JP3351304B2 - System for detecting the applied voltage polarity of a cable line and the system for detecting the breakdown position of a 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 system for detecting a voltage polarity at the time of insulation breakdown of a cable line and a system for detecting a breakdown position of the cable line, and more particularly to a long-distance cable line using an insulated connection (IJB). The present invention relates to a detection system for detecting the polarity of the applied voltage and the position of the dielectric breakdown in the apparatus.

[0002]

2. Description of the Related Art As a conventional system for detecting a dielectric breakdown position of a cable line, for example, there is one disclosed in Japanese Utility Model Laid-Open No. 4-59483. This system for detecting the insulation breakdown position of the cable line is provided at each end of the cable line with an optical magnetic field sensor for detecting a surge current by a magnetic field,
These optical magnetic field sensors are connected to a measuring instrument via an optical fiber cable. This measuring instrument includes a light source, a photoelectric conversion element, an A / D converter, a memory circuit, and a CPU. When a dielectric breakdown occurs in a cable line, a surge current generated at a location where the dielectric breakdown has occurred is detected by the optical magnetic field sensors at both ends, and the detected surge current waveform is sent to a measuring instrument via an optical fiber cable. The surge current waveform from the optical magnetic field sensor is input to the photoelectric conversion element of the measuring device, converted into digital data by the A / D converter, and stored in the memory circuit. A dielectric breakdown position is detected based on a surge current waveform of digital data stored in the memory circuit.

[0003]

However, according to the conventional system for detecting the breakdown position of a cable line, optical magnetic field sensors for detecting a surge current are arranged at both ends of the cable line, and the output of the optical magnetic field sensor is Since it is intended to detect the breakdown position based on the surge current waveform after being transmitted by the fiber cable, it is difficult to detect the exact breakdown position in a long cable line having a plurality of connection parts. There's a problem. Another problem is that it is necessary to keep the system in an operating state at all times. Further, when an insulation breakdown accident occurs, there is a problem that electromagnetic waves are generated due to the strong energy, and the failures make normal operation of the measurement system difficult and often cause malfunctions.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a system for detecting a breakdown position of a cable line capable of detecting a breakdown position with high accuracy and a high accuracy even in a long cable line with a simple configuration. It is an object of the present invention to provide a system for detecting the applied voltage polarity of a cable line that can be used for the detection system.

[0005]

According to the present invention, in order to achieve the above object, a polarity of a voltage applied to a cable conductor is changed to a cross bond wire connected to a sheath of an insulating connection of each phase. In a system for detecting a voltage imposed polarity of a cable line which detects based on a flowing current, a first detecting means for detecting a current of a first cross bond wire connected to a sheath of a first insulated connecting portion; A second detecting means for detecting a current of a second cross-bond wire connected to a sheath of an adjacent second insulating connection electrically connected to the sheath of the first insulating connection; 2. Magnetizing means for magnetizing the magnetic steel piece by the current of the vector sum of the respective currents detected by the detecting means of No. 2 and detecting the polarity of the imposed voltage at the time of dielectric breakdown of the line from the polarity of the magnetization of the magnetic steel piece. Cable line Providing the division voltage polarity detection system.

In order to achieve the above object, the present invention provides a system for detecting a dielectric breakdown position of a cable line which detects a dielectric breakdown position based on a surge voltage or a surge current between sheaths of an insulated connecting portion of the cable line. ,
A recording means for magnetizing and recording magnetic recording means such as a magnetic steel piece or a magnetic tape based on the surge voltage or the surge current when the dielectric breakdown accident occurs, and the cable when the dielectric breakdown accident occurs And a polarity detecting means for detecting the polarity of the applied voltage applied to the line, wherein the dielectric breakdown accident is determined from the polarity and magnitude of the magnetization of the recording means and the polarity of the applied voltage detected by the polarity detecting means. Provided is a system for detecting a breakdown position of a cable line for detecting a direction and a distance of a cable line.

