JP6627242B2 - Partial discharge measurement device - Google Patents

Description

  The present invention relates to a partial discharge measuring device that measures a partial discharge generated inside a metal shielding device.

   Diagnosis of insulation deterioration of electrical equipment is performed by measuring partial discharge that occurs as a precursory phenomenon of dielectric breakdown. As a method of detecting a partial discharge generated in an electric device in a non-contact manner, there is a method of detecting an occurrence of a partial discharge by receiving electromagnetic waves radiated from a partial discharge power source by a plurality of antennas (for example, see Patent Document 1).

  In addition, there is one in which a plurality of acoustic sensors (AE sensors) are used to specify a partial discharge and its discharge power (see, for example, Patent Document 2). In this technique, at least three AE sensors are mounted, and the position of the discharge power source is determined in consideration of the arrival time of the direct wave of the AE signal output from each AE sensor and the arrival time delay of the high-frequency component. When the discharge power is inside the winding, the propagation speed of the discharge sound is changed according to the different propagation medium, the propagation distance from the discharge power to each AE sensor is obtained, and the position of the discharge power is located.

  Further, there is a device that detects a partial discharge using a surface current sensor (for example, see Patent Document 3). This is done by providing a detection line that is excited only by the high-frequency surface current flowing on the ground layer surface of the external grounding device without being affected by an external electromagnetic field, connecting a terminating resistor to one end of the detection line, and connecting a measurement cable to the other end. It is connected, the detection line is held by a metal housing at a position close to the surface of the ground layer, and partial discharge is taken out by a measurement cable.

JP 2011-85393 A JP 2013-44616 A JP-A-10-170591

  However, since the electromagnetic wave is detected by the antenna in Patent Literature 1, it is affected by noise due to the electromagnetic wave outside the panel in which the electric device is stored, and a measure for improving the detection accuracy is required. The device configuration becomes complicated.

  In Patent Document 2, since a slight vibration due to the partial discharge is detected, it is possible to detect that the partial discharge is occurring, but it is possible to specify in which phase of the three-phase AC the partial discharge is occurring. For this purpose, it is necessary to use a plurality of AE sensors, and it takes much time to specify the phase in which the partial discharge is occurring.

  In Patent Document 3, the plane wave (electromagnetic wave) inside the device generated by the partial discharge leaks from the non-metallic part to the outside of the device, and the plane wave propagating on the leaked device surface is detected. In addition to the waveform detected by the plane wave due to the partial discharge generated in the above, a plane wave due to an external influence such as corona discharge in the aerial part or switching during operation of the device is also detected, and it is very difficult to distinguish between the two. Further, it is not possible to determine the phase in which partial discharge has occurred by measuring only the surface current sensor.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a partial discharge measuring device capable of improving the detection accuracy of a partial discharge without complicating the device configuration and easily determining a phase in which a partial discharge is occurring.

The partial discharge measuring device according to the first aspect of the present invention is a surface current sensor that is installed on an exterior surface of a gas insulated switchgear as a metal shielding device and detects a current excited by a partial discharge in the gas insulated switchgear , A voltage detection device that detects a voltage applied to the gas insulated switchgear, and synchronizes a current waveform detected by the surface current sensor with a voltage waveform detected by the voltage detection device on the same time axis. and a display device for displaying the magnitude of the current value of the detected current waveform in the surface current sensor in the vicinity of the peak of the voltage waveform, the current of the current waveform detected by said face current sensor near the peak of the voltage waveform By checking the magnitude of the value, it is possible to determine whether or not the discharge is due to partial discharge from inside the gas insulated switchgear .

In the partial discharge measuring device according to a second aspect of the present invention, in the first aspect of the present invention, the surface current sensor is disposed on a flexible insulating base material and the gas-insulated switchgear together with the insulating base material. A conductor that is bent in close contact with the curved surface of the exterior surface, a flexible shield portion that electromagnetically shields the conductor, and a detection formed at one end of the conductor and detecting a current excited by the conductor A terminal and a terminating resistor formed at the other end of the conductor for preventing reflection of a current excited by the conductor are provided.

