CN108828398B - Single-core cable partial discharge positioning method based on structural similarity algorithm - Google Patents

Single-core cable partial discharge positioning method based on structural similarity algorithm Download PDF

Info

Publication number
CN108828398B
CN108828398B CN201810198075.3A CN201810198075A CN108828398B CN 108828398 B CN108828398 B CN 108828398B CN 201810198075 A CN201810198075 A CN 201810198075A CN 108828398 B CN108828398 B CN 108828398B
Authority
CN
China
Prior art keywords
ssim
cable
source
value
algorithm
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.)
Active
Application number
CN201810198075.3A
Other languages
Chinese (zh)
Other versions
CN108828398A (en
Inventor
夏向阳
郑泷康
黄润知
赵威
刘炎
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Changsha University of Science and Technology
Original Assignee
Changsha University of Science and Technology
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Changsha University of Science and Technology filed Critical Changsha University of Science and Technology
Priority to CN201810198075.3A priority Critical patent/CN108828398B/en
Publication of CN108828398A publication Critical patent/CN108828398A/en
Application granted granted Critical
Publication of CN108828398B publication Critical patent/CN108828398B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • 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
    • G01R31/088—Aspects of digital computing
    • 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

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Testing Relating To Insulation (AREA)
  • Locating Faults (AREA)

Abstract

The invention discloses a single-core cable partial discharge positioning method based on a structural similarity algorithm, aiming at insulation faults frequently occurring in a power cable line, the cable partial discharge positioning accuracy is improved based on the structural similarity algorithm, and further the stability of a power transmission line is improved. The positioning method mainly comprises the following steps: firstly, measuring relevant experimental parameters of a cable with a specific model through off-line measurement; secondly, a PD signal is monitored in real time through a high-frequency current transformer arranged at the grounding end of the metal protective layer at the cable joint and is transmitted back to a control center for analysis; and finally, comparing the similarity of the pulse signals at two ends by using an SSIM algorithm to realize the accurate positioning of the PD source. The method can not only complete PD source positioning on line, but also effectively position the PD source close to the cable joint and the terminal, and the error of the test result is within 1m, thereby providing reliable protection action basis for subsequent fault control and clearing.

