JP6331521B2 - Partial discharge monitoring device and partial discharge monitoring system - Google Patents

Description

  This invention occurs in the electrical equipment of a power distribution facility in which one or more electrical equipment such as a transformer, a reactor, a power factor improving capacitor, a rectifier, a circuit breaker, and a switch are housed in a metal container. The present invention relates to an apparatus and a system for monitoring partial discharge.

  Many of the partial discharge monitoring (detection) devices that have been proposed in the past, when a partial discharge occurs in an electrical device housed in a metal container, is a discharge current (for example, MHz) that flows through the ground line of the electrical device. Is a high-frequency current of the order).

  For example, in Patent Document 1, a discharge current flowing through a ground bus in which a plurality of electrical devices are connected via a ground wire in a metal container is detected (more specifically, differential detection). Describes a partial discharge detection device for detecting a partial discharge in the electric device.

  However, the method of detecting the discharge current flowing through the ground line including the one described in Patent Document 1 has a problem that it is difficult to accurately detect the partial discharge. This is because the ground circuit of each electric device is not as simple as being grounded at one point by one ground wire (or connected to the ground bus). In addition, the outer wall of each electrical device is usually connected to the ground circuit, and the path through which the discharge current of the partial discharge flows is complex, and the discharge current often circulates in the ground circuit. This is because it is difficult to detect accurately. In particular, the discharge current of the partial discharge is a high-frequency current, and the path through which the high-frequency current flows is usually not always as designed and complex and difficult to grasp, and also has a problem that it differs depending on the structure of each facility.

  On the other hand, Patent Document 2 discloses, as a factory test facility for partial discharge measurement, a test AC power source for applying a test AC voltage to an electrical device (power device) to be tested, and a parallel connection to the AC power source. When a partial discharge occurs in an electrical device, prepare a coupling capacitor that supplies the electrical device with a charging current corresponding to the lost charge that accompanies the partial discharge, and attach these externally to the electrical device under test. A technique for detecting the charging current supplied from the coupling capacitor to the electrical device when partial discharge occurs is described.

  Since this technology detects the charging current supplied from the coupling capacitor, the current to be detected is clear. Therefore, the above-described problem of the method for detecting the discharge current flowing through the grounding wire described above is present. Can be solved.

Japanese Patent Laid-Open No. 9-5386 (FIG. 1, paragraphs 0012-0017) Japanese Patent Laying-Open No. 2011-149896 (FIG. 4, paragraphs 0011-0016)

  Although the above technique described in Patent Document 2 can solve the above-described problem of the method of detecting the discharge current flowing through the ground line, as described in Patent Document 2 (paragraph 0018- 0020), since the frequency of the charging current supplied from the coupling capacitor to the electric device in which the partial discharge has occurred is low (for example, several tens of kHz to several hundreds of kHz), the duration of the current is long and the same charge (= current) In the case of supplying the time integral), the value of the charging current becomes small, thereby the SN ratio becomes worse, and there is a problem that accurate detection of partial discharge is difficult.

  Moreover, since the said technique of patent document 2 is factory test equipment, there also exists a subject that application to the existing power distribution equipment is difficult, and lacks in mass production.

  Patent Document 2 describes a method of detecting the wall potential of a metal container of an electric device as one means for solving the problem that the charging current value is small and the SN ratio is poor. However, this method utilizes the fact that the charging current is supplied to the partial discharge location from the floating capacitance that naturally exists in the metal container of the electrical equipment. Although it depends on the capacity, there is still room for improvement in that the frequency of the charging current cannot be artificially selected because the floating electrostatic capacity cannot be artificially selected.

  Therefore, the present invention further improves the technique described in Patent Document 2, and selects the frequency of the charging current supplied from the capacitor to the electrical equipment in which the partial discharge has occurred to select a relatively high frequency to enhance the monitoring accuracy of the partial discharge. Another object is to provide a partial discharge monitoring device that can be applied to existing power distribution facilities and has high mass production.

  Another object of the present invention is to provide a partial discharge monitoring system including a plurality of such partial discharge monitoring devices.

The partial discharge monitoring apparatus according to the present invention is an electric device of a power distribution facility having a configuration in which a voltage bus to which a commercial frequency voltage is applied and one or more electric devices connected thereto are housed in a metal container. A device for monitoring partial discharges generated in the above, wherein: (a) an electrical device having a built-in capacitor for supplying a charging current associated with the partial discharge to the electrical device in which the partial discharge has occurred; The metal container is housed, and one end of the capacitor is electrically connected to a voltage bus in the metal container, and the other end is electrically grounded. A ground detector is provided with a current detector that detects the charging current flowing therethrough, and (c) further includes a signal processing device that detects the value of the charging current detected by the current detector. part of the configuration of the It has been adopted.

  As in the factory test facility described in Patent Document 2 above, in the technique of externally attaching a coupling capacitor to an electrical device to be tested, the inductance between the coupling capacitor and the electrical device to be tested is inevitably increased. This is considered to be a major factor that lowers the frequency of the charging current when partial discharge occurs.

