JP3528544B2 - Method of locating insulation breakdown of power cable line - Google Patents

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 dielectric breakdown of a power cable line, and more particularly to a method for locating a dielectric breakdown position of a power cable line which has low cost and high reliability.

[0002]

2. Description of the Related Art In order to ensure the reliability of a power transmission system,
When insulation breakdown occurs in the ultra-high voltage CV cable line, it is necessary to find the location of the breakdown in a short time and perform quick recovery. In this case, in a power cable line having three lines (two lines, three lines or more) by laying three single-core power cables per line, if insulation breakdown occurs at any place, the transformers at both ends will change. The line and the accident phase in which insulation breakdown has occurred at the station and other parent stations can be immediately identified by the operation of the relay and other factors. However, it is very difficult to locate the position (distance from the substation or the like) where the insulation breakdown occurs in the long-distance power cable line. Therefore, an accident section or accident point detection system (FL system) has been developed and installed on an important track.

As a method of detecting the position of an accident point on a CV cable line, an optical magnetic field sensor for detecting a surge current generated at the time of insulation breakdown of a power cable by a magnetic field is provided at both ends of the cable line, and these optical magnetic field sensors are used. There is an optical magnetic field sensor system that connects to a measuring instrument via an optical fiber and performs dielectric breakdown position determination based on a surge current waveform of digital data in a memory circuit.

An optical output CT for detecting a ground-fault zero-phase current by providing an optical CT on a cross bond wire or a ground wire of an insulating connection part.
There is also a method. Furthermore, a low-voltage Murray loop system, a pulse radar system, etc. may be applied.

[0005]

However, according to the optical magnetic field sensor system, there is a problem that it is apt to malfunction due to the influence of the peripheral or other phase magnetic field, and a large number of optical fiber cores are required, and the system is expensive. There is a problem that is. Further, the optical output CT method has problems that the determination software is sophisticated, that line-based determination cannot be performed, and that the system is expensive.

Further, in the Murray loop system, since the length of the cable to be measured is included in the calculation formula in principle, there is a problem in the fault point locating precision, and in the pulse radar system, the locating precision depends on the fault point grounding resistance. However, these methods are not suitable as fault location methods for power cable lines, and have not been applied to long-distance power cable lines. Therefore, the current main methods are the above-mentioned optical magnetic field sensor method and optical output CT method, but these both have a problem that they are expensive, and new low cost and highly reliable accident location method is required. Was there.

[0007] Therefore, an object of the present invention is to provide a method for locating the dielectric breakdown of a power cable line which is lower in cost and higher in reliability.

[0008]

In order to achieve the above-mentioned object, the present invention has an insulating connecting portion at the same position of each phase.
In breakdown position location how <br/> method of the power cable line for locating the breakdown positions of the multi-phase power cable line of the line or multi-line, before the surge currents produced by the breakdown
A pair of metal foil electrodes provided on both sides of the insulated connection
Out, each of the insulating connection of the same position of the each phase of the multiphase power cable line before Symbol 1 line or multi-line
Converts to a unipolar pulse current according to the surge current
And a magnetizing piece common to each phase is attached by a sum signal obtained by adding the respective dielectric breakdown signals obtained from the detecting section at the same position of each phase. Magnetize and detect multiple of the polyphase power cable
Based on the distribution of the magnitude of the magnetization amount of the plurality of magnetizing pieces
There is provided a method for locating a dielectric breakdown position of a power cable line, characterized by locating the dielectric breakdown position.

A method for locating a dielectric breakdown of a power cable line according to the present invention is a new method in which a magnetizing piece is magnetized by utilizing a surge current generated at the time of dielectric breakdown, and a fault point is located from a distribution of the magnetizing amount. Is. This system has features of high reliability of operation and low cost because no power supply is required. In this new method, surge current is detected for each phase at the insulation connection part of the same position of each phase of the multi-phase power cable line connected by multiple insulation connection parts, and each magnetized piece is magnetized. Was transmitted to the master station, and the master station evaluated the accident point from the distribution of the magnetization quantity between the same detection positions.

In the present invention, the signals detected from each phase of the power cable line are collectively magnetized, read out, and the position where the dielectric breakdown occurs is evaluated without distinguishing the line. Since the line in which the dielectric breakdown has occurred can be identified by the master station, if the distance from the detection position to the position where the dielectric breakdown has occurred is known, the accident phase and the position where the dielectric breakdown has occurred can be located.

