JP2001033508A - Method for locating partial discharge position of power cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to locate a position of partial discharge of a power cable with high precision even when propagation speed of a partial discharge signal in the power cable is not known. SOLUTION: Partial discharge signals 10 from a pair of foil electrodes 3A, 3B are detected and inputted in a signal processing unit 8 through pre-amplifiers 4A, 4B. The signal processing unit 8 detects the difference of magnitude and the directions of signals 10 detected at a point A and a point B, and locates an approximate position X of partial discharge. The foil electrodes 3A, 3B are so moved that difference of the signals 10 detected at the point A and B the point approaches zero, and the signals 10 are detected. When difference of the signals 10 detected at the point A and the point B becomes zero, the signal processing unit 8 locates a middle point between the point A and the point B as the partial discharge position X.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for locating a partial discharge position of a power cable for locating a partial discharge position of a power cable, and more particularly to a method of locating a partial discharge signal in a power cable even when the propagation speed of the partial discharge signal is unknown. The present invention relates to a method for locating a partial discharge position of a power cable, which is capable of locating a partial discharge position of a cable with high accuracy.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional partial discharge position locating method. This method is for a power cable 1 that does not include a cable connection portion. A foil electrode 3 is attached to one end portion 2A of the power cable 1 and a first wave of a first wave directly propagating from a partial discharge position X to the foil electrode 3 is attached. Partial discharge pulse signal 1
0 and the reflected wave signal 11 reflected at the other end 2B are detected by the measuring instrument 5 via the preamplifier 4, and the time difference between the detection of the partial discharge pulse signal 10 and the reflected wave signal 11 and the time difference in the power cable 1 The partial discharge position X is determined based on the propagation speed of the pulse signal 10.

FIG. 4 shows another conventional partial discharge position locating method. In this method, a plurality of insulated connection parts (IJ parts) 6
A, 6B, 6C,..., And a long-distance power cable 1 connected by a normal connection portion (NJ portion) 7, and a set of adjacent IJ portions 6A, 6A,
A pair of partial discharge pulse signals 10 and 10 propagating from the partial discharge position X to the foil electrode 3 attached to the foil electrode 6B are detected by the measuring device 5 via the preamplifiers 4A and 4B, respectively. Time difference and power cable 1
A set of IJ units 6A,
This is for locating the partial discharge position X between 6B.

[0004]

However, according to the conventional partial discharge position locating method shown in FIGS. 3 and 4, since the attenuation of the pulse signal varies depending on the propagation distance, the position of the partial discharge cannot be accurately located. There is a problem. Further, since it is necessary to know in advance the propagation speed of the partial discharge pulse signal in the power cable, there is a problem that the position of the partial discharge cannot be located for a power cable whose propagation speed is unknown.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a partial discharge position of a power cable capable of accurately locating the partial discharge of the power cable even when the propagation speed of the partial discharge signal in the power cable is unknown. It is to provide an orientation method.

[0006]

In order to achieve the above object, the present invention provides a method for locating a partial discharge of a power cable for detecting a partial discharge signal of the power cable and locating the partial discharge of the power cable. A first step of detecting a level and a direction of the partial discharge signal at two points of the power cable, and a second step of locating the partial discharge based on the level and the direction of the partial discharge signal And a method for locating a partial discharge position of a power cable. According to the above configuration, by detecting the level and direction of the partial discharge signal at two points on the power cable, accurate localization of the position of the partial discharge can be performed even when the propagation speed of the partial discharge signal in the power cable is unknown. It becomes possible.

In order to achieve the above object, the present invention provides a method for locating a partial discharge of a power cable by detecting a partial discharge signal of the power cable and locating a partial discharge position of the power cable. A first step of detecting the direction of the partial discharge signal at a point, and a second step of locating, as the position of the partial discharge, a point at which the direction of the partial discharge signal reverses across the predetermined point.
A method for locating a partial discharge of a power cable, comprising the steps of: According to the above configuration, by detecting the point where the direction of the partial discharge signal reverses in the power cable, it is possible to accurately locate the partial discharge position even when the propagation speed of the partial discharge signal in the power cable is unknown. Becomes

[0008]

FIG. 1 shows a method for locating a partial discharge of a power cable according to a first embodiment of the present invention.
The partial discharge position locating device used in the first embodiment detects from a pair of foil electrodes 3A and 3B as detection electrodes movably attached to the power cable 1 and a pair of foil electrodes 3A and 3B. A signal processing device 8 is provided which takes in the partial discharge pulse signals 10 obtained via the preamplifiers 4A and 4B, respectively, and obtains the propagation direction and magnitude of the signal 10. In addition, the foil electrodes 3A, 3B
It is a known technique that the partial discharge pulse signal 10 can be detected by attaching the.

