JP3295607B2 - Partial discharge measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a partial discharge measuring method for measuring a partial discharge of a power cable line,
The present invention relates to a method for measuring a partial discharge which is optimal for achieving low noise and high sensitivity.

[0002]

2. Description of the Related Art FIG. 4 shows a first example of a partial discharge measuring method proposed by the present applicant. The connection part of the power cable in which this partial discharge measurement method is performed is a conductor 20 disposed at the center.
1. Connection sleeve 20 for connecting conductor 201
2. an insulator 203 (for a line portion) that insulates the conductor 201;
And an outer semiconductive layer 205 (on the side of the connecting portion) and 225 (on the side of the line) covering the insulator 203 and the insulating reinforcing portion 204, and the outer semiconductive layer 20.
5, a metal shielding layer 206,
207, outer semiconductive layer 205 and metal shielding layer which form an axially electrically interrupted portion by circumferentially cutting metal sheath 226, outer semiconductive layer 205 and metal shielding layer 206 connected to A waterproof compound 208 that seals 206 from the surface, a copper tube 209 that covers the metal shielding layer 206 and the waterproof compound 208, and the copper tube 209.
And an insulating cylinder 211 for isolating the copper body tube 209 and the anticorrosion vinyl layer 210 on both sides of the connection portion.

At the connection portion of the power cable, metal foil electrodes 212a and 212b are adhered to the surface of the corrosion-resistant vinyl layer 210 on both sides of the insulating cylinder 211. Mounting brackets 213a, 213 on both sides of metal foil electrodes 212a, 212b
A jumper wire 214 is connected to 13b, and a plurality of high-frequency iron cores 215 functioning as filters are mounted on the jumper wire 214. Further, the metal foil electrode 21
A detection impedance 216 is connected between 2a and 212b, and a partial discharge measuring device 217 is connected to an output terminal of the detection impedance 216.

When measuring partial discharge in the configuration of FIG. 4, a high-frequency iron core 215 is mounted on a jumper wire 214 attached so as to have a function as a normal connection portion, and copper tubes on both sides of an insulating cylinder 211 are mounted. 209 are insulated from high-frequency signals. In this state, when a partial discharge occurs in the insulating layer portion of the connection portion, a partial discharge pulse is induced between the copper tubes 209 on both sides of the insulating cylinder 211, and the partial discharge pulse is detected from the metal foil electrodes 212a and 212b. You. The partial discharge pulse is applied to the pair of metal foil electrodes 212a, 212.
2b, the detection impedance 216
, A partial discharge measuring device 217 tunes and amplifies the partial discharge signal based on the potential difference at the frequency having the highest S / N ratio to measure the partial discharge.

FIG. 5 shows a second example of the partial discharge measurement method proposed by the present applicant. The same reference numerals as those in FIG. Will not be described again. This configuration is different from the configuration of the portion of the external semiconductive layer 205 and the metal shielding layer 206 in FIG. That is, in FIG. 4, the edge cut portion 207 is provided, whereas in FIG.
Only the metal shielding layer 306 at a portion facing the first and connection sleeves 302 is partially cut away to provide an edge cutout 306a. Other configurations and operations are the same as those in FIG.

The configurations shown in FIGS. 4 and 5 are examples in which a sensor is externally attached. Partial discharge can be directly detected from a connection portion, and measurement is performed with a detection sensitivity substantially equal to the partial discharge detection sensitivity from an insulated connection portion. Is possible. However, FIGS. 4 and 5
According to the partial discharge measurement method described in (1), it is difficult to further increase the detection sensitivity. Therefore, the present inventors have proposed a partial discharge measurement method shown in FIG. 6 to solve this problem (Japanese Patent Application No. 8-13045).