Description

Single-core cable partial discharge positioning method based on structural similarity algorithm
Technical Field
The invention relates to a single-core cable partial discharge positioning method based on a structural similarity algorithm, and belongs to the technical field of power system relay protection.
Background
With the continuous development of modern power grids, power transmission lines are increasingly regarded as an important part of the power transmission lines, cross-linked polyethylene (XLPE) power cables are widely applied to systems such as smart power grids, power plants, airplanes, rail transit, large ships and the like with excellent electrical insulation performance, and the running conditions and the insulation performance of the power cables are directly related to the stable running of the whole system. According to the design of the power cable, the service life of the power cable is generally between 15 and 20 years, but the failure rate is high at the initial stage of operation because Partial Discharge (PD) is easily caused by insulation defects existing in the cable and accessories, particularly in an urban power grid, the development process of the partial discharge in an insulation layer is accelerated due to the influence of temperature, water, organic compounds, acid, alkali, microorganisms and the like on the cable which is directly buried underground all the year round, electric branches are gradually formed, and finally permanent failure is induced, so that the shutdown and even the runaway of the whole partial system are caused. To reduce the failure rate of the cable, it is important to locate the PD source before a permanent failure occurs.
The current common positioning method comprises the following steps: an amplitude frequency diagram (AF) method, which realizes positioning by analyzing and calculating time domain and frequency domain through PD signals collected at different positions, but can only be used as a prediction means due to a fuzzy positioning result; the phase difference method, which realizes positioning according to the phase difference of incident waves and reflected waves in the frequency domain, cannot position a PD source close to a cable joint or a terminal.
The invention aims to overcome the defects of a traditional partial discharge positioning method and provides a single-core cable partial discharge positioning method based on a structural similarity algorithm. The method monitors the PD signal of the metal protective layer at the cable joint in real time, performs data analysis, and compares the similarity of pulse signals at two ends of a line by applying an SSIM algorithm, so as to realize accurate positioning of a PD source and provide a reliable protection action basis for subsequent fault control and removal.
The technical scheme adopted by the invention is as follows: measuring relevant experimental parameters of a cable with a certain specific model through off-line measurement, and laying a cushion for subsequent analysis and calculation; then, a high-frequency current transformer arranged at the grounding end of the metal sheath layer at the joint monitors a PD signal which possibly appears in real time, and transmits back the SSIM value of the pulse signal analyzed and calculated by the control center, and when the value is larger than a set threshold value, the value is judged to be an external source, otherwise, the value is judged to be an internal source; and finally, under the condition of judging as an internal source, applying SSIM algorithm comparison to accurately position the partial discharge source.
Drawings
FIG. 1 is an equivalent model of a power cable
FIG. 2 is a flow chart of PD source positioning based on SSIM algorithm
Detailed Description
The invention is further described with reference to the accompanying drawings and the detailed description.
Referring first to fig. 1, when a PD source is provided inside the cable 1, it is specified that the PD source belongs to an external source with respect to the cable joints 1 and 2 and to an internal source with respect to the cable joints 1 and 3. And a high-frequency current transformer is arranged at the grounding end of the metal sheath at each cable joint to monitor PD pulse signals in real time. In the figure, L is the length of a cable and U is the partial discharge flowing through the cable jointVoltage signal, I being current signal of cable joint earth point, IRSIs the modulus transformation value of the grounding point current of the cable joint.
Referring to fig. 2, the single-core cable partial discharge positioning method based on the structure similarity algorithm includes the following steps:
(1) measuring the transmission function A off line, calculating the step length delta t and the unit length L of the cableminPropagation delay tau and selecting appropriate data window (DataWindows, DW)
DW＝min{DW1,DW2}
Wherein
Figure BDA0001592130920000021
In the formulaCAnd τSThe propagation time delays of the wire core and the metal sheath are respectively in two modes;
(2) PD signals of the metal protective layer outside each joint are monitored in real time through a high-frequency current transformer, for example, a cable 2 section, the first pulse signals monitored by the joint 1 and the joint 2 are respectively I after signal processingRS1And I2·mThen, mixing IRS1And
Figure BDA0001592130920000022
multiplied curve waveforms x and I2·mComparing the two curve waveforms, obtaining a similarity value SSIM (x, y) of the two curve waveforms by applying an SSIM algorithm, comparing the similarity value with a set threshold value 1, and if the similarity value is larger than the threshold value 1, judging as an external source, otherwise, judging as an internal source.
Figure BDA0001592130920000023
The threshold value 1 is set between 0.7 and 0.9 for the transfer function of the cable core. The calculation formula is as follows:
Figure BDA0001592130920000024
wherein mux、μyRespectively the luminance average of the two image signals,
Figure BDA0001592130920000025
standard deviation, σ, of the image signals x and y, respectivelyxyIs the covariance of x, y, c1、c2、c3Is a very small constant that makes the denominator in the formula non-zero, and α, β, γ are the weights of the corresponding factors. The result of the SSIM algorithm is bounded: 0 < SSIM (x, y) ≦ 1, the larger the result, the higher the similarity of the two graphs, when the two graphs are identical, SSIM (x, y) ≦ 1.
(3) When it is determined as an internal source, it is necessary to further determine the position of the PD source, which is arranged in the cable 1 section, assuming a calculated length L from the splice 1, with a value LminInteger multiples of. Processing the pulse signals monitored by the joint 1 and the joint 2 to obtain I1·mAnd I3·mThen, mixing I1·mAnd
Figure BDA0001592130920000031
multiplied curve waveforms x' and I3·mAnd
Figure BDA0001592130920000032
comparing the multiplied curve waveforms y ', obtaining a similarity value SSIM (x ', y ') of the two curves by applying an SSIM algorithm, comparing the value with a set threshold value 2, and if the value is greater than the threshold value 2, taking a position corresponding to the similarity value as a reference result. If the value is less than the threshold value 2, comparing L with L, if L is greater than L, carrying out comprehensive evaluation reference result, and taking the position corresponding to the maximum value of SSIM (x ', y') as a PD source. And if L is smaller than L, re-assigning L for judgment.