The signal processing device 8 includes a processing unit having a spectrum analyzer function, a noise removing function, an arithmetic function, and the like.
A display unit having an oscilloscope function and the like, a frequency with less noise can be selected according to the on-site environment, and in which direction the partial discharge pulse signal 10 detected from the pair of foil electrodes 3A and 3B propagates And the calculation processing of the magnitude of the partial discharge pulse signal 10 can be performed.

Next, a method for locating the partial discharge position in the first embodiment will be described. For example, a case where the partial discharge position X is between points A and B as shown in FIG. 1 will be described. First, a pair of foil electrodes 3A and 3B are attached to points A and B on the power cable 1. In this case, the partial discharge pulse signal 10 propagates right and left from the point X. This signal 10 is detected by foil electrodes 3A and 3B at points A and B,
The signal is input to the signal processing device 8 via the preamplifiers 4A and 4B. The processing unit of the signal processing device 8 selects an optimum frequency with little noise by using a spectrum analyzer function and a noise removing function. The display unit of the signal processing device 8 displays the signal 10
The direction and magnitude of the signal 10 are displayed on the display screen by the oscilloscope function based on the optimum frequency component selected among the above. Further, the processing unit of the signal processing device 8 obtains the difference between the magnitudes of the signals 10 detected at the points A and B by an arithmetic function, and locates the approximate partial discharge position X. Furthermore, foil electrodes 3A and 3B (one foil electrode may be used) so that the difference between signals 10 detected at points A and B approaches zero.
Is moved to narrow down. When the difference between the signals 10 detected at the points A and B becomes zero, the processing unit of the signal processing device 8 locates an intermediate point between the points A and B as the partial discharge position X.

According to the above-described first embodiment, the following effects can be obtained. (A) By attaching the foil electrodes 3A and 3B to arbitrary positions of the power cable 1 and narrowing down the partial discharge positions, it is possible to accurately locate the partial discharge positions. (B) It is possible to locate the partial discharge position even for a power cable whose propagation speed of the partial discharge pulse signal is unknown. (C) Normal connection part (NJ without insulation connection part (IJ part))
) Can be applied to long-distance power cables connected only by

FIG. 2 shows a partial discharge position locating method according to a second embodiment of the present invention. The partial discharge position locating device used in the second embodiment uses a wire shielded cable as the power cable 1 and a pair of coiled electrodes 9A and 9B as detection electrodes. The configuration is the same as that of the embodiment. It is a known technique that the coil electrodes 9A and 9B can be attached to the surface of the power cable 1 to detect the partial discharge pulse 10. It is also a known technique that the coiled electrodes 9A and 9B are effective for a wire shielded cable.

According to the above-described second embodiment, it is possible to accurately locate the partial discharge position on the wire shielded cable as in the first embodiment.

The present invention is not limited to the above embodiment, but can be variously modified. For example, one detection electrode may be moved along the power cable to detect a point where the direction of the partial discharge pulse signal reverses, and that point may be located as the partial discharge position. Thereby, even when the propagation speed of the partial discharge pulse signal in the power cable is unknown, it is possible to accurately locate the position of the partial discharge.

[0015]

As described above, according to the method for locating the partial discharge position of the power cable of the present invention, the power cable 2
By detecting the level and direction of the partial discharge signal at a point, or by detecting the point where the direction of the partial discharge signal reverses in the power cable, even if the propagation speed of the partial discharge signal in the power cable is unknown, The position of the partial discharge of the power cable can be located with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a partial discharge position locating method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a partial discharge position locating method according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a conventional partial discharge position locating method.

FIG. 4 is a diagram showing another conventional partial discharge position locating method.

[Explanation of symbols]

 Reference Signs List 1 power cable 3A, 3B foil electrode 4A, 4B preamplifier 8 signal processing device 9A, 9B coiled electrode 10 partial discharge pulse signal A, B detection position X partial discharge position

Claims (5)

[Claims] 1. A method for locating a partial discharge of a power cable, comprising detecting a partial discharge signal of the power cable and locating a partial discharge of the power cable, wherein a level of the partial discharge signal is determined at two points of the power cable. A first step of detecting a direction; and a second step of locating a position of the partial discharge based on the level and the direction of the partial discharge signal. . 2. The method according to claim 1, wherein the first step detects the partial discharge signal at two points where the levels of the partial discharge signals are equal and the directions are opposite to each other. 2. The method for locating a partial discharge position of a power cable according to claim 1, wherein a position of the partial discharge is determined as a midpoint. 3. A method according to claim 1, wherein said first step is performed by movably providing detection electrodes for detecting said partial discharge signal at said two points. 4. A method of locating a partial discharge of a power cable by detecting a partial discharge signal of the power cable and locating a partial discharge of the power cable, the direction of the partial discharge signal at a predetermined point on the power cable. And a second step of locating, as the position of the partial discharge, a point at which the direction of the partial discharge signal reverses across the predetermined point. Partial discharge location method. 5. The method according to claim 4, wherein said first step is performed by movably providing a detection electrode for detecting said partial discharge signal at said predetermined point.