  On the other hand, the partial discharge monitoring device according to the present invention includes an insulator containing a capacitor for supplying a charging current at the time of partial discharge in the same metal container that houses the electrical device to be monitored. Therefore, the inductance between the capacitor and the electrical device to be monitored can be reduced. Therefore, the frequency of the charging current supplied from the capacitor to the electric device in which the partial discharge has occurred can be made relatively high. In addition, since the capacitance of the capacitor can be freely selected, the frequency of the charging current can be relatively freely selected. As a result, when the same charge is supplied to the partial discharge location, the value (amplitude) of the charging current is larger than that in the technique of externally attaching the coupling capacitor described in Patent Document 2, so that the SN ratio is improved. Discharge monitoring accuracy can be increased.

  In addition, since the insulator containing the capacitor is housed in a metal container that houses the electrical device to be monitored, the periphery of the capacitor can be configured compactly, and the existing power distribution facility can be installed. It is easy to apply and has high mass productivity.

  The insulator incorporating the capacitor may also serve as a support insulator for supporting the voltage bus from the ground potential portion in the metal container.

  The current detector may be a Rogowski coil surrounding a ground wire that grounds the capacitor.

  The signal processing device may include a band-pass filter that is connected to the current detector and selectively passes a signal in a frequency band including a resonance frequency of an electric circuit through which the charging current flows.

Partial discharge monitoring system according to the present invention transmits and receives a communication line, a signal via the signal processing device, the communication line a (b) unit-discharge monitoring apparatus for transmitting (a) signaling A plurality of partial discharge monitoring devices configured to have a circuit; (c) a communication circuit that transmits and receives signals via the communication line; and each partial discharge via the communication line every predetermined time A data collection processing device including a data collection means for giving a command for transmitting the measurement data to the monitoring device and collecting and storing the measurement data stored in each partial discharge monitoring device at that time Is adopted as part of the configuration .

The invention according to claim 1 has the following effects.
(A) Since the insulator containing the capacitor that supplies the charging current at the time of partial discharge is housed in the same metal container that houses the electrical device to be monitored, it is monitored with the capacitor. It is possible to reduce the inductance with the target electric device. Therefore, the frequency of the charging current supplied from the capacitor to the electric device in which the partial discharge has occurred can be made relatively high. In addition, since the capacitance of the capacitor can be freely selected, the frequency of the charging current can be relatively freely selected. As a result, when the same charge is supplied to the partial discharge location, the value (amplitude) of the charging current is larger than that in the technique of externally attaching the coupling capacitor described in Patent Document 2, so that the SN ratio is improved. Discharge monitoring accuracy can be increased.

(B) Since the insulator containing the capacitor is housed in a metal container housing the electrical equipment to be monitored, the periphery of the capacitor can be made compact, and the existing power distribution facility can be constructed. Is easy to apply and mass productivity is high.

(C) Even if the power receiving / distributing facility has a plurality of electric devices built in , any electric device connected to the voltage bus generates a partial discharge from the capacitor. And since the said charging current can be detected, the partial discharge in the several electric equipment in a power receiving / distribution installation can be monitored collectively.

(D) Since the insulator containing the capacitor also serves as the supporting insulator for the voltage bus, the insulator containing the capacitor may be replaced with the existing supporting insulator for the voltage bus in the existing power distribution facility. it can. Therefore, since an insulator with a built-in capacitor can be provided without requiring an extra space, application to existing power distribution equipment becomes easier.

(E) A voltage dividing capacitor provided in the insulator and a DC power supply circuit that receives an AC voltage shared by the voltage dividing capacitor can be supplied from the outside to the signal processing device. There is no need to supply power to the partial discharge monitoring device. Therefore, installation of the partial discharge monitoring device is facilitated.

According to invention of Claim 2, there exists the following further effect. That is, the signal processing device has means for creating and storing measurement data in which the phase of the commercial frequency voltage component and the value of the charging current detected at that phase are correlated with each other. In addition, it is possible to specify in which phase of the three phases of the electrical equipment the partial discharge is generated.

According to the third aspect of the present invention, the communication line, the plurality of partial discharge monitoring devices, and the data collection processing device are provided, and the measurement data of the plurality of partial discharge monitoring devices are collected at a remote location in a lump. Therefore, partial discharges in electrical devices of a plurality of power receiving and distribution facilities provided with the partial discharge monitoring devices can be collectively monitored at remote locations.

In addition , it has been found that there is a possibility that electrical discharge phenomena other than partial discharge may occur in electrical equipment during periods when the weather is rainy or snowy or when the humidity is high. By excluding this measurement data, the reliability of the measurement data can be further increased, and as a result, the partial discharge monitoring accuracy can be further increased.

It is the schematic which shows an example of the power distribution equipment provided with the partial discharge monitoring apparatus which concerns on this invention. It is a figure which shows the other example of a partial discharge monitoring apparatus. It is a block diagram which shows the other example of a signal processing apparatus. It is a figure for demonstrating the relationship between the phase of a commercial frequency voltage, and a partial discharge phenomenon. It is a figure for demonstrating the relationship between the phase of a 3-phase commercial frequency voltage, and a partial discharge phenomenon. It is the schematic which shows an example of the partial discharge monitoring system which concerns on this invention. It is a figure which shows the schematic example of the time transition of the value of the charging current contained in trend data.