Claims (2)

1. A single-core cable partial discharge positioning method based on a structure similarity algorithm is characterized by comprising the following steps: firstly, measuring related parameters of a cable with a specific model through off-line measurement;
the method specifically comprises the following steps: measuring the transmission function off line, calculating the step length delta t and the unit length L of the cableminThe propagation delay is taken as an experimental parameter, and a proper data window DW is selected,
DW＝min{DW1,DW2}
wherein the content of the first and second substances,
Figure FDA0002671031230000011
in the formulaCAnd τSRespectively representing propagation time delays of a wire core and a metal sheath under two modes, wherein L is the length of a section of cable;
secondly, PD signals are monitored in real time through a high-frequency current transformer arranged at the grounding end of the metal protective layer at each cable joint and are transmitted back to a control center for analysis; finally, comparing the similarity of the pulse signals at two ends by using an SSIM algorithm to realize the accurate positioning of the PD source, which specifically comprises the following steps:
the first pulse signals monitored by the joints at the two ends of the cable are respectively processed into IRS1And I2·mThen, mixing IRS1And
Figure FDA0002671031230000012
multiplied curve waveforms x and I2·mComparing the two curve waveforms, obtaining a similarity value SSIM (x, y) of the two curve waveforms by applying an SSIM algorithm, comparing the similarity value SSIM (x, y) with a set threshold value 1, and if the similarity value SSIM (x, y) is greater than the threshold value 1, judging as an external source, otherwise, judging as an internal source;
Figure FDA0002671031230000013
for the transfer function of the cable core, the threshold value 1 is set between 0.7 and 0.9, and the calculation formula is as follows:
Figure FDA0002671031230000014
wherein mux、μyRespectively, the luminance average values of the curve waveform x and the curve waveform y,
Figure FDA0002671031230000015
standard deviation, σ, of the curve waveform x and the curve waveform y, respectivelyxyIs the covariance of the curve waveform x, the curve waveform y, c1、c2Is a constant that makes the denominator in the formula non-zero; the result of the SSIM algorithm isThe following boundary: 0 < SSIM (x, y) is less than or equal to 1, the larger the result is, the higher the similarity of the two curve waveforms is, and when the two curve waveforms are identical, SSIM (x, y) is 1;
when the internal source is judged, the position of the PD source needs to be further determined, the PD source is supposed to be arranged in the cable 1 section, joints at two ends of the cable 1 section are respectively a joint 1 and a joint 3, the PD source has a calculated length L away from the joint 1, and the calculated length L is the value of LminIntegral multiple of the first time, and processing the pulse signals monitored by the joint 1 and the joint 3 to obtain I1·mAnd I3·mThen, mixing I1·mAnd
Figure FDA0002671031230000016
multiplied curve waveforms x' and I3·mAnd
Figure FDA0002671031230000017
comparing the multiplied curve waveforms y ', obtaining a similarity value SSIM (x ', y ') of the two by applying an SSIM algorithm, comparing the similarity value SSIM (x ', y ') with a set threshold value 2, if the similarity value SSIM (x ', y ') is larger than the threshold value 2, using a position corresponding to the similarity value SSIM (x ', y ') as a reference result, if the similarity value SSIM (x ', y ') is smaller than the threshold value 2, comparing L with L, if L is larger than L, carrying out comprehensive evaluation on the reference result, taking a position corresponding to the maximum value of the SSIM (x ', y ') as a PD source, and if L is smaller than L, re-assigning L for judgment.
2. The single-core cable partial discharge positioning method based on the structural similarity algorithm is characterized in that the method adopts a modular design and mainly comprises the following three parts: the device comprises an offline measuring module, a primary positioning module and an accurate positioning module; the off-line measuring module measures relevant experimental parameters of a cable with a specific model and lays a cushion for subsequent analysis and calculation; the primary positioning module monitors possible PD signals in real time through a high-frequency current transformer installed at a grounding end of a metal sheath at a joint, and transmits back a value obtained by analyzing and calculating a pulse signal from an SSIM algorithm by a control center, and when the value is greater than a set threshold value 1, the value is judged as an external source, otherwise, the value is judged as an internal source; and under the condition of judging as an internal source, accurately positioning the partial discharge source by comparing the partial discharge source with the SSIM algorithm.
CN201810198075.3A 2018-03-09 2018-03-09 Single-core cable partial discharge positioning method based on structural similarity algorithm Active CN108828398B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810198075.3A CN108828398B (en) 2018-03-09 2018-03-09 Single-core cable partial discharge positioning method based on structural similarity algorithm

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810198075.3A CN108828398B (en) 2018-03-09 2018-03-09 Single-core cable partial discharge positioning method based on structural similarity algorithm

Publications (2)

Publication Number Publication Date
CN108828398A CN108828398A (en) 2018-11-16
CN108828398B true CN108828398B (en) 2020-11-06

Family

ID=64154079

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810198075.3A Active CN108828398B (en) 2018-03-09 2018-03-09 Single-core cable partial discharge positioning method based on structural similarity algorithm