According to the invention of claim 1, a surface current sensor is installed on the outer surface of the gas insulated switchgear which is a metal shielding device to detect a current excited by a partial discharge in the gas insulated switchgear. Detects the voltage applied to the gas insulated switchgear , synchronizes the current waveform detected by the surface current sensor with the voltage waveform detected by the voltage detector on the display device, and sets the peak of the voltage waveform on the same time axis. Since the magnitude of the current value of the current waveform detected by the surface current sensor is displayed in the vicinity , it is easy to determine whether or not partial discharge has occurred in the gas insulated switchgear based on the positional relationship between the current waveform and the voltage waveform. The phase in which partial discharge has occurred can be easily determined. Also, since the current waveform detected by the surface current sensor and the voltage waveform detected by the voltage detection device are synchronized and only displayed on the display device on the same time axis, partial discharge detection can be performed without complicating the device configuration. Accuracy can be improved.

  According to the invention of claim 2, since the surface current sensor is bendable, it can be installed in close contact with the curved surface of the exterior surface of the metal shielding device, so that the detection accuracy of the surface current sensor can be improved.

FIG. 1 is a configuration diagram of a partial discharge measuring device according to an embodiment of the present invention. FIG. 4 is a waveform diagram illustrating an example of a current waveform and a voltage waveform displayed on the display device according to the embodiment of the present invention. FIG. 1 is a configuration diagram illustrating an example of a surface current sensor according to an embodiment of the present invention. FIG. 4 is a configuration diagram illustrating another example of the surface current sensor according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described. FIG. 1 is a configuration diagram of a partial discharge measuring device according to an embodiment of the present invention. The surface current sensor 11 is installed on an exterior surface of the metal shielding device 12 and detects a current excited by a partial discharge in the metal shielding device 12. The metal shielding device 12 is, for example, a gas-insulated switchgear GIS that is a gas-insulated device. Gas insulated switchgear GIS uses sulfur hexafluoride SF6 gas, which has better insulating properties and extinguishing ability than air, and uses a circuit breaker, disconnector, and ground switch in a grounded metal hermetic container. , Bus bars, lightning arrestors, instrument transformers, current transformers, etc. are housed and gas-insulated.

When a partial discharge occurs inside such a metal shielding device 12, a plane wave (electromagnetic wave) is generated inside the metal shielding device 12 due to the partial discharge. Plane wave generated is leaked from a non-metallic portion (e.g. bushing) to the outside of the metal shielding devices 12, it propagates the surface of the exterior surface of the metal shielding device 12. The conductor inside the surface current sensor 11 is excited by the plane wave propagating on the surface of the exterior surface of the metal shielding device 12, and a current flows through the conductor. As a result, a voltage is generated in the conductor inside the surface current sensor 11. By detecting this voltage, the current due to the partial discharge in the metal shielding device 12 is detected.

  On the other hand, a commercial voltage is applied to the mini clad 13 from the metal shielding device 12. The mini-clad 13 is formed by hardening the main circuit breaker, the instrumentation transformer PT, the instrumentation current transformer CT, etc. necessary for distributing the three-phase commercial voltage with resin so that the charged part (metal part) is not exposed. It has three-phase power distribution terminals 14r, 14s, and 14t, and these three-phase power distribution terminals 14r, 14s, and 14t are connected to a distribution line. The power distribution terminals 14r, 14s, and 14t are mini clad 13 cable heads. In FIG. 1, only the three-phase power distribution terminals 14 r, 14 s, and 14 t are shown, and the illustration of the main breaker, the instrument transformer PT, the instrument current transformer CT, and the connection cables from the metal shield device 12 is omitted. ing.