As described above, in the method for locating the dielectric breakdown position of the power cable line of the present invention, since the magnetizing portion is made common, the system can be simplified and the cost can be reduced.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the method for locating the dielectric breakdown of a power cable line according to the present invention will be described below. First, a description will be given new breakdown position location method for magnetic wear aforementioned wear magnetic piece. When insulation breakdown occurs in a power cable, a single, steep surge current is generated during the insulation breakdown. This surge wave propagates from the accident point toward both ends of the line. At this time, the higher the frequency of the surge wave, the greater the attenuation. Therefore, the position of the accident point can be located by measuring the intensity of a specific high frequency component at a plurality of points. A new orientation method (surge peak hold method) is based on this principle, and when a magnetizing piece is magnetized by surge electric energy, the amount of magnetization depends on the distance from the surge wave detection position to the dielectric breakdown point. It is what is used.

FIG. 1 shows a general embodiment of the surge and hold method. The power gable 10 is connected by a plurality of insulating connection parts 11. In this insulating connection portion 11, the sheath of the power cable is cut off by a sheath insulating tube 12. A detection unit 20 that detects surge electric energy from the sheath is installed in the insulating connection unit 11. This detection unit 20 serves as a surge wave sensor, and is used as an insulating connection unit 1.
A pair of metal foil electrodes 21 installed on both sides of one sheath insulating cylinder 12, a bandpass filter 24 composed of a capacitor 22 and a high frequency coil 23 connected to the metal foil electrodes 21, and a bandpass filter A double-wave detector (rectifier) 25 based on a diode bridge connected to the filter 24 is provided. The double-wave detector 25 of the detector 20 has
The magnetizing unit 30 is connected.

The magnetizing section 30 is provided with a magnetizing piece 31 and a magnetizing coil 32 wound around the magnetizing piece 31 and connected to the double-wave detector 25. A detector 33, which is a Hall effect element that detects the amount of magnetization, is arranged to face one edge of the magnetizing piece 31. This detector 33
Is connected to a master station such as a substation by an optical fiber 34.
In FIG. 1, the surge current generated in the sheath of the power cable 10 due to the dielectric breakdown is detected between the metal foil electrodes 21, and the surge electric energy is taken into the metal foil electrodes 21. The surge electric energy taken in is selected by the bandpass filter 24 only for signals in a specific frequency range, further rectified by the double wave detector 25 , and converted into a unipolar pulse current. Next, this unipolar pulse current flows through the magnetizing coil 32 and magnetizes the magnetizing piece 31. Detector 33 by Hall effect element arranged in magnetic flux circuit
Reads the magnetic flux density, that is, the amount of magnetization, and outputs the DC output voltage as a signal. This signal is a normal optical fiber 3
It is sent to the master station such as a substation by the signal information transmission method using 4.
The strength is measured here. The master station evaluates the position of the accident point from the distribution of the amount of magnetization at each measurement point.

The accident point locating system of this type is
Since only passive elements are used, there are features such as no power supply required, easy operation verification, high reliability of operation, and low cost. In the multi-phase power cable line, each phase is connected by a plurality of insulation connection parts 11, and the insulation connection part 1 of each phase is connected.
1 is installed in the same place. If such a surge wave detecting section 20 and a magnetizing section 30 are provided for each insulated connection section 11 at the same location in each phase, the cost will increase. Therefore, if the detection phase is UVW and 3 phases, 3 per connection point
If the signal is a three-line circuit, nine signals are individually sent to the master station. In this case, it is possible to add an address signal to 3 signals or 9 signals, multiplex the signals, send them by one transmission system, and restore them to 9 signals by the master station, but the apparatus becomes expensive.

FIG. 2 shows an embodiment of the dielectric breakdown position locating method for a power cable line according to the present invention. This orientation method is
It is intended to specify how far away from the detection position the insulation breakdown has occurred without specifying the power cable where the insulation breakdown has occurred. In this embodiment, a system for collectively synthesizing, reading, and transmitting three signals from a three-way cable is shown.

The U-phase, V-phase, and W-phase of the multi-phase power cable line are connected by a plurality of insulating connection portions 11,
The U-phase, V-phase, and W-phase insulating connection portions 11 are installed at the same location. The system shown in FIG. 2 has a U phase, V
Insulation tube 12 of insulation connection portion 11 for each of the W and W phases
A pair of metal foil electrodes 21 are installed on both sides of each. The metal foil electrodes 21 of the three power cables 10 are connected to one magnetizing unit 30 via a bandpass filter (BPF) 24 and a double- wave detector 25, respectively.
0 is common to all phases. Each double wave detector 25
Is connected to one magnetizing coil 31, and this magnetizing coil 3
2 is in the <br/> so that can magnetization wearing one wearing magnetic piece 31 by winding the Chaku磁片31. Further, a detector 33, which is a Hall effect element for detecting the magnetization amount of the magnetizing piece 31, is arranged so as to face one edge of the magnetizing piece 31, and a signal of the read magnetization amount is output to one optical fiber. It can be transmitted to the parent station such as a substation at 34 or the like.

