CN109188214B - A kind of simulation of EP rubbers cable terminal insulation layer typical fault and test method - Google Patents
A kind of simulation of EP rubbers cable terminal insulation layer typical fault and test method Download PDFInfo
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- CN109188214B CN109188214B CN201810958192.5A CN201810958192A CN109188214B CN 109188214 B CN109188214 B CN 109188214B CN 201810958192 A CN201810958192 A CN 201810958192A CN 109188214 B CN109188214 B CN 109188214B
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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
- G01R31/1227—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 of components, parts or materials
- G01R31/1263—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 of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—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 of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
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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
- G01R31/003—Environmental or reliability tests
-
- 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
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/083—Locating faults in cables, transmission lines, or networks according to type of conductors in cables, e.g. underground
Abstract
The invention discloses a kind of simulation of EP rubbers cable terminal insulation layer typical fault and test methods, the fault simulation terminal enclosure of simulator is in cold-contraction type external shed, the end of the cable core plug at both ends protrudes from cold-contraction type external shed, copper is grounded one end and is connected to metallic shield set, the other end is connected to copper interface of the ground wire, waveform acquisition equipment is connected to pulse coupler, and pulse coupler is sleeved on copper ground line.Assessment method includes obtaining the standard discharge waveform of EP rubbers cable termination, digital simulation curve model, calculating wavy curve drift rate and judge after the factor progress Test and analysis.The invention has the benefit that the typical defect failure of EP rubbers cable terminal insulation really, can be simulated effectively and conveniently, and simulation while multiclass failure may be implemented, realizes multidimensional simulation；Assessment method can identify fault type, and comprehensive and accurate assessment is realized to terminating insulation state.
Description
Technical field
The invention belongs to high-speed railway motor-car cable termination failure assessment fields, and in particular to a kind of EP rubbers cable is whole
Hold the simulation of insulating layer typical fault and test method.
Background technique
With the continuous progress and the fast development of high-speed railway of China railways electrification innovation, electric locomotive and
Effect of the EMU played in railway transportation is increasing, therefore guarantees the safety of power supply system of train and system of transmitting electricity
Reliability service becomes the importance for guaranteeing safe railway operation.But due to that can frequently suffer from train travelling process
Extraneous adverse circumstances, impact load overvoltage and train turning radius are small, and the larger equal influence of mechanical stress undertakes transmission of electricity and appoints
The train EP rubbers cable of business, especially terminal region, it may appear that multiple types failure, along with terminal is in manufacturing process,
Inevitably there are suspended metal particles and surface scratching to occur, causes the fault type of cable termination more complicated, simultaneously
The shelf depreciation of generation can also weaken the normal work ability of cable significantly.Therefore, in order to guarantee the safe operation of train, answer and
When and accurately judge the typical fault type occurred inside cable termination.
At present for the detection of cable termination typical defect failure, be all much according to the more simple and crude method such as megger into
Row, discrimination is low, and recognition effect is limited, there is an urgent need to one kind can effectively detect and identification terminal inside typical fault method.
Summary of the invention
The object of the present invention is to provide a kind of simulation of EP rubbers cable terminal insulation layer typical fault and test methods.