  The voltage detection device 15 detects a voltage applied to the metal shielding device 12. For example, a Rogowski coil for measuring a commercial voltage waveform, a clamp CT, etc., which can be easily attached and detached around the cable heads of the three-phase power distribution terminals 14r, 14s, 14t, and are applied to the metal shielding device 12. The commercial voltage is detected for each phase.

  The current waveform detected by the surface current sensor 12 and the voltage waveform detected by the voltage detection device 15 are input to the display device 16. The display device 16 synchronizes the current waveform detected by the surface current sensor 12 with the voltage waveform detected by the voltage detection device 15 and displays the same on the same time axis, and is, for example, an oscilloscope or a liquid crystal display device. .

  When displaying the current waveform and the voltage waveform, the display device 16 synchronizes the current waveform and the voltage waveform and displays them on the same time axis. The display device 16 uses a device having a time axis of 5 ms / div and a sampling frequency of 50 MS / s or more. When measuring the current waveform and the voltage waveform, the time axis of the display device 16 is set to about 5 ms / div where the commercial voltage waveform enters for two or more cycles.

  FIG. 2 is a waveform diagram illustrating an example of a current waveform and a voltage waveform displayed on the display device. In FIG. 2, the commercial voltage is 50 Hz, and the R-phase voltage of the three-phase AC RST is shown. Therefore, one cycle of the voltage waveform of the commercial voltage, that is, the time from time t01 to time t02, which is the zero cross point where the voltage waveform changes from minus to plus, is 20 ms. The current waveform detected by the surface current sensor 12 is displayed on the same time axis in synchronization with the voltage waveform detected by the voltage detection device 15.

  Here, the partial discharge waveform is generated at a period of 10 ms (in the case of the commercial voltage waveform of 50 Hz) in synchronization with the vicinity of the peak of the voltage waveform of the commercial voltage or the zero-cross point, though it depends on the cause of the occurrence. Therefore, by checking the synchronization between the current waveform detected by the surface current sensor 11 and the voltage waveform of the commercial voltage, it can be determined whether or not the detected waveform is due to partial discharge from inside the metal shielding device 12. . That is, by determining whether or not the current value of the current waveform detected by the surface current sensor 11 is large near the peak of the voltage waveform of the commercial voltage or at the zero crossing point, partial discharge from inside the metal shielding device 12 is performed. Can be determined.

As shown in FIG. 2, the current value X2 detected by the surface current sensor 11 near the peak (near the negative peak) Y1 of the voltage waveform of the commercial voltage at the time point t11 is large, and the commercial value at the time point t12 is large. The current value X3 detected by the surface current sensor 11 is large near the peak Y2 of the voltage waveform (near the peak on the plus side). Further, the current value X1 detected by the surface current sensor 11 at the zero cross point Z of the voltage waveform of the commercial voltage at the time point t01 is large.

  From this, in the voltage waveform (R phase) of the commercial voltage, the current waveform of the partial discharge is detected before the peak value and near the zero cross, and the phase in which the partial discharge occurs is determined to be the R phase. it can.

  As described above, the synchronization between the current waveform detected by the surface current sensor 11 and the voltage waveform of the commercial voltage is confirmed, that is, the current waveform detected by the surface current sensor 11 near the peak of the voltage waveform of the commercial voltage or at the zero cross point. By checking the magnitude of the current value of the current waveform, it can be determined whether or not the detected waveform is due to partial discharge from inside the metal shielding device 12. The phase in which the partial discharge is occurring can be determined by comparing the synchronization between the current waveform of the partial discharge and the voltage waveform of the commercial voltage of each phase. Furthermore, by measuring the peak value of the current value of the partial discharge, the degree of abnormal progress of the metal shielding device 12 can be grasped.

