CN108169645A - A kind of high-tension cable Partial Discharge Detection structure - Google Patents
A kind of high-tension cable Partial Discharge Detection structure Download PDFInfo
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- CN108169645A CN108169645A CN201810092330.6A CN201810092330A CN108169645A CN 108169645 A CN108169645 A CN 108169645A CN 201810092330 A CN201810092330 A CN 201810092330A CN 108169645 A CN108169645 A CN 108169645A
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- cable
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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Abstract
The invention discloses a kind of high-tension cable Partial Discharge Detection structure, including the first cable and the second cable；First cable and the second cable are connected by connector；First cable is provided with the first metal foil close to the outer surface of the joint external screen layer；Second cable is provided with the second metal foil close to the outer surface of the joint external screen layer；Detection impedance is electrically connected between first metal foil and the second metal foil；Insulating cylinder is provided in the connector；The metal screen layer of first cable and the second cable is disconnected by the insulating cylinder.The present invention is due to the noise signal from wire stylet, both ends in detection impedance cannot generate pressure drop, it thus can be very good to inhibit noise, and due to there is the metal foils such as aluminum shell to connect with external screen layer, so external noise will not enter amplifier by signal input part, this just preferably inhibits site environment noise, so as to fulfill the accurate positionin of partial discharge position.
Description
Technical field
The present invention relates to a kind of high-tension cable Partial Discharge Detection structures.
Background technology
With the rapid development of economy, the electricity consumption of urban distribution network increases year by year, with reference to the design for aesthetic in city, electric power electricity
The a large amount of use of cable, it has also become the major product of electric power is transmitted in city.Since the insulating structure design of cable and scene are applied
The service life aging of the reasons such as work technique and cable, the Insulation Problems of cable are more and more, shelf depreciation (hereinafter referred to as partial discharge)
It is especially prominent.If cannot timely detect and handle cable partial discharge Insulation Problems, once cable insulation breakdown may result in weight
Large-scale blackout influences the normal operation in city.Therefore, to the research of the partial discharge detection of twisted polyethylene cable and localization method
It is particularly important.
At present, high-tension cable partial discharge location method mainly uses the time domain reflectometry of HF current transformer.This method
When an existing serious problems are exactly wireline test, due to environment complexity, live serious interference, cable partial discharge signal belongs to high
Frequency signal, detection signal sensitivity is small, and interference is larger and transmits on long cables there are severe transmission attenuation characteristic, so with
Time domain reflectometry can not carry out partial discharge location in the positioning of long cable partial discharge.Current cable partial discharge detecting instrument both domestic and external is all
It can not realize the cable partial discharge positioning of long range.
Therefore those skilled in the art are dedicated to developing a kind of detection structure that cable local discharge position is accurately positioned.
Invention content
In view of the drawbacks described above of the prior art, the technical problems to be solved by the invention, which are to provide one kind, to be accurately positioned
The detection structure of cable local discharge position.
To achieve the above object, the present invention provides a kind of high-tension cable Partial Discharge Detection structure, including the first cable
With the second cable；First cable and the second cable are connected by connector；First cable is close to the joint external screen
The outer surface of layer is provided with the first metal foil；Second cable is provided with second close to the outer surface of the joint external screen layer
Metal foil；Detection impedance is connected between first metal foil and the second metal foil；Insulating cylinder is provided in the connector；Institute
The metal screen layer for stating the first cable and the second cable is disconnected by the insulating cylinder.
The beneficial effects of the invention are as follows：The present invention is due to the noise signal from wire stylet, the both ends in detection impedance
Pressure drop cannot be generated, thus can be very good to inhibit noise, and due to there is the metal foils such as aluminum shell to connect with external screen layer, other than institute
Portion's noise will not enter amplifier by signal input part, this just preferably inhibits site environment noise, so as to realize
The accurate positionin of partial discharge position.
Description of the drawings
Fig. 1 is Partial Discharge Detection structural profile illustration.
Fig. 2 is Partial Discharge Detection structure diagram.
Fig. 3 is the schematic diagram of Partial Discharge Detection structure in the specific embodiment of the invention.
Fig. 4 is the equivalent circuit diagram of Partial Discharge Detection structure in the specific embodiment of the invention.
Fig. 5 is the electrical schematic diagram of Partial Discharge Detection in the specific embodiment of the invention.
Fig. 6 is the denoising system flow chart that Partial Discharge Detection structure is realized in the specific embodiment of the invention.
