JPH05164808A - Detecting method for partial discharge from phase-segragated, sealed bus-bar - Google Patents

Abstract

(57) [Summary] [Purpose] Using the inspection window of the phase-separated closed bus bar, detect the partial discharge that occurs around the phase-separated closed bus bar. [Structure] A metal plate electrode is provided on the surface of the inspection window of the transparent glass plate or plastic plate of the phase separation busbar used between the generator and the main transformer in the power plant to form a capacitance with the center conductor. This functioned as a coupling capacitor, and the partial discharge pulse current was detected between the phase-separated closed bus and the phase-separated closed bus metal case in which the partial discharge pulse current flows.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection method for detecting a partial discharge generated around a phase-separated closed busbar through an inspection window of the phase-separated closed busbar.

[0002]

2. Description of the Related Art Since there has been no example of detecting partial discharge from a phase-separated closed bus bar, an example of a partial discharge detection technique from an insulated device of a closed substation will be described. JP-A-2-7117
As shown in FIG. 4, when the metal wires 11 to 14 are mixed in the ground tank 10 or the cracks 16 are generated in the spacer 15, as shown in FIG. Partial discharge occurs at the tips of the lines 11 to 14 and the crack 16, and this is detected by the partial discharge detector. Although this example is not related to the partial discharge detection method, it is a method of providing a detector inside the insulating device and detecting the partial discharge from the detector. As a detection method similar to this, there is also a method in which an optical sensor is provided inside to detect light emission due to partial discharge.

In Japanese Patent Laid-Open No. 2-203284, an insulating plate is arranged so as to insulate a joint portion of a closed metal container, and a ring-shaped metal is arranged so as to surround the outside of the insulating plate. This makes it possible to detect partial discharge with high sensitivity. That is, as shown in FIG. 5, an insulating plate 22 having an inner diameter equal to or larger than the inner diameter is interposed midway in the axial direction of the grounded container 21 to partition the electric passage of the metal container 21. .. In addition, a metal ring 23 is arranged via a support 24 so as to surround the outer periphery of the insulating plate 22. A detection resistor 25 is electrically connected between the metal ring 23 and the ground, and coaxial cables 26 are connected to both ends of the resistor 25. When a partial discharge occurs inside the metal container 21, the discharge pulse flows through the high voltage conductor 27 and the inner surface of the metal container 21. At this time, the resistor 25 produces a voltage determined by the capacitance of the high-voltage conductor 27 and the metal ring 23 and the capacitance between the metal ring 23 and the insulating plate 22, the metal container 21, and the ground, and this voltage is detected. By doing so, the partial discharge is confirmed.

Further, the one disclosed in Japanese Patent Application Laid-Open No. 3-42579 is to detect the partial discharge generated in the gas-insulated equipment with high sensitivity by directly connecting the measuring device to the end of the insulated metal container. is there. That is, as shown in FIG. 6, if the metal particles 32 are mixed in the metal container 31, a high voltage is applied between the high-voltage conductor 33 and the metal container 31, so that an electric force is applied to the particles. With the onset of movement, a very high frequency current pulse is generated.
The current pulse travels inside the metal container 31 while repeating complex reflections on the inner wall of the metal container 31, the surface of the high-voltage conductor 33, or the like, and reaches the end portion 34 thereof. At this time, since the insulating plate 35 is interposed between the terminal end portion 34 and the metal container 31, a pulsed voltage due to the partial discharge is generated at the terminal end portion 34. This voltage is detected by the sensor 36, guided to the measuring instrument 38 via the measuring cable 37, and the partial discharge is detected. Similar to this, there is a sensor in which the sensor unit 36 is a flow-through type detector (CT).

[0005]

By the way, in the one disclosed in Japanese Patent Laid-Open No. 2-71170, it is difficult to measure the existing line because the sensor part is inside the insulating device.

Further, in the above-mentioned Japanese Patent Laid-Open No. 2-203283, it is necessary to interpose an insulating plate, and when measuring an existing line, the structure of the insulating device has to be changed, which is realistic. Is very difficult.

Further, in the one disclosed in Japanese Patent Laid-Open No. 3-42579, since the partial discharge pulse signal flowing to the ground is small, there is a problem that it cannot be detected with high sensitivity.

The object of the present invention is made in view of the above point, and it is possible to detect the partial discharge in the vicinity of the phase-separated closed busbar with high sensitivity, and to detect it safely and easily. A partial discharge detection method is provided. And it is possible to detect even on existing lines,
It can be detected even in a live state.

[0009]

According to the present invention, a metal plate electrode is provided on the surface of an inspection window of a transparent glass plate or a plastic plate of a phase separation busbar used between a generator and a main transformer in a power plant, and a center conductor is provided. It acts as a coupling capacitor by forming a capacitance between the partial discharge pulse current and the phase-separated closed bus where the partial discharge current flows and the metal case of the phase-separated closed bus. This is a partial discharge detection method.