FIG. 6 shows a third example of the partial discharge measuring method proposed by the present applicant. The connection part of the power cable in which this partial discharge measurement method is implemented is a conductor 40 disposed at the center.
1, a connecting sleeve 402 for connecting the conductors 401 to each other, an outer semiconductive layer 403 provided coaxially with the connecting sleeve 402, a metal shielding layer 404 covering the outer semiconductive layer 403, A main marginal cut portion 405 in which the outer semiconductive layer 403 and the metal shielding layer 404 in the vicinity of the center are cut off in the circumferential direction to form an axially electrically interrupted portion, and only the metal shielding layer 404 near both sides of the connection portion is circular. A metal shielding marginal portion 40 which is cut off on the ring to form an electrically interrupted portion and form detection electrodes 404a and 404b
6a, 406b, a predetermined gap is provided in the metal shielding layer 404 at the connection portion, and the metal shielding layer 404 is provided at other portions than the connection portion.
Copper tube 407 which is coated in close contact with
7 and a copper body tube 407
An insulating cylinder 409 separating the anticorrosion vinyl layer 408 from the conductor 401 and the outer semiconductive layer 403 and the metal shielding layer 4
04, detection electrodes 404a and 404b, and copper tube 407
The configuration is provided with each of the insulators 416 provided between them.

At the connection portion of the power cable, metal foil electrodes 410a and 410b are adhered to the surface of the corrosion-resistant vinyl layer 408 on both sides of the insulating cylinder 409. Lead wire lead-out portions 412a, 412 are provided on both sides of the insulating tube 409.
b are attached, and lead wires 411a, 411 are provided inside.
b is inserted. These lead wires 411a, 411b
Are connected to the detection electrodes 404a and 404b, respectively. Further, mounting fittings 413a and 413b connected to the copper body tube 407 are attached to both ends of the connecting portion. A jumper wire 414 is connected between the mounting brackets 413a and 413b, and a plurality of high-frequency iron cores 415a, 415b and 415 functioning as filters are connected to the jumper wire 414.
c, 415d are attached.

The measuring system is composed of metal foil electrodes 410a and 410b.
A detection impedance (not shown) is connected therebetween, and a partial discharge measuring device is connected to the detection impedance. Also, the lead wire 411 connected to the detection electrodes 404a, 404b
A different detection impedance (not shown) is also connected to a and 411b, and a partial discharge measuring device (not shown) is connected to this detection impedance.

As described above, according to the configuration shown in FIG. 6, two cylindrical detection electrodes are formed by removing a part of both sides of the metal shielding layer in the connection portion in the circumferential direction and separating the two. Since the partial discharge pulse is detected between the two detection electrodes, the partial discharge from the insulation reinforcing portion can be detected with high sensitivity. In addition, metal foil electrodes are mounted on the surface of the corrosion-resistant vinyl layer on both sides of the insulating cylinder, and partial discharge pulses between the two metal foil electrodes are detected. Can be detected.

Japanese Patent Application Laid-Open No. Hei 7-260869 discloses that
It shows that external noise in the measurement of the partial discharge is eliminated and the measurement of the partial discharge is performed with high sensitivity. For this purpose, a reactor member magnetically coupled to a power supply line or a ground line is provided.

[0012]

However, according to the conventional partial discharge measuring method, a metal sheath circuit current may flow through a jumper wire in which a high-frequency iron core is inserted, and a condition under which such a sheath circuit current flows. In some cases, the high-frequency core causes a magnetic saturation phenomenon and loses its function as the high-frequency core. In some cases, the action of the high-frequency iron core is maintained only in a certain power supply voltage phase band in which the sheath circuit current value decreases.

According to the measurement of partial discharge in Japanese Patent Application Laid-Open No. Hei 7-260869, although external noise can be eliminated, the influence of the magnetic saturation phenomenon cannot be avoided. Therefore, an object of the present invention is to provide a partial discharge measurement method that eliminates saturation of a high-frequency iron core and can exhibit its original function.

