO) voltage of the insulating gas (SF ₆ ) in the atmosphere. ) Obtained the knowledge that dielectric breakdown occurs. Further, it has been found that the partial discharge preceding the dielectric breakdown also occurs in the atmosphere at a test voltage sufficiently lower than the insulating gas (SF ₆ ) (for example, 1/30 of SF ₆ ). On the other hand, when conducting an insulation test of gas-insulated equipment in the atmosphere, there was a concern that the withstand voltage performance would decline if the humidity was high, but even if the humidity was high, the surface of the insulating material would not be condensed. Since it was confirmed that the withstand voltage did not decrease by 10% or more, it was found that there was no practical problem.

In particular, it has been found that there is a certain correlation between the withstand voltage and partial discharge characteristics under insulating gas and the withstand voltage and partial discharge characteristics under atmospheric pressure. As a result, even with a method of applying a low test voltage that does not cause dielectric breakdown under atmospheric pressure, it can be said that the withstand voltage performance of gas-insulated equipment and the presence or absence of partial discharge can be sufficiently verified. Thereby, the voltage of the high-voltage power supply used in the test can be greatly lowered compared with the case where the insulation performance is verified by filling the gas-insulated equipment with high-pressure insulating gas (SF ₆ gas).

  Therefore, in order to solve the above-described problem, the present invention tests the insulation performance of a gas-insulated device in which a conductor portion of an electric device is supported by an insulating material in a metal container and an insulating gas is sealed in the metal container. In the insulation performance test method, a test voltage of a commercial frequency is applied to the conductor portion via the section wire while the inside of the metal container is in an atmospheric state, and the test voltage is boosted and flows to the section wire. A discharge current is detected, and the insulation performance of the gas insulation device is tested based on the detected discharge current.

  The test voltage can be applied by directly applying a high-voltage test voltage to a high-voltage conductor exposed in the atmosphere of the gas-insulated equipment. Further, when the high voltage conductor is not exposed, the electric wire can be inserted from an opening such as a hand hole of the gas insulating device and connected to the high voltage conductor. Further, it is possible to apply power via the ground terminal of the ground switch constituting the gas insulated switchgear.

  That is, according to the present invention, a test voltage is applied to the conductor portion in a state where the conductor portion constituting the electric device is insulated from the ground. The test voltage may be a commercial frequency voltage, and can be applied by gradually increasing the voltage from a low voltage including zero. And the discharge current which flows into a section line is detected, and the insulation performance of a gas insulation apparatus is tested based on the detected discharge current. In addition, this invention can test in air | atmosphere for the whole or part of gas insulation equipment or a gas insulation apparatus. Moreover, the metal container which comprises a gas insulation apparatus may be in the airtight state, or the open state, and the essential point is that the inside of the metal container is in an atmospheric state. Moreover, it is desirable that the humidity be within a range where condensation does not occur.

  In addition, the inventors measured the starting voltage and dielectric breakdown voltage of partial discharge in the atmosphere using a gas insulating disconnector as a model of the gas insulating device. Although details of the measurement results will be described later, as shown in FIG. 5, partial discharge such as (a) foreign matter on the conductor, (b) foreign matter on the inner surface of the tank that is a metal container, (c) foreign matter adhering to the insulating spacer, etc. The measurement was made separately for the case where the foreign matter that is the cause of the occurrence of the problem is present. According to this, partial discharge occurs at a voltage sufficiently lower than the withstand voltage leading to dielectric breakdown regardless of the type of insulation defect due to foreign matter. In addition, when partial discharge occurs, the dielectric breakdown (FO) voltage becomes lower than the normal insulation state. Therefore, in the present invention, an insulation performance test method will be described focusing on detection of partial discharge.

  That is, the present invention detects the occurrence of a partial discharge by a current pulse included in the discharge current, measures the generation phase of the current pulse corresponding to the phase of the test voltage, and the current with respect to the phase of the test voltage. The cause (generation source) of the partial discharge is specified based on the correspondence relationship between the generation phases of the pulses. Thereby, the cause of the partial discharge can be quickly removed. Conventionally, since the partial discharge signal is very small and weak, it is difficult to detect the partial discharge signal, and it is difficult to specify the cause of the occurrence. In this regard, according to the present invention, as shown in FIG. 3, the correspondence relationship between the phase of the test voltage and the generation phase of the current pulse is the cause of partial discharge, that is, foreign matter on the conductor, foreign matter on the tank inner surface, insulating spacer It has been found that there is a specific relationship with the type of defects caused by the adhered foreign matter. Therefore, it is possible to identify the cause of the partial discharge based on the correspondence between the test voltage phase and the current pulse generation phase. If the type of defect that is the cause of the partial discharge can be identified, the repair work for removing the cause can be performed quickly.

  Furthermore, the present invention detects an electromagnetic wave inside the metal container, analyzes the detected frequency distribution characteristic of the electromagnetic wave and the phase characteristic of the electromagnetic wave with respect to the phase of the test voltage, and analyzes the analyzed frequency distribution characteristic of the electromagnetic wave. And the cause of the partial discharge can be identified based on at least one of the phase characteristics of the electromagnetic wave.

  By the way, the partial discharge includes external noise such as external noise that partially discharges from a charged line that applies a test voltage, and electromagnetic waves that are generated from surrounding electromagnetic equipment. It is necessary to remove such external noise and detect the partial discharge of the gas insulation device to be tested. Therefore, in the present invention, by comparing the waveform of the current pulse and the waveform of the electromagnetic wave, it is determined that the portion of the waveform that is included in only one is a noise signal that is not included in the partial discharge. It is preferable to do so.

