CN112034307A - Cable early fault detection method based on stationary wavelet transform and symmetric component method - Google Patents

Cable early fault detection method based on stationary wavelet transform and symmetric component method Download PDF

Info

Publication number
CN112034307A
CN112034307A CN202010921225.6A CN202010921225A CN112034307A CN 112034307 A CN112034307 A CN 112034307A CN 202010921225 A CN202010921225 A CN 202010921225A CN 112034307 A CN112034307 A CN 112034307A
Authority
CN
China
Prior art keywords
value
voltage
current
component
zero sequence
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
Application number
CN202010921225.6A
Other languages
Chinese (zh)
Inventor
瞿科
张文海
楚恬歆
肖先勇
陈琳
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.)
Sichuan University
Original Assignee
Sichuan University
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 Sichuan University filed Critical Sichuan University
Priority to CN202010921225.6A priority Critical patent/CN112034307A/en
Publication of CN112034307A publication Critical patent/CN112034307A/en
Pending legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08Locating faults in cables, transmission lines, or networks
    • G01R31/088Aspects of digital computing
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/02Measuring effective values, i.e. root-mean-square values
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R29/00Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
    • G01R29/16Measuring asymmetry of polyphase networks
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04SSYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52Outage or fault management, e.g. fault detection or location

Abstract

The invention discloses a cable early fault detection method based on stationary wavelet transform and a symmetric component method, which comprises the steps of reconstructing through discrete stationary wavelet transform to obtain a voltage fundamental frequency component and a current fundamental frequency component, calculating a zero-sequence current root mean square value, obtaining preliminary fault judgment according to a threshold value of the zero-sequence current root mean square value, calculating the zero-sequence voltage root mean square value, preliminarily eliminating three-phase symmetric faults, capacitor switching, large motor starting and load switching interference in a power distribution network through 0.1 time of rated phase voltage, limiting fault duration, further eliminating other interference and finally accurately obtaining the early fault.