[0010]

The metal plate electrode is attached so as to be in contact with the portion of the inspection window provided on the metal case outside the phase-separated closed busbar, and the partial discharge pulse signal is detected between the metal case and the electrode.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In general, the power system in a power plant connects a generator and a main transformer with a phase-separated closed bus. The phase-separated closed bus bar is provided with an inspection window made of transparent glass or transparent plastic for inspecting the inside.
This inspection window is used to detect the partial discharge pulse signal around the phase-separated closed bus.

FIG. 1 is a side view of the phase-separated closed bus bar. The phase-separated closed bus bar 1 is provided with an inspection window 2 made of transparent glass or transparent plastic. The metal plate electrode 3 is attached from the outside so as to contact the inspection window 2. When the inner diameter of the inspection window 2 is 200 mm, the metal plate electrode 3 has a diameter of 180 m.
Use m.

FIG. 2 shows an equivalent circuit. Cm is the center conductor 4
And Cg are the capacitances between the closed metal case 7 and Cg, and Cb is the capacitance at the partial discharge occurrence point, and Cb is the partial discharge point Cg.
Is the capacitance of a healthy part connected in series with. A capacitance Ck is formed between the center conductor 4 and the metal plate electrode 3. A partial discharge detection impedance (Zd) 5 is connected between the metal plate electrode 3 and a ground side closed metal case 7 provided outside the phase separation closed bus bar 1, and a partial discharge measuring instrument 6 of a spectrum analyzer is connected from here. Then, the signal is detected.

FIG. 3 is a graph showing a frequency spectrum as a result of measuring the relationship between the detection frequency and the signal strength by the partial discharge measuring instrument 6. As you can see from this figure,
It can be seen that the signal level of 0.2 GHz or higher is high and pulses are intermittently detected.

It is considered that this is because the electrostatic coupling between the central conductor 4 and the metal plate electrode 3 is improved at a high frequency of 0.2 GHz or more. In this case, the detection frequency was set to 0.6 GHz where the partial discharge pulse signal was the strongest.

Since this detection circuit performs detection by using a slight electrostatic capacitance between the detection circuit and the internal high voltage conductor, the low frequency signal component is cut off due to its high impedance. Further, a high frequency signal from a distance is attenuated during propagation. As a result, by detecting a signal with a frequency of 200 MHz to 1 GHz, it is possible to detect only the partial discharge pulse in the vicinity of the detector with high sensitivity.

In the above example, one measurement window is used for measurement. However, partial discharge pulse signals are simultaneously measured by a spectrum analyzer from a plurality of inspection windows provided on the phase-separated closed bus, The detection output using a digital memory, the presence or absence of a pulse depending on the detection location,
It is also possible to estimate the generation position of the partial discharge pulse by measuring the pulse time difference and the magnitude of the discharge charge amount.

It is also possible to provide a transparent electrode in the inspection window instead of the metal plate electrode to detect a partial discharge pulse, and to observe the corona of the phase-separated closed bus and the generator winding through the inspection window.

[0019]

As described above, according to the method for detecting a partial discharge from a phase-separated closed bus of the present invention, a metal plate electrode is attached from the outside of the inspection window for detection, so that it is safe even in a live state. It is possible to perform the work of attaching the metal plate electrode. Moreover, it is possible to perform measurement without changing the structure of the phase-separated bus bar, and it is possible to easily adapt to existing lines. Further, since the high frequency component is detected, noise from a distance is reduced, and the partial discharge pulse only around the phase separation bus can be measured with high sensitivity.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a method for detecting partial discharge from a phase-separated closed bus of an embodiment of the present invention,

FIG. 2 is an equivalent circuit diagram showing the detection principle,

FIG. 3 is a frequency spectrum when a partial discharge occurs, which is obtained by the detection method of the present invention;

FIG. 4 is a cross-sectional view showing a conventional method for diagnosing partial discharge of a gas-insulated device,

FIG. 5 is a side view of a conventional partial discharge measuring device,

FIG. 6 is a cross-sectional view of a conventional partial discharge discharge measuring method of a gas insulated device.

[Explanation of symbols]

 1 Phase-separated closed bus bar (ground side closed metal case) 2 Inspection window 3 Metal plate electrode 4 Internal high voltage conductor 5 Partial discharge detection impedance 6 Partial discharge measuring instrument

Claims (2)

[Claims] 1. A metal plate electrode is provided on the surface of an inspection window of a transparent glass plate or a plastic plate of a phase separation busbar used between a generator in a power plant and a main transformer, and a capacitance is provided between the center conductor and the metal plate electrode. By forming it so as to act as a coupling capacitor, the partial discharge pulse current is detected between the phase-separated closed bus and the phase-separated closed bus metal case where the partial discharge pulse current flows. Partial discharge detection method from bus bar. 2. 200 from between the phase-separated closed bus and the metal case of the phase-separated closed bus in which the partial discharge pulse current flows.
The method for detecting partial discharge from a phase-separated closed bus according to claim 1, wherein a signal of MHz to 1 GHz is detected.