CN113359080A - Fault test distance error calibration method for cable fault flash tester - Google Patents
Fault test distance error calibration method for cable fault flash tester Download PDFInfo
- Publication number
- CN113359080A CN113359080A CN202110773681.5A CN202110773681A CN113359080A CN 113359080 A CN113359080 A CN 113359080A CN 202110773681 A CN202110773681 A CN 202110773681A CN 113359080 A CN113359080 A CN 113359080A
- Authority
- CN
- China
- Prior art keywords
- fault
- cable
- distance
- point
- cable fault
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 46
- 238000012360 testing method Methods 0.000 title claims abstract description 40
- 238000004088 simulation Methods 0.000 claims abstract description 47
- 238000005259 measurement Methods 0.000 claims abstract description 33
- 230000005540 biological transmission Effects 0.000 claims description 10
- 229920003020 cross-linked polyethylene Polymers 0.000 claims description 6
- 239000004703 cross-linked polyethylene Substances 0.000 claims description 6
- 230000000630 rising effect Effects 0.000 claims description 6
- 238000004364 calculation method Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 12
- 238000011156 evaluation Methods 0.000 description 7
- 238000001514 detection method Methods 0.000 description 4
- 230000004075 alteration Effects 0.000 description 2
- 230000003750 conditioning effect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/005—Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Locating Faults (AREA)
Abstract
The invention discloses a method for calibrating a fault test distance error of a cable fault flash tester. The digital oscilloscope is used as a standard device for measuring time intervals, the calibrated cable fault flash tester is placed in a low-voltage pulse method measuring mode during calibration, a single simulation fault point is arranged on the cable fault simulation device, and the simulation fault point can be adjusted according to the nominal farthest fault testing distance of the calibrated cable fault flash tester; injecting a measuring pulse signal into the cable fault simulation device by the corrected cable fault flash detector, simultaneously recording a waveform, measuring and displaying a fault distance, and reading a time interval value delta t of an incident wave and a fault reflected wave by a digital oscilloscope; and calculating a fault distance standard value corresponding to the simulated fault point, and calculating a fault distance measurement display value error of the corrected cable fault flash detector. The invention can calibrate the accuracy of the cable fault flash tester for measuring the simulated fault distance, thereby effectively evaluating the performance of the cable fault flash tester.
Description
Technical Field
The invention relates to the field of cable fault testing, in particular to a fault testing distance error calibration method for a cable fault flash tester.
Background
With the increase of cable lines, the influence of cable faults on the power supply reliability is increasingly increased, so that the position of a cable fault point is rapidly and accurately detected, and the cable fault point has important significance for ensuring the timely repair of the cable. Power cable faults can be divided into two main categories: in the first category, short circuit, grounding or flashover breakdown is formed due to insulation damage between cable cores or between the cable cores and sheaths; secondly, broken lines or incomplete broken lines are formed due to the fact that the continuity of the cable core is damaged; hybrid faults, which have both cases, sometimes occur.
The power cable is mostly buried underground, once a fault occurs, the finding is very difficult, hours or even days are often spent, a large amount of manpower and material resources are wasted, and power failure loss which is difficult to measure is caused. The finding of the cable fault point is generally divided into two steps of rough measurement and fine measurement. The rough measurement is to judge the approximate position of a cable fault point; and the accurate measurement is to accurately position the fault point of the cable in the rough measurement range. The cable fault rough measurement method is various, such as a bridge method, a standing wave method, a pulse method, a flashover method and the like. Each method has its own applicable fault type and different test operation methods, and thus has its own characteristics. In practical application, the pulse method is widely used due to the fact that the pulse method is suitable for multiple cable fault types and simple to operate.
The cable fault flash detector is an instrument for roughly measuring the fault distance of a cable, mainly comprises a low-voltage pulse output unit, a pulse signal sampling unit, a microprocessor, a storage unit, a display unit, a communication unit and the like, and generally has a working mode of a low-voltage pulse method as shown in figure 1. The low-voltage pulse method is suitable for detecting faults such as short circuit or open circuit of the cable. When the cable testing device works, a low-voltage pulse signal is injected into one end of a cable to be tested by the flash tester, and the fault distance is calculated by detecting the time difference between the incident signal and the reflected signal.