Fig. 7 is the method for realizing Partial Discharge Detection in the specific embodiment of the invention using this Partial Discharge Detection structure
Flow chart.
Fig. 8 is the method for realizing Partial Discharge Detection in the specific embodiment of the invention using this Partial Discharge Detection structure
Cable local discharge detects schematic diagram.
Specific embodiment
The invention will be further described with reference to the accompanying drawings and examples：
As shown in Figures 1 to 4, a kind of high-tension cable Partial Discharge Detection structure, including the first cable 1 and the second cable 2,
First cable 1 and the second cable 2 are connected by connector 3.First cable 1 outer surface of external screen layer at connector 3 is provided with
One copper foil 4, the second cable 2 outer surface of external screen layer at connector 3 are provided with the second copper foil 5；First copper foil 4 and the second copper foil
Detection impedance 6 is electrically connected between 5.
It is provided with insulating cylinder 3a in connector 3, the metal screen layer of the first cable 1 and the second cable 2 is broken by insulating cylinder 3a
It opens.
In this case, metal foil in other schemes, can also realize metal preferably with copper foil using similar metal
Concrete function.
Wherein, Rc is the characteristic impedance of cable；C is the capacitance between conducting wire core wire and capacitance sensor copper foil；Cs is capacitance
The stray capacitance of coupler and metallic shield interlayer；Rs is the resistance between capacity coupler copper foil and shielded layer；Rf is to measure
The input impedance of unit；C1 is the capacitance between the first metal foil 4 and cable；C2 is the electricity between the first metal foil 4 and cable
Hold.
Such as Fig. 5, capacitance is formed between copper foil and cable core, the detection impedance in 50 Europe is connected between two copper foil outputs.
Detection impedance is just collected into the signal that Partial discharge signal acquires on two built-in capacitance sensors, this signal passes through differential amplification,
The processing of input computer is converted through A/D or input oscillograph is shown.The study found that Partial discharge signal frequency spectrum is in 1MHz-
In the range of 300MHz, centre frequency is in 10MHz-20MHz, to-noise ratio highest.The measure loop of calculus of finite differences is similar to differential flat
Weigh circuit, the noise signal from wire stylet, and the both ends in detection impedance cannot generate pressure drop, thus can be very good to inhibit
Noise.And due to there is copper foil to connect with the metal external screen layer of conducting wire, it is put so external noise will not be entered by signal input part
Big device, this just preferably inhibits site environment noise.
As shown in fig. 6, above-mentioned detection structure can be applied to a kind of high-tension cable PD On-Line Measurement System, including two
Detection structure as above is organized, transition joint NJ, the gold of transition joint NJ both sides cable are in series between the connector of two detection structures
Belong to shielded layer to be connected as one.
First group of detection structure is connect with the first signal receiving device, and the near joints of first group of detection structure are provided with
One antenna T1, first antenna T1 are connect with the first signal receiving device, the first signal receiving device and the first frequency-selecting amplifying device
Connection.First frequency-selecting amplifying device is connect by four road signal outputs with the first modulator, and the first modulator is connected by optical fiber
There is the first demodulator, the first demodulator is provided with four road signal outputs, and wherein two paths of signals output is connect with the first Noise gate, separately
Two paths of signals output is connect with the second Noise gate.First Noise gate continues door with first and connect, and the second Noise gate is connect with NJ,
NJ continue door with second and connect.
Second group of detection structure is connect with second signal reception device, and the near joints of second group of detection structure are provided with
Two antenna T2, the second antenna T2 are connect with second signal reception device, second signal reception device and the second frequency-selecting amplifying device
Connection.Second frequency-selecting amplifying device is connect by four road signal outputs with the second modulator, and the second modulator is connected by optical fiber
There is the second demodulator, the second demodulator is provided with four road signal outputs, and wherein two paths of signals output is connect with third Noise gate, separately
Two paths of signals output is connect with the 4th Noise gate, and third Noise gate is connect with NJ, and the 4th Noise gate continues door with third and connect.
In Fig. 6, the centre frequency of signal H is set in the frequency for properly detecting the IJ transition joint Partial discharge signals, more excellent
, the central frequency range of H signal could be provided as 50MHZ---300MHz；The centre frequency of signal L is set in suitable detection
In the frequency of adjacent NJ transition joint Partial discharge signals, preferably, the central frequency range of L could be provided as 1MHZ----
50MHZ；The centre frequency of signal H and L are different, and the signal that h, l are then coupled to for antenna, after corresponding frequency-selecting amplification
Signal.