(1) Partial Discharge Monitoring Device FIG. 1 shows an example of power distribution / distribution equipment provided with a partial discharge monitoring device according to the present invention.

  In this example, the power receiving / distributing facility 4 is configured by housing a plurality of electric devices 10 in a metal container 6. A partition wall 8 may be provided between the electric devices 10 as in this example. Further, the metal container 6 may be formed by connecting a plurality of metal boxes. Such a configuration is also included in the concept of the metal container 6 in this application. One electrical device 10 may be accommodated in the metal container 6.

  Each electrical device 10 is, for example, a transformer, a reactor, a power factor improving capacitor, a rectifier, a circuit breaker, a switch, or the like, but is not limited to a specific one.

  Each electric device 10 is connected to a voltage bus 12 and a ground bus 14 provided in the metal container 6. The ground bus 14 and the metal container 6 are electrically grounded. Commercial power is supplied from the commercial power source 2 between the voltage bus 12 and the ground bus 14. The voltage bus 12 is, for example, a high voltage bus of 6.6 kV or the like, or a low voltage bus of 440 V or the like, but when the electric device 10 has a transformer, the primary high voltage bus and the secondary side Both low-pressure buses may be used.

  The power distribution facility 4 is provided with a partial discharge monitoring device 20 for monitoring partial discharge generated in each electric device 10 incorporated therein.

  The commercial power source 2, each electric device 10, the voltage bus 12 and the like are usually three-phase. Although the partial discharge monitoring device 20 may be provided for each of the three phases, even if it is provided for only one phase, it is possible to monitor partial discharges in other phases. This will be further described later. FIG. 1 etc. show an example in which the partial discharge monitoring device 20 is provided for one phase.

  When a partial discharge occurs in the electric device 10 (for example, the electric device 10a), as described in Patent Document 2 as a partial discharge generation mechanism, the partial discharge portion is a kind of charge disappearance source 16, It can be considered that this occurred in the electric device 10. Then, the charge q disappeared from the charge disappearance source 16 is charged from the outside to be compensated.

The partial discharge monitoring device 20 supplies a charging current i ₀ (this is a current corresponding to the lost charge q) associated with the partial discharge to the electric device 10 (for example, 10a) in which the partial discharge has occurred as described above. It has the insulator 22 which contains the capacitor | condenser 24 which carries out. That is, the insulator 22 containing the capacitor 24 is housed in a metal container 6 housing the electrical device 10 to be monitored, and one end of the capacitor 24 is electrically connected to the voltage bus 12, etc. The end is electrically grounded. In this example, it is connected to the ground bus 14 via the ground wire 26 and grounded.

  The insulator 22 is, for example, a porcelain insulator, a resin insulator or the like, and the shape, material, and the like are not limited to specific ones.

The charging current i ₀ generally has a damped oscillation waveform determined by the inductance L, capacitance C and resistance R of the electric circuit (closed circuit) through which the charging current i ₀ flows. That is, the charging current i ₀ is alternating current (more specifically, high frequency), and its direction is reversed with time.

Partial discharge monitoring device 20 further includes a current detector 28 for detecting the charging current i ₀ which flows therethrough provided in the ground circuit of the capacitor 24, the value of the charging current i ₀ detected by the current detector 28 ( And a signal processing device 30 for detecting (amplitude).

  The current detector 28 is, for example, a Rogowski coil, but may be other types. The current detector 28 may be built in the insulator 22 as in this example. The Rogowski coil will be described later.

  The signal processing device 30 may be stored in the metal container 6 as in this example, or may be provided outside the metal container 6. For example, you may attach to the outer surface of the metal container 6. FIG. A more specific example of the signal processing device 30 will be described later.

The partial discharge monitoring device 20 includes an insulator 22 including a capacitor 24 that supplies a charging current i ₀ at the time of partial discharge, in the same metal container 6 that houses the electrical device 10 to be monitored. Therefore, the inductance between the capacitor 24 and the monitored electrical device 10 can be reduced. Therefore, the frequency of the charging current i ₀ supplied to the electrical device 10 where partial discharge has occurred from the capacitor 24 can be made relatively high. In addition, since the capacitance of the capacitor 24 can be freely selected, the frequency of the charging current i ₀ can be relatively freely selected. As a result, when the same charge (the above-mentioned disappearance charge q) is supplied to the part of the partial discharge, the value (amplitude) of the charging current i ₀ is larger than that in the technique of externally attaching the coupling capacitor described in Patent Document 2. . This is because high frequency charging current i _0, shortens its duration t, as can be seen from the following equation, when the short duration t, the case of supplying the same loss charge q, the charging current i ₀ This is because the value of increases. As a result, the SN ratio is improved, and the monitoring accuracy of partial discharge can be increased.