  In order to remove external noise, the present invention is based on the magnitude of the absolute value of the current pulse in the positive cycle of the test voltage and the magnitude of the absolute value of the current pulse in the negative cycle of the test voltage. The ratio of the difference to the sum is obtained as the polarity difference of the current pulse, and is based on the magnitude of the absolute value of the electromagnetic wave in the positive cycle of the test voltage and the magnitude of the absolute value of the electromagnetic wave in the negative cycle of the test voltage. Then, the ratio of the difference with respect to the sum thereof was obtained as the polarity difference of the electromagnetic wave, and was detected when the polarity difference of the current pulse was 0.7-1 and the polarity difference of the electromagnetic wave was 0-0.4. It can be determined that the current pulse and the electromagnetic wave are not noise but the partial discharge.

  An apparatus for directly carrying out the insulation performance test method of the present invention is an electric charging apparatus for applying a test voltage having a variable commercial frequency to the conductor portion via an electric line while the inside of the metal container is in an atmospheric state. And a discharge current detector that detects a discharge current flowing through the section, and a determination device that determines the insulation performance of the gas insulation device based on the discharge current detected by the discharge current detector. be able to. The determiner basically determines whether or not a partial discharge has occurred below a preset first set voltage. In addition, it is determined whether or not dielectric breakdown occurs at a voltage that is equal to or lower than a preset second set voltage.

  The determination unit includes a discharge measuring device such as an oscilloscope that measures a generation phase of a current pulse included in the discharge current in correspondence with a phase of the test voltage, a phase of the test voltage, and a generation phase of the current pulse. On the basis of the correspondence relationship, the calculation means for specifying the cause of the partial discharge can be configured. In this case, a data table in which the correspondence relationship between the phase of the test voltage and the generation phase of the current pulse and the cause of occurrence of partial discharge are set in advance is set in the memory of the calculation means.

  Further, an antenna for detecting an electromagnetic wave is provided inside the metal container, and an analysis device for analyzing the frequency distribution characteristic of the electromagnetic wave detected by the antenna and the phase characteristic of the electromagnetic wave with respect to the phase of the test voltage is provided. can do. In this case, the determination device may include a calculation unit that identifies a cause of occurrence of the partial discharge based on at least one of the frequency distribution characteristic of the electromagnetic wave analyzed by the analyzer and the phase characteristic of the electromagnetic wave. In this case as well, a data table in which at least one of the frequency distribution characteristics of electromagnetic waves and the phase characteristics of electromagnetic waves and the cause of occurrence of partial discharge are associated in advance is set in the memory of the calculation means.

  Further, the determiner is configured to calculate a difference between the absolute value of the current pulse in the positive cycle of the test voltage and the absolute value of the current pulse in the negative cycle of the test voltage. A ratio as a polarity difference of the current pulses, and based on the magnitude of the absolute value of the electromagnetic wave in the positive cycle of the test voltage and the magnitude of the absolute value of the electromagnetic wave in the negative cycle of the test voltage. The ratio of the difference to the sum is obtained as the polarity difference of the electromagnetic wave, and when the polarity difference of the current pulse is 0.7-1 and the polarity difference of the electromagnetic wave is 0-0.4, the detected current pulse and It can be determined that the electromagnetic wave is not noise but the partial discharge.

According to the insulation performance test method of the present invention, it is possible to perform a withstand voltage test at a test voltage that is significantly lower than the test voltage when the insulation gas (SF ₆ gas) is enclosed. As a result, not only does it require a large power distribution device, but also does not require a large power transmission bushing or power cable, so it is possible to check insulation performance with economical and simple work. Become. In addition, it is very difficult to perform a partial insulation performance test at a substation at the installation site by dividing it into parts that constitute gas-insulated substation equipment. In this respect, according to the present invention, since it can be performed in the atmosphere, a partial insulation performance test can be performed, and highly reliable facility operation can be performed.

  As described above, according to the present invention, it is possible to verify the insulating performance equivalent to the insulating gas in the atmosphere of the gas insulating device.

It is a figure which shows schematic structure of one Embodiment of the insulation performance test apparatus of this invention, and the gas insulation disconnector of the object. It is a diagram illustrating a comparison of the breakdown voltage and the partial discharge starting voltage at the ₆ gas pressure SF and the atmosphere. It is a figure which shows the phase relationship of a partial discharge charge amount (equivalent to the current pulse of partial discharge) and a test voltage about the various defects which are generation sources of partial discharge. It is a figure explaining the characteristic relationship between various insulation defects and a current pulse. It is a figure which shows the relationship between the partial discharge charge amount of various insulation defects, and a test voltage. It is a figure which shows the relationship between the partial discharge charge amount at the time of changing the length of protrusion on a conductor, and a test voltage. It is a figure which shows the example of the frequency distribution characteristic and phase characteristic of the partial discharge signal detected by electromagnetic waves about various insulation defects. It is a figure which compares and shows an example of the current pulse waveform and electromagnetic wave waveform of the partial discharge measured simultaneously. It is a figure explaining an example of the discrimination method of the internal partial discharge and external noise which used the polarity difference of the current pulse and electromagnetic wave of a partial discharge. It is a figure which shows one Example of the electrical charging part of the insulation performance test apparatus of this invention. It is a figure which shows the example of schematic structure of the conventional insulation performance test apparatus for the comparison. It is a figure which shows the other Example which formed the electrical application part of the insulation performance test apparatus of this invention using the ground terminal of the earthing switch. It is a figure which shows the conventional schematic structure of the drawer | drawing-out part of the ground terminal of the ground switch corresponding to FIG. It is a systematic diagram which shows an example of the division of the electric power application range of the insulation performance test method of this invention.