In the present embodiment, the dielectric breakdown signals from the U-phase, V-phase, and W-phase detection points at the same connection point 11 of the one-line, three-way cable line are added, and one added signal is obtained by the added signals. The magnetic piece 31 is magnetized.
That is, the common magnetizing piece 31 is magnetized by the sum signal obtained by adding the dielectric breakdown signals obtained from the detection units 20 of the respective phases, the magnitude of the magnetizing amount is detected, and the signal is sent to the master station as a signal. To do. At the master station, the dielectric breakdown position is evaluated based on the distributions of a plurality of magnetization amounts detected at different positions in the length direction of the power cable line.

Dielectric breakdown is any one of U phase, V phase and W phase
Assuming that it occurs only in one place, even if signals from these three places are added together, there is only one surge due to dielectric breakdown, so the breakdown position is different from that in the vicinity where the breakdown occurred. It can be specified by comparing the intensities of the signals from the detection points. On the other hand, although the dielectric breakdown position locating method of this embodiment cannot specify the dielectric breakdown phase (article),
The dielectric breakdown phase can be identified by the information from the protective relay of the parent station such as a substation. As a result, it is possible to evaluate the breakdown phase and the breakdown position with the same accuracy as in the case of sending the signals even if the signals for a large number of power cables are collectively combined.

As described above, according to the insulation breakdown position locating method of the power cable line of the present embodiment, since the magnetizing portion is common, the number of magnetizing circuits and detectors is reduced, and the transmission system is simplified, resulting in an accident point. The system can be operated while maintaining the location accuracy.
It was possible to achieve simplification and cost reduction. In addition,
In the description, the description has been given by taking the one-line / three-signal system as an example, but similarly, all the two-line / six-signal, three-line / nine-signal system, or more lines are collectively combined and transmitted, or if necessary. The system can be simplified and the cost can be reduced by the two-branch composite transmission.

Further, in the present embodiment, the magnetizing portion is made common, but a metal foil electrode (detector) of surge electric energy is used.
21 can be arranged on each power cable, and other bandpass filters, detectors, etc. can be shared,
As a result, it is possible to achieve further cost reduction.

[0022]

As described above, according to the dielectric breakdown position locating method of the power cable line of the present invention, in the locating method of low cost and high reliability, since the magnetized portion is made common to each phase, it is further reduced. We were able to achieve cost reduction.

[Brief description of drawings]

FIG. 1 is a circuit diagram illustrating a method for locating a dielectric breakdown position of a power cable line of a surge peak hold type.

FIG. 2 is a conceptual diagram illustrating an embodiment of the method for locating the dielectric breakdown of a power cable line according to the present invention.

[Explanation of symbols]

10 Electric Cable 11 Insulation Connection Part 12 Sheath Insulation Cylinder 20 Detection Part 21 Metal Foil Electrode 22 Capacitor 23 High Frequency Coil 24 Bandpass Filter 25 Double Wave Detector (Diode) 30 Magnetization Part 31 Magnetization Piece 32 Magnetization Coil 33 Holes Effect element detector 34 optical fiber

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichiro So, Inventor Kenichiro So, 5-1, 1-1 Hidaka-cho, Hitachi City, Ibaraki Power Systems Research Laboratory, Hitsuritsu Cable Co., Ltd. (72) Masayuki Yamaguchi Hidaka, Hitachi City, Ibaraki Prefecture 5-1-1, Machi, Power Systems Research Center, Nitrate Electric Cable Co., Ltd. (56) Reference JP-A-6-235748 (JP, A) JP-A-9-89942 (JP, A) JP-A-6-258381 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01R 31/08-31/11

Claims (3)

(57) [Claims] 1. A 1 having an insulating connection portion at the same position of each phase
In the method of locating the dielectric breakdown position of a power cable line for locating the dielectric breakdown position of a multi-phase or multi-phase power cable line, a surge current generated by the dielectric breakdown is applied to the insulation connection part.
Detected by a pair of metal foil electrodes which are provided on both sides, on each of the insulating connection of the same position of the each phase of the multiphase power cable line before Symbol 1 line or multi-line, the
Insulation converted to unipolar pulse current according to surge current
A detection unit for detecting an edge breakdown signal is provided, and a magnetizing piece common to each phase is magnetized by a sum signal obtained by adding the respective insulation breakdown signals obtained from the detection unit at the same position of each phase. breakdown location of the power cable line, characterized by locating the breakdown position based on the size distribution of the magnetization amount of the plurality of the deposition magnetic piece of the plurality of the detecting portions of the multi-phase power cable Orientation method. 2. The method for locating the dielectric breakdown position of a power cable line according to claim 1, wherein the amount of magnetization of the magnetizing piece is transmitted from the same position of each phase to the master station. 3. The distribution of the magnetization amount of the magnetizing piece is transmitted from the same position of each of the plurality of phases to the master station, and the distribution of the magnetization amount between the same positions of the plurality of each of the phases is transmitted. breakdown position location method of claim 2, wherein the power cable line for locating the breakdown location based.