JPH11125651A - Method for orientating breakdown position of power cable line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost and highly reliable method for orientating a breakdown position of a power cable line. SOLUTION: According to this method, a breakdown position of a multiphase power cable line having insulating connection parts 11 at the same position of respective phases is orientated, thereby orientating a breakdown position of a power cable line. At this time, a detecting part 20 for detecting a breakdown signal corresponding to a surge current resulting from a breakdown is set at each insulating connection part 11 of the same position of each phase of the multiphase power cable line. A magnetization element 31 in common to the phases is magnetized by a sum signal obtained by adding the breakdown signals from the detecting parts 20 at the same position of the phases. A breakdown position is evaluated in accordance with a magnetization amount of the magnetization element 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for locating a dielectric breakdown of a power cable line, and more particularly to a method of locating a dielectric breakdown of a power cable line at low cost and high reliability.

[0002]

2. Description of the Related Art In order to ensure the reliability of a transmission system,
When insulation breakdown occurs in an ultra-high voltage CV cable line, it is necessary to find out the location of the breakdown in a short time and to quickly restore the location. In this case, if a single-core power cable is laid in three lines per line and a multi-line (two lines, three lines or more) configuration is made, and an insulation breakdown occurs at an arbitrary position, the voltage at both ends is changed. The line and the accident phase in which the insulation breakdown has occurred in other places, can be immediately identified by the operation of the relay or the like. However, it is very difficult to locate a position (distance from a substation or the like) in a long-distance power cable line. Therefore, an accident section or an accident point detection system (FL system) has been developed and installed on an important railway.

[0003] As a method of detecting the location of an accident point on a CV cable line, optical magnetic sensors are provided at both ends of the cable line to detect a surge current generated at the time of insulation breakdown of a power cable by a magnetic field. There is an optical magnetic field sensor system which is connected to a measuring instrument via an optical fiber and locates a dielectric breakdown position based on a surge current waveform of digital data in a memory circuit.

Further, an optical output CT for detecting a zero-phase-to-ground current by providing an optical CT on a cross bond line or a ground line of an insulating connection portion.
There is also a method. Further, a low-pressure Marley loop system, a pulse radar system, or the like may be applied.

[0005]

However, according to the optical magnetic field sensor system, there is a problem that it is likely 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, according to the optical output CT method, there are problems such as that the judgment software is sophisticated, judgment by line cannot be made, and the system is expensive.

Further, in the Murray loop method, since the length of the cable to be measured is included in the calculation formula in principle, there is a problem in the fault locating accuracy. In the pulse radar method, the locating accuracy is influenced by the fault point grounding resistance. However, these methods are unsuitable 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 the light output CT method. However, both of these methods are expensive, and a new low-cost and highly reliable method for locating accidents is demanded. I was

It is, therefore, an object of the present invention to provide a lower cost and more reliable method of locating the breakdown of a power cable line.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a power supply for evaluating a dielectric breakdown position of a single or multi-line multi-phase power cable line having an insulating connection at the same position of each phase. In the method of evaluating the insulation breakdown position of a cable line, a detection unit for detecting an insulation breakdown signal corresponding to a surge current caused by insulation breakdown is provided at the same position of each phase of the one-line or multi-line multi-phase power cable line. The magnetizing pieces common to the respective phases are magnetized by a sum signal obtained by adding the respective dielectric breakdown signals obtained from the detectors at the same position of the respective phases. The present invention provides a method for locating a dielectric breakdown position of a power cable line, wherein the dielectric breakdown position is evaluated according to a magnetization amount of a piece.

A method for locating a dielectric breakdown of a power cable line according to the present invention is a new method for locating a magnetized piece using a surge current generated at the time of a dielectric breakdown, and locating a fault point from a distribution of the amount of magnetization. It is. This method is characterized by high operation reliability and low cost because no power supply is required. In this new method, surge current is detected for each phase at the same position of the insulation connection of each phase of the multi-phase power cable line connected by multiple insulation connections, and the magnetized pieces are magnetized, respectively. Was transmitted to the master station, and the master station evaluated the fault point from the distribution of the magnetization amount between the same detection positions.