Realize that the technical solution of the object of the invention is as follows:
A kind of simulation of EP rubbers cable terminal insulation layer typical fault and test method, including simulation below and test
Step:
Step 1: the assembling of EP rubbers cable termination typical fault simulator；
1.1 fault simulators include fault simulation terminal；The fault simulation terminal includes from inside to outside in concentric circles
The inner copper core (11) of structure, the first semi-conductive layer (12), ethylene propylene rubber insulated layer (13), the second semi-conductive layer (14), fastening
Restrictive coating (15)；The upper/lower terminal of inner copper core (11) is also respectively connected cable core plug (1), and cable core plug (1) is coated with end
Mouth insulation sleeve (4), wherein the port isolation set outside of lower end is also wrapped on metallic shield set (19)；Fastening sheath layer (15) it is upper
Portion is additionally provided with a set of above U-shaped fastener mutually fastened, and the lower part of fastening sheath layer (15) is also wrapped on copper mesh layers (16),
Copper mesh layers (16) are connected to metallic shield set (19)；The fault simulation terminal enclosure is interior in cold-contraction type external shed (3), both ends
The end of cable core plug protrudes from cold-contraction type external shed (3), and is set with fastening rubber plug；
1.2 fault simulators further include copper ground line (20), and copper ground line (20) one end is connected to metallic shield
It covers (19), the other end is connected to copper interface of the ground wire (22)；
1.3 fault simulators further include waveform acquisition equipment (23), and waveform acquisition equipment (23) is connected to pulse-couple
Device (21), pulse coupler (21) are sleeved on copper ground line (20)；
Step 2: the processing of the fault simulation terminal of typical fault simulator；
2.1 prepare completely new EP rubbers cable fault simulation terminal, do one at its ethylene propylene rubber insulated layer (13)
Above to scratch trace, scratch depth is 0.5mm~1.0mm, obtains the fault simulation terminal of insulating surface void defects failure；
2.2 prepare completely new EP rubbers cable fault simulation terminal, carry out aging to its ethylene propylene rubber insulated layer (13)
Temperature is 120 DEG C~150 DEG C, and ageing time is the degradation treatment of 1.0h~10h, obtains the event of ethylene propylene rubber insulated degradation failure
Barrier simulation terminal；
2.3 prepare completely new EP rubbers cable fault simulation terminal, in its ethylene propylene rubber insulated layer (13) and the second half
Conductive copper adhesive tape block is added between conductive layer (14) and the second semi-conductive layer (14) and external fastening sheath layer (15) respectively,
Obtain the fault simulation terminal of internal floating potential failure；
2.4 prepare completely new EP rubbers cable fault simulation terminal, in its ethylene propylene rubber insulated layer (13) and the second half
Addition immersion cotton thread, obtains interior layer between conductive layer (14) and the second semi-conductive layer (14) and external fastening sheath layer (15)
Between make moist failure fault simulation terminal；
Step 3: the test of different EP rubbers cable termination typical fault simulators；
Terminal is simulated for typical fault obtained in step 2, is assembled respectively according to step 1, obtains different second
Third rubber cable terminal typical fault simulator, tests the fault simulator, comprising the following steps:
3.1: the shielded layer of EP rubbers cable termination to be tested and assessed is passed through into copper ground connection, waveform acquisition equipment
It is connected to pulse coupler, pulse coupler is sleeved on copper ground line；25kV voltage is applied to EP rubbers cable termination,
It tests at intervals of two minutes and draws the discharge waveform curve in a sinusoidal cycles；After after many tests, it is most to choose the frequency of occurrences
Discharge pulse waveform as standard discharge waveform f (t)；
3.2: calculating waveform parameter, comprising:
3.2.1: utilizing waveform acquisition equipment (23), standard discharge waveform f (t) medium wave peak number N is determined, according to wave crest
Number extracts the coordinate of N number of wave crest point in standard discharge waveform f (t), is denoted as P respectively1、P2、P3……PN；
3.2.2: determine standard discharge waveform curve model F (t), firstly, parameter calculating is carried out according to N number of peak point, it is N number of