[0007]

FIG. 1 shows a first embodiment of a system for detecting a dielectric breakdown position of a cable line according to the present invention. In this system, an insulation breakdown detection circuit 3 (only one is shown) is connected to a plurality of insulation connection parts 2 (only one is shown) provided in the length direction of the power cable line 1, respectively.
Each of the insulation breakdown detection circuits 3 is connected to a central monitoring station (for example, a substation) 5 by an optical fiber cable 4 (only one is shown). The insulated connecting portion 2 includes an insulating tube 2a
The metal foil electrode 2c is provided outside the sheath 2b located on both sides of the metal foil electrode 2c, and the metal foil electrode 2c is connected to the insulation breakdown detection circuit 3 via a high-pass filter (hereinafter, referred to as "filter") 30 by a lead wire 2d. .

The dielectric breakdown detecting circuit 3 includes a magnetic holding unit 33 connected to the filter 30, a degaussing circuit 34, a magnetoresistive element 35, a light emitting diode 36, and a serial connection with the magnetoresistive element 35 and the light emitting diode 36. And a DC power supply 37 connected thereto, and the metal foil electrode 2 c of the insulated connection portion 2.
It detects the surge electric energy (hereinafter, abbreviated as "surge energy") generated between them. The detection of surge energy is basically the same as the detection of minute partial discharge pulses (Katsuta, Endo, et al .: "Development of a method for detecting a live-line partial discharge of an ultra-high voltage long CV cable line"). Vol.111-B, No. 11, P1.
223, Nov. , 1991).

The filter 30 detects a predetermined high-frequency component in the surge energy, for example, a component of 1 MHz or more. When an insulation breakdown accident occurs, for example, surge energy propagates to another insulated connecting portion 2 that is several hundred meters away, but the frequency component of the detected surge energy is limited to only the high-frequency component. Since the energy is rapidly attenuated, the energy reaching the adjacent insulating connection 2 is reduced, and the insulation connecting
This makes it easy to distinguish between a normal insulation connection portion 2 where no insulation breakdown has occurred.

The magnetic holding part 33 includes a magnetic steel piece 33a,
A yoke 33b for closing the magnetic pole of the magnetic steel piece 33a in a closed loop;
An exciting coil 33c for magnetizing the magnetic steel piece 33a. The magnetization of the magnetic steel piece 33a can be performed in the same manner as the recording of the lightning current. (The Institute of Electrical Engineers of Japan: “Electrical Engineering Handbook”, P1301, February 1985).

The degaussing circuit 34 includes a magnetic steel piece 33 once magnetized.
a degaussing coil 34a for degaussing a, and a drive circuit 34b for driving the degaussing coil 34a by inputting a degaussing signal.

The magnetoresistive effect element 35 is disposed on the periphery of the magnetic steel piece 33a or between the magnetic steel piece 33a and the yoke 33b, and has a characteristic of increasing electric resistance by a magnetic field.

The centralized monitoring station 5 includes a photodiode 50 for receiving an optical signal from the light emitting diode 36 via the optical fiber cable 4, a surge energy intensity indicating the photocurrent of the photodiode 50, and a surge energy intensity indicating the polarity. Polarity display section 51, photodiode 50
And a DC power supply 52 connected in series with the surge energy intensity and polarity display section 51.

The power cable line 1 is supplied with power from a substation as a centralized monitoring station 5, and a conductor (not shown) of the power cable line 1 is connected to a conductor (not shown) for ground voltage measurement at the substation. 60) is connected and the transformer 6
At 0, a digital oscilloscope 70 for recording the applied voltage waveform of the power cable line 1 is connected.