The principle of the low-voltage pulse method is as follows:
during testing, a low voltage pulse is injected into the cable, the pulse propagates along the cable to the point of impedance mismatch, such as a short circuit point, a fault point, an intermediate junction, etc., and the pulse is reflected and transmitted back to the measurement point to be recorded by the instrument (fig. 2). The time difference Δ t between the transmitted pulse and the reflected pulse on the waveform corresponds to the time when the pulse makes a round trip with the impedance mismatch point at the measuring point, and the impedance mismatch point distance can be calculated by the following formula given the wave velocity v of the pulse in the cable.
L＝υ·△t/2
By identifying the polarity of the reflected pulse, the nature of the fault can be determined. The reflected pulse of the low resistance, short circuit fault is of opposite polarity to the transmitted pulse (fig. 2), while the reflected pulse of the open circuit fault is of the same polarity as the transmitted pulse (fig. 3).
From the above equation, the wave velocity of the pulse in the cable is critical to accurately calculate the fault distance. In the case where the wave velocity value of the cable is unclear, the measurement can be performed as follows. If the length L of the cable to be measured is known, the wave velocity in the cable can be derived from the time Δ t between the transmitted pulse and the reflected pulse at the end of the cable by the following equation:
V＝2·L/△t
for a cable fault flash tester, the accuracy of its fault tester distance needs to be calibrated (for use in the field after calibration in a laboratory or other location) to ensure that the field fault location is accurate.
At present, various cable fault flash testers are developed according to the opinion of manufacturers of electric power test instruments, and according to the standard DLT849.1-2019 part 1 of the general technical conditions of special test instruments for electric power equipment: the cable fault flash tester requires that the cable fault flash tester needs to be subjected to the evaluation work of distance measurement precision.
Chinese patent publication No. CN111579922A discloses a performance evaluation device for cable fault flash detector, which includes a CPLD control circuit, a two-way pulse driver, a two-way gating pulse generating circuit, a pulse width detection circuit, and a pulse transformer.
The chinese patent publication No. CN111579922A also provides a cable fault flash tester performance evaluation method, which adopts the above evaluation apparatus to perform the method, and includes the following steps:
the pulse transformer 6 receives incident pulses output by the cable fault flash detector 7 and sends the incident pulses to the pulse width detection circuit 4;
the pulse width detection circuit 4 detects a pulse signal, generates a trigger level and sends the trigger level to the CPLD control circuit 1;
the CPLD control circuit 1 obtains a pulse trigger signal and a pulse width signal of an incident pulse according to the trigger level detected by the pulse width detection circuit 4, outputs a pulse control signal with the same pulse width as the incident pulse and the same delay time from the edge of the pulse trigger signal, and selects and controls one path of the two-path pulse driver 2 to output the pulse control signal according to different fault types set by software;
the two-way gating pulse generating circuit 3 enables the corresponding positive polarity pulse generating circuit or negative polarity pulse generating circuit to work under the control of the pulse control signal output by the two-way pulse driver 2, and generates a reflected pulse signal with corresponding polarity;
the pulse transformer 6 performs impedance matching and polarity change on the reflected pulse signal generated by the two-way gating pulse generating circuit 3, converts the reflected pulse signal into a reflected pulse square wave signal and sends the reflected pulse square wave signal to the cable fault flash detector 7;
the flash detector 7 calculates a fault distance by detecting a reflected pulse square wave signal and compares the fault distance with a fault distance set by the cable fault flash detector performance evaluation device to calculate an error, so that the performance evaluation work of the flash detector is realized;
the CPLD control circuit 1 adjusts the voltage amplitude of the direct-current power supply 5 and outputs the voltage amplitude to the power supply end of the positive polarity pulse generating circuit or the negative polarity pulse generating circuit in the double-path gating pulse generating circuit 3 so as to adjust the waveform amplitude of the output reflected pulse;
wherein the pulse width of the reflected pulse waveform sent to the cable fault flash detector 7 by the pulse transformer 6 is consistent with the width of the pulse waveform sent by the cable fault flash detector 7.