The coordinate of peak point is expressed as P1(tp1, Ip1), P2(tp2, Ip2) ... ..., PN(tpN, IpN), it is bent to obtain characterization discharge waveform
The damped oscillation parameter alpha of line F (t), and the form parameter β of characterization discharge waveform curve F (t) are as follows:
In formula,Indicate the rise time of each peak value；I0Indicate the width of initial time discharge waveform
Value, i.e. P1Ordinate value, I0=Ip1；Wherein, when to α and β solution, since there are exponential types and logarithmic to close in relational expression
System, therefore when determining the value, in the way of symbolic algebra solving equations in MATLAB software, and take least square method
Principle carries out approximate solution to α and β value；
Then, the curve model equation F (t) of standard discharge waveform is obtained are as follows:
In formula, I0Indicate the amplitude of initial time discharge waveform, i.e. P1Ordinate value, I0=Ip1；t0When indicating initial
It carves, i.e. P1Abscissa value, t0=tp1；The approximation of damped oscillation parameter and form parameter that α and β have respectively been solved；
3.2.3: calculating wavy curve drift rate and judge factors AXSize:
Firstly, determining the maximum of points P of the curve model equation F (t) of standard discharge waveformmax(tpmax, Ipmax), it determines former
It is then as follows: when the curve model equation F (t) of standard discharge waveform is in coordinate Pi(ti, Ii) when meeting following relationship,
Then have, in formula, there are tpmax=ti, Ipmax=Ii；
Then, the curve model equation F (t) of the standard discharge waveform obtained to above-mentioned fitting optimizes processing, as follows:
In formula, h#It (t) is the curve model equation F (t) of standard discharge waveform after optimization, expression takes ordinate IpmaxIt is exhausted
To value；
Utilize fitting formula h after optimization#(t) initial decision factors A is carried outpAnd AtCalculating, with coordinate Pmax(tpmax, Ipmax)
As separation, calculate as follows:
In formula, ApAnd AtThe curve model equation F (t) of signature criteria discharge waveform occupies sky in left and right side respectively
Between, AXCharacterize the drift rate of matched curve F (t)；
Further, further comprising the steps of:
Step 4: comparison curves drift rate judges factors AXSize, if AX=1.0, then cable termination to be tested and assessed is normal
Otherwise state continues determination step 2；
Step 5: the judgement of waveform main energetic distributed areas is carried out according to the Energy distribution of standard discharge waveform f (t), really
Determine dominant frequency recognition factor zfX:
Fourier decomposition is carried out to f (t), it is as follows to obtain corresponding frequency-domain waveform curve:
In formula, F (f) is after Fourier decomposition, and in obtained frequency domain, the distribution of standard discharge waveform is bent
Line, f are the Frequency point after decomposing, and j is the imaginary unit in decomposable process, indicate the operation for frequency
Domain mapping mode；In the frequency-domain waveform curve of acquisition, selecting frequency range 100kHz~20MHz inner curve is done
The analysis of discharge energy distributed areas in frequency domain, as follows:
In formula, f1For 100kHz, f2For 20MHz, zfXIndicate the Frequency point that discharge energy is concentrated the most, as dominant frequency identifies
The factor；
Step 6: judging dominant frequency recognition factor zfXSize:
In AXIn the case of < 1.0, if zfX≤ 5MHz, then cable termination to be tested and assessed is that insulating layer scratches defect failure, if zfX
> 5MHz, then cable termination to be tested and assessed is insulating layer degradation failure；
In AXIn the case of > 1.0, if zfX≤ 5MHz, then cable termination to be tested and assessed is floating potential failure, if zfX> 5MHz,
Then cable termination to be tested and assessed is interlayer dampness failure.
The invention has the benefit that the typical case of EP rubbers cable terminal insulation can really, effectively and conveniently be simulated
Defect failure, and simulation while multiclass failure may be implemented, realize multidimensional simulation；Assessment method can identify failure classes
Type realizes comprehensive and accurate assessment to terminating insulation state.
Detailed description of the invention
Fig. 1 is EP rubbers cable termination typical fault simulator structure figure.
Fig. 2 is the flow chart of EP rubbers cable termination typical fault assessment method.
Specific embodiment
Below with reference to embodiment, the present invention is further illustrated.