Country Status (1)

Country Link
CN (1) CN108828398B (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112540269A (en) * 2020-12-04 2021-03-23 广东电网有限责任公司 Method for improving local discharge positioning accuracy of distribution cable
CN113759224B (en) * 2021-11-08 2022-03-22 广东电网有限责任公司惠州供电局 Cable terminal head discharge sensing measurement and control circuit, device and cable distribution box
CN114065825B (en) * 2022-01-17 2022-04-19 北京航空航天大学杭州创新研究院 Brain magnetic MEG source positioning method based on structural similarity

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102221665A (en) * 2011-03-21 2011-10-19 江苏省电力公司无锡供电公司 Power cable partial discharge detection contrast method
WO2016156875A1 (en) * 2015-04-01 2016-10-06 High Voltage Partial Discharge Limited Apparatus and method for monitoring partial discharge
CN106353648A (en) * 2016-08-30 2017-01-25 浙江新图维电子科技有限公司 Comprehensive partial discharge monitoring device and method
CN106526440A (en) * 2016-12-29 2017-03-22 重庆奥海辉龙大数据有限公司 Cable partial discharge monitoring system and method
CN206038828U (en) * 2016-08-30 2017-03-22 浙江新图维电子科技有限公司 Monitoring devices is put in combined office

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102221665A (en) * 2011-03-21 2011-10-19 江苏省电力公司无锡供电公司 Power cable partial discharge detection contrast method
WO2016156875A1 (en) * 2015-04-01 2016-10-06 High Voltage Partial Discharge Limited Apparatus and method for monitoring partial discharge
CN106353648A (en) * 2016-08-30 2017-01-25 浙江新图维电子科技有限公司 Comprehensive partial discharge monitoring device and method
CN206038828U (en) * 2016-08-30 2017-03-22 浙江新图维电子科技有限公司 Monitoring devices is put in combined office
CN106526440A (en) * 2016-12-29 2017-03-22 重庆奥海辉龙大数据有限公司 Cable partial discharge monitoring system and method

Also Published As

Publication number Publication date
CN108828398A (en) 2018-11-16

Similar Documents

Publication Publication Date Title
CN108828398B (en) Single-core cable partial discharge positioning method based on structural similarity algorithm
EP2518521B1 (en) System and device for detecting defects in underground cables
EP3896468B1 (en) Platform for testing leakage current difference factor of aged xlpe cable, and method
US20200166559A1 (en) Method, device and system for determining the fault position of a fault on a line of an electrical power supply network
Nanayakkara et al. Fault location in extra long HVDC transmission lines using continuous wavelet transform
CN111433616B (en) Parametric traveling wave based fault location for power transmission lines
CN112067946A (en) Cable sheath fault monitoring device and method for broadcasting synchronous signals by multiple Rogowski coils
CN114217164B (en) Cable fault distance measurement method and system based on discharge waveform intelligent identification
CN111929532A (en) 10kV distribution cable intermediate joint positioning method
CN105223293A (en) Based on the transformer state method for early warning of oil chromatography on-line monitoring
CN114675145B (en) High-frequency partial discharge double-end monitoring partial discharge source positioning method for high-voltage cable
CN114384382B (en) Online monitoring method for insulation state of cable for transformer substation
Sallem et al. Self-adaptive correlation method for soft defect detection in cable by reflectometry
CN109596935A (en) A kind of transmission line malfunction traveling wave method of combined magnetic field energy decay characteristics
CN113805007A (en) High-voltage cable health state online monitoring system and monitoring method thereof
CN117310374A (en) Distance measurement method for submarine cable faults
CN115128403B (en) Online signal measurement method for power cable
US20050212524A1 (en) Electric power line on-line diagnostic method
Mao et al. Research on power penetration cable line fault location based on distributed traveling wave location technology
Tian et al. Accurate fault location of hybrid lines in distribution networks
CN112462195A (en) Small current fault positioning method based on fault characteristic value
CN115356588B (en) GIL fault transient ground potential rising waveform characteristic moment extraction method, system and medium
CN114285007B (en) Pilot protection method, pilot protection system, storage medium and computing equipment
Lewin et al. Condition monitoring of power cables
CN117538796B (en) XLPE cable open circuit and short circuit fault identification method based on impedance spectrum resonance peak value counting

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
GR01 Patent grant
GR01 Patent grant