CN208060655U - A kind of high-tension cable PD On-Line Measurement System - Google Patents
A kind of high-tension cable PD On-Line Measurement System Download PDFInfo
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Abstract
The utility model discloses a kind of high-tension cable PD On-Line Measurement Systems, including high-tension cable Partial Discharge Detection structure；It is in series with transition joint between the connector of two detection structures；The metal screen layer of transition joint both sides cable is connected as one；First group of detection structure is connect with the first signal receiving device；The near joints of first group of detection structure are provided with first antenna；The first antenna is connect with first signal receiving device；First signal receiving device is connect with the first frequency-selecting amplifying device；The first frequency-selecting amplifying device is connect by four road signal outputs with the first modulator；The utility model provides a kind of high-tension cable PD On-Line Measurement System, pass through this on-line detecting system, it can maximumlly realize that removing for Partial discharge signal is made an uproar, and then realize the remote transmission of partial discharge detection signal, and it is capable of the detection of accurate judgement partial discharge position by computer, realize the accurate positionin of cable local discharge position.
Description
Technical field
The utility model is related to a kind of high-tension cable PD On-Line Measurement Systems.
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 detecting system 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 detecting system of positioning cable partial discharge position.
To achieve the above object, the utility model provides a kind of high-tension cable PD On-Line Measurement System, including
High-tension cable Partial Discharge Detection structure；It is in series with transition joint between the connector of two detection structures；The transition joint
The metal screen layer of both sides cable is connected as one；First group of detection structure is connect with the first signal receiving device；First
The near joints of group detection structure are provided with first antenna；The first antenna is connect with first signal receiving device；Institute
The first signal receiving device is stated to connect with the first frequency-selecting amplifying device；The first frequency-selecting amplifying device passes through four road signal outputs
It is connect with the first modulator；First modulator is connected with the first demodulator by optical fiber；First demodulator is provided with
Four road signal outputs, wherein two paths of signals output are connect with the first Noise gate, and another two paths of signals output is connect with the second Noise gate；
First Noise gate continues door with first and connect；Second Noise gate is connect with NJ；Described NJ continues door with second
Connection；Second group of detection structure is connect with second signal reception device；The near joints of second group of detection structure are provided with second
Antenna；Second antenna is connect with the second signal reception device；The second signal reception device is put with the second frequency-selecting
Big device connection；The second frequency-selecting amplifying device is connect by four road signal outputs with the second modulator；Second modulation
Device is connected with the second demodulator by optical fiber；Second demodulator is provided with four road signal outputs, and wherein two paths of signals exports
It is connect with third Noise gate, another two paths of signals output is connect with the 4th Noise gate；The third Noise gate is connect with described NJ；
4th Noise gate continues door with third and connect；Described first continues the signal biography that door, the second lasting door and third continue door
It is defeated by computer.
Preferably, the described first lasting door, the second lasting door and third continue door and are connect with third signal receiving device；Institute
Third signal receiving device is stated to connect with selecting switch；The selecting switch is connected with A/D switches；The A/D switches and calculating
Machine connects.
Preferably, including the first cable and the second cable；First cable and the second cable are connected by connector；It is special
Sign is：First cable is provided with the first metal foil close to the outer surface of the joint external screen layer；Second cable leans on
The outer surface of the nearly joint external screen layer is provided with the second metal foil；It is electrically connected between first metal foil and the second metal foil
It is connected to detection impedance；
It is provided with insulating cylinder in the connector；The metal screen layer of first cable and the second cable passes through the insulation
Cylinder disconnects.
The utility model has the beneficial effects that：The utility model provides a kind of high-tension cable shelf depreciation on-line checking system
System can maximumlly realize that removing for Partial discharge signal is made an uproar, and then realize partial discharge detection signal by this on-line detecting system
It transmits at a distance, and is capable of the detection of accurate judgement partial discharge position by computer, realize cable local discharge position
It is accurately positioned.
Description of the drawings
Fig. 1 is realization partial discharge detecting system connection diagram in specific embodiment of the present invention.
Fig. 2 is Partial Discharge Detection structural profile illustration.
Fig. 3 is Partial Discharge Detection structural schematic diagram.
Fig. 4 is the schematic diagram of Partial Discharge Detection structure in one specific implementation mode of the utility model.
Fig. 5 is the equivalent circuit diagram of Partial Discharge Detection structure in one specific implementation mode of the utility model.
Fig. 6 is the electrical schematic diagram of Partial Discharge Detection in one specific implementation mode of the utility model.
Fig. 7 is the method flow diagram in one specific implementation mode of the utility model.