Description

Cable early fault detection method based on stationary wavelet transform and symmetric component method
Technical Field
The invention relates to the field of power line control, in particular to a cable early fault detection method based on stationary wavelet transformation and a symmetric component method.
Background
Most of distribution networks in China operate in a neutral point ungrounded mode, and under the condition, when an early cable fault occurs, the phase current amplitude of the fault is not obviously changed, so that the early cable fault is difficult to detect and a feeder line with the early cable fault is difficult to determine.
There are currently studies on detecting and identifying early faults of cables, which can be mainly divided into signal processing-based and machine learning-based methods. Because the number of samples of early cable faults in an actual power distribution network is small, a large number of simulation samples need to be obtained by means of simulation software and used as training samples of a machine learning method. But the simulation sample is different from the actual situation, and the practicability of the simulation sample needs to be further verified.
Disclosure of Invention
Aiming at the defects in the prior art, the cable early fault detection method based on the stable wavelet transform and the symmetric component method solves the problem of cable early fault detection of a system that a neutral point is grounded through a small resistor and the neutral point is not grounded.
In order to achieve the purpose of the invention, the invention adopts the technical scheme that: a cable early fault detection method based on stationary wavelet transform and a symmetric component method comprises the following steps:
s1, collecting three-phase voltage signals and current signals in the transformer substation;
s2, carrying out discrete stationary wavelet transformation on the three-phase voltage signals and the three-phase current signals, and reconstructing to obtain voltage fundamental frequency components and current fundamental frequency components;
s3, calculating a zero sequence current root mean square value according to the current fundamental frequency component and a symmetrical component method;
s4, judging whether the maximum value of the root mean square value of the zero sequence current is larger than the zero sequence current threshold value, if so, jumping to a step S5, if not, judging that the fault is not an early fault, and jumping to a step S1;
s5, calculating zero sequence voltage for the voltage fundamental frequency component by adopting a symmetrical component method;
s6, calculating a zero sequence voltage root mean square value through half-wave RMS point-by-point sliding according to the zero sequence voltage;
s7, judging whether the maximum value of the root mean square value of the zero sequence voltage is larger than 0.1U, if so, jumping to a step S8, if not, judging that the zero sequence voltage is not an early fault, and jumping to a step S1, wherein U is a rated phase voltage;
s8, counting that the root mean square value of zero sequence voltage is more than 0.1VmaxIs recorded as the duration, wherein VmaxIs the maximum value of the zero sequence voltage;
and S9, judging whether the duration time is within the duration time interval, if so, judging the fault to be an early fault, if not, judging the fault to be not an early fault, and jumping to the step S1.
Further, the expressions of the voltage fundamental frequency component and the current fundamental frequency component reconstructed in step S2 are:
Va_cJ+1=HJVa_cJ
Va_dJ+1=GJVa_cJ
Vb_cJ+1=HJVb_cJ
Vb_dJ+1=GJVb_cJ
Vc_cJ+1=HJVc_cJ
Vc_dJ+1=GJVc_cJ
Ia_cJ+1=HJIa_cJ
Ia_dJ+1=GJIa_cJ
Ib_cJ+1=HJIb_cJ
Ib_dJ+1=GJIb_cJ
Ic_cJ+1=HJIc_cJ
Ic_dJ+1=GJIc_cJ
wherein, VaJ,nVoltage value, Vb, of the nth sampling point of the fundamental frequency component of the A-phase voltageJ,nThe voltage value Vc of the nth sampling point of the fundamental frequency component of the B-phase voltageJ,bThe voltage value at the b-th sampling point of the fundamental frequency component of the C-phase voltage, IaJ,nCurrent value of the nth sampling point, Ib, being the fundamental component of A-phase currentJ,nCurrent value, Ic, of the nth sampling point of the fundamental component of the B-phase currentJ,nThe current value of the nth sampling point of the fundamental frequency component of the C-phase current,in order to be the first reconstruction operator,for the second reconstruction operator, Va _ cJ,nApproximating the nth value of the coefficient, Va _ d, for the fundamental frequency component of the A-phase voltageJ,nFor the