The above prior art has the following disadvantages: the device disclosed in the patent publication CN111579922A requires a relatively complex design of a double pulse generating and conditioning circuit; the method described in CN111579922A, in which the time interval of occurrence of double pulses cannot be monitored, if the programmed time interval has an error from the actual time (i.e., the time interval has an error) due to the fact that the fault measurement distance is equal to L ═ ν · Δ t/2, the evaluation result will be affected; the wave transmission condition of the cable fault is simulated by adopting a common low-voltage circuit, and the wave transmission condition may not be consistent with the transmission condition of an actual cable (mainly a distributed parameter circuit).
Disclosure of Invention
The invention aims to solve the technical problem of calibrating the fault testing distance error of the conventional cable fault flash tester, and provides a method for calibrating the fault testing distance error of the cable fault flash tester.
Therefore, the invention adopts the following technical scheme: the method for calibrating the fault testing distance error of the cable fault flash tester adopts equipment comprising a cable fault simulation device, a digital oscilloscope and a calibrated cable fault flash tester, and comprises the following steps:
the digital oscilloscope is used as a standard device for measuring time intervals, when in calibration, the calibrated cable fault flash tester is placed in a low-voltage pulse method measuring mode, a single simulation fault point is arranged on the cable fault simulation device, or the simulation fault point is adjusted according to the nominal farthest fault testing distance of the calibrated cable fault flash tester; injecting a measuring pulse signal into the cable fault simulation device by the corrected cable fault flash detector, simultaneously recording a waveform, measuring and displaying a fault distance, and reading a time interval value delta t of an incident wave and a fault reflected wave by a digital oscilloscope; calculating a fault distance standard value corresponding to the simulated fault point according to a formula (1), and calculating a fault distance measurement display value error of the corrected cable fault flash detector according to a formula (2); the error calibration of the fault distance measurement display value is performed once under the conditions of open circuit and short circuit of a fault point;
Ls＝△t·υ/2 (1)
in the formula:
Lsrepresenting a fault distance standard value m corresponding to the simulated fault point;
the delta t represents the time interval value of incident wave and fault reflected wave measured by the digital oscilloscope, mu s;
upsilon represents a set value of medium transmission speed, m/mus;
△L＝Lx-Ls (2)
in the formula:
delta L represents the error of the fault distance measurement display value m of the corrected cable fault flash detector;
Lxthe method comprises the steps of (1) representing a fault distance measurement display value m of a corrected cable fault flash detector;
Lsand representing a fault distance standard value m corresponding to the simulated fault point.
The device disclosed in the publication number CN111579922A needs to design a relatively complex double-pulse generating and conditioning circuit, and the device can complete calibration work only by a common commercial oscilloscope and a cable fault simulation device; in the method disclosed in CN111579922A, the time interval of occurrence of double pulses cannot be monitored, and since the measured distance of the fault is equal to L ═ ν · Δ t/2, if the programmed time interval has an error from the actual time (i.e., Δ t has an error), the calibration result is affected; the invention can utilize the digital oscilloscope to monitor the waveform and determine the actual time, so that the calibration result of the distance of the fault tester has traceability; the method disclosed in the publication number CN111579922A cannot simulate the transmission characteristics of an actual fault in a cable; the invention can simulate the transmission of the cable through a cable fault simulation device or a physical cable, so that the calibration result is more reliable.
The cable fault simulation device and the digital oscilloscope adopted by the invention can accurately calibrate the fault position, and a signal source does not need to be additionally arranged to calibrate the fault testing distance of the cable fault flash tester.
Furthermore, during calibration, because the waveform of an incident pulse signal is changed after the incident pulse signal is reflected by a simulation fault point of the cable fault simulation device, when the distance between the simulation fault point and a test end (namely the output end of the calibrated cable fault flash tester) is determined, the method comprises the following steps:
1) determining a timing starting point: determining the crossing point of the rising edge of the input pulse square wave at the test end and the horizontal axis as a timing starting point t1；
2) Determining a first reflected wave: taking a waveform corresponding to the maximum or minimum peak amplitude in the reflected waveforms as a first reflected wave;
3) determining a timing end point: determining the intersection point of the rising edge of the first reflected wave and the horizontal axis as a timing end point t2；
4) Reading t by digital oscilloscope1、t2The time difference value is used as a time interval value delta t of the incident wave and the fault reflected wave, and a fault distance standard value L is obtained through calculation according to a formula (1)sReading the fault distance measurement display value L by the calibrated cable fault flash detectorxAnd calculating the error of the display value of the fault distance measurement according to the formula (2).