[0014]

In order to achieve the above object, a first aspect of the present invention is to provide an insulated connecting portion on both sides of an insulating cylinder.
The insulation unit surface adhering a metal foil electrodes, in a partial discharge measuring method for detecting a connection to the partial discharge detection impedance to the metal foil electrodes, jumpers between both sides of the metal sheath sandwiching the insulating cylinder At the jumper wire.
One end is grounded with a ground wire, and the gap length can be set so that magnetic flux saturation does not occur due to the commercial frequency current.
A ring-shaped high-frequency core having at least one place a cap attached to the jumper line and the ground line, commercial circumferential
In the wave band, the insulated connection is used as a normal connection.
Function as an insulated connection in partial discharge measurement
The gap length of the high-frequency core
A partial discharge measurement method characterized in that the method is set according to a commercial frequency current value flowing through a metal sheath . According to this method, magnetic flux saturation does not occur even when a commercial frequency current flows through the metal sheath circuit, a sufficiently high impedance value is obtained in the frequency band where the partial discharge measurement is performed, and the function of the short-circuit jumper wire is invalidated. can do. Therefore, even when a commercial frequency current is flowing through the metal sheath circuit, magnetic saturation of the high-frequency iron core due to the commercial frequency current is avoided, the impedance drop in the high frequency band is reduced, and partial discharge is measured without being affected by the commercial frequency current. It becomes possible to do.

The high-frequency iron core may have a ring shape and a structure having a gap at at least one position. According to this method, the magnetic flux density is reduced by providing a gap in the conventional high-frequency iron core. As a result, magnetic saturation of the iron core due to the application of the commercial frequency current to the sheath circuit can be prevented. It is possible to increase the impedance value in the frequency band where the measurement is performed.

In the high-frequency iron core having this gap, the gap length of the magnetic path can be set according to the commercial frequency current value. According to this method, the highest impedance value can be obtained by optimally setting the gap of the gap provided in the iron core according to the commercial frequency current value.

According to a second aspect of the present invention, an insulating tube of an insulated connecting portion is sandwiched.
Attach metal foil electrodes to the insulating surface of both sides
Connect a detection impedance to the electrode to detect partial discharge
In the partial discharge measurement method, both sides of the insulating cylinder are sandwiched.
Short the jumper wire between the metal sheaths.
Ground one end with a ground wire, and
Setting impedance so as not to cause magnetic flux saturation
Wound secondary winding with high-frequency reactor connected
Put the ring-shaped high-frequency iron core
In the commercial frequency band, the insulation
The connection part functions as a normal connection part for partial discharge measurement.
Measurement as an insulated connection, the secondary winding and
And the impedance values of the high-frequency reactor
Set according to the commercial frequency current flowing through the metal sheath.
And a method for measuring partial discharge. According to this method, by appropriately setting the impedance values of the secondary winding and the high-frequency reactor, magnetic saturation of the iron core due to the commercial frequency current can be prevented, and the impedance value in the frequency band for performing partial discharge measurement can be increased. become.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a connection section to which the partial discharge measurement method according to the present invention is applied. In a cross-bond grounding circuit system for a cable line, conventionally, a normal connecting portion having no edge cutting structure in a metal sheath circuit has been used as a connecting portion at a metal sheath grounding position. However, in the present invention, an insulated connecting portion is used instead of the normal connecting portion,
A connecting portion having a configuration shown in FIG. 4 is used in which the metal sheaths on both sides are short-circuited by a jumper wire and function as a normal connecting portion in a commercial frequency band. Therefore, in the following, the detailed configuration inside the connection unit is omitted, and only the external configuration will be described.

An insulating connection 102 is provided between the main cables 101a and 101b. This insulated connection 1
An insulating cylinder 103 is provided in a ring shape at an intermediate portion of the cylinder 02. Further, mounting brackets 104a and 104b are provided on the outer surfaces of both ends of the insulated connecting portion 102, and the mounting bracket 10
4a and 104b are connected by a short-circuit jumper wire 105. A high-frequency iron core 106 with a gap is attached (outside fitted) to the short-circuit jumper wire 105.

FIG. 2A shows this high-frequency iron core 106 with a gap, in which a gap 106a is provided. It should be noted that the gapless high-frequency iron core 107 having the configuration shown in FIG. Details of these will be described later. (C) shows a high-frequency iron core 112 for comparison with the high-frequency iron cores 106 and 107 according to the present invention.

A ground wire 108 is connected between one end of the mounting brackets 104a and 104b and the ground. In addition, ground wire 1
A high-frequency core 109 with a gap having the same configuration as that of the high-frequency core 106 with a gap is attached to 08. Metal foil electrodes 110a and 110b are adhered to both sides of the insulating cylinder 103 on the outer surface of the insulating connecting portion 102.
A detection impedance (Zd) 111 is connected to each of the metal foil electrodes 110a and 110b.