Hereinafter, an insulation performance test apparatus to which an insulation performance test method for gas insulation equipment of the present invention is applied will be described based on embodiments and examples.
(Embodiment)

  FIG. 1 is a diagram showing a schematic configuration in which an insulation performance test apparatus according to an embodiment of the present invention is applied to a gas insulation disconnector. As shown in the figure, a gas insulated disconnector, which is one element constituting a gas insulated switchgear, is a test object. The gas insulation disconnector is shown in an assembled state, and the high voltage conductors 3 (3a, 3b) are respectively opposed to the grounded metal container 1 by insulating spacers 2 (2a, 2b). It is supported. At the ends of the high voltage conductors 3a and 3b, a movable side electrode 6a and a fixed side electrode 6b are respectively provided. In the figure, the movable side electrode 6a and the fixed side electrode 6b are electrically connected by a mover 7, It shows that the insulation disconnector is in the “closed” state. Further, the metal container 1 is open to the atmosphere, and the inside of the metal container 1 communicates with the atmosphere 5 of the surrounding environment. Note that the ends of the high voltage conductors 3a and 3b supported by the insulating spacers 2a and 2b are exposed to the atmosphere.

  The insulation performance test apparatus according to the present embodiment includes a high voltage power source 21 and an electric line 20 that constitute an electric charging apparatus. The electric line 20 is configured to apply an AC high voltage test voltage of commercial frequency (50 Hz) output from the high voltage power source 21 to the high voltage conductor 3a.

  The electric line 20 connected to the high voltage conductor 3 a is grounded via a series circuit of a coupling capacitor 22 for detecting partial discharge and a detection impedance 23. The detection impedance 23 is a parallel circuit of RC (resistance and capacitor) and RLC (resistance, inductance and capacitor), and a voltage signal proportional to the magnitude of partial discharge is output. The coupling capacitor 22 has a capacitance of about 1000 pF, for example, and the magnitude of the partial discharge is measured by the detection impedance 23 as the partial discharge charge amount [pC]. A partial discharge signal having a pulse voltage correlated with a partial discharge current pulse detected by the detection impedance 23 is input to the oscilloscope 25. The oscilloscope 25 is provided with a determination unit including a calculation unit and a memory for verifying the insulation performance based on the input partial discharge signal. In addition, it is not restricted to the oscilloscope 25, The partial discharge signal correlated with an electric current pulse can be measured with a discharge measuring device.

  Further, an antenna 11 for detecting electromagnetic waves is installed using the hand hole 10 of the metal container 1. The antenna 11 is a broadband antenna that can receive high-frequency electromagnetic waves of several hundred MHz or more resulting from partial discharge. The electromagnetic wave signal detected by the antenna 11 is input to the oscilloscope 25. The oscilloscope 25 is configured to be able to detect the frequency distribution of the electromagnetic wave signal. Note that the electromagnetic wave signal detected by the antenna 11 is not limited to the oscilloscope 25, and the frequency distribution may be detected by a spectrum analyzer or the like.

  The oscilloscope 25 receives a current pulse signal correlated with the current pulse, and obtains the generation phase of the current pulse corresponding to the phase of the test voltage. In the present embodiment, the current pulse is detected as the discharge charge amount (pC). The oscilloscope 25 is configured to detect voltage phase characteristics corresponding to the frequency distribution of the electromagnetic wave signal and the phase of the test voltage.

An operation and usage method of the insulation performance test apparatus of the embodiment configured as described above will be described. In FIG. 1, the metal container 1 constituting the gas insulated disconnector is held in a state where the atmosphere 5 is filled or the inside of the metal container 1 is opened to the atmosphere. Then, the commercial voltage test voltage V _T is applied to the high voltage conductor 3 a through the charging line 20. While increasing the test voltage V _T , a change in the discharge current I flowing through the section 20 is detected by the detection impedance 23 and recorded, analyzed and observed by the oscilloscope 25. In addition, the oscilloscope 25 includes a determiner that determines whether or not a partial discharge has occurred at a preset first set voltage or less. Furthermore, the determination device may have a function of determining whether or not dielectric breakdown has occurred at a preset second set voltage or lower. The determiner can be configured with a general calculation means and a memory.

  The insulation performance test performed using the insulation performance test apparatus of the embodiment configured as described above will be described below by dividing it into examples.

First, an example of conducting a dielectric breakdown test and a partial discharge test at atmospheric pressure will be described using the embodiment of FIG. When there is no insulation defect in the gas insulation disconnector, when the test voltage _VT is increased, insulation breakdown eventually occurs. On the other hand, when there is an insulation defect, partial discharge occurs at the partial discharge start voltage. In the partial discharge, the oscilloscope 25 measures a partial discharge signal correlated with a current pulse flowing through the section 20. FIG. 2 shows a comparison between the breakdown voltage and the partial discharge start voltage in SF ₆ gas at high pressure and in the atmosphere. The bar chart 27 shows a dielectric breakdown voltage of 100 (a.n.) when SF ₆ gas having a pressure of 0.6 (MPa · abs) is filled in a clean state in which there is no insulation defect in the gas insulation disconnector to be tested. u). The bar chart 29 has the same conditions as the bar chart 27 except that it is a test in the atmosphere, and the bar chart 29 is expressed as a ratio based on the voltage of the bar chart 27.