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

As described above, according to the method for locating a dielectric breakdown of a power cable line of the present invention, since the magnetized portion is shared, the system can be simplified and the cost can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for locating a dielectric breakdown of a power cable line according to the present invention will be described below. First, a new dielectric breakdown position locating method for holding the above-described magnetized piece will be described. When insulation breakdown occurs in a power cable, a single steep surge current occurs at the time of insulation breakdown. This surge wave propagates from the accident point to the both ends of the line with the accident point as a starting point. At this time, the higher the surge wave component, 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. Based on this principle, a new orientation method (surge peak hold method) is based on this principle. When the magnetized piece is magnetized by the surge electric energy, the amount of magnetization depends on the distance from the surge wave detection position to the insulation breakdown point. It is a thing that uses that it becomes.

FIG. 1 shows a general embodiment of the surge peak hold method. The power cable 10 is connected by a plurality of insulated connection parts 11. In the insulated connecting portion 11, the sheath of the power cable is cut off by the sheath insulating tube 12. The insulated connection section 11 is provided with a detection section 20 for detecting surge electric energy from the sheath. The detecting unit 20 serves as a surge wave sensor,
A pair of metal foil electrodes 21 provided on both sides of one sheathed insulating tube 12, a band-pass filter 24 including a capacitor 22 and a high-frequency coil 23 connected to the metal foil electrodes 21, A dual wave detector (rectifier) 25 connected to the filter 24 is provided. The magnetizing unit 30 is connected to the dual-wave detector 25 of the detecting unit 20.

A magnetizing piece 31 and a magnetizing coil 32 wound around the magnetizing piece 31 and connected to the detector 25 are arranged in the magnetizing section 30. In addition, a Hall effect element 33 that detects the amount of magnetization is arranged to face one edge of the magnetized piece 31. The Hall effect element 33 is connected to a master station such as a substation via an optical fiber 34. In FIG. 1, a surge current generated in the sheath of the power cable 10 due to insulation breakdown is detected between the foil electrodes 21, and the surge electric energy is taken into the foil electrodes 21. The captured surge electric energy is transmitted to the bandpass filter 24.
Thus, only a signal in a specific frequency range is selected, further rectified by the dual-wave detector 24, and converted into a unipolar pulse current. Next, this unipolar pulse current flows through the magnetizing coil 32 to magnetize the magnetizing piece 31. The Hall effect element 33 arranged in the magnetic flux circuit reads out the magnetic flux density, that is, the amount of magnetization, and outputs a DC output voltage as a signal. This signal is sent to a master station such as a substation by a signal information transmission method using an ordinary optical fiber 34, where the intensity is measured. The master station evaluates the position of the accident point from the distribution of the magnetization at each measurement point.

An accident point locating system of such a type is as follows.
Since only passive elements are used, a power supply is not required, operation verification is easy, operation reliability is high, and cost is low. In the multi-phase power cable line, each phase is connected by a plurality of insulated connection portions 11, and the insulated connection portions 1 of each phase are connected.
1 is installed in the same place. If such a surge wave detecting unit 20 and a magnetizing unit 30 are provided for each of the insulated connecting portions 11 at the same position in each phase, the cost increases. Therefore, if the detection phase is UVW and three phases, 3
If the signals are three-line circuits, nine signals are individually sent to the master station. In this case, it is possible to multiplex the signals by adding an address signal to three or nine signals, transmit the signals by one transmission system, and return to the original signal at the parent station to obtain nine signals, but the apparatus becomes expensive.

FIG. 2 shows an embodiment of the method for locating a dielectric breakdown of 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 cable has occurred without identifying the power cable where the insulation breakdown has occurred. In this embodiment, a system is shown in which three signals from three cables are combined, magnetized, read, and transmitted.