nth value, Vb c, of the detail coefficient of the fundamental component of the A-phase voltageJ,nApproximating the nth value, Vb _ d, of the coefficient for the fundamental frequency component of the B-phase voltageJ,nFor the nth value, Vc _ c, of the detail coefficient of the fundamental component of the B-phase voltageJ,nApproximating the nth value of the coefficient, Vc _ d, for the fundamental frequency component of the C-phase voltageJ,nFor details of fundamental frequency components of C-phase voltageThe nth value, Ia _ cJ,nFor the nth value of the approximation coefficient for the fundamental component of the A-phase current, Ia _ dJ,nFor the nth value of the detail coefficient of the fundamental component of the A-phase current, Ib _ cJ,nFor the nth value of the B-phase current fundamental frequency component approximation coefficient, Ib _ dJ,nFor the nth value of the detail coefficient of the fundamental component of the B-phase current, Ic _ cJ,nFor the nth value of the C-phase current fundamental frequency component approximation coefficient, Ic _ dJ,nFor the nth value, H, of the detail coefficient of the fundamental component of the C-phase currentJIs a low-pass filter, GJIs a high pass filter, and J is the level of stationary wavelet transform corresponding to the fundamental frequency component.
Further, step S3 includes the steps of:
s31, calculating zero sequence current for the current fundamental frequency component by adopting a symmetrical component method;
and S32, calculating the root mean square value of the zero sequence current through half-wave RMS point-by-point sliding according to the zero sequence current.
Further, the formula for calculating the zero-sequence current in step S31 is as follows:
wherein, I0(n) is the zero sequence current of the nth sampling point, IaJ,nCurrent value of the nth sampling point, Ib, being the fundamental component of A-phase currentJ,nCurrent value of the nth sampling point, Jc, of fundamental component of B-phase currentJ,nThe current value of the nth sampling point of the fundamental frequency component of the C-phase current.
Further, the zero sequence current root mean square value calculated in step S32 is represented by the following formula:
wherein, I0(N) is the zero sequence current of the b-th sampling point, N is the number of sampling points of half cycle, I0_rmsAnd (n) is the root mean square value of the zero sequence current of the nth sampling point.
Further, the zero-sequence current threshold value in step S4 is 10A.
The beneficial effects of the above further scheme are: since the early fault of the cable is mainly represented by a single-phase earth fault, according to the symmetrical component method, when the early fault of the cable occurs, the system generates zero-sequence voltage and zero-sequence current. For a fault feeder line, the zero sequence current flowing through the monitoring point contains the zero sequence currents of other normal feeder lines, so the amplitude of the zero sequence current of the fault feeder line is larger than that of the zero sequence current of the normal feeder line. By setting a reasonable threshold, which feeder the early fault is located on can be determined.
Further, the formula for calculating the zero sequence voltage in step S5 is as follows:
wherein, V0(n) zero sequence voltage of nth sampling point, VaJ,nVoltage value, Vb, of the nth sampling point of the fundamental frequency component of the A-phase voltageJ,nThe voltage value Vc of the nth sampling point of the fundamental frequency component of the B-phase voltageJ,nThe voltage value of the nth sampling point of the fundamental frequency component of the C-phase voltage is obtained.
Further, the zero sequence voltage root mean square value calculated in step S6 is represented by the following formula:
wherein, V0(N) is the zero sequence voltage of the nth sampling point, N is the number of sampling points of half cycle, V0_rmsAnd (n) is the root mean square value of the zero sequence voltage of the nth sampling point.
Further, the duration interval is [5ms,80ms ] in step S9.
In conclusion, the beneficial effects of the invention are as follows: a cable early fault detection method based on stationary wavelet transform and a symmetric component method comprises the steps of obtaining a voltage fundamental frequency component and a current fundamental frequency component through discrete stationary wavelet transform and reconstruction, calculating a zero sequence current root mean square value, obtaining preliminary fault judgment according to a threshold value of the zero sequence current root mean square value, calculating the zero sequence voltage root mean square value, preliminarily eliminating three-phase symmetric faults, capacitor switching, large motor starting and load switching interference in a power distribution network through 0.1-time rated phase voltage, limiting fault duration, further eliminating other interference and finally accurately obtaining the early fault.