[Equation 1]
q = ∫i ₀ (t) dt

For example, when the inductance L of the closed circuit through which the charging current i ₀ flows is 5 μH to 20 μH, the capacitance of the capacitor 24 is selected to be 1000 pF, and the capacitance between the electric device 10 where the partial discharge has occurred and the ground Assuming a closed circuit with a combined capacitance of 50 pF to 1000 pF, the frequency (= 1 / 2π√LC) of the charging current i ₀ is 1 MHz to ₁₀ MHz. This is about two orders of magnitude larger than the frequency (several tens of kHz to several hundreds of kHz) in the case of the technique of externally attaching the coupling capacitor described in Patent Document 2.

  In addition, since the partial discharge monitoring device 20 is configured to store the insulator 22 including the capacitor 24 in the metal container 6 that stores the electrical device 10 to be monitored, the periphery of the capacitor is configured to be compact. It can be easily applied to existing power distribution facilities, and mass productivity is high.

Further, as in the example of FIG. 1, even if the power distribution facility 4 includes a plurality of electric devices 10, even if any of the electric devices 10 generates a partial discharge, charging from the capacitor 24 is caused by the partial discharge. Since the current i ₀ can be supplied and the charging current i ₀ can be detected, partial discharges in a plurality of electrical devices 10 in the power distribution facility 4 can be monitored collectively. FIG. 1 shows an example in which a partial discharge occurs in the electric device 10a, but partial discharges in other electric devices 10 in the power receiving and distribution facility 4 can be monitored in the same manner.

Even if one of the electric devices 10 is a transformer (for example, a step-down transformer) and the voltage bus 12 is divided between the primary side and the secondary side, the electrostatic capacitance between the primary and secondary sides of the transformer Since the capacity is usually quite large (for example, several hundred pF or more), the charging current i _{0 in} the frequency band of the MHz order as described above is equivalent to a state where both voltage buses are connected. Therefore, it is usually possible to monitor the partial discharge of the electrical device 10 connected to the voltage bus 12 on the other side from the partial discharge monitoring device 20 connected to the voltage bus 12 on one side.

  The insulator 22 incorporating the capacitor 24 may also serve as a support insulator for supporting the voltage bus 12 from the ground potential portion in the metal container 6. If it does in that way, the insulator 22 which contains the said capacitor | condenser 24 can be replaced with the existing support insulator in the existing power distribution equipment. Therefore, since the insulator 22 incorporating the capacitor 24 can be provided without requiring an extra space, the application of the partial discharge monitoring device 20 to the existing power distribution facility 4 becomes easier. If the current detector 28 is also built in the insulator 22 as in this example, the application of the partial discharge monitoring device 20 to the existing power distribution facility 4 becomes easier.

  The current detector 28 may be a Rogowski coil surrounding a ground line 26 that grounds the capacitor 24 as in the example shown in FIG. Although the Rogowski coil is shown in a greatly simplified manner in FIG. 1 and the like, as is well known, the Rogowski coil is an annular coil in which a conductive wire is wound around the core (or air core) of the annular body. By detecting the change in magnetic flux due to the current passing through the inside, the current can be detected and measured.

When the current detector 28 is a Rogowski coil as described above, the ground line 26 becomes the primary circuit of the Rogowski coil as it is. Therefore, even if the current detector 28 is provided, the capacitor 24 and the electric device 10 to be monitored The charging current i ₀ at the time of partial discharge can be detected without increasing the inductance between the two. Therefore, it is not necessary to decrease the frequency of the charging current i ₀ , thereby increasing the value of the charging current i ₀ and improving the S / N ratio, thereby improving the partial discharge monitoring accuracy.

Moreover, since the Rogowski coil is a differential current detector that outputs a differential signal of the signal to be detected, it is excellent in detecting a minute signal in a high frequency range, and the charging current i ₀ when a partial discharge occurs is also the same. Since it is a kind of such a small signal, the charging current i ₀ can be detected with higher accuracy, and the monitoring accuracy of partial discharge can be improved.

FIG. 2 shows a more specific example of the signal processing device 30. The signal processing device 30 includes an amplifier 36 that amplifies a signal from the current detector 28 that detects the charging current i ₀ , a band-pass filter 38 that selectively passes the signal from the amplifier 36, and a band-pass filter 38. And a processing circuit 40 that detects the value of the charging current i ₀ by processing the signal from the. The band-pass filter 38 selectively passes a signal in a frequency band including the resonance frequency of the electric circuit through which the charging current i ₀ flows (this is, for example, in the range of 1 MHz to 10 MHz as described above). .

  There is a possibility that various disturbance signals are transmitted from outside to the power distribution facility 4. For example, a disturbance signal having a low frequency (for example, several hundred kHz or less) due to a discharge phenomenon, a surge, or the like may be transmitted from the commercial power supply 2 side or the load side opposite thereto. Considering the length of the power cable connected to the power receiving and distribution facility 4, the high frequency component is highly likely to be greatly attenuated during its propagation. In addition, a disturbance signal having a high frequency (for example, about 10 MHz or more) such as a broadcast radio wave or a radio wave accompanying air discharge may be transmitted. These disturbance signals may be included in the signal from the current detector 28.