In actual application, since the structure of conductor cable is different, the frequency of Partial Discharge Detection structure detection
Rate range is had nothing in common with each other, and the central frequency range of signal is accordingly changed the skill that can equally realize the present invention afterwards between H and L
Art effect.
First, which continues door, the second lasting door and third, continues the signal transmission of door to computer.
First, which continues door, the second lasting door and third, continues door and is connect with third signal receiving device；Third signal receives
Device is connect with selecting switch；Selecting switch is connected with A/D switches；A/D switches are connect with computer.
The effect of Noise gate is the noise signal that the signal that comparison calculus of finite differences device detects is coupled to antenna, by this
Corresponding signal is considered as noise signal and is rejected in the two.Continuing the effect of door is, is occurred according to discharge pulse signal
Frequent degree determines whether local discharge signal and exports the signal.The effect of NJ is the knot for exporting both sides Noise gate
Corresponding signal is considered as partial discharge pulse and exports the signal in fruit.Wherein, continue door, NJ, noise gate circuit all may be used
To be realized by more conventional circuit.
IJ1 and IJ2 is the acquisition signal at left and right sides of connector respectively, and NJ is opposite in the signal for exporting both sides Noise gate
The signal answered is considered as partial discharge pulse and exports the signal.
The effect of selecting switch is, selection is IJ1, that exports give A/D switches all the way for IJ2, NJ this 3 road signal, mainly
In order to reduce processing circuit cost.
As shown in Figure 7 and Figure 8, it can realize a kind of high voltage cable partial discharge detection method using said detecting system, wrap
Include following steps：
1) two groups of local discharge signals are obtained on cable transmission line road
Two near joints of head and the tail set detection structure as claimed in claim 1 on cable transmission line road；Two detection structures
Connector between be in series with transition joint；The metal screen layer of transition joint both sides cable is connected as one；
The local discharge signal that two detection structures receive is respectively：
X1(t)=S1(t,r1)+n1(t) (1)
X2(t)=S1(t,r2)+n2(t) (2)
Wherein, X1(t) local discharge signal received for first group of detection structure of t moment；
S1(t,r1) it is t moment, apart from shelf depreciation distance r1Locate the signal observation that first group of detection structure obtains；
n1(t) random noise in the signal observation transmission process obtained for first group of detection structure；
r1For distance of first group of detection structure apart from shelf depreciation point；Detection structure capacitance only has 6 centimetres, 16 lis of overall length
Rice；It can regard as a little with respect to cable length；
X2(t) local discharge signal received for second group of detection structure of t moment；
S2(t,r2) it is t moment, apart from shelf depreciation distance r2Locate the signal observation that second group of detection structure obtains；
n2(t) random noise in the signal observation transmission process obtained for second group of detection structure；
r2For distance of second group of detection structure apart from shelf depreciation point；
2) the maximal correlation delay time τ for obtaining two groups of local discharge signals is calculatedm
Formula (1) and (2) using cosine signal are analyzed, enable the signal equation be：
S1(t,r1)=Ui e-ɑr1cos w0(t-r1/v) (3)
S2(t,r2)=Ui e-ɑr2cos w0(t-r2/v) (4)
The correlation function of the observation for the local discharge signal that two detection structures obtain is：
Wherein, X1(t) local discharge signal received for first group of detection structure of t moment；
X2(t+ τ) is the local discharge signal that second group of detection structure of t+ τ moment receives；
T is the signal period；
Amplitude for the cosine signal that first group of testing agency receives；
Amplitude for the cosine signal that second group of testing agency receives；
-aFor decay factor；
Formula (1) and (2) are substituted into formula (5) to obtain：
Wherein, S1(t,r1) it is t moment, apart from shelf depreciation distance r1Locate the signal observation that first group of detection structure obtains
Value；
n1(t) random noise in the signal observation transmission process obtained for first group of detection structure；
r1For distance of first group of detection structure apart from shelf depreciation point；
S2(t,r2) it is t moment, apart from shelf depreciation distance r2Locate the signal observation that second group of detection structure obtains；
n2(t) random noise in the signal observation transmission process obtained for second group of detection structure；
r2For distance of second group of detection structure apart from shelf depreciation point；
T is the signal period；
It is assumed that Partial discharge signal and noise are altogether irrelevant, (6) can be reduced to：
Wherein, S1(t,r1) it is t moment, apart from shelf depreciation distance r1Locate the signal observation that first group of detection structure obtains
Value；