The bar chart 28 shows the partial discharge start voltage when the SF ₆ gas of the same pressure is filled in the state where the metal foreign object having a length of 3 mm is present on the high voltage conductor 2 in the gas insulated disconnector, and the voltage of the bar chart 27. It is expressed as a ratio as a standard. The bar charts 29 and 30 in the figure show the insulation edge breakdown voltage and the partial discharge start voltage in the atmosphere when tested in the atmosphere (20 ° C., 20 to 80% Rh), and the voltage in the bar chart 27. It is expressed as a ratio as a standard.

As is clear from FIG. 2, the high pressure SF ₆ gas is significantly different from the atmosphere, and the dielectric breakdown (FO) voltage is reduced to about 1/10 in the atmosphere compared to the high pressure SF ₆ gas. I understand that. In other words, in the case of air, it is possible that an insulation performance test may be performed at a test voltage V _T that is significantly lower than that of SF ₆ gas. The partial discharge start voltage in the atmosphere is even lower, indicating that the insulation performance when a metallic foreign object is present can be detected with an applied voltage of about 1/30 of that in high-pressure SF ₆ gas.

  As an example, in a withstand voltage test of a gas insulation device having a voltage class of 245 kV, a standard lightning impulse voltage is 1050 kV, and a commercial frequency AC voltage requires a withstand voltage of 460 kV. In the atmosphere according to the present invention, the withstand voltage can be confirmed by applying an AC voltage of 80 kV. Moreover, it is possible to detect an abnormality (partial discharge) due to a foreign matter on a conductor of 3 mm at an AC voltage of 30 kV.

On the other hand, when a withstand voltage test is performed on a gas insulation device filled with high-pressure SF ₆ gas, it is necessary to apply a considerably high voltage as shown in FIG. For this reason, partial discharge may occur from the section 20 or discharge may occur from metal objects having a floating potential around the equipment, which may cause noise of several hundred pC or more. However, in the partial discharge test in SF ₆ gas at high pressure, it is necessary to detect a partial discharge of several pC level. Therefore, it is very difficult to detect a partial discharge signal of several pC from a noise signal of several hundred pC. Have difficulty. On the other hand, in the atmosphere, a partial discharge in the same state as in the high-pressure SF ₆ gas generates a discharge having a magnitude of several hundred pC or more, so that a true partial discharge signal is buried in noise and detected. The problem that it is difficult can be avoided.

Here, an embodiment will be described in which, when the occurrence of partial discharge is detected using the insulation performance test apparatus shown in FIG. 1, the type of insulation defect present in the gas insulation apparatus is determined. FIGS. 3A to 3C show the relationship between the discharge charge amount and the voltage phase of the partial discharge when there is a defect in the gas-insulated equipment with an oscilloscope waveform. Oscilloscope waveform diagram, the horizontal axis represents the phase (degrees) of the test voltage V _T, the vertical axis represents the amount of discharged electric charge (pC). In the figure, typical defect types due to metal foreign matter are: (a) foreign matter on conductor (projection formed on or attached to conductor), (b) foreign matter on tank (projection formed on inner surface of metal container or For example, the metal foreign matter such as an attached wire) and (c) the foreign matter attached to the spacer surface (the metal foreign matter such as the wire attached to the surface of the insulating spacer) are shown.

As can be seen from Figure 3, the relationship between the phase of the generator phase and the test voltage V _T of each pulse of the partial discharge signal corresponding to a current pulse by partial discharge, it is found to have a specific phase pattern with respect to the defect type. The main features of this phase pattern are shown in FIG. 3 and 4, in any of the defect type in the positive cycle of the test voltage V _T, a relatively large partial discharge signal is detected than the negative cycle. However, in the case of conductors on foreign matter (a), the partial discharge signal appears in the vicinity of the peak phase of the test voltage V _T, it can be seen that a phase pattern having an intensity distribution of the chevron (discharge charge quantity distribution). On the other hand, in the case of tanks on foreign matter (b), that the partial discharge signal appears in the vicinity of the peak phase of the test voltage V _T is the same as (a), the intensity distribution has a rectangular phase pattern. Further, in the case of the foreign substance adhering to the spacer (c), the partial discharge signal appears near the phase before the peak phase of the test voltage V _T , and the intensity distribution is correlated with the amplitude of the test voltage V _T. In addition, in the case of the foreign matter on the conductor (a), it can be seen that the partial discharge has started at the negative polarity of the test voltage V _T.

Therefore, the oscilloscope 25 measures the generation phase of the current pulse included in the discharge current in accordance with the phase of the test voltage, and the determination unit provided in the oscilloscope 25 matches the phase of the test voltage with the generation phase of the current pulse. The cause of partial discharge can be identified by obtaining the relationship. In this case, a data table in which the correspondence between the phase of the test voltage and the generation phase of the current pulse and the cause of occurrence of partial discharge are previously associated is set in the memory of the determiner. That is, the characteristic relationship between the oscilloscope waveform of the test voltage V _T and the phase of the partial discharge signal is a current pulse in a phase of FIG. 3, to create a data table organized in association with the defect type in advance, the determination of the oscilloscope 25 If it is stored in the memory of the vessel, the characteristics of the phase pattern of the detected partial discharge signal can be determined, and the defect type can be identified based on this. If the type of defect causing the partial discharge can be identified, the defect location may be narrowed down and the defect can be quickly removed.

  That is, in this embodiment, the occurrence of partial discharge is detected by a current pulse included in the discharge current, the current pulse generation phase is measured in correspondence with the phase of the test voltage, and the current pulse generation phase with respect to the phase of the test voltage is measured. The defect type that is the cause of occurrence of the discharge current is specified based on the correspondence relationship.