Further, the cable fault simulation device is calculated by the propagation speed of electric waves in the cross-linked polyethylene medium of 172 m/mu s, and is required to be respectively provided with three states of open circuit, short circuit and normal state at four distance points of 100m, 2km, 10km and 20 km.
Furthermore, the cable fault simulation device adopts a real cable with a known fault distance to replace the cable, the real cable is a 10kV cross-linked polyethylene power cable with a metal shield, two ends of the real cable are respectively provided with a terminal, and the length between the two terminals is not less than 20 m.
Further, the manufacturing method of the cable fault simulation device comprises the following steps:
in order to realize the simulation of a long-distance cable structure, a unit circuit equivalent to a small section of cable is built, then a plurality of unit circuits are connected in series, and a fault is arranged at the connection position of the unit circuits; in the unit circuit, a resistance element is erected between the analog core wire and the analog armor, and a resistor and an inductor are connected on the analog core wire in series;
the disconnection fault adopts the mode that the disconnection is directly carried out at a certain position of the unit circuit connection;
after the cable fault simulation device is manufactured, a precise oscilloscope and a function signal generator are needed to calibrate the precise distance of a simulation fault point.
Further, for a high-resistance failure, the resistance value R of the resistance elementgNot less than 100 omega; resistance R of the resistive element for low resistance and short circuit faultsg< 100 Ω or direct shorting.
The invention has the following beneficial effects: the distance between the fault testers of the cable fault flash tester is calibrated by adopting a commercial oscilloscope and a cable fault simulation device, the calibration result is traceable, the accuracy of measurement of the quantity value is ensured, and equipment required by the calibration of the conventional cable fault flash tester is simplified; calibrating incident and reflected waveforms of the cable fault flash detector by using an oscilloscope, accurately determining the initial timing point of the incident and reflected pulses, and determining the time interval of the fault waveform by using the method; and calculating the measured fault distance and comparing the actual fault distance by adopting the calibrated time interval and utilizing the transmission speed of the cable, and calibrating the fault tester distance of the cable fault flash tester.
Drawings
FIG. 1 is a schematic structural diagram of a conventional cable fault flash tester;
FIG. 2 is a schematic diagram of a conventional low resistance, short circuit fault test;
FIG. 3 is a schematic diagram of a conventional open circuit fault test;
FIG. 4 is a schematic diagram of the test distance calibration operation in the low voltage pulse method operation mode according to the embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating measurement of an open circuit fault reflection waveform time interval in an embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating short-circuit fault reflected waveform time interval measurement in accordance with an embodiment of the present invention;
FIG. 7 is a schematic diagram of a physical cable calibration operation according to an embodiment of the present invention;
FIG. 8 is an equivalent circuit diagram of a short section of cable in accordance with an embodiment of the present invention;
FIG. 9 is a schematic diagram of a simulated high resistance, low resistance, short circuit fault setup in an embodiment of the present invention;
fig. 10 is a schematic diagram of a simulated disconnection fault setup in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention relates to a method for calibrating fault testing distance errors of a cable fault flash tester, which adopts equipment comprising a cable fault simulation device (which can also be replaced by a real cable with known fault distance), a digital oscilloscope and a cable fault flash tester. The digital oscilloscope may be a general commercial oscilloscope.
Equipment for calibration
a. Cable fault simulation device
The calculation of the propagation speed of electric waves in the cross-linked polyethylene medium is 172 m/mu s, and three states of open circuit, short circuit and normal (no fault) are required to be respectively set at four distance points of 100m, 2km, 10km and 20 km. The error of the fault distance under the 4 test points is better than +/-20%.
b. Material object cable (alternative a)
One 10kV crosslinked polyethylene power cable with a metal shield is provided with two terminals at two ends, and the length between the two terminals is not less than 20 m.
c. Digital oscilloscope
The technical indexes of a common commercial oscilloscope are as follows:
time measurement error: better than +/-0.1%;
amplitude measurement error: better than +/-1%;
sampling rate: not less than 5X 108 times/s;
simulating the bandwidth: not lower than 100 MHz.
d. Cable fault flash tester.