Therefore, as in this example, if the band-pass filter 38 described above is provided, the disturbance signal included in the signal from the current detector 28 can be blocked, so that the charging current i by the processing circuit 40 can be prevented. The detection accuracy of ₀ can be increased, and consequently the partial discharge monitoring accuracy can be increased.

  As shown in the example of FIG. 2, a voltage dividing capacitor 32 is provided in series in the insulator 22 and on the ground side of the capacitor 24. Further, an AC voltage having a commercial frequency shared by the voltage dividing capacitor 32 is supplied to a desired voltage. It is also possible to provide a direct current power supply device 34 that converts the direct current voltage into a direct current voltage for output and supplies the output of the direct current power supply device 34 as a power source for the signal processing device 30. The DC power supply device 34 is, for example, a switching power supply device, but may be other than that.

  If comprised as mentioned above, since it becomes unnecessary to supply a power supply (control power supply) to the partial discharge monitoring apparatus 20 from the outside, installation of the partial discharge monitoring apparatus 20 becomes easy. Moreover, application of the partial discharge monitoring device 20 to the existing power distribution facility 4 is simplified.

  Another example of the signal processing device 30 is shown in FIG. The amplifier 36 and the band pass filter 38 are the same as those described with reference to FIG.

As a more specific example of the processing circuit 40, the signal processing device 30 detects a peak value of the charging current i ₀ detected by the current detector 28 and holds it until a reset signal RS is given from the data processing device 46. A peak value detector 42, an A / D converter 44 for A / D converting the peak value, and measurement data relating the peak value to the phase φ of the commercial frequency voltage component supplied from the counter 52 And a data processing device 46 (data processing means) for saving. Since the frequency of the charging current i ₀ detected by the current detector 28 is high as described above, the peak value detector 42 detects and holds the peak value of the charging current i ₀ , thereby burdening the subsequent signal processing. Can be reduced. A more specific example of the function of the data processing device 46 will be described later. The data processing device 46 is configured using, for example, a microprocessor and a memory.

The signal detected by the current detector 28 naturally includes a commercial frequency voltage component in addition to the signal corresponding to the charging current i ₀ . This is because the commercial frequency voltage is applied from the commercial power source 2 between the voltage bus 12 and the ground bus 14 as shown in FIG. Since this commercial frequency current flows through the capacitor 24, it becomes a lead current of 90 degrees from the voltage phase.

  The signal processing device 30 of this example only makes it possible to monitor partial discharges in other phases by using the partial discharge monitoring device 20 provided in one phase by making good use of the phase information of the commercial frequency voltage component. In addition, it is possible to specify in which phase of the three phases of the electric device 10 the partial discharge occurs.

That is, it can be considered that the voltage bus 12 constituting the power receiving and distribution facility 4 and the phases of the electric device 10 are usually coupled with a relatively large capacitance. Therefore, even if the partial discharge monitoring device 20 is provided in one phase, even if a partial discharge occurs in another phase, whether or not the value is large or small, the charging current i ₀ flows and the current is detected. Since it can be detected by the detector 28, partial discharge in other phases can be monitored.

  In addition, in order to enable the identification of the phase in which the partial discharge has occurred, the signal processing device 30 uses the commercial frequency voltage component (which includes the partial discharge monitoring device 20) from the signal detected by the current detector 28. A low-pass filter 48 (extracting means) for extracting the phase of the commercial frequency voltage component of the main phase, that is, a representative phase commercial frequency voltage component described later, and a zero-cross detector 50 for detecting the zero-cross point of the commercial frequency voltage component extracted by the low-pass filter 48; A clock signal generator 54 for generating a clock signal, and the clock signal is counted for each period of the commercial frequency voltage component, and the phase φ of the commercial frequency voltage component is determined to indicate the phase φ (specifically Is further provided with a counter 52 for supplying the data processing device 46 with a count value. The zero cross detector 50, the counter 52, and the clock signal generator 54 constitute phase determining means.

The data processing device 46 creates and stores measurement data in which the phase φ of the commercial frequency voltage component and the value of the charging current i ₀ detected at that phase (in this example, the peak value) are associated with each other. By creating and storing such measurement data, in addition to monitoring the occurrence of partial discharge, it is also possible to specify in which phase of the three phases of the electrical device 10 the partial discharge has occurred. This will be described below.

(A) When there is a small void (void defect) in the dielectric of the electric device 10 and a partial discharge occurs there, the partial discharge occurs in a voltage region where the commercial frequency voltage applied to the void exceeds the discharge voltage of the void. Therefore, the phase of the commercial frequency voltage is usually (a) up to a positive peak value where the voltage rises from 0, or (b) up to a negative peak value where the voltage falls from 0. However, since the absolute value of the voltage applied to the void needs to be increased to some extent, the phase at which the partial discharge occurs is considered to be after the middle. This will be explained with reference to FIG. 4 showing a one-phase commercial frequency voltage. When a partial discharge occurs in a void, the phase φ of the commercial frequency voltage is usually from the middle between 0 and 90 degrees. It can be considered that the phase interval S _{1 is} up to 90 degrees or the phase interval S ₂ is from the middle of 180 degrees and 270 degrees to 270 degrees.