FIG. 5 shows the test voltage dependence of the discharge charge amount obtained by performing the test for each defect type defined in the first embodiment. In the figure, the horizontal axis represents the normalized values (%) by conductor Kaden was actually measured breakdown voltage test voltage V _T in a clean test subject tested (FO voltage), the vertical axis on the oscilloscope 25 This is the measured discharge charge amount (pC). As can be seen from the figure, in the case of the foreign matter on the conductor (a), a small partial discharge of about several tens of pC occurs near the start of the partial discharge. However, it can be seen that as the voltage rises, a large partial discharge occurs, and as the dielectric breakdown (FO) voltage approaches, a partial discharge exceeding 1000 pC occurs. It can be seen that, regardless of the defect type, when a test voltage of 20% is applied, a very large partial discharge exceeding 1000 pC is generated. As described above, in the case of partial discharge detection by current pulse measurement, the external noise that cannot be generally taken is about 100 pC. Therefore, according to the partial discharge test in the atmosphere as in the present invention, the amount of discharge charge is external. Since it is larger than noise, it is possible to easily perform a partial discharge test by eliminating external noise.

Further, according to the present embodiment, since external noise can be eliminated, the dependence of the discharge charge amount of the partial discharge on the test voltage by changing the foreign matter length of the foreign matter on the defect type (a) conductor is shown in FIG. Thus, it was confirmed that even a foreign matter length of 2 mm could be detected sufficiently. Normally, foreign matter management of gas-insulated equipment targets a foreign matter length of 3 mm or more because it is difficult to eliminate external noise. However, according to the partial discharge test in the atmosphere of the present invention, since external noise can be eliminated, even a small foreign object exceeding the control value can be detected. Accordingly, SF in ₆ filled with gas gas-insulated equipment to be used, SF than evaluate the withstand voltage performance of the ₆ gas is filled, effective for the detection of minute metallic foreign substance better to the partial discharge measurement in the air It is.

  In this example, the same insulation performance test apparatus as that in the embodiment of FIG. 1 is used. In other words, in addition to the detection of the partial discharge by the current pulse of the first embodiment, the electromagnetic wave signal detected by the antenna 11 is analyzed by the oscilloscope 25 to detect the frequency distribution of the electromagnetic wave signal, thereby improving the detection accuracy of the partial discharge. It is characterized by improving and improving reliability. As the antenna 11, a broadband antenna that can receive high-frequency electromagnetic waves of several hundred MHz or more generated due to partial discharge is used. The oscilloscope 25 measures the frequency distribution of the electromagnetic wave received by the antenna 11.

  FIG. 7 shows the frequency distribution characteristics and voltage phase characteristics of the electromagnetic waves detected by the oscilloscope 25. In the frequency distribution characteristic, a partial discharge signal is detected in a frequency band of several hundred MHz or more. The method of measuring partial discharge with electromagnetic waves is an effective method for detecting electromagnetic waves with low noise of several hundred MHz or more, and can sufficiently detect even partial discharge signals generated in the metal container 1 in the atmosphere. . Further, the electromagnetic wave detection can be obtained by analyzing the phase of the electromagnetic wave synchronized with the phase of the test voltage. 7 is obtained by integrating the electromagnetic waves input to the oscilloscope 25. In addition, since the measurement frequency band of the present embodiment is a frequency band of several hundred MHz or more, it is possible to obtain characteristics that are relatively close to the characteristics of the current pulse shown in FIGS.

  In this case, based on at least one of the frequency distribution characteristic of the electromagnetic wave analyzed by the oscilloscope 25 and the phase characteristic of the electromagnetic wave, the determination cause provided in the oscilloscope 25 can identify the cause of the partial discharge. That is, a data table in which at least one of the frequency distribution characteristics of electromagnetic waves and the phase characteristics of electromagnetic waves and the cause of occurrence of partial discharge are associated in advance is set in the memory of the determiner.

  According to the present embodiment, the electromagnetic wave is detected inside the metal container 1, the frequency distribution characteristic of the detected electromagnetic wave and the phase characteristic of the electromagnetic wave with respect to the phase of the test voltage are analyzed, and the analyzed frequency distribution characteristic of the electromagnetic wave The cause of the partial discharge can be specified based on at least one of the phase characteristics of the electromagnetic wave.

  Further, according to the present embodiment, it is possible to detect a partial discharge signal caused by partial discharge with high reliability by eliminating external noise. In other words, there are various noise sources around factories and installation sites where gas-insulated equipment is tested. May result in poor measurement. For example, external noise sources include the influence of radio waves such as mobile phones and radio waves, and electromagnetic radiation noise from inverters and rotating machines. Since these external noise sources have different frequencies and different frequency distribution characteristics, external noise can be eliminated if partial discharge is detected by a plurality of different detection methods, so that detection reliability can be improved. it can. Examples of the partial discharge detection method other than the current pulse detection or the electromagnetic wave detection include a detection method using sound and vibration, and a weak light detection method that captures light emission of the partial discharge.

  An example of the waveform of the partial discharge signal measured simultaneously by the current pulse detection method and the high-frequency electromagnetic wave detection method according to this embodiment is shown in FIG. In FIG. 8, the horizontal axis is the time axis (10 μsec / div), and the vertical axis is the intensity of the partial discharge signal. As can be seen from the figure, since the waveform in which the signal is detected at the same timing is assumed to be a signal generated from the same signal source, the partial discharge signal generated in the metal container 1 is detected. There is a high probability of being. On the other hand, in the current pulse measurement, a signal not detected in the high frequency electromagnetic wave measurement is detected, and it can be seen that an external noise signal is detected. As described above, according to the present embodiment, since partial discharge is detected by the current pulse detection method and the high-frequency electromagnetic wave detection method, waveforms other than the discharge waveform common to both are caused by the external noise source. Since it can be determined, the reliability of partial discharge detection can be improved.