The calibration object of the present invention.
The calibration method comprises the following specific contents:
the cable fault flash tester fault distance calibration performed by the invention is a standard device using a digital oscilloscope as time interval measurement, and the working principle of the test distance calibration is shown in fig. 4. During calibration, the calibrated flash tester is placed in a low-voltage pulse method measurement mode, a single simulation fault point is arranged on the cable fault simulation device, or the simulation fault point is adjusted according to the nominal farthest fault test distance of the calibrated cable fault flash tester; injecting a measuring pulse signal into the cable fault simulation device by the corrected cable fault flash detector, simultaneously recording a waveform, measuring and displaying a fault distance, and reading a time interval value delta t of an incident wave and a fault reflected wave by a digital oscilloscope; calculating a fault distance standard value corresponding to the simulated fault point according to a formula (1), and calculating a fault distance measurement display value error of the corrected cable fault flash detector according to a formula (2); the error calibration of the fault distance measurement display value is performed once in the open circuit and short circuit conditions of the fault point.
Ls＝△t·υ/2 (1)
In the formula:
Lsrepresenting a fault distance standard value m corresponding to the simulated fault point;
the delta t represents the time interval value of incident wave and fault reflected wave measured by the digital oscilloscope, mu s;
upsilon represents a set value of medium transmission speed, m/mus;
△L＝Lx-Ls (2)
in the formula:
delta L represents the error of the fault distance measurement display value m of the corrected cable fault flash detector;
Lxthe method comprises the steps of (1) representing a fault distance measurement display value m of a corrected cable fault flash detector;
Lsand representing a fault distance standard value m corresponding to the simulated fault point.
By the method, the fault testing distance of the cable fault flash tester can be calibrated.
The method for reading the time interval value delta t of the incident wave and the fault reflected wave by the digital oscilloscope comprises the following steps:
when the flash detector is calibrated, if the time interval between the incident pulse and the reflected pulse cannot be accurately measured, errors are brought to the fault distance test, so that it is very important to accurately determine the initial timing point of the incident pulse and the reflected pulse. And under the working mode of the low-voltage pulse method, calibrating the fault testing distance by using a digital oscilloscope. During calibration, the waveform of the incident pulse signal is changed after the incident pulse signal is reflected by a fault point of the cable fault simulation device. When the distance between the simulated fault point and the test end is determined, the following steps can be carried out:
(1) determining a timing starting point: determining the crossing point of the rising edge of the input pulse square wave at the test end and the horizontal axis as a timing starting point t1。
(2) Determining fault reflection waves: and taking the waveform corresponding to the maximum or minimum peak amplitude in the reflected waveform as a first reflected wave.
(3) Determining a timing end point: determining the intersection point of the rising edge of the first reflected wave and the horizontal axis as a timing end point t2。
(4) Reading t by digital oscilloscope1、t2Calculating the time difference value delta t according to the formula (1) to obtain a standard distance value LsReading the distance display value L by the calibrated cable fault flash detectorxAnd calculating the display value error of the corrected cable fault flash detector according to the formula (2).
As shown in fig. 5 and 6.
The invention can adopt the mode shown in fig. 7, the cable fault simulation device shown in fig. 4 is replaced by a real cable with the length of not less than 20m and an actual fault point (the fault distance is known), and the calibration steps of the rest fault testing distances are unchanged.
The manufacturing method of the cable fault simulation device comprises the following steps:
a power cable is a type of transmission line, which can be seen on an electrical model as being formed by coupling a large number of elements, such as resistance R, conductance G, capacitance C, and inductance L, which are referred to as the distribution parameters of the cable. The equivalent circuit (T-circuit) of a short section of cable is shown in fig. 8, where in fig. 8, R is the resistance per unit length, Ω/km; l is inductance of unit length, H/km; c is capacitance of unit length, F/km; g is the conductance per unit length, S/km.