The general procedure for measuring the partial discharge in the insulated connection section 102 having the above-described configuration is the same as that described in the prior art, and thus the description thereof is omitted here. Referring to FIG. 2, (a) shows a pair of gaps 106 as described above.
Example of high-frequency core 106 with gap having a, (b)
Is the secondary winding 107 on the ring-shaped iron core 107 with no gap.
The secondary winding 107a is connected to an air-core or iron-core high-frequency reactor 107b, and has a characteristic of having a sufficiently low impedance in a low-frequency range.
(C) shows a normal high-frequency core 112 without a gap.

FIG. 3 shows (a), (b) and (b) shown in FIG.
(C) shows the characteristics of each high-frequency iron core (representing the relationship between the flowing current i and the inductance L). In the figure, the characteristic I is based on the high-frequency iron core of (a), the characteristic II is based on (b), and the characteristic III is based on (c). Energizing current i
Is sufficiently small, the characteristic III of the gapless high-frequency core 112 shown in (c) has the largest inductance L, but the core is rapidly magnetically saturated with an increase in the current i, and the inductance L is reduced. In the characteristic I according to (a), since the absolute value of the inductance L depends on the gap length, the inductance L decreases as the gap length increases, and further, when the current i increases, magnetic saturation starts. The inductance L decreases. Further, the characteristic II according to (b) depends on the impedance value of the secondary winding 107a itself and the impedance value of the high-frequency reactor 107b in the high-frequency band, and is determined by the relationship between the current value i and the inductance value.

As is apparent from FIG. 3, the characteristic I or the characteristic
If a high-frequency iron core having II is used, the current value range of the conduction current i at which the inductance L is constant can be widened. That is, it is possible to obtain a high-frequency iron core that hardly causes magnetic saturation. The secondary winding 1 is connected to a high-frequency iron core 106 in which a ring-shaped high-frequency iron core as shown in FIG. 2A is provided with a gap, or a high-frequency iron core having no gap as shown in FIG.
When the high-frequency iron core 107 having a structure in which the secondary winding 107a is wound and the high-frequency reactor 107b is connected to the secondary winding 107a is fitted (fitted) to the short-circuit jumper wire 105, the inductance of the short-circuit jumper wire 105 is slightly increased.
As a result, a sufficiently high impedance value is obtained in a frequency band of several MHz or more where the partial discharge measurement is performed, and the operation state is the same as in the case where the short-circuit jumper wire 105 is not provided in the partial discharge measurement frequency band.

When the ground line 108 hinders the measurement of the partial discharge, for example, when the external noise level increases or the partial discharge detection pulse voltage decreases, the high-frequency core 106 according to the present invention is also connected to the ground line 108. , 107 can eliminate the grounding effect in the high frequency band. Further, even when the commercial frequency current is superimposed on the short-circuit jumper wire 105 or the ground wire 108, the high-frequency iron core 106 having the structure shown in FIG. 2A or the high-frequency iron core 107 having the structure shown in FIG. In addition, since saturation of the iron core due to the commercial frequency can be avoided, an effect of increasing the impedance in a high frequency band can be obtained.

In the configuration example of the present invention, an example is shown in which one high-frequency iron core 106, 109 with a gap is used. However, the number of high-frequency iron cores 106, 109 can be increased as necessary.
In addition, the number of gaps in the high-frequency iron cores 106 and 109 with a gap can be arbitrarily set.

[0027]

As described above, according to the present invention, the high-frequency iron core mounted on the jumper wire or the ground wire has a characteristic that does not cause magnetic flux saturation even when a commercial frequency current flows through the metal sheath circuit. In addition, a sufficiently high impedance value can be obtained in the frequency band where the partial discharge measurement is performed, and the function of the short-circuit jumper wire can be invalidated. As a result, even when the commercial frequency current is flowing through the metal sheath circuit, magnetic saturation of the high-frequency iron core due to the commercial frequency current is avoided, the impedance is not reduced in the high frequency band, and the partial discharge is measured without being affected by the commercial frequency current. It becomes possible to do.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a connection section to which a partial discharge measurement method according to the present invention is applied.