(B) On the other hand, when the electric device 10 has a sharp end portion of a conductor and a partial discharge occurs between the sharp end portion and the opposite portion, the commercial device is usually applied to the space gap between the two. It is considered that the vicinity of the positive or negative peak value of the frequency voltage is the phase at the start of discharge. This will be described with reference to FIG. 4. The phase φ of the commercial frequency voltage in the case where partial discharge occurs at the sharp end of the conductor is usually the phase interval S ₃ or 270 degrees before and after 90 degrees. It is considered that the phase interval S ₄ before and after that is interposed. However, partial discharges in sharp end is close to the needle end discharge phenomenon, as is well known in the needle end discharge, sharp end toward the phase section S ₄ is more partial discharge occurs, which is in the vicinity negative peak It can be said that it tends to be easy.

When the above (A) and (B) are combined, the partial discharge is likely to occur in the electric device 10 in general, in terms of the phase φ of the commercial frequency voltage, and immediately after 90 degrees from the middle of 0 degrees and 90 degrees. It is conceivable that the phase interval S ₅ to the vicinity or the phase interval S ₆ from the vicinity of the middle between 180 degrees and 270 degrees to the vicinity immediately after 270 degrees.

As described above, since the commercial power source 2 and the electric device 10 are usually three-phase, the case of the three-phase will be described with reference to FIG. The A phase, B phase, and C phase are each 120 degrees out of phase. As described with reference to FIG. 4, the partial discharge in the A phase of the electric device 10 is likely to occur in the phase section S _A corresponding to the phase sections S ₅ and S ₆ in FIG. 4. Similarly, the partial discharge in the B phase of the electric device 10 is likely to occur in the phase interval S _B corresponding to the phase intervals S ₅ and S ₆ in FIG. 4, and the partial discharge in the C phase of the electric device 10 is in the phase interval S. It is likely to occur in _C.

Therefore, the phase φ of the commercial frequency voltage of the A phase is about 90 degrees or 270 with reference to the phase φ of the commercial frequency voltage of the phase with the current detector 28 as a representative phase, for example, the A phase as a representative phase. When partial discharge is detected in the phase interval S _A before and after this, there is a high possibility that partial discharge has occurred in the A phase of the electrical device 10. Similarly, when detecting the partial discharge when the phase φ of the commercial frequency voltage of the A-phase is 30 degrees before, after, or 210 degrees before and after the phase section S _B, partial discharge occurs in phase B of the electrical device 10 Probability is high. When the phase φ of the commercial frequency voltage of the A-phase is detected partial discharge when the front and rear 150 degrees back and forth, or 330 degree phase intervals S _C, possibly partial discharge occurs in the phase C of the electrical device 10 high.

Therefore, as described above, by creating and storing measurement data that correlates the phase φ of the commercial frequency voltage component and the value of the charging current i ₀ detected at that phase, it is possible to monitor the occurrence of partial discharge. In addition, it is possible to specify in which phase of the three phases of the electrical device 10 the partial discharge has occurred.

As described with reference to FIGS. 4 and 5, since the partial discharge phenomenon is likely to occur collectively within a specific phase interval of the commercial frequency voltage, the data processing device 46 uses the commercial frequency voltage described above. The measurement data in which the phase φ of the component and the value of the charging current i ₀ detected at that phase are correlated with each other is divided into phase intervals of 5 to 30 degrees of the commercial frequency voltage component, the peak value of the charging current i ₀ may have a function to create and save the measurement data to the value of the charging current of the respective phase intervals. As described above, by dividing the measurement data for each phase interval, it becomes easier to specify which of the three phases has the partial discharge.

  An example of the measurement data divided as described above is shown in Table 1. This is an example of an interval of 30 degrees, but is not limited to an interval of 30 degrees.

The reason why the phase interval is preferably 5 ° to 30 ° is that variation in the partial discharge generation phase is taken into consideration. That is, if the interval is smaller than the 5 degree interval, there is almost no meaning for dividing the phase interval. When the interval is larger than 30 degrees, the phase sections S _A , S _B , and S _C shown in FIG. 5 are close to each other, and there is a high possibility of being confused with other phases.

Since the knowledge that the possibility of the partial discharge phenomenon occurring at every cycle of the commercial frequency voltage is basically high is obtained when the partial discharge phenomenon starts to occur, the data processing device 46 determines the charge current i ₀ of each phase interval. As for the value, it has a function of calculating an average value between a plurality of cycles of the commercial frequency voltage for each phase interval, and creating and storing measurement data using the average value as the value of the charging current i ₀ in each phase interval. May be. The average value may be obtained, for example, about 100 cycles of the commercial frequency voltage. In this way, by taking the average value of the commercial frequency voltage for a plurality of cycles with respect to the value of the charging current i _{0 in} each phase section, there is a sporadic unique charging current i ₀ value due to the influence of noise or the like. However, since the influence can be made very small, the reliability of the measurement data can be increased, and as a result, the monitoring accuracy of partial discharge can be increased.