In the above figure, conductance is negligible, and the remaining distribution parameters can be consulted with electrical parameter data provided by the cable manufacturer to obtain the resistance, inductance and capacitance values for each kilometer of length of a cable of a particular specification. In order to realize the simulation of the long-distance cable structure, the unit circuit can be firstly built, and then a plurality of series circuits are connected. The high-resistance, low-resistance and short-circuit fault setting of the cable can be referred to as a schematic diagram 9.
The faults are arranged at the connection position of the unit circuit, and a resistance element is erected between the simulation core wire and the simulation armor (for high-resistance faults, the resistance Rg is more than or equal to 100 omega, and for low-resistance and short-circuit faults, the resistance Rg is less than 100 omega or is directly in short circuit).
The disconnection fault setting can be directly disconnected somewhere in the cell circuit connection, as seen in the schematic diagram 10.
After the cable fault simulation device is manufactured, a precise oscilloscope and a function signal generator are needed to calibrate the precise distance of a fault point.
While the invention has been described in further detail with reference to preferred embodiments thereof, it should be emphasized that the above-described embodiments are not to be considered as limiting. After reading the above description, it will be apparent to those skilled in the art that various modifications, substitutions and alterations can be made without departing from the spirit of the invention, and all such modifications, substitutions and alterations should be considered as the scope of the invention. Accordingly, the scope of the invention should be determined from the following claims.
Claims (6)
1. The method for calibrating the fault testing distance error of the cable fault flash tester is characterized in that the equipment adopted by the method comprises a cable fault simulation device, a digital oscilloscope and a calibrated cable fault flash tester, and the method for calibrating the fault testing distance error comprises the following steps:
the digital oscilloscope is used as a standard device for measuring time intervals, when in calibration, the calibrated cable fault flash tester is placed in a low-voltage pulse method measuring mode, a single simulation fault point is arranged on the cable fault simulation device, and the simulation fault point can be adjusted according to the nominal farthest fault testing distance of the calibrated cable fault flash tester; injecting a measuring pulse signal into the cable fault simulation device by the corrected cable fault flash detector, simultaneously recording a waveform, measuring and displaying a fault distance, and reading a time interval value delta t of an incident wave and a fault reflected wave by a digital oscilloscope; calculating a fault distance standard value corresponding to the simulated fault point according to a formula (1), and calculating a fault distance measurement display value error of the corrected cable fault flash detector according to a formula (2); the error calibration of the fault distance measurement display value is performed once under the conditions of open circuit and short circuit of a fault point;
Ls＝△t·υ/2 (1)
in the formula:
Lsrepresenting a fault distance standard value m corresponding to the simulated fault point;
the delta t represents the time interval value of incident wave and fault reflected wave measured by the digital oscilloscope, mu s;
upsilon represents a set value of medium transmission speed, m/mus;
△L＝Lx-Ls (2)
in the formula:
delta L represents the error of the fault distance measurement display value m of the corrected cable fault flash detector;
Lxthe method comprises the steps of (1) representing a fault distance measurement display value m of a corrected cable fault flash detector;
Lsa fault distance standard value corresponding to the simulated fault point is represented,m。
2. the method for calibrating the fault testing distance error of the cable fault flash tester according to claim 1, wherein during calibration, since the waveform of the incident pulse signal is changed after the incident pulse signal is reflected by the simulated fault point of the cable fault simulation device, when the distance between the simulated fault point and the testing end is determined, the method is performed according to the following steps:
1) determining a timing starting point: determining the crossing point of the rising edge of the input pulse square wave at the test end and the horizontal axis as a timing starting point t1；
2) Determining a first reflected wave: taking a waveform corresponding to the maximum or minimum peak amplitude in the reflected waveforms as a first reflected wave;
3) determining a timing end point: determining the intersection point of the rising edge of the first reflected wave and the horizontal axis as a timing end point t2；
4) Reading t by digital oscilloscope1、t2The time difference value is used as a time interval value delta t of the incident wave and the fault reflected wave, and a fault distance standard value L is obtained through calculation according to a formula (1)sReading the fault distance measurement display value L by the calibrated cable fault flash detectorxAnd calculating the error of the display value of the fault distance measurement according to the formula (2).