Drawings
Fig. 1 is a flow chart of a cable early fault detection method based on stationary wavelet transform and a symmetric component method.
Fig. 2 is a waveform diagram illustrating the duration of an early fault.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
As shown in fig. 1, a method for detecting early failure of a cable based on stationary wavelet transform and symmetric component method includes the following steps:
s1, collecting three-phase voltage signals and current signals in the transformer substation;
in this embodiment: the three-phase voltage signal and the current signal can be obtained through an electric energy quality device, a fault recording device and the like which are arranged in the transformer substation.
S2, carrying out discrete stationary wavelet transformation on the three-phase voltage signals and the three-phase current signals, and reconstructing to obtain voltage fundamental frequency components and current fundamental frequency components;
the expressions of the voltage fundamental frequency component and the current fundamental frequency component reconstructed in step S2 are:
Va_cJ+1=HJVa_cJ
Va_dJ+1=GJVa_cJ
Vb_cJ+1=HJVb_cJ
Vb_dJ+1=GJVb_cJ
Vc_cJ+1=HJVc_cJ
Vc_dJ+1=GJVc_cJ
Ia_cJ+1=HJIa_cJ
Ia_dJ+1=GJIa_cJ
Ib_cJ+1=HJIb_cJ
Ib_dJ+1=GJIb_cJ
Ic_cJ+1=HJIc_cJ
Ic_dJ+1=GJIc_cJ
wherein, VaJ,nVoltage value, Vb, of the nth sampling point of the fundamental frequency component of the A-phase voltageJ,nThe voltage value Vc of the nth sampling point of the fundamental frequency component of the B-phase voltageJ,nVoltage value at the nth sampling point of fundamental frequency component of C-phase voltage IaJ,nCurrent value of the nth sampling point, Ib, being the fundamental component of A-phase currentJ,nCurrent value, Ic, of the nth sampling point of the fundamental component of the B-phase currentJ,nThe current value of the nth sampling point of the fundamental frequency component of the C-phase current,in order to be the first reconstruction operator,for the second reconstruction operator, Va _ cJ,nApproximating the nth value of the coefficient, Va _ d, for the fundamental frequency component of the A-phase voltageJ,nFor the nth value, Vb c, of the detail coefficient of the fundamental component of the A-phase voltageJ,nApproximating the nth value, Vb _ d, of the coefficient for the fundamental frequency component of the B-phase voltageJ,nFor the nth value, Vc _ c, of the detail coefficient of the fundamental component of the B-phase voltageJ,nApproximating the nth value of the coefficient, Vc _ d, for the fundamental frequency component of the C-phase voltageJ,nFor the nth value of the detail coefficient of the fundamental frequency component of the C-phase voltage, Ia _ CJ,nFor the nth value of the approximation coefficient for the fundamental component of the A-phase current, Ia _ dJ,nFor the nth value of the detail coefficient of the fundamental component of the A-phase current, Ib _ cJ,nFor the nth value of the B-phase current fundamental frequency component approximation coefficient, Ib _ dJ,nFor the nth value of the detail coefficient of the fundamental component of the B-phase current, Ic _ cJ,nFor the nth value of the C-phase current fundamental frequency component approximation coefficient, Ic _ dJ,nFor the nth value, H, of the detail coefficient of the fundamental component of the C-phase currentJIs a low-pass filter, GJIs a high pass filter, and J is the level of stationary wavelet transform corresponding to the fundamental frequency component.
The three-phase voltage signals and the three-phase current signals are processed by adopting discrete stationary wavelet transform, so that the approximate coefficients and the detail coefficients obtained after the wavelet transform are consistent with the lengths of the original three-phase voltage signals and the original three-phase current signals, the defect that the lengths of wavelet coefficients of each layer are inconsistent after the ordinary discrete wavelet transform is overcome, the characteristics of translation invariance and redundancy are simultaneously realized, and the phenomenon of Gibbs oscillation caused by the fact that the wavelet base does not have the translation invariance is avoided.
S3, calculating a zero sequence current root mean square value according to the current fundamental frequency component and a symmetrical component method;