In this system for detecting a dielectric breakdown position, when a dielectric breakdown accident occurs at any of the insulated connecting portions 2 of the power cable line 1, a strong low voltage is applied between the metal foil electrodes 2c of the insulated connecting portion 2. A surge voltage (surge energy) including a wide frequency component of a high frequency to a high frequency is generated. A component of 1 MHz or more in the surge energy is a capacitance between the sheath 2b and the metal foil electrode 2c,
And the filter 30. The detected surge energy flows to the exciting coil 33c. Magnetic steel slab 3
3a is magnetized according to the magnitude of the pulse current flowing through the exciting coil 33c. The magnetoresistive element 35 is a magnetic steel piece 3
The electric resistance changes by a magnetic field corresponding to the strength and polarity of the magnetization of 3a. Due to this resistance change, the current of the light emitting diode 36 that emits light when a DC voltage is supplied from the DC power supply 37 changes, and the light emission intensity of the light emitting diode 36 changes. The light emitting diode 36 transmits an optical signal having a light intensity depending on the strength and polarity of magnetization to the centralized monitoring station 5 via the optical fiber cable 4. The photodiode 50 of the centralized monitoring station 5 receives the optical signal from the light emitting diode 36, the DC power is supplied, and the surge energy intensity and the current of the polarity display unit 51 which emit light at a predetermined luminance change, and the luminance is reduced. Change.

FIG. 2 shows a recorded waveform of the digital oscilloscope 70 observing the applied voltage waveform via the transformer 60 of the substation when an insulation breakdown accident occurs. This recording waveform indicates that the breakdown occurred when the applied voltage was positive (time t ₀ ). Here, if a dielectric breakdown accident occurs on the right side of the insulating connection part 2 in FIG.
The magnetic steel piece 33a is magnetized to the N pole on the right side (the part near the magnetoresistive element 35) and to the S pole on the opposite side. The magnitude of the magnetization is inversely proportional to the distance to the accident point. The centralized monitoring station 5 can know the information from the display content of the surge energy intensity and polarity display section 51. Since the accident point occurs on the right side of the insulating connection portion 2, a positive surge is induced in the right metal foil electrode 2c, and the surge energy intensity and polarity display section 51 performs display corresponding to the positive polarity. Thus, the power cable line 1 on the accident side
The fault point can be accurately specified based on the polarity of the imposed voltage and the display effect of the display unit 51. After specifying the accident point, the magnetic steel piece 33a is demagnetized by the degaussing circuit 34.

FIG. 3 shows a second embodiment of the system for detecting a dielectric breakdown position of a cable line according to the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals. Although omitted, the configuration is different in that a Hall effect element 35A is used instead of the magnetoresistive element.

In FIG. 3, the insulating tube 2a of the insulating connecting portion 2
A metal foil electrode 2c is provided on the outer side of the anticorrosion sheath 2b on both sides, and only a high-frequency component of a steep unipolar pulse caused by a ground fault in the cable insulating layer is extracted through the filter 30, thereby magnetizing the magnetic steel piece 33a. Here, if insulation breakdown occurs in the positive direction of the cable application voltage in the rightward direction of the insulating cylinder 2a of the insulating connection portion 2, the magnetic steel piece 33a
It is assumed that the side adjacent to the Hall effect element 35A is magnetized to the N pole.

The magnitude of the magnetization changes depending on the distance from the insulating connection portion 2 to the break point, and the amount of attenuation of the surge voltage changes. The polarity and magnitude of this magnetization are detected by the Hall effect element 35A, and the information is transmitted to the central monitoring station 5 via, for example, the emitting diode 36, the optical fiber cable 4, and the photodiode 50. In the centralized monitoring station 5, the transformer 6 for detecting the voltage phase
The waveform at the moment when the insulation breakdown of the imposed voltage waveform of 0 occurs is recorded on the digital oscilloscope 70, and as shown in FIG. 2, it can be seen that the insulation breakdown occurred due to the positive polarity.

When the applied voltage at the time of the dielectric breakdown is positive,
When a positive surge is induced in the right metal foil electrode 2c and the output of the phototransistor 50 has a positive polarity, the rightward direction of the insulated connecting portion 2 becomes the dielectric breakdown direction. If the applied voltage polarity and the magnetization polarity are reversed, the respective directions will be reversed.
Further, since the magnitude of the magnetization of the surge, that is, the magnitude of the output voltage of the phototransistor 50 depends on the distance from the insulating connection portion 2 to the breaking point, the breaking point is specified from these relationships. The magnetized state of the magnetic steel piece 33a is demagnetized by the degaussing coil 34a as necessary.