3. The method for calibrating the error in the fault testing distance of the cable fault flash tester according to claim 1 or 2, wherein the cable fault simulation device is calculated by the propagation speed of the electric wave in the cross-linked polyethylene medium of 172m/μ s, and is required to set three states of open circuit, short circuit and normal state at four distance points of 100m, 2km, 10km and 20 km.
4. The method for calibrating the fault testing distance error of the cable fault flash tester according to claim 1 or 2, wherein the cable fault simulation device is replaced by a physical cable with a known fault distance, the physical cable is a 10kV crosslinked polyethylene power cable with a metal shield, two ends of the physical cable are respectively provided with a terminal, and the length between the two terminals is not less than 20 m.
5. The method for calibrating the fault testing distance error of the cable fault flash tester according to claim 1 or 2, wherein the method for manufacturing the cable fault simulation device is as follows:
in order to realize the simulation of a long-distance cable structure, a unit circuit equivalent to a small section of cable is built, then a plurality of unit circuits are connected in series, and a fault is arranged at the connection position of the unit circuits; in the unit circuit, a resistance element is erected between the analog core wire and the analog armor, and a resistor and an inductor are connected on the analog core wire in series;
the disconnection fault adopts the mode that the disconnection is directly carried out at a certain position of the unit circuit connection;
after the cable fault simulation device is manufactured, a precise oscilloscope and a function signal generator are needed to calibrate the precise distance of a simulation fault point.
6. The method according to claim 5, wherein the resistance R of the resistive element is the resistance of the resistive element for high resistance faultsgNot less than 100 omega; resistance R of the resistive element for low resistance and short circuit faultsg< 100 Ω or direct shorting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110773681.5A CN113359080A (en) | 2021-07-08 | 2021-07-08 | Fault test distance error calibration method for cable fault flash tester |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110773681.5A CN113359080A (en) | 2021-07-08 | 2021-07-08 | Fault test distance error calibration method for cable fault flash tester |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113359080A true CN113359080A (en) | 2021-09-07 |
Family
ID=77538614
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110773681.5A Pending CN113359080A (en) | 2021-07-08 | 2021-07-08 | Fault test distance error calibration method for cable fault flash tester |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113359080A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113990160A (en) * | 2021-12-30 | 2022-01-28 | 国网江西省电力有限公司电力科学研究院 | Modular cable simulation and fault simulation system and method |
| CN114325239A (en) * | 2021-12-30 | 2022-04-12 | 成都高斯电子技术有限公司 | Fault positioning simulation device and fault positioning precision calibration method |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101706564A (en) * | 2009-11-19 | 2010-05-12 | 国网电力科学研究院 | Cable failure flash detector calibrating device |
| CN105589014A (en) * | 2016-02-20 | 2016-05-18 | 广州启光智造技术服务股份有限公司 | Cable breakpoint lossless on-line detection system and cable breakpoint lossless on-line detection method |
| CN106443359A (en) * | 2016-11-11 | 2017-02-22 | 南京工程学院 | Short-distance cable fault ranging system and ranging method with low-voltage pulse method |
| CN108181552A (en) * | 2018-01-17 | 2018-06-19 | 武汉科技大学 | Buried cable fault detection system and its fault detection method |
| CN209373028U (en) * | 2018-10-29 | 2019-09-10 | 云南电网有限责任公司德宏供电局 | Travelling wave ranging equipment verification device and can self-test travelling wave ranging system |
| CN110940933A (en) * | 2019-12-02 | 2020-03-31 | 国网河北省电力有限公司电力科学研究院 | Comprehensive calculation method for measuring rising edge starting time of steep pulse |
| CN111693821A (en) * | 2020-06-19 | 2020-09-22 | 国网浙江省电力有限公司 | Testing method and device for traveling wave fault location device of cable-overhead mixed line |
| CN111854679A (en) * | 2020-08-20 | 2020-10-30 | 杭州瑞盟科技有限公司 | Laser ranging telescope and ranging circuit, method, equipment and medium thereof |
-
2021