Fig. 1 is high-speed rail train EP rubbers cable termination fault simulation schematic diagram, including cable core plug (1), upside are tight
Solid glue plug (2), cold-contraction type external shed (3), upside port insulation sleeve (4), the first U-shaped fastener (5), the first fastening bolt (6),
Second U-shaped fastener (7), the second fastening bolt (8), the U-shaped fastener of third (9), third fastening bolt (10), inner copper core
(11), the first semi-conductive layer (12), ethylene propylene rubber insulated layer (13), the second semi-conductive layer (14), external fastening sheath layer (15),
Exterior copper stratum reticulare (16), downside port insulation sleeve (17), downside fastening rubber plug (18), metallic shield set (19), copper ground line
(20), pulse coupler (21), copper interface of the ground wire (22), waveform acquisition equipment (23)；Inner copper core (11), the first semiconductive
Layer (12), ethylene propylene rubber insulated layer (13), the second semi-conductive layer (14), external fastening sheath layer (15) form fault simulation terminal
Part, and the laminated mode of each layer is successively in close contact, tightness degree can pass through the first U-shaped fastener (5), the first fastening bolt
(6), the second U-shaped fastener (7), the second fastening bolt (8), the U-shaped fastener of third (9), third fastening bolt (10) are adjusted
Section, can preset typical defect, different faults type in dummycable terminal between the layers；The exterior copper stratum reticulare (16)
Only downside position be closely laid in downside port insulation sleeve (17) surface, and with downside port metallic shield set (19), copper
Ground line (20), copper interface of the ground wire (22) communicate；When the fault simulation terminal part carries out fastening adjustment, it can operate simultaneously
First fastening bolt (6), the second fastening bolt (8), third fastening bolt (10), fit closely each layer.
In specific test, by layer (13) ethylene propylene rubber insulated in fault simulation terminal part, the second semiconductive
Layer (14), each layer of external fastening sheath layer (15) or the setting and processing that carry out typical defect between layers, change internal copper
Insulation system between sandwich layer (11) and external fastening sheath layer (15) realizes simulation EP rubbers cable termination typical fault mould
Quasi- function；It, can be by before lamination at ethylene propylene rubber insulated layer (13) when needing dummycable terminating insulation layer defects
Scuffing trace is done, scratch length can be determined according to specific requirement, realize the simulation of insulating surface void defects failure；When needing mould
It is 120 DEG C~150 DEG C by carrying out aging temperature to ethylene propylene rubber insulated layer (13) when quasi- terminating insulation layer entirety degradation failure
Degradation treatment realize that ageing time can be selected suitably with temperature, realize the simulation of ethylene propylene rubber insulated degradation failure；
It, can be by ethylene propylene rubber insulated layer (13) and the second semi-conductive layer when needing to carry out the simulation of floating potential failure in terminal
(14), the conductive copper adhesive tape block of addition is realized that the position of adhesive tape block, quantity can bases between external fastening sheath layer (15)
Specific requirement determines, to realize the simulation of floating potential failure；When need to simulate in terminal interlayer make moist failure when, can by
The mode of addition immersion cotton thread between ethylene propylene rubber insulated layer (13) and the second semi-conductive layer (14), external fastening sheath layer (15)
It is realized, the position for the cotton thread that soaks, length, quantity can be adjusted according to specific requirements；During fault simulation, it is not destroyed
Layer it is reusable, improve analog platform utilization rate, and can realize the simulation of five quasi-representative failures, i.e., insulating layer scratches, absolutely
Edge layer aging, floating potential, interlayer dampness failure, successively are as follows: failure 1, failure 2, failure 3, failure 4.