  Table 2 shows an example of measurement data obtained by taking the average value as described above. This is an example of an interval of 30 degrees, but is not limited to an interval of 30 degrees.

(2) Partial Discharge Monitoring System FIG. 6 shows an example of a partial discharge monitoring system according to the present invention.

  This partial discharge monitoring system includes a communication line 60 for transmitting signals, a plurality of partial discharge monitoring devices 20 as described above, each having a communication circuit, and data collection processing placed in a central data center or the like. Device 62. Each partial discharge monitoring device 20 is provided in each power receiving and distribution facility to be monitored, and these may be installed in a wide area.

  The communication line 60 may be wired, wireless, or an optical line. A network communication line or the Internet may be used.

  The signal processing device 30 of each partial discharge monitoring device 20 has a communication circuit that transmits and receives signals via the communication line 60. An example is shown in FIG. The signal processing device 30 transmits the measurement data created and stored in the data processing device 46 as described above via the communication line 60 and also sent from the data collection processing device 62 via the communication line 60. A communication circuit 56 is provided for receiving incoming command signals. When the communication line 60 is wireless, the communication circuit 56 exchanges signals with the communication line 60 via the antenna 58.

  Referring again to FIG. 6, the data collection processing device 62 includes a communication circuit 64 that transmits and receives signals via the communication line 60, and each communication via the communication line 60 via the communication line 64 at predetermined intervals. A data collection device 66 (data collection means) that gives a command to transmit the measurement data to the partial discharge monitoring device 20 and collects and stores the measurement data stored in each partial discharge monitoring device 20 at that time. Have. You may further have the determination apparatus 68 mentioned later. The data collection processing device 62 may be constituted by, for example, a computer having a processing device, a storage device, and a man-machine interface (eg, an input / output device, a display device, etc.).

  According to this partial discharge monitoring system, the measurement data of a plurality of partial discharge monitoring devices 20 can be collected collectively by the data collection processing device 62 at a remote location via the communication line 60. Partial discharges in electrical equipment of a plurality of power receiving and distribution facilities provided with the devices 20 can be collectively monitored at a remote place.

  The data collection device 66 of the data collection processing device 62 collects the measurement data for each area where each partial discharge monitoring device 20 is installed, which is provided from the weather information provider 70 via the communication line 60. When weather information including the weather and humidity is collected in the time zone during which the partial discharge monitoring device 20 is installed, the weather in the time zone of the measurement data collection is rain or snow or the humidity is a predetermined value or more In addition, the measurement data collected from the partial discharge monitoring device 20 may be excluded and stored.

  The weather information provider 70 is, for example, the Japan Meteorological Agency or a private weather information provider.

  Humidity is usually the relative humidity generally used. When the humidity is high, for example, when the humidity is 90% or more, the exclusion process is performed.

  It has been found that there is a possibility that a discharge phenomenon in the air other than partial discharge may occur in the electric device 10 in a time zone where the weather is rain or snow or humidity is high. Therefore, by excluding the measurement data in such a time zone as described above, the reliability of the measurement data can be further increased, and the partial discharge monitoring accuracy can be further increased.

The data collection device 66 of the data collection processing device 62 may have a function of creating and storing trend data representing the time transition of the collected measurement data for each partial discharge monitoring device 20. Further, the data collection processing device 62, based on the trend data for each partial discharge monitoring device 20, increases the value of the charging current i ₀ included in the trend data by a predetermined width or more within a predetermined period, and increases it. The determination apparatus which determines whether the state which was performed continued for the predetermined period, and determines that the partial discharge has generate | occur | produced in the electric equipment 10 of the power distribution equipment 4 which provides the said partial discharge monitoring apparatus 20 when it continues 68 (determination means) may be included.

A schematic example of the time transition of the value of the charging current i ₀ included in the trend data is shown in FIG.

It has been found that partial discharge in the electric device 10 occurs suddenly when it occurs, and once generated, it is highly likely that it will continue for a long period of time. Accordingly, the discharge current i included in the trend data is obtained. The value of ₀ also increases suddenly, for example, as shown in part A in FIG. 7, and the increased state continues for a long period of time. Therefore, by determining whether the value of the charging current i ₀ included in the trend data increases (a) within a predetermined period (b) over a predetermined width, (c) and whether the increased state continues for a predetermined period It is possible to accurately determine the occurrence of partial discharge by eliminating the influence of discharge phenomena other than partial discharge.

The predetermined period of the determination (a) is, for example, about 2 to 3 days or 5 to 6 days. The predetermined width of the determination in (b) may be, for example, the value of the charging current i ₀ itself (that is, the absolute value) or the rate of change. For example, in the former case, it is determined that the value of the charging current i ₀ has increased by 50 μA or more, and in the latter case, it is determined that the ratio of the value of the charging current i ₀ has increased by 50% or more. .