  That is, according to the present embodiment, the current pulse waveform and the electromagnetic wave waveform are contrasted, and the portion of the waveform that is included only in either one is an external noise signal that is not included in the partial discharge. Can be determined.

  Another example of performing a partial discharge test at atmospheric pressure using the embodiment of FIG. 1 will be described. In the present embodiment, as in the third embodiment, the partial discharge signals detected by the current pulse detection method and the high-frequency electromagnetic wave detection method are combined to generate a partial discharge signal generated by an insulation defect inside the metal container 1, Or it is characterized by determining whether it is a noise signal from an external noise source. In general, the partial discharge waveform in air has a large polarity difference between the positive and negative cycles of the test voltage, and it is known that the partial discharge signal in the negative cycle is much faster than the partial discharge signal in the positive cycle. ing. That is, in the method of detecting a frequency band of several hundred kHz to several MHz such as the current pulse detection method, a large positive cycle is detected. On the other hand, in a method of detecting a frequency in the several hundred MHz band, such as a high-frequency electromagnetic wave detection method, a negative cycle signal is largely detected. Whether the signal is a partial discharge signal in the metal container 1 or a noise signal outside the metal container 1 can be identified by the ratio of the magnitudes of the signals detected in the positive cycle and the negative cycle.

FIG. 9 shows the measurement results when electric discharge is generated inside and outside the metal container 1. The horizontal axis of FIG. 9 shows the polarity difference of the current pulse signal, and the vertical axis shows the polarity difference of the electromagnetic wave signal. The polarity difference is obtained by the following equation (1). In formula (1), the absolute value of the positive or negative cycle is the absolute value of the peak value.
Polarity difference = (Absolute value of positive cycle-Absolute value of negative cycle)
÷ (Absolute value of positive cycle + Absolute value of negative cycle) (1)
When the partial discharge signal measured by such a polarity difference was plotted, as shown in the figure, the ◯ mark was the internal partial discharge of the metal container 1, and the X mark was the external noise signal. That is, the partial discharge signals generated inside the metal container 1 are located at relatively the same place. On the other hand, the aerial corona signal and radio signal generated outside the metal container 1 are located at different locations from the internal partial discharge signal. This shows that an internal partial discharge signal and an external noise signal can be distinguished. Therefore, according to the present embodiment, it is possible to accurately determine the partial discharge signal generated inside the metal container 1.

  That is, in the present embodiment, the determination unit provided in the oscilloscope 25 is based on the magnitude of the absolute value of the current pulse in the positive cycle of the test voltage and the magnitude of the absolute value of the current pulse in the negative cycle of the test voltage. The ratio of the difference to the sum is obtained as the polarity difference of the current pulse. Similarly, based on the magnitude of the absolute value of the electromagnetic wave in the positive cycle of the test voltage and the magnitude of the absolute value of the electromagnetic wave in the negative cycle of the test voltage, the ratio of the difference to the sum is obtained as the polarity difference of the electromagnetic wave. When the polarity difference between the current pulses is 0.7 to 1 and the polarity difference between the electromagnetic waves is 0 to 0.4, it is determined that the detected current pulse and electromagnetic waves are not noise but partial discharge.

  In the insulation performance test apparatus of the embodiment shown in FIG. 1, a specific method for applying a test voltage to the conductor of the gas insulation disconnector to be tested has not been shown, but the insulation performance in the atmosphere according to the present invention. As shown in FIG. 2, the test can be performed at an extremely low test voltage as compared with the case where the insulating gas is enclosed. Therefore, FIG. 10 shows an example of a specific configuration of the power application unit that applies power to the conductor of the gas insulation disconnector, and FIG. 11 shows a schematic configuration example of a conventional insulation performance test apparatus for comparison.

  As shown in FIG. 10, the power application section of this example is in a state in which the lid of the handhole 15 originally provided in the gas insulation disconnector is removed, and a high voltage is applied using the insulation-coated electric wire 20. It can be set as the structure connected to the voltage conductor 3a. The section line 20 is formed by using a wire having a thickness (diameter) that does not generate partial discharge at a predetermined voltage, and a connection conductor 33 connected to the tip of the section line 20 with a bolt 34 is wound around the high voltage conductor 3a. . The connection conductor 33 is made of a flexible copper plate or a braided wire so as to be in close contact with the high voltage conductor 3a. If the high voltage conductor 3a near the hand hole 15 has a bolt hole or the like, the connection conductor 33 may be connected using the bolt hole instead of winding the connection conductor 33 around the high voltage conductor 3a.

  That is, according to the present invention, as shown in the present embodiment, it is possible to apply power by directly connecting the electric wire 20 to the high voltage conductor 3a. A power supply unit having a special withstand voltage as required is not required, and the test apparatus can be realized with a simple configuration. In addition, according to the present invention, since the inside of the metal container 1 is in the atmospheric state, the outer and inner conditions of the insulating spacer 2a are the same, so the outer and inner insulating performance of the insulating spacer 2a is evaluated in a single test. It is possible.