Fig. 8 is cable local discharge detection method principle schematic.
Specific implementation mode
The utility model is described in further detail with reference to the accompanying drawings and examples：
As shown in Figure 1, a kind of high-tension cable PD On-Line Measurement System, including Partial Discharge Detection structure, two inspections
Transition joint NJ is in series between the connector of geodesic structure, the metal screen layer of the both sides transition joint NJ cable is connected as one knot
Structure.
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.
By modulation-demodulation, it can realize that the teletransmission of signal, anti-stop signal decay in transmission process.In the present embodiment,
The frequency range of the detection of Partial Discharge Detection structure is 1MHz -300MHz.
In Fig. 1, 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.
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.
Such as Fig. 2 to Fig. 6, high-tension cable Partial Discharge Detection structure here, including the first cable 1 and the second cable 2, the
One 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 first
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 5
Between be electrically connected with detection impedance 6.
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.
If Fig. 2 to Fig. 6, Rc are the characteristic impedances of cable；C is the capacitance between conducting wire core wire and capacitance sensor copper foil；Cs
It is the stray capacitance of capacity coupler and metallic shield interlayer；Rs is the resistance between capacity coupler copper foil and shielded layer；Rf
It is the input impedance of measuring unit；C1 is the capacitance between the first metal foil 4 and cable；C2 be the first metal foil 4 and cable it
Between capacitance.
Capacitance is constituted between copper foil and cable core, and the detection impedance in 50 Europe is connected between two copper foil outputs.Detection resistance
Anti- to be just collected into the signal that Partial discharge signal acquires on two built-in capacitance sensors, this signal passes through differential amplification, turns through A/D
It changes the processing of input computer or input oscillograph is shown.The study found that Partial discharge signal frequency spectrum is in 1MHz-300MHz ranges
Interior, centre frequency is in 10MHz-20MHz, to-noise ratio highest.The measure loop of calculus of finite differences is similar to differential balance circuit, comes from
The noise signal of wire stylet, 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, so external noise will not enter amplifier by signal input part, this is just more
Site environment noise is inhibited well.
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：
Its value tends to 0 (11)
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-ντm (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- ν 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 (3)
1. a kind of high-tension cable PD On-Line Measurement System, it is characterized in that：Including high-tension cable Partial Discharge Detection structure；
It is in series with transition joint between the connector of two detection structures；The metal screen layer of transition joint both sides cable is connected as
Integral structure；
First group of detection structure is connect with the first signal receiving device；The near joints of first group of detection structure are provided with first day
Line；The first antenna is connect with first signal receiving device；First signal receiving device and the first frequency-selecting are amplified
Device connects；The first frequency-selecting amplifying device is connect by four road signal outputs with the first modulator；First modulator
It is connected with the first demodulator by optical fiber；First demodulator is provided with four road signals outputs, wherein two paths of signals output with
First Noise gate connects, and another two paths of signals output is connect with the second Noise gate；First Noise gate continues door with first and connect；
Second Noise gate is connect with NJ；Described NJ continues door with second and connect；
Second group of detection structure is connect with second signal reception device；The near joints of second group of detection structure are provided with second day
Line；Second antenna is connect with the second signal reception device；The second signal reception device is amplified with the second frequency-selecting
Device connects；The second frequency-selecting amplifying device is connect by four road signal outputs with the second modulator；Second modulator
It is connected with the second demodulator by optical fiber；Second demodulator is provided with four road signals outputs, wherein two paths of signals output with
Third Noise gate connects, and another two paths of signals output is connect with the 4th Noise gate；The third Noise gate is connect with described NJ；Institute
It states the 4th Noise gate and continues door with third and connect；
Described first, which continues door, the second lasting door and third, continues the signal transmission of door to computer.
2. high-tension cable PD On-Line Measurement System as described in claim 1, it is characterized in that：Described first lasting door,
Second lasting door and third continue door and are connect with third signal receiving device；The third signal receiving device connects with selecting switch
It connects；The selecting switch is connected with A/D switches；The A/D switches are connect with computer.
3. high-tension cable PD On-Line Measurement System as described in claim 1, it is characterized in that：Including the first cable (1)
With the second cable (2)；First cable (1) and the second cable (2) are connected by connector (3)；First cable (1) is close
The outer surface of external screen layer is provided with the first metal foil (4) at the connector (3)；Second cable (2) is close to the connector (3)
The outer surface of place's external screen layer is provided with the second metal foil (5)；It is electrically connected between first metal foil (4) and the second metal foil (5)
It is connected to detection impedance (6)；
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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