FIG. 4 shows a third embodiment of the system for detecting a dielectric breakdown position of a power cable line according to the present invention. FIG.
In the above, the foil electrode 2c is used. Here, the surge current flowing in the circuit of the inter-sheath bridging arrester 90 is detected by the high-frequency transformer 80. High frequency transformer 80
1 may be applied to the detection circuit 3 of FIG. 1, but the direction of the surge is measured by magnetizing a magnetic steel piece having no degaussing circuit and measuring the amount of magnetization and polarity by a dedicated analyzer. And size can also be detected.

In FIG. 1, when an insulation breakdown accident occurs,
Although the polarity of the applied voltage was detected from the digital oscilloscope 70 connected to the transformer 60 installed at the substation, the instrument transformer for measuring the applied voltage at the substation is an important equipment at the center of the substation. If possible, it is desirable not to input application voltage information from there. This is because the reliability of the substation equipment may be reduced. With this background, a system for detecting the polarity of the applied voltage of the cable line, which detects the polarity of the applied voltage without using the equipment of the substation, will be described below.

FIG. 5 shows a system for detecting the applied voltage polarity of this cable line. In this detection system, the power cable line is constituted by three phases of U-phase, V-phase, and W-phase, and each phase is composed of conductors 10U, 10V, 10W and a sheath 11
U, 11V, and 11W, and a capacitance C is formed between each conductor and each sheath. Conductors 10U, 10V, 10
W is connected by a conductor connection portion J, and the sheath 11U, 1
1V, 11W has an insulating cylinder 2a at an insulating connecting portion. Each sheath is a cross bond wire 12UV, 12UW, 12V
W, 13UV, 13UW, 13VW. A sheath current measurement current transformer (hereinafter, referred to as “CT”) 15a is connected to the cross bond line 12UW, and a CT 15b is connected to the cross bond line 13UV. Heisei 8
The same current is applied to each section of the sheath connected in series by cross-bond wires, as described in "Development of a method for locally capturing the cable line voltage phase in the 1717 partial discharge measurement" of the IEEJ National Convention. Flows. This current flows due to the unbalance of each phase of the sheath circuit electromotive force induced by the load currents of the conductors 10U, 10V, and 10W, and the charging current flowing through the capacitance C due to the voltage applied to each phase cable. The unbalanced component flows as a vector sum of sheath circuit currents. The charging current I (I _L + I _R ) flowing through the U-phase capacitance C is
The sum of the currents I _XL and I _XR flowing in UW and 13UV is obtained, and the sheath circuit current is canceled and becomes zero. Therefore, the currents I _XL and I _XR of the cross bond wires 12UW and 13UV are changed to CT1.
When the detection is made at 5a and 15b and the vector sum is obtained by the integration circuit 32, the charging current I is obtained. Where I,
It is assumed that I _L , I _R , I _XL , and I _XR have a vector symbol as shown in FIG. Thus, when the exciting coil 33c is energized and the magnetic steel piece 33a is magnetized, the polarity of the imposed voltage on the U-phase conductor 10U can be known from the magnetoresistive element 35. This information, as explained in FIG.
It is transmitted to the monitoring station 5. The location of the dielectric breakdown accident can be specified based on the polarity of the applied voltage and the direction and magnitude of the surge current described above.

[0024]

As described above, according to the system for detecting the applied voltage polarity of the cable line and the system for detecting the insulation breakdown position of the cable line according to the present invention, when an insulation breakdown accident occurs, the voltage applied to the cable at that time is determined. The breakdown position is specified based on the polarity of the current and the polarity and magnitude of the surge current or surge voltage.Since a simple configuration, there is little malfunction and the direction and distance of the breakdown can be specified with high accuracy. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of a system for detecting a dielectric breakdown position of a cable line according to the present invention.