Fig. 2 is the flow chart of high-speed rail train EP rubbers cable termination failure assessment method, and assessment method can be to second third
The cable termination that rubber cable terminal typical fault simulator is simulated is tested and assessed, including cable termination fault simulation platform
It builds and measures, three calculating of waveform parameter, Test and analysis steps:
Step 1: the shielded layer of EP rubbers cable termination to be tested and assessed is passed through into copper ground connection, waveform acquisition
Equipment is connected to pulse coupler, and pulse coupler is sleeved on copper ground line；25kV is applied to EP rubbers cable termination
Voltage is tested at intervals of two minutes and draws the discharge waveform curve in a sinusoidal cycles；After after many tests, chooses and frequency occur
The most discharge pulse waveform of rate is as standard discharge waveform f (t)；Step 2: calculating waveform parameter, including
2.1 determine standard discharge waveform f (t) medium wave peak number N, according to wave crest number, in standard discharge waveform f (t)
The coordinate for extracting N number of wave crest point, is denoted as P respectively1、P2、P3……PN；
2.2 determine standard discharge waveform curve model F (t), firstly, carrying out parameter calculating, N number of peak according to N number of peak point
The coordinate representation of value point is P1(tp1, Ip1), P2(tp2, Ip2) ... ..., PN(tpN, IpN), obtain characterization discharge waveform curve F (t)
Damped oscillation parameter alpha, and characterization discharge waveform curve F (t) form parameter β it is as follows:
In formula,Indicate the rise time of each peak value；I0Indicate the width of initial time discharge waveform
Value, i.e. P1Ordinate value, I0=Ip1；Wherein, when to α and β solution, since there are exponential types and logarithmic to close in relational expression
System, therefore when determining the value, in the way of symbolic algebra solving equations in MATLAB software, and take least square method
Principle carries out approximate solution to α and β value；
Then, the curve model equation F (t) of standard discharge waveform is obtained are as follows:
In formula, I0Indicate the amplitude of initial time discharge waveform, i.e. P1Ordinate value, I0=Ip1；t0When indicating initial
It carves, i.e. P1Abscissa value, t0=tp1；The approximation of damped oscillation parameter and form parameter that α and β have respectively been solved；
2.3 calculating wavy curve drift rates judge factors AXSize:
Firstly, determining the maximum of points P of the curve model equation F (t) of standard discharge waveformmax(tpmax, Ipmax), it determines former
It is then as follows: when the curve model equation F (t) of standard discharge waveform is in coordinate Pi(ti, Ii) when meeting following relationship,
Then have, in formula, there are tpmax=ti, Ipmax=Ii；
Then, the curve model equation F (t) of the standard discharge waveform obtained to above-mentioned fitting optimizes processing,
In formula, h#It (t) is the curve model equation F (t) of standard discharge waveform after optimization, expression takes ordinate IpmaxIt is exhausted
To value；
Utilize fitting formula h after optimization#(t) initial decision factors A is carried outpAnd AtCalculating, with coordinate Pmax(tpmax, Ipmax)
As separation, calculate as follows:
In formula, ApAnd AtThe curve model equation F (t) of signature criteria discharge waveform occupies sky in left and right side respectively
Between, AXThe offset direction of the curve model equation F (t) of signature criteria discharge waveform；
Step 3: Test and analysis
3.1 comparison curves drift rates judge factors AXSize, if AX=1.0 cable terminations to be tested and assessed are normal, otherwise after
Continuous determination step 3.2；
3.2 carry out the judgement of waveform main energetic distributed areas according to the Energy distribution of standard discharge waveform f (t), determine
Dominant frequency recognition factor zfX:
Fourier decomposition is carried out to f (t), it is as follows to obtain corresponding frequency-domain waveform curve:
In formula, F (f) is after Fourier decomposition, and in obtained frequency domain, the distribution of standard discharge waveform is bent
Line, f are the Frequency point after decomposing, and j is the imaginary unit in decomposable process, indicate that the operation is frequency-domain transform mode；It is obtaining
Frequency-domain waveform curve in, selecting frequency range 100kHz~20MHz inner curve does discharge energy distributed areas in frequency domain
Analysis, it is as follows:
In formula, f1For 100kHz, f2For 20MHz, zfXIndicate the Frequency point that discharge energy is concentrated the most, as dominant frequency identifies
The factor；
3.3 judge dominant frequency recognition factor zfXSize:
In AXIn the case of < 1.0, if zfX≤ 5MHz, then cable termination to be tested and assessed is that insulating layer scratches defect failure, if zfX
> 5MHz, then cable termination to be tested and assessed is insulating layer degradation failure；
In AXIn the case of > 1.0, if zfX≤ 5MHz, then cable termination to be tested and assessed is floating potential failure, if zfX> 5MHz,
Then cable termination to be tested and assessed is interlayer dampness failure.
Claims (1)
1. a kind of EP rubbers cable terminal insulation layer typical fault simulation and test method, which is characterized in that including below
Simulation and testing procedure:
Step 1: the assembling of EP rubbers cable termination typical fault simulator；
1.1 fault simulators include fault simulation terminal；The fault simulation terminal includes from inside to outside in concentric structure
Inner copper core (11), the first semi-conductive layer (12), ethylene propylene rubber insulated layer (13), the second semi-conductive layer (14), fastening sheath
Layer (15)；The upper/lower terminal of inner copper core (11) is also respectively connected cable core plug (1), and it is exhausted that cable core plug (1) is coated with port
Edge set (4), wherein the port isolation set outside of lower end is also wrapped on metallic shield set (19)；The top of fastening sheath layer (15) is also
It is provided with a set of above U-shaped fastener mutually fastened, the lower part of fastening sheath layer (15) is also wrapped on copper mesh layers (16), copper mesh
Layer (16) is connected to metallic shield set (19)；The fault simulation terminal enclosure is in cold-contraction type external shed (3), the cable core at both ends
The end of plug protrudes from cold-contraction type external shed (3), and is set with fastening rubber plug；
1.2 fault simulators further include copper ground line (20), and copper ground line (20) one end is connected to metallic shield set
(19), the other end is connected to copper interface of the ground wire (22)；
1.3 fault simulators further include waveform acquisition equipment (23), and waveform acquisition equipment (23) is connected to pulse coupler
(21), pulse coupler (21) is sleeved on copper ground line (20)；
Step 2: the processing of the fault simulation terminal of typical fault simulator；
2.1 prepare completely new EP rubbers cable fault simulation terminal, do one or more at its ethylene propylene rubber insulated layer (13)
Trace is scratched, scratch depth is 0.5mm~1.0mm, obtains the fault simulation terminal of insulating surface void defects failure；
2.2 prepare completely new EP rubbers cable fault simulation terminal, carry out aging temperature to its ethylene propylene rubber insulated layer (13)
It is 120 DEG C~150 DEG C, ageing time is the degradation treatment of 1.0h~10h, obtains the failure mould of ethylene propylene rubber insulated degradation failure
Quasi- terminal；
2.3 prepare completely new EP rubbers cable fault simulation terminal, in its ethylene propylene rubber insulated layer (13) and the second semiconductive
Conductive copper adhesive tape block is added between layer (14) and the second semi-conductive layer (14) and external fastening sheath layer (15) respectively, is obtained
The fault simulation terminal of internal floating potential failure；
2.4 prepare completely new EP rubbers cable fault simulation terminal, in its ethylene propylene rubber insulated layer (13) and the second semiconductive
Addition is soaked cotton thread between layer (14) and the second semi-conductive layer (14) and external fastening sheath layer (15), obtain internal interlayer by
The fault simulation terminal of damp failure；
Step 3: the test of different EP rubbers cable termination typical fault simulators；
Terminal is simulated for typical fault obtained in step 2, is assembled respectively according to step 1, obtains different the third rubbers of second
Glue cable termination typical fault simulator, tests the fault simulator, comprising the following steps:
3.1: the shielded layer of EP rubbers cable termination to be tested and assessed is passed through into copper ground connection, the connection of waveform acquisition equipment
To pulse coupler, pulse coupler is sleeved on copper ground line；25kV voltage is applied to EP rubbers cable termination, every
It tests and draws the discharge waveform curve in a sinusoidal cycles within 2 minutes；After after many tests, the selection frequency of occurrences is most to be put
Electric pulse waveform is as standard discharge waveform f (t)；
3.2: calculating waveform parameter, comprising:
3.2.1: utilizing waveform acquisition equipment (23), determine standard discharge waveform f (t) medium wave peak number N, according to wave crest
Number, the coordinate of N number of wave crest point is extracted in standard discharge waveform f (t), is denoted as P respectively1、P2、P3……PN；
