CN207851223U - 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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- CN207851223U CN207851223U CN201820158558.6U CN201820158558U CN207851223U CN 207851223 U CN207851223 U CN 207851223U CN 201820158558 U CN201820158558 U CN 201820158558U CN 207851223 U CN207851223 U CN 207851223U
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Abstract
The utility model discloses a kind of high-tension cable Partial Discharge Detection structures, 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；It is electrically connected with detection impedance between first metal foil and the second metal foil；It is provided with insulating cylinder in the connector；The metal screen layer of first cable and the second cable is disconnected by the insulating cylinder.The utility model 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, to realize the accurate positionin of partial discharge position.
Description
Technical field
The utility model is related 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, in conjunction with 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 cable partial discharge Insulation Problems cannot be detected timely and be handled, 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.
Currently, 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 there are severe transmission attenuation characteristics for transmission on long cables, 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 cannot achieve 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.
Utility model content
In view of the drawbacks described above of the prior art, the technical problem to be solved by the utility model is to provide one kind can be accurate
The detection structure of positioning cable partial discharge position.
To achieve the above object, the utility model provides a kind of high-tension cable Partial Discharge Detection structure, including first
Cable and the second cable；First cable and the second cable are connected by connector；First cable is close to the joint
The outer surface of external screen layer is provided with the first metal foil；Second cable is provided with close to the outer surface of the joint external screen layer
Second metal foil；It is connected with detection impedance between first metal foil and the second metal foil；Insulation is provided in the connector
Cylinder；The metal screen layer of first cable and the second cable is disconnected by the insulating cylinder.
The utility model has the beneficial effects that：The utility model is due to the noise signal from wire stylet, in detection impedance
On both ends cannot generate pressure drop, thus can be very good to inhibit noise, and due to having the metal foils such as aluminum shell and external screen layer phase
It connects, so external noise will not enter amplifier by signal input part, this just preferably inhibits site environment noise, to
It can 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 structural schematic diagram.
Fig. 3 is the schematic diagram of Partial Discharge Detection structure in specific embodiment of the present invention.
Fig. 4 is the equivalent circuit diagram of Partial Discharge Detection structure in specific embodiment of the present invention.
Fig. 5 is the electrical schematic diagram of Partial Discharge Detection in specific embodiment of the present invention.
Fig. 6 is the denoising system flow chart that Partial Discharge Detection structure is realized in specific embodiment of the present invention.
Fig. 7 is to realize Partial Discharge Detection using this Partial Discharge Detection structure in specific embodiment of the present invention
Method flow diagram.
Fig. 8 is to realize Partial Discharge Detection using this Partial Discharge Detection structure in specific embodiment of the present invention
The cable local discharge detects schematic diagram of method.
Specific implementation mode
The utility model is described in further detail 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 disconnected by insulating cylinder 3a
It opens.
In this case, metal foil preferably uses copper foil, in other schemes, can also realize metal 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 constituted 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-
Within the scope 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 the both sides transition joint NJ 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 are the first demodulator, the first demodulator to be provided with four road signal outputs, 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 are the second demodulator, the second demodulator to be provided with four road signal outputs, 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 h, l are then the signal that antenna is coupled to, 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 utility model can be equally realized after the central frequency range of signal is accordingly changed between H and L
Technique 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.NJ effects are the knots 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
Detection structure as claimed in claim 1 is arranged in two near joints of head and the tail 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 of first group of detection structure acquisition；
n1(t) random noise in the signal observation transmission process obtained for first group of detection structure；
r1Distance for first group of detection structure apart from shelf depreciation point；Detection structure capacitance only has 6 centimetres, 16 lis of overall length
Rice；Opposite cable length can be regarded as a little；
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 of second group of detection structure acquisition；
n2(t) random noise in the signal observation transmission process obtained for second group of detection structure；
r2Distance for 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) are analyzed using cosine signal, 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 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；
For the amplitude for the cosine signal that first group of testing agency receives；
For the amplitude for the cosine signal that second group of testing agency receives；
-aFor decay factor；
Formula (1) and (2), which are substituted into formula (5), to be obtained：
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；
r1Distance for 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 of second group of detection structure acquisition；
n2(t) random noise in the signal observation transmission process obtained for second group of detection structure；
r2Distance for 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；
r1Distance for 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；
r2Distance for 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, 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；
r1Distance for 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；
r2Distance for second group of detection structure apart from shelf depreciation point；
T is the signal period；
If noise signal is relevant 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) formula (8) is substituted into, can be obtained by integral：
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 constitute；The maximum of sinc function is：
So the maximum value of correlation function corresponds to：
W0 can not possibly be 0, so：
Therefore,
Wherein, r1Distance for first group of detection structure apart from shelf depreciation point；
r2Distance for second group of detection structure apart from shelf depreciation point；
V is the transmission speed of local discharge signal in the cable；
τmFor the maximal correlation delay time of 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, r1Distance for first group of detection structure apart from shelf depreciation point；
r2Distance for second group of detection structure apart from shelf depreciation point；
V is the transmission speed of local discharge signal in the cable；
τmFor the maximal correlation delay time of 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 utility model described in detail above.It should be appreciated that the ordinary skill people of this field
Member according to the present utility model can conceive without creative work makes many modifications and variations.Therefore, all this technology necks
Technical staff passes through logic analysis, reasoning or limited reality on the basis of existing technology according to the design of the utility model in domain
Available technical solution is tested, it 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 by connector (3) with the second cable (2)；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)；
It is provided with insulating cylinder (3a) in the connector (3)；The metal screen layer of first cable (1) and the second cable (2) is logical
Cross the insulating cylinder (3a) disconnection.
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| CN201820158558.6U CN207851223U (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 |
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| CN201820158558.6U CN207851223U (en) | 2018-01-30 | 2018-01-30 | A kind of high-tension cable Partial Discharge Detection structure |
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