FIG. 2 is an explanatory diagram showing a voltage application waveform recorded in FIG. 1;

FIG. 3 is an explanatory view showing a second embodiment of a system for detecting a dielectric breakdown position of a cable line according to the present invention.

FIG. 4 is an explanatory view showing a third embodiment of a system for detecting a dielectric breakdown position of a cable line according to the present invention.

FIG. 5 is an explanatory diagram showing an embodiment of a system for detecting the applied voltage polarity of a cable line according to the present invention.

[Explanation of symbols]

 1, power cable line 2, insulating connection part 2a, insulating cylinder 2b, sheath 2c, metal foil electrode 2d, lead wire 3, insulation breakdown detection circuit 4, optical fiber cable 5, centralized monitoring station 8, light emitting diode 10U, 10V, 10W, conductor 11U, 11V, 11W, sheath 12UV, 12UW, 12VW, cross bond wire 13UV, 13UW, 13VW, cross bond wire 15a, 15b, sheath current measuring current transformer 30, high pass filter 30a, capacitor 30b, high frequency coil 33 , Magnetic holding part 33a, magnetic steel piece 33b, yoke 33c, excitation coil 34, degaussing circuit 34a, degaussing coil 34b, drive circuit 35, magnetoresistive element 36, light emitting diode 37, DC power supply 37 50, photodiode 51, surge Energy intensity and polarity display section 52, Flow supply 60, division voltage phase detection transformer 70, the digital oscilloscope 80, a surge current measuring current transformer 90, the sheath between bridging arrester

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-158774 (JP, A) JP-A-4-223281 (JP, A) JP-A-5-312890 (JP, A) JP-A-58-58 223769 (JP, A) JP-A-61-31973 (JP, A) JP-A-3-246473 (JP, A) JP-A-9-281180 (JP, A) JP-A-10-246749 (JP, A) JP-A-6-333191 (JP, A) JP-A-62-261078 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/12 G01R 31/08

Claims (4)

(57) [Claims] 1. A system for detecting a polarity of a voltage applied to a cable line, wherein the polarity of the voltage applied to the cable conductor is detected based on a current flowing through a cross-bond line connected to a sheath of an insulated connecting portion of each phase. A first detecting means for detecting a current of a first cross bond wire connected to a sheath of the first insulated connecting portion; and a first detecting means electrically connected to the sheath of the first insulated connecting portion. A second detecting means for detecting a current of a second cross-bond wire connected to the sheath of the second insulated connecting portion; and a current of a vector sum of the respective currents detected by the first and second detecting means. A magnetizing means for magnetizing the magnetic steel piece by using the magnetic steel piece, and detecting the polarity of the applied voltage at the time of insulation breakdown of the line from the polarity of the magnetization of the magnetic steel piece. 2. A system for detecting a breakdown position of a cable line based on a surge voltage or a surge current between sheaths of an insulated connection portion of the cable line. Recording means for magnetizing and recording magnetic recording means such as a magnetic steel piece, a magnetic tape based on the voltage or the surge current, and a voltage applied to the cable line when the dielectric breakdown accident occurs. Polarity detecting means for detecting the polarity, and detecting the direction and distance of the dielectric breakdown accident from the polarity and magnitude of the magnetization of the recording means and the polarity of the applied voltage detected by the polarity detecting means. Detection system for insulation breakdown position of cable line. 3. The cable line according to claim 2, wherein said polarity detecting means detects a polarity of said applied voltage based on an output of a transformer for measuring a ground voltage of a substation. Detection system. 4. A first detecting means for detecting a current of a first cross bond wire connected to a sheath of a first insulating connection part, wherein the polarity means comprises: Second electrically connected
A second detection means for detecting a current of a second cross-bond line connected to the sheath of the insulated connection part, and a current of a vector sum of respective currents detected by the first and second detection means. 3. The dielectric breakdown position of the cable line according to claim 2, further comprising a magnetizing means for magnetizing the magnetic steel piece, wherein the polarity of the applied voltage at the time of dielectric breakdown of the line is detected from the polarity of the magnetization of the magnetic steel piece. Detection system.