n1(t) random noise in the signal observation transmission process obtained for first group of detection structure；
r1For distance of first group of detection structure apart from shelf depreciation point；
S2(t+ τ, r2) it is the t+ τ moment, apart from shelf depreciation distance r2Locate the signal observation that second group of detection structure obtains
Value；
n2(t) random noise in the signal observation transmission process obtained for second group of detection structure；
r2For distance of second group of detection structure apart from shelf depreciation point；
T is the signal period；
If noise signal n1 (t) and n2 (t) are altogether irrelevant, then Partial discharge signal is separated from noise, i.e.,：
Wherein, S1(t,r1) it is t moment, apart from shelf depreciation distance r1Locate the signal observation that first group of detection structure obtains
Value；
r1For distance of first group of detection structure apart from shelf depreciation point；
S2(t+ τ, r2) it is the t+ τ moment, apart from shelf depreciation distance r2Locate the signal observation that second group of detection structure obtains
Value；
r2For distance of second group of detection structure apart from shelf depreciation point；
T is the signal period；
If noise signal is concerned with local discharge signal, denoising is carried out to local discharge signal, suppresses noise
n1(t) and n2(t) interference obtains (8) formula；
Formula (8) is integrated in a cycle；The period of known Partial discharge signal isSo by formula (3) and (4)
Substitution formula (8), can obtain by integration：
Wherein：
By (9) it is found that S1And S2The correlation function of two Partial discharge signals is by a special function(sinc function) with
One invariant k0Product form；The maximum of sinc function is：
So the maximum value of correlation function corresponds to：
W0 can not possibly be 0, so：
Therefore,
Wherein, r1For distance of first group of detection structure apart from shelf depreciation point；
r2For distance of second group of detection structure apart from shelf depreciation point；
V is the transmission speed of local discharge signal in the cable；
τmMaximal correlation delay time for two groups of local discharge signals；
3) position of shelf depreciation point is determined
It can be obtained according to formula (13)：
r1=r2-vτm (14)
Wherein, r1For distance of first group of detection structure apart from shelf depreciation point；
r2For distance of second group of detection structure apart from shelf depreciation point；
V is the transmission speed of local discharge signal in the cable；
τmMaximal correlation delay time for two groups of local discharge signals；
If the distance of the first detection structure and the second detection structure is D, and r1=L, then r2=D-L can be obtained：
L=D-L-v τm (15)
Then partial discharge point and the horizontal distance of the first detection structure are：
Wherein, τmIt is the maximal correlation delay that can be read from related partial discharge detection instrument record.
The preferred embodiment of the present invention described in detail above.It should be appreciated that those of ordinary skill in the art without
Creative work is needed according to the present invention can to conceive and makes many modifications and variations.Therefore, all technologies in the art
Personnel are available by logical analysis, reasoning, or a limited experiment on the basis of existing technology under this invention's idea
Technical solution, all should be in the protection domain being defined in the patent claims.
Claims (1)
1. a kind of high-tension cable Partial Discharge Detection structure, including the first cable (1) and the second cable (2)；First cable
(1) it is connected with the second cable (2) by connector (3)；It is characterized in that：First cable (1) is close to external screen at the connector (3)
The outer surface of layer is provided with the first metal foil (4)；Second cable (2) is close to the outer surface of external screen layer at the connector (3)
It is provided with the second metal foil (5)；Detection impedance (6) is electrically connected between first metal foil (4) and the second metal foil (5)；
Insulating cylinder (3a) is provided in the connector (3)；The metal screen layer of first cable (1) and the second cable (2) leads to
Cross the insulating cylinder (3a) disconnection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810092330.6A CN108169645A (en) | 2018-01-30 | 2018-01-30 | A kind of high-tension cable Partial Discharge Detection structure |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810092330.6A CN108169645A (en) | 2018-01-30 | 2018-01-30 | A kind of high-tension cable Partial Discharge Detection structure |
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| CN108169645A true CN108169645A (en) | 2018-06-15 |
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| CN201810092330.6A Pending CN108169645A (en) | 2018-01-30 | 2018-01-30 | A kind of high-tension cable Partial Discharge Detection structure |
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2018
- 2018-01-30 CN CN201810092330.6A patent/CN108169645A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| 李华春: ""电缆局部放电在线检侧方法的分析比较"", 《电力设备》 * |
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Application publication date: 20180615 |
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