On the other hand, when the gas insulation disconnector shown in the embodiment of FIG. 1 is filled with the high pressure SF ₆ gas and tested, since the atmospheric breakdown voltage is low, the line 20 and the high voltage in contact with the atmosphere are high. Dielectric breakdown will occur at the power application section connecting the conductor 3a. Therefore, even if the inside of the metal container 1 is sealed and filled with SF ₆ gas, the insulation performance test cannot be performed with the configuration of FIG. 1 as it is. Therefore, in order to carry out the insulation performance test inside the gas insulation equipment filled with SF ₆ gas, it is necessary to configure the power application section so as to satisfy a withstand voltage capable of applying a predetermined test voltage.

That is, as shown in FIG. 11, terminal covers 52 a and 52 b are provided at both ends of the metal container 1 so that the high pressure SF ₆ gas 9 can be filled. And it is necessary to provide the opening part 54 which connects the bushing 51 to one terminal cover 52a, and to form the electrical charging part of the structure which connects the electrical conductor 55 to the high voltage conductor 3a via the bushing 51. FIG. In addition, although a power cable can be used instead of the bushing 51, in any case, it is necessary to use a voltage applying unit having a withstand voltage performance capable of performing a dielectric breakdown test. That is, in order to perform the insulation performance test in the state filled with SF ₆ gas according to the embodiment of FIG. 1, as shown in FIG. 11, the bushing 51 and the terminal cover 52a are provided separately from the gas insulation disconnector to be tested. , B need to be attached, which is unavoidable.

  FIG. 12 shows another embodiment of a specific configuration of the power application unit that applies power to the conductor of the gas insulation disconnector. This embodiment is an example in which a test voltage is applied using a ground terminal of a ground switch which is one of the constituent elements of a gas insulating device. That is, originally, as shown in FIG. 13, the grounding switch portion is provided with a movable element 7 rotatably provided on the high-voltage conductor 3, and a grounding terminal mounting flange 41 provided on the wall surface of the metal container 1. A grounding terminal 43 supported by a bushing-like insulating material 42 is provided so as to face the rotation range of the mover 7. The ground terminal 43 is a terminal that is grounded together with the metal container 1 as a connection terminal of the ground switch during operation.

Therefore, in this embodiment, the ground wire of the ground terminal 43 is removed and the test voltage is applied using the ground terminal 43. According to the present invention, since the test voltage is significantly lower than the test performed by filling the high-pressure SF ₆ gas, it is sufficient that the ground terminal 43 has sufficient insulation performance with respect to the test voltage in the atmosphere. However, since the ground terminal is at the ground potential and is substantially the same potential as that of the metal container 1, it is not structured to apply a high voltage. Therefore, in this embodiment, in order to improve the withstand voltage of the ground terminal 43, as shown in FIG. 12, a bushing-like internal insulating material that surrounds the outer periphery of the ground terminal 43 on the metal container 1 side of the insulating material 42. 44 is provided, and the withstand voltage is secured by increasing the insulation distance. With such a shape, the withstand voltage performance of the ground terminal 43 can be improved, and the test voltage of the present invention from the ground terminal 43 can be applied.

  Example 6 or Example 7 is suitable, for example, when an insulation performance test is performed in a state where gas-insulated substation equipment is assembled at a substation. That is, when installing the gas-insulated substation equipment, it is possible to perform an insulation performance test by attaching a bushing for applying power without being connected to the system. However, once the operation is started, there is no method for partially evaluating the insulation performance, and there is only a method for confirming the insulation performance by applying a system voltage. Therefore, if it is necessary to open the metal container 1 to the atmosphere for some reason such as gas leakage or partial discharge after the start of operation, there is a high possibility that foreign substances will be mixed in the metal container 1. If the presence / absence can be easily confirmed, it is possible to prevent a secondary breakdown accident.

In this regard, according to Example 6 and Example 7, even when the substation is assembled, the voltage can be partially applied to check the insulation performance. For example, FIG. 14 shows an example of a system of gas-insulated substation equipment. As shown in FIG. 14A, the circuit breaker CB and the two disconnectors DS are opened, and a high-voltage conductor is formed as shown in FIG. 12 by using a ground switch ES that grounds the high-voltage conductor sandwiched between them. A test voltage can be applied. Thereby, insulation performance can be confirmed with simple equipment using a high voltage power supply with a low test voltage for the atmosphere without preparing a high voltage power supply with a particularly high test voltage for SF ₆ gas and a bushing for charging. As a result, it is possible to easily confirm the presence or absence of foreign matter in the partial equipment. In FIG. 14B, only the power application range of FIG. 14A is different, and similarly, the insulation performance evaluation can be easily performed by partially distinguishing the gas-insulated substation equipment.

  As described above, according to the present invention, the insulation performance test is partially performed in the assembly process of the gas insulation substation equipment or in the assembled state before the insulation performance test finally performed with the insulation gas sealed. It is possible to provide an insulation performance test method and apparatus suitable for a screening test to be performed and to find and repair defects in advance.

DESCRIPTION OF SYMBOLS 1 Metal container 2, 2a, 2b Insulation spacer 3, 3a, 3b High voltage conductor 5 Air | atmosphere 6a Movable side electrode 6b Fixed side electrode 7 Movable element 9 SF ₆ gas 11 Antenna 20 Electric power line 21 High voltage power supply 22 Coupling capacitor 23 Detection impedance 25 Oscilloscope 33 Connecting conductor 34 Bolt 41 Flange 42 Insulating material 43 Grounding terminal 44 Internal insulating material 51 Bushing 52a, 52b Terminal cover 53 End electrode 54 Opening 55 Electric conductor

Claims (10)