FIG. 2 shows an example of a high-frequency iron core used in the present invention,
(A) is an example of a high-frequency core with a gap, (b) is a configuration example in which a secondary winding and a high-frequency reactor are connected to a high-frequency core without a gap, and (c) is a configuration example of a conventional high-frequency core shown for comparison. Is shown.

FIG. 3 is a characteristic diagram showing a relationship between a flowing current i and an inductance L of each of the three types of high-frequency cores shown in FIG.

FIG. 4 is a connection diagram and a cable cross-sectional view illustrating a first example of a conventional partial discharge measurement method.

FIG. 5 is a connection diagram and a cable cross-sectional view illustrating a second example of the conventional partial discharge measurement method.

FIG. 6 is a connection diagram and a cable cross-sectional view illustrating a third example of the conventional partial discharge measurement method.

[Explanation of symbols]

 101a, 101b Main cable 102 Insulated connection part 103 Insulation tube 104a, 104b Mounting bracket 105 Short-circuit jumper wire 106, 109 High-frequency iron core with gap 107 High-frequency iron core 107a Secondary winding 107b High-frequency reactor 108 Ground wire 110a, 110b Metal foil electrode

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kan Endo 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture Inside the Power Systems Research Laboratories, Hitachi, Ltd. (72) Inventor Tomoaki Imai Hidaka, Hitachi City, Ibaraki Prefecture 5-1-1, Machi-cho, Power Systems Laboratory, Hitachi, Ltd. (72) Inventor Tsutomu Tashiro 5-1-1, Hidaka-cho, Hitachi, Hitachi, Ibaraki, Japan Power Systems Laboratory, Hitachi Ltd. (56) References JP-A-6-331685 (JP, A) JP-A-2-154170 (JP, A) JP-A-3-175379 (JP, A) JP-A-5-172889 (JP, A) JP-A-7-94330 (JP, A) JP 6-9115 (JP, U) JP 60-179012 (JP, U) Registered utility model 3031158 (JP, U) Hiroshi Nakatogawa et al. Partial discharge detection , 1996 Institute of Electrical Engineers of power and energy sector competition Papers, Japan, the Institute of Electrical Engineers of power and energy sector University committees, July 15, 1996, 725-726 (58) investigated the field (Int.Cl. ^7, (DB name) G01R 31/12

Claims (2)

(57) [Claims] 1. A bonded metal foil electrodes on the insulation part surface of both sides of the insulation cylinder of the insulation connection portion, the partial discharge measurement method for detecting a connection to the partial discharge detection impedance to the metal foil electrodes A short circuit is made between the metal sheaths on both sides of the insulating cylinder with a jumper wire, one end of the jumper wire is grounded with a ground wire, and a gap is provided to prevent magnetic flux saturation due to a commercial frequency current.
At least one gap for which the length can be set
A ring-shaped high-frequency iron core having a place is attached to the jumper wire and the grounding wire, and in a commercial frequency band, the insulated connection portion is used as a normal connection portion.
Function as an insulated connection for partial discharge measurement
And the gap length of the high-frequency iron core is set to the metal sheath.
A partial discharge measurement method, wherein the partial discharge measurement method is set according to a commercial frequency current value flowing through the battery . 2. The insulation on both sides of the insulating connecting portion with respect to the insulating cylinder.
Attach a metal foil electrode to the edge surface and detect on this metal foil electrode
Partial discharge to detect partial discharge by connecting impedance
In the measuring method, a jumper wire is provided between the metal sheaths on both sides of the insulating cylinder.
And one end of the jumper wire is grounded with a ground wire to prevent magnetic flux saturation due to the commercial frequency current.
A high-frequency reactor capable of setting
A ring-shaped high-frequency iron core with a continuous secondary winding wound
Attached to the jumper wire and the ground wire, and in a commercial frequency band, the insulated connection portion is a normal connection portion.
Function as an insulated connection for partial discharge measurement
And each input of the secondary winding and the high-frequency reactor
The commercial frequency current value flowing through the metal sheath for the impedance value
A partial discharge measurement method, wherein the method is set according to the following conditions .