- 2021-07-08 CN CN202110773681.5A patent/CN113359080A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101706564A (en) * | 2009-11-19 | 2010-05-12 | 国网电力科学研究院 | Cable failure flash detector calibrating device |
| CN105589014A (en) * | 2016-02-20 | 2016-05-18 | 广州启光智造技术服务股份有限公司 | Cable breakpoint lossless on-line detection system and cable breakpoint lossless on-line detection method |
| CN106443359A (en) * | 2016-11-11 | 2017-02-22 | 南京工程学院 | Short-distance cable fault ranging system and ranging method with low-voltage pulse method |
| CN108181552A (en) * | 2018-01-17 | 2018-06-19 | 武汉科技大学 | Buried cable fault detection system and its fault detection method |
| CN209373028U (en) * | 2018-10-29 | 2019-09-10 | 云南电网有限责任公司德宏供电局 | Travelling wave ranging equipment verification device and can self-test travelling wave ranging system |
| CN110940933A (en) * | 2019-12-02 | 2020-03-31 | 国网河北省电力有限公司电力科学研究院 | Comprehensive calculation method for measuring rising edge starting time of steep pulse |
| CN111693821A (en) * | 2020-06-19 | 2020-09-22 | 国网浙江省电力有限公司 | Testing method and device for traveling wave fault location device of cable-overhead mixed line |
| CN111854679A (en) * | 2020-08-20 | 2020-10-30 | 杭州瑞盟科技有限公司 | Laser ranging telescope and ranging circuit, method, equipment and medium thereof |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113990160A (en) * | 2021-12-30 | 2022-01-28 | 国网江西省电力有限公司电力科学研究院 | Modular cable simulation and fault simulation system and method |
| CN114325239A (en) * | 2021-12-30 | 2022-04-12 | 成都高斯电子技术有限公司 | Fault positioning simulation device and fault positioning precision calibration method |
| CN114325239B (en) * | 2021-12-30 | 2024-01-19 | 成都高斯电子技术有限公司 | Fault positioning simulation device and fault positioning precision verification method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8278936B2 (en) | Test circuits and current pulse generator for simulating an electrostatic discharge | |
| CN107015119B (en) | A kind of signal cable Circuit fault diagnosis device and method | |
| US8339141B2 (en) | Method and apparatus for locating a fault in an electrical conductor, with interference compensation | |
| CN113359080A (en) | Fault test distance error calibration method for cable fault flash tester | |
| CN103954886A (en) | Cable fault positioning simulation method using time domain reflectometry | |
| CN103336259A (en) | Detecting system and method for partial discharge detecting sensor of GIS (gas insulated switchgear) | |
| Paulter | An assessment on the accuracy of time-domain reflectometry for measuring the characteristic impedance of transmission lines | |
| US8570049B2 (en) | Method and apparatus for measuring AC shield continuity for shielded twisted pair structured datacomm cable link | |
| US5498965A (en) | Driving point reference plane time domain reflectometry method for measuring characteristic impedance | |
| JPH04305170A (en) | Method for precise measurement of impedance of transmission line | |
| CN114325239B (en) | Fault positioning simulation device and fault positioning precision verification method | |
| CN111239559A (en) | Online measurement method for equivalent discharge capacity of line fault arc | |
| Böhme et al. | Cable fault location in high voltage cables–a new solution | |
| JPH01502391A (en) | Cable failure detection device | |
| CN114371324B (en) | Method for measuring source impedance of spike signal generator | |
| CN112083237B (en) | Wide-frequency characteristic time domain measurement method and system for large-scale electrical equipment | |
| CN111239558B (en) | Online measurement method for equivalent discharge capacity of line fault arc | |
| Wild et al. | Power cable modeling for PD pulse propagation and sensitivity | |
| CN110345887B (en) | Network cable length measuring method based on TDR technology adaptive range | |
| CN112180311B (en) | Calibration and positioning method for station-area partial discharge detection | |
| Liu et al. | The propagation of partial discharge pulses in a high voltage cable | |
| Meisner et al. | Intercomparison of reference measuring systems for lightning impulses between three National Metrology Institutes | |
| CN116299112A (en) | Device, method and application for simulating and calibrating partial discharge of high-voltage cable | |
| CN118501793B (en) | Pulse measurement error evaluation method and system for full waveform inversion reconstruction | |
| Costello et al. | Distance-to-fault estimation for low-energy, high-voltage fault location in aircraft wiring |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210907 |