In the insulation performance test method for testing the insulation performance of the gas insulation equipment in which the conductor part of the electrical equipment is supported by the insulating material in the metal container and the insulation gas is sealed in the metal container,
Prior to the insulation performance test performed by sealing the insulation gas, the test voltage of the commercial frequency is applied to the conductor portion via the electric line while the inside of the metal container is in an atmospheric state. To detect the discharge current flowing through the section, detect the occurrence of partial discharge by the current pulse included in the detected discharge current, and measure the generation phase of the current pulse according to the phase of the test voltage Then, the correspondence relationship of the generation phase of the current pulse with respect to the phase of the test voltage is obtained, and based on the correspondence relationship of the generation phase of the current pulse with respect to the phase of the test voltage set in advance for each generation cause of the discharge current, A method for testing insulation performance of a gas-insulated device, characterized by identifying and repairing the cause of discharge current . In the insulation performance test method for gas insulation equipment according to claim 1 ,
Further, the electromagnetic wave is detected inside the metal container, the frequency distribution characteristic of the detected electromagnetic wave and the phase characteristic of the electromagnetic wave with respect to the phase of the test voltage are analyzed, and the analyzed frequency distribution characteristic of the electromagnetic wave and the electromagnetic wave A method for testing an insulation performance of a gas-insulated device, wherein the cause of occurrence of the partial discharge is specified based on at least one of the phase characteristics. In the insulation performance test method for gas insulation equipment according to claim 2 ,
By comparing the waveform of the current pulse and the waveform of the electromagnetic wave, it is determined that a waveform portion included in only one of the waveforms is a noise signal not included in the partial discharge. Insulation performance test method for insulation equipment. In the insulation performance test method for gas insulation equipment according to claim 2 ,
Based on the magnitude of the absolute value of the current pulse in the positive cycle of the test voltage and the magnitude of the absolute value of the current pulse in the negative cycle of the test voltage, the ratio of the difference to the sum of them is determined as the polarity of the current pulse. As a difference,
Based on the magnitude of the absolute value of the electromagnetic wave in the positive cycle of the test voltage and the magnitude of the absolute value of the electromagnetic wave in the negative cycle of the test voltage, the ratio of the difference to the sum is obtained as the polarity difference of the electromagnetic wave. ,
When the polarity difference of the current pulse is 0.7 to 1 and the polarity difference of the electromagnetic wave is 0 to 0.4, it is determined that the detected current pulse and the electromagnetic wave are not noise but the partial discharge. A method for testing the insulation performance of a gas-insulated device. In the insulation performance test apparatus for testing the insulation performance of the gas insulation equipment in which the conductor part of the electrical equipment is supported by the insulating material in the metal container and the insulation gas is enclosed in the metal container,
An electric charging device for applying a test voltage having a variable commercial frequency to the conductor part via the electric line while the inside of the metal container is in an atmospheric state, and a discharge current for detecting the discharge current flowing through the electric line A detector, and a determiner that determines the insulation performance of the gas-insulated equipment based on the discharge current detected by the discharge current detector,
The determination unit measures a generation phase of a current pulse included in the discharge current in correspondence with the phase of the test voltage , obtains a correspondence relationship of the generation phase of the current pulse with respect to the phase of the test voltage, and discharges in advance An insulation performance test apparatus for gas insulation equipment , wherein the cause of occurrence of the discharge current is specified based on a correspondence relationship of the generation phase of the current pulse with respect to the phase of the test voltage set for each cause of occurrence . In the insulation performance test apparatus for gas insulation equipment according to claim 5,
And an analyzer for detecting an electromagnetic wave in the metal container, and analyzing the frequency distribution characteristic of the electromagnetic wave detected by the antenna and the phase characteristic of the electromagnetic wave corresponding to the phase of the test voltage; With
The determination device specifies the cause of the discharge current based on at least one of the frequency distribution characteristic of the electromagnetic wave analyzed by the analyzer and the phase characteristic of the electromagnetic wave, and the insulation performance of the gas-insulated equipment Test equipment. In the insulation performance test apparatus for gas insulation equipment according to claim 6 ,
The determination unit compares the waveform of the current pulse and the waveform of the electromagnetic wave, and determines that a waveform portion included in only one of the waveforms is a noise signal not included in the partial discharge. Insulation performance testing equipment for gas insulation equipment. In the insulation performance test apparatus for gas insulation equipment according to claim 6 ,
The determiner determines a ratio of the difference to the sum based on the magnitude of the absolute value of the current pulse in the positive cycle of the test voltage and the magnitude of the absolute value of the current pulse in the negative cycle of the test voltage. Obtained as the polarity difference of the current pulse, and based on the magnitude of the absolute value of the electromagnetic wave in the positive cycle of the test voltage and the magnitude of the absolute value of the electromagnetic wave in the negative cycle of the test voltage The ratio of the difference is obtained as the polarity difference of the electromagnetic wave. When the polarity difference of the current pulse is 0.7-1 and the polarity difference of the electromagnetic wave is 0-0.4, the detected current pulse and the electromagnetic wave Is an insulation performance test apparatus for gas insulation equipment, wherein it is determined that the partial discharge is not noise. The insulation performance test apparatus for gas insulation equipment according to claim 5 to 8 ,
An insulation performance testing apparatus for gas insulation equipment, wherein a lid of a hand hole provided in the metal container is removed, the electric wire is introduced from the hand hole into the metal container and connected to the conductor portion. The insulation performance test apparatus for gas insulation equipment according to claim 5 to 8 ,
Wherein the ground terminal led out from the metal container, the gas-insulated apparatus by connecting the Division wire, characterized in that voltage application to the conductor section for grounding the conductor portion of the gas insulated apparatus via the disconnector Insulation performance testing equipment.

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