  Next, the surface current sensor will be described. 3A and 3B are configuration diagrams illustrating an example of a surface current sensor. FIG. 3A is a perspective view illustrating an internal structure, and FIG. 3B is an external perspective view. The surface current sensor 11 includes a conductor 18 disposed on an insulating base 17, a shield 19 for electromagnetically shielding the conductor 18, and a detection terminal 20 formed at one end of the conductor 18 and detecting a current excited by the conductor 18. And a terminating resistor 21 formed at the other end of the conductor 18 to prevent reflection of a current excited by the conductor 18.

  The conductor 18 is, for example, a copper foil having a certain width and is disposed on the insulating base material 17. The shield portion 19 electromagnetically shields the conductor 18 so that the conductor 18 is excited only by a current due to a partial discharge flowing on the surface of the exterior surface of the metal shielding device without being affected by an external electromagnetic field. It is formed of a housing. A detection terminal 20 for detecting a current excited in the conductor 18 is connected to one end of the conductor 18, and a terminating resistor 21 for preventing reflection of the current excited in the conductor 18 is connected to the other end of the conductor 18. . The detection terminal 20 and the terminating resistor 21 are attached to the shield part 19 which is a metal housing. Then, the current due to the partial discharge flowing through the conductor 18 is detected by the detection terminal 20 and input to the display device.

  4A and 4B are configuration diagrams showing another example of the surface current sensor. FIG. 4A is an exploded perspective view, FIG. 4B is an external perspective view, and FIG. 4C is an external view showing a bent state. It is a perspective view. In another example, the surface current sensor 11 shown in FIG. 3 is bendable.

  As shown in FIG. 4A, the shield portion 19 is formed of a flexible metal member which is formed on a plane. Similarly, the insulating base 17 is also formed of a material having flexibility, and the conductor 18 disposed on the insulating base 17 is also formed of a metal sheet (for example, copper foil) so as to have flexibility. . A detection terminal 20 for detecting a current excited in the conductor 18 is connected to one end of the conductor 18, and a terminating resistor 21 for preventing reflection of the current excited in the conductor 18 is connected to the other end of the conductor 18. Is done. As shown in FIG. 4B, the shield 19 surrounds the conductor 18 and electromagnetically shields the conductor 18.

  Since the surface current sensor 11 configured as described above is bendable, it can be bent as shown in FIG. Thereby, it can be installed in close contact with the curved surface of the exterior surface of the metal shielding device. Therefore, the detection accuracy of the surface current sensor 11 can be improved.

  Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. The new embodiment can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 11 ... Surface current sensor, 12 ... Metal shielding equipment, 13 ... Mini clad, 14 ... Power distribution terminal part, 15 ... Voltage detection device, 16 ... Display device, 17 ... Insulating base material, 18 ... Conductor, 19 ... Shield part, 20 ... Detection terminal, 21 ... Terminal resistor

Claims (2)

A surface current sensor that is installed on the outer surface of a gas insulated switchgear that is a metal shielding device and detects a current excited by partial discharge in the gas insulated switchgear ,
A voltage detection device that detects a voltage applied to the gas-insulated switchgear ,
The current value of the current waveform detected by the surface current sensor near the peak of the voltage waveform on the same time axis by synchronizing the current waveform detected by the surface current sensor with the voltage waveform detected by the voltage detection device A display device for displaying the size of the
By confirming the magnitude of the current value of the current waveform detected by the surface current sensor near the peak of the voltage waveform, it can be determined whether or not the current is due to partial discharge from inside the gas insulated switchgear. Partial discharge measuring device. The surface current sensor is disposed on a flexible insulating base material, and a conductor that is bent together with the insulating base material in close contact with the curved surface of the exterior surface of the gas insulated switchgear ,
A flexible shield part for electromagnetically shielding the conductor,
A detection terminal formed at one end of the conductor and detecting a current excited by the conductor;
2. The partial discharge measuring device according to claim 1, further comprising a terminating resistor formed at the other end of the conductor to prevent reflection of a current excited by the conductor.

Images