Each of the U-phase, V-phase, and W-phase of the multi-phase power cable line is connected by a plurality of insulated connecting portions 11,
The U-phase, V-phase, and W-phase insulating connection parts 11 are installed at the same place. The system shown in FIG.
Insulation tube 12 of the insulation connection part 11 of each phase and W phase
A pair of metal foil electrodes 21 are provided on both sides of the metal foil. The foil electrodes 21 of the three power cables 10 are respectively connected to one magnetized unit 30 via a band pass filter (BPF) 24 and a detector 25, and the magnetized unit 30 is common to each phase. ing. Each detector 25 is connected to one magnetizing coil 31, and this magnetizing coil 32 is
1 is wound so that one magnetized piece 31 can be held. A detector 3 for detecting the amount of magnetization of the magnetized piece 31
Reference numeral 3 is arranged so as to face one end of the magnetized piece 31 so that the read signal of the magnetized amount can be transmitted to a master station such as a substation via one optical fiber 34 or the like.

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

The dielectric breakdown is any one of U phase, V phase and W phase.
Assuming that the surge occurs only at the location, even if these three signals are added, only one surge due to the dielectric breakdown occurs. It can be specified by comparing the intensity of the signal from the detection point. On the other hand, the dielectric breakdown phase (strip) cannot be specified by the dielectric breakdown position locating method of the present embodiment,
The insulation breakdown phase can be specified by information from a protection relay of a master station such as a substation. As a result, even if signals for a large number of power cables are combined together, the breakdown phase and the breakdown position can be evaluated with the same accuracy as in the case of individually sending the signals.

As described above, according to the method for locating the dielectric breakdown of the power cable line of the present embodiment, since the magnetized portion is made common, the number of magnetized circuits and detectors is reduced, and the transmission system is simplified, so that the fault point is reduced. The system was simplified and the cost was reduced while maintaining the location accuracy. In addition,
In the explanation, one signal and three signal systems have been described as an example, but similarly, two lines and six signals, three lines and nine signal systems, or even more lines are collectively combined and transmitted, or as necessary. The system can be simplified and the cost can be reduced by the two-branch combining transmission.

Furthermore, in the present embodiment, the magnetized portion is shared, but the surge electric energy detector 21 is arranged on each power cable, and the other band-pass filters, detectors and the like are also shared. It is possible to further reduce the cost.

[0022]

As described above, according to the method for locating a dielectric breakdown of a power cable line according to the present invention, the magnetized portion is commonly used for each phase in the low-cost and highly reliable locating method. Cost reduction was achieved.

[Brief description of the 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 method.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Power cable 11 Insulated connection part 12 Sheath insulating cylinder 20 Detecting part 21 Detector 22 Capacitor 23 High frequency coil 24 Bandpass filter 25 Detector (diode) 30 Magnetized part 31 Magnetized piece 32 Magnetized coil 33 Readout part 34 Transmission line

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Yamaguchi 5-1-1, Hidaka-cho, Hitachi City, Ibaraki Prefecture Power Systems Research Laboratory, Hitachi Cable, Ltd.

Claims (3)

[Claims] 1. An apparatus having an insulated connection at the same position in each phase.
In the method for evaluating a breakdown position of a power cable line for evaluating a breakdown position of a multi-phase power cable line of a circuit or a multi-line, the detecting unit for detecting a breakdown signal corresponding to a surge current caused by the breakdown is provided by the one line. Alternatively, the sum is obtained by adding the respective insulation breakdown signals obtained from the detection unit at the same position of each phase in the insulated connection unit at the same position of each phase of the multi-phase multi-phase power cable line. A magnetized piece common to each phase is magnetized by a signal, and the dielectric breakdown position is evaluated according to the amount of magnetization of the magnetized piece. 2. The method according to claim 1, wherein the amount of magnetization of the magnetized piece is transmitted from a same position of each phase to a master station. 3. The magnetization amount of the magnetized 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 phases is determined. 3. The method for evaluating a dielectric breakdown position of a power cable line according to claim 2, wherein the dielectric breakdown position is evaluated based on the electrical breakdown.