The knowledge that the leakage current due to dirt on the surface of the electrical device 10 does not increase suddenly but gradually increases with time has been obtained, and by adding the determinations (a) and (b) above, It is possible to distinguish between an increase in the value of the charging current i ₀ due to such a leakage current and an increase in the value of the charging current i ₀ due to the occurrence of partial discharge. Therefore, it is possible to improve the accuracy of determining the occurrence of partial discharge.

  The predetermined period of the continuation determination in (c) is, for example, one month, but may be shorter or longer than this.

When the partial discharge monitoring device 20 detects external noise or when the power distribution facility 4 provided with the partial discharge monitoring device 20 is exposed to high humidity, the value of the detected charging current i ₀ increases. However, the knowledge that it does not continue for a long time has been obtained, and by adding the continuation determination of (c) above, an increase in the value of the charging current i ₀ due to such noise, high humidity, etc. It can be distinguished from an increase in the value of the charging current i ₀ due to partial discharge. Therefore, it is possible to improve the accuracy of determining the occurrence of partial discharge.

DESCRIPTION OF SYMBOLS 4 Power distribution equipment 6 Metal container 10, 10a Electric equipment 12 Voltage bus 14 Ground bus 20 Partial discharge monitoring device 22 Insulator 24 Capacitor 26 Ground wire 28 Current detector 30 Signal processing device 32 Voltage dividing capacitor 34 DC power supply device 46 Data processing Device 56 Communication circuit 60 Communication line 62 Data collection processing device 64 Communication circuit 66 Data collection device 68 Judgment device i ₀ Charging current

Claims (3)

A device for monitoring a partial discharge generated in an electric device of a power distribution facility having a structure in which a voltage bus to which a commercial frequency voltage is applied and one or more electric devices connected thereto are housed in a metal container. There,
(A) An insulator containing a capacitor for supplying a charging current associated with the partial discharge to the electrical device in which the partial discharge has occurred is housed in the metal container housing the electrical device to be monitored, One end of the capacitor is electrically connected to the voltage bus in the metal container, and the other end is electrically grounded,
(B) a current detector for detecting the charging current flowing therethrough is provided in the ground circuit of the capacitor;
(C) further comprising a signal processing device for detecting the value of the charging current detected by the current detector ;
(D) And the insulator incorporating the capacitor also serves as a support insulator for supporting the voltage bus from the ground potential portion in the metal container,
(E) A voltage dividing capacitor is provided in series within the insulator and on the ground side of the capacitor, and is configured to extract an AC voltage of a commercial frequency shared by the voltage dividing capacitor from the insulator.
(F) a DC power supply circuit that receives the AC voltage of the commercial frequency shared by the voltage dividing capacitor taken out, converts it into a DC voltage, and outputs the DC voltage;
(G) The partial discharge monitoring device characterized in that the output of the DC power supply circuit is used as the power supply of the signal processing device. The signal processing device includes:
(A) extraction means for extracting a commercial frequency voltage component from the signal detected by the current detector;
(B) phase determining means for determining the phase of the commercial frequency voltage component;
(C) phase and the detected portion of the data processing means and to which claim 1 has to create and save measurement data and values associated with each other of the charging current to the phase when the commercial frequency voltage component Discharge monitoring device. A partial discharge monitoring system comprising a communication line for transmitting a signal, a plurality of partial discharge monitoring devices, and a data collection processing device,
(A) Each partial discharge monitoring device is a partial discharge monitoring device for monitoring partial discharge generated in the electrical equipment of a power distribution facility that houses one or more electrical equipment in a metal container,
(A) An insulator containing a capacitor for supplying a charging current associated with the partial discharge to the electrical device in which the partial discharge has occurred is housed in the metal container housing the electrical device to be monitored, One end of the capacitor is electrically connected to the voltage bus in the metal container, and the other end is electrically grounded,
(B) a current detector for detecting the charging current flowing therethrough is provided in the ground circuit of the capacitor;
(C) further comprising a signal processing device for detecting the value of the charging current detected by the current detector;
(D) and the signal processing apparatus includes an extraction unit that extracts a commercial frequency voltage component from the signal detected by the current detector, a phase determination unit that determines a phase of the commercial frequency voltage component, and the commercial frequency voltage component. Data processing means for creating and storing measurement data that correlates the phase and the value of the charging current detected at that phase, and a communication circuit that transmits and receives signals via the communication line And
(B) The data collection processing device includes:
(A) a communication circuit for transmitting and receiving signals via the communication line, and a command for transmitting the measurement data to each partial discharge monitoring device via the communication line every predetermined time, Data collecting means for collecting and storing the measurement data stored in each partial discharge monitoring device;
(B) and the data collection means is provided by a weather information provider via the communication line for each area where the partial discharge monitoring devices are installed and for collecting the measurement data Collecting weather information including weather and humidity, and when the weather in the measurement data collection time zone of the area where the partial discharge monitoring device is installed is rain or snow or humidity is above a predetermined value, partial discharge monitoring system for has a function of storing by excluding the measurement data collected from the partial discharge monitoring device, that said.

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