3.2.2: standard discharge waveform curve model F (t) is determined, firstly, carrying out parameter calculating, N number of peak value according to N number of peak point
The coordinate of point is expressed as P1(tp1, Ip1), P2(tp2, Ip2) ... ..., PN(tpN, IpN), obtain characterization discharge waveform curve F
(t) damped oscillation parameter alpha, and the form parameter β of characterization discharge waveform curve F (t) are as follows:
In formula,Indicate the rise time of each peak value；I0Indicate the amplitude of initial time discharge waveform, i.e. P1
Ordinate value, I0=Ip1；Wherein, when to α and β solution, due in relational expression there are exponential type and logarithmic relationship,
When determining numerical value, in the way of symbolic algebra solving equations in MATLAB software, and the principle of least square method is taken, it is right
α and β value carry out approximate solution；Then, the curve model equation F (t) of standard discharge waveform is obtained are as follows:
In formula, I0Indicate the amplitude of initial time discharge waveform, i.e. P1Ordinate value, I0=Ip1；t0Indicate initial time, i.e. P1
Abscissa value, t0=tp1；The approximation of damped oscillation parameter and form parameter that α and β have respectively been solved；
3.2.3: calculating wavy curve drift rate and judge factors AXSize:
Firstly, determining the maximum of points P of the curve model equation F (t) of standard discharge waveformmax(tpmax, Ipmax), determine principle such as
Under: when the curve model equation F (t) of standard discharge waveform is in coordinate Pi(ti, Ii) when meeting following relationship,
Then have, in formula, there are tpmax=ti, Ipmax=Ii；
Then, the curve model equation F (t) of the standard discharge waveform obtained to fitting optimizes processing, as follows:
In formula, h#It (t) is the curve model equation F (t) of standard discharge waveform after optimization, | | expression takes ordinate IpmaxIt is absolute
Value；
Utilize fitting formula h after optimization#(t) initial decision factors A is carried outpAnd AtCalculating, with coordinate Pmax(tpmax, Ipmax) conduct
Separation calculates as follows:
In formula, ApAnd AtCurve model equation F (t) the taking up space in left and right side of signature criteria discharge waveform respectively, AX
The drift rate of the curve model equation F (t) of signature criteria discharge waveform；
Step 4: comparison curves drift rate judges factors AXSize, if AX=1.0, then cable termination to be tested and assessed is normal condition,
Otherwise continue determination step 5；
Step 5: carrying out the judgement of waveform main energetic distributed areas according to the Energy distribution of standard discharge waveform f (t), determine master
Frequency recognition factor zfX:
Fourier decomposition is carried out to f (t), it is as follows to obtain corresponding frequency-domain waveform curve:
In formula, F (f) is after Fourier decomposition, and in obtained frequency domain, the distribution curve of standard discharge waveform, f is
Frequency point after decomposition, j are the imaginary unit in decomposable process, and expression operation is frequency-domain transform mode；In the frequency domain wave of acquisition
In shape curve, selecting frequency range 100kHz~20MHz inner curve does the analysis of discharge energy distributed areas in frequency domain,
It is as follows:
In formula, f1For 100kHz, f2For 20MHz, zfXIndicate the Frequency point concentrated the most of discharge energy, as dominant frequency identification because
Son；
Step 6: judging dominant frequency recognition factor zfXSize:
In AXIn the case of < 1.0, if zfX≤ 5MHz, then cable termination to be tested and assessed is that insulating layer scratches defect failure, if zfX>
5MHz, then cable termination to be tested and assessed is insulating layer degradation failure；
In AXIn the case of > 1.0, if zfX≤ 5MHz, then cable termination to be tested and assessed is floating potential failure, if zfX> 5MHz, then to
Cable termination of testing and assessing is interlayer dampness failure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810958192.5A CN109188214B (en) | 2018-08-22 | 2018-08-22 | A kind of simulation of EP rubbers cable terminal insulation layer typical fault and test method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810958192.5A CN109188214B (en) | 2018-08-22 | 2018-08-22 | A kind of simulation of EP rubbers cable terminal insulation layer typical fault and test method |
Publications (2)
| Publication Number | Publication Date |
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