s31, calculating zero sequence current for the current fundamental frequency component by adopting a symmetrical component method;
the formula for calculating the zero-sequence current in step S31 is as follows:
wherein, I0(n) is the zero sequence current of the nth sampling point, IaJ,nCurrent value of the nth sampling point, Ib, being the fundamental component of A-phase currentJ,nCurrent value, Ic, of the nth sampling point of the fundamental component of the B-phase currentJ,nThe current value of the nth sampling point of the fundamental frequency component of the C-phase current.
And S32, calculating the root mean square value of the zero sequence current through half-wave RMS point-by-point sliding according to the zero sequence current.
The zero sequence current root mean square value calculation formula in step S32 is:
wherein, I0(N) is the zero sequence current of the nth sampling point, N is the number of sampling points of half cycle, I0_rmsAnd (n) is the root mean square value of the zero sequence current of the nth sampling point.
S4, judging whether the maximum value of the root mean square value of the zero sequence current is larger than the zero sequence current threshold value, if so, jumping to a step S5, if not, judging that the fault is not an early fault, and jumping to a step S1;
the zero-sequence current threshold value in step S4 is 10A.
When the capacitive current of a cable line is large and the capacitive zero-sequence current in a 10kV system is greater than 10A in the system operation regulation, an arc suppression coil needs to be arranged to reduce the zero-sequence current. Therefore, the invention intends to adopt 10A as the basis for determining early failure, and the threshold value can be adjusted according to actual conditions.
S5, calculating zero sequence voltage for the voltage fundamental frequency component by adopting a symmetrical component method;
the formula for calculating the zero sequence voltage in step S5 is as follows:
wherein, V0(n) zero sequence voltage of nth sampling point, VaJ,nVoltage value, Vb, of the nth sampling point of the fundamental frequency component of the A-phase voltageJ,nThe voltage value Vc of the nth sampling point of the fundamental frequency component of the B-phase voltageJ,nThe voltage value of the nth sampling point of the fundamental frequency component of the C-phase voltage is obtained.
S6, calculating a zero sequence voltage root mean square value through half-wave RMS point-by-point sliding according to the zero sequence voltage;
the zero sequence voltage root mean square value calculation formula in step S6 is:
wherein, V0(N) is the zero sequence voltage of the nth sampling point, N is the number of sampling points of half cycle, V0_rmsAnd (n) is the root mean square value of the zero sequence voltage of the nth sampling point.
S7, judging whether the maximum value of the root mean square value of the zero sequence voltage is larger than 0.1U, if so, jumping to a step S8, if not, judging that the zero sequence voltage is not an early fault, and jumping to a step S1, wherein U is a rated phase voltage;
normally, the zero sequence voltage exceeds 0.15 times of rated phase voltage, namely, single-phase earth fault occurs. In order to improve the sensitivity of early fault detection, the threshold value of the zero sequence voltage is set to be 0.1 time of the rated phase voltage. In addition, the threshold value can be adjusted according to actual conditions.
S8, counting the time that the zero sequence voltage root mean square value is larger than the threshold value, recording as the duration, selecting the threshold value of the threshold value according to the actual situation, and implementing the methodExample with 0.1VmaxWherein V ismaxIs the maximum value of the zero sequence voltage;
and S9, judging whether the duration time is within the duration time interval, if so, judging the fault to be an early fault, if not, judging the fault to be not an early fault, and jumping to the step S1.
The duration interval is [5ms,80ms ] in step S9, as shown in fig. 2.
Zero sequence voltages are also generated by asymmetric permanent faults and transformer switching in the distribution network. However, due to the intermittent and self-cleaning properties of early cable faults, the duration of the cable faults is generally 1/4-4 cycles, and the duration of the cable faults is 5-80 ms for a 50Hz power distribution network. While the duration of an asymmetric permanent fault and transformer switching can typically last tens of cycles. The influence of the disturbance can be eliminated by judging the duration time of the zero sequence voltage.

Claims (9)

1. A cable early fault detection method based on stationary wavelet transform and a symmetric component method is characterized by comprising the following steps:
s1, collecting three-phase voltage signals and current signals in the transformer substation;
s2, carrying out discrete stationary wavelet transformation on the three-phase voltage signals and the three-phase current signals, and reconstructing to obtain voltage fundamental frequency components and current fundamental frequency components;
s3, calculating a zero sequence current root mean square value according to the current fundamental frequency component and a symmetrical component method;
s4, judging whether the maximum value of the root mean square value of the zero sequence current is larger than the zero sequence current threshold value, if so, jumping to a step S5, if not, judging that the fault is not an early fault, and jumping to a step S1;
s5, calculating zero sequence voltage for the voltage fundamental frequency component by adopting a symmetrical component method;
s6, calculating a zero sequence voltage root mean square value through half-wave RMS point-by-point sliding according to the zero sequence voltage;
s7, judging whether the maximum value of the root mean square value of the zero sequence voltage is larger than 0.1U, if so, jumping to a step S8, if not, judging that the zero sequence voltage is not an early fault, and jumping to a step S1, wherein U is a rated phase voltage;
s8, counting that the root mean square value of zero sequence voltage is more than 0.1VmaxIs recorded as the duration, wherein VmaxIs the maximum value of the zero sequence voltage;
and S9, judging whether the duration time is within the duration time interval, if so, judging the fault to be an early fault, if not, judging the fault to be not an early fault, and jumping to the step S1.
2. The method for detecting the early failure of the cable based on the wavelet transform and the symmetric component method as claimed in claim 1, wherein the expressions of the voltage fundamental frequency component and the current fundamental frequency component reconstructed in the step S2 are:
Va_cJ+1=HJVa_cJ
Va_dJ+1=GJVa_cJ
Vb_cJ+1=HJVb_cJ
Vb_dJ+1=GJVb_cJ
Vc_cJ+1=HJVc_cJ
Vc_dJ+1=GJVc_cJ
Ia_cJ+1=HJIa_cJ
Ia_dJ+1=GJIa_cJ
Ib_cJ+1=HJIb_cJ
Ib_dJ+1=GJIb_cJ
Ic_cJ+1=HJIc_cJ
Ic_dJ+1=GJIc_cJ
wherein, VaJ,nVoltage value, Vb, of the nth sampling point of the fundamental frequency component of the A-phase voltageJ,nThe voltage value Vc of the nth sampling point of the fundamental frequency component of the B-phase voltageJ,nVoltage value at the nth sampling point of fundamental frequency component of C-phase voltage IaJ,nCurrent value of the nth sampling point, Ib, being the fundamental component of A-phase currentJ,nCurrent value, Ic, of the nth sampling point of the fundamental component of the B-phase currentJ,nThe current value of the nth sampling point of the fundamental frequency component of the C-phase current,in order to be the first reconstruction operator,for the second reconstruction operator, Va _ cJ,nApproximating the nth value of the coefficient, Va _ d, for the fundamental frequency component of the A-phase voltageJ,nFor the nth value, Vb c, of the detail coefficient of the fundamental component of the A-phase voltageJ,nApproximating the nth value, Vb _ d, of the coefficient for the fundamental frequency component of the B-phase voltageJ,nFor the nth value, Vc _ c, of the detail coefficient of the fundamental component of the B-phase voltageJ,nIs a C-phase voltage baseThe nth value of the frequency component approximation coefficient, Vc _ dJ,nFor the nth value of the detail coefficient of the fundamental frequency component of the C-phase voltage, Ia _ CJ,nFor the nth value of the approximation coefficient for the fundamental component of the A-phase current, Ia _ dJ,nFor the nth value of the detail coefficient of the fundamental component of the A-phase current, Ib _ cJ,nFor the nth value of the B-phase current fundamental frequency component approximation coefficient, Ib _ dJ,nFor the nth value of the detail coefficient of the fundamental component of the B-phase current, Ic _ cJ,nFor the nth value of the C-phase current fundamental frequency component approximation coefficient, Ic _ dJ,nFor the nth value, H, of the detail coefficient of the fundamental component of the C-phase currentJIs a low-pass filter, GJIs a high pass filter, and J is the level of stationary wavelet transform corresponding to the fundamental frequency component.
3. The method for detecting the early failure of the cable based on the wavelet transform of stationary wavelet and the symmetric component method as claimed in claim 1, wherein said step S3 comprises the steps of:
s31, calculating zero sequence current for the current fundamental frequency component by adopting a symmetrical component method;
and S32, calculating the root mean square value of the zero sequence current through half-wave RMS point-by-point sliding according to the zero sequence current.
4. The method for detecting the early failure of the cable based on the stationary wavelet transform and the symmetric component method as claimed in claim 3, wherein the formula for calculating the zero sequence current in the step S31 is as follows:
wherein, I0(n) is the zero sequence current of the nth sampling point, IaJ,nCurrent value of the nth sampling point, Ib, being the fundamental component of A-phase currentJ,nCurrent value of the nth sampling point, Jc, of fundamental component of B-phase currentJ,nThe current value of the nth sampling point of the fundamental frequency component of the C-phase current.
5. The method for detecting the early failure of the cable based on the stationary wavelet transform and the symmetric component method as claimed in claim 3, wherein the formula for calculating the root mean square value of the zero sequence current in the step S32 is as follows:
wherein, I0(N) is the zero sequence current of the nth sampling point, N is the number of sampling points of half cycle, I0_rmsAnd (n) is the root mean square value of the zero sequence current of the nth sampling point.
6. The method for detecting the early failure of the cable based on the stationary wavelet transform and the symmetric component method as claimed in claim 1, wherein the zero sequence current threshold value in the step S4 is 10A.
7. The method for detecting the early failure of the cable based on the stationary wavelet transform and the symmetric component method as claimed in claim 1, wherein the formula for calculating the zero sequence voltage in the step S5 is as follows:
wherein, V0(n) zero sequence voltage of nth sampling point, VaJ,nVoltage value, Vb, of the nth sampling point of the fundamental frequency component of the A-phase voltageJ,nThe voltage value Vc of the nth sampling point of the fundamental frequency component of the B-phase voltageJ,nThe voltage value of the nth sampling point of the fundamental frequency component of the C-phase voltage is obtained.
8. The method for detecting the early failure of the cable based on the stationary wavelet transform and the symmetric component method as claimed in claim 1, wherein the zero sequence voltage root mean square value calculated in the step S6 is represented by the following formula:
wherein, V0(N) is the zero sequence voltage of the b-th sampling point, N is the number of sampling points of half cycle, V0_rmsAnd (n) is the root mean square value of the zero sequence voltage of the nth sampling point.
9. The method for detecting the early failure of the cable based on the wavelet transform and the symmetric component method as claimed in claim 1, wherein the duration interval in step S9 is [5ms,80ms ].
CN202010921225.6A 2020-09-04 2020-09-04 Cable early fault detection method based on stationary wavelet transform and symmetric component method Pending CN112034307A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010921225.6A CN112034307A (en) 2020-09-04 2020-09-04 Cable early fault detection method based on stationary wavelet transform and symmetric component method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010921225.6A CN112034307A (en) 2020-09-04 2020-09-04 Cable early fault detection method based on stationary wavelet transform and symmetric component method

Publications (1)

Publication Number Publication Date
CN112034307A true CN112034307A (en) 2020-12-04

Family

ID=73591528

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010921225.6A Pending CN112034307A (en) 2020-09-04 2020-09-04 Cable early fault detection method based on stationary wavelet transform and symmetric component method

Country Status (1)

Country Link
CN (1) CN112034307A (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2009592C1 (en) * 1992-03-29 1994-03-15 Всероссийский научно-исследовательский, проектно-конструкторский и технологический институт релестроения Device for protecting generator-transformer units of power station against faults on the side of high voltage
CN103728532A (en) * 2013-12-26 2014-04-16 长园深瑞继保自动化有限公司 Power distribution network single-phase grounding fault judging and locating method
CN104779594A (en) * 2015-04-27 2015-07-15 西安热工研究院有限公司 Inter-phase short circuit and single-phase grounding comprehensive protection method for small-current grounding power system
CN110543921A (en) * 2019-10-14 2019-12-06 四川大学 cable early fault identification method based on waveform learning
CN112067948A (en) * 2020-10-14 2020-12-11 长沙理工大学 Fault line selection method, system and terminal for single-phase earth fault of power distribution network and readable storage medium
CN112415426A (en) * 2020-11-18 2021-02-26 长沙理工大学 Single-phase earth fault detection method, system, terminal and readable storage medium of small-resistance earth system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2009592C1 (en) * 1992-03-29 1994-03-15 Всероссийский научно-исследовательский, проектно-конструкторский и технологический институт релестроения Device for protecting generator-transformer units of power station against faults on the side of high voltage
CN103728532A (en) * 2013-12-26 2014-04-16 长园深瑞继保自动化有限公司 Power distribution network single-phase grounding fault judging and locating method
CN104779594A (en) * 2015-04-27 2015-07-15 西安热工研究院有限公司 Inter-phase short circuit and single-phase grounding comprehensive protection method for small-current grounding power system
CN110543921A (en) * 2019-10-14 2019-12-06 四川大学 cable early fault identification method based on waveform learning
CN112067948A (en) * 2020-10-14 2020-12-11 长沙理工大学 Fault line selection method, system and terminal for single-phase earth fault of power distribution network and readable storage medium
CN112415426A (en) * 2020-11-18 2021-02-26 长沙理工大学 Single-phase earth fault detection method, system, terminal and readable storage medium of small-resistance earth system

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
JUN MENG ET AL: "Zero-sequence voltage trajectory analysis for unbalanced distribution networks on single-line-to-ground fault condition", 《ELECTRIC POWER SYSTEMS RESEARCH》 *
任思璟: "《电力系统分析》", 31 January 2016 *
张文海: "基于故障暂态信号及其衰减特征的配网单相接地故障测距", 《电力自动化设备》 *
汪 颖: "基于优化卷积神经网络的电缆早期故障分类识别", 《电力系统保护与控制》 *
贾渭娟: "《供配电系统》", 31 August 2016 *

Similar Documents

Publication Publication Date Title
Nam et al. A modeling method of a high impedance fault in a distribution system using two series time-varying resistances in EMTP
CN103135031B (en) Coal mine high-voltage grid system insulation state monitoring method
CN108957244B (en) Single-phase earth fault line selection positioning method for distribution network main station
CN103197202A (en) Distribution network fault line selection method based on wavelet coefficient correlation analysis in three-phase breaking current component characteristic frequency band
CN107045093B (en) Low-current single-phase earth fault line selection method based on quick S-transformation
CN106970302B (en) Power distribution network high-resistance fault positioning and simulating method based on integrated empirical mode decomposition
Aslan An alternative approach to fault location on power distribution feeders with embedded remote-end power generation using artificial neural networks
CN107329044A (en) A kind of wire selection method for power distribution network single phase earthing failure based on electric arc transient state component
CN108802566B (en) Grounding line selection method based on HHT signal analysis
Li et al. Improved S Transform-Based Fault Detection Method in Voltage Source Converter Interfaced DC System
CN112034307A (en) Cable early fault detection method based on stationary wavelet transform and symmetric component method
CN109975653B (en) 10kV distribution line fault location method
CN111650470A (en) Method for rapidly and adaptively detecting and identifying faults of microgrid circuit sections
Huang et al. A Principle of Fault Line Selection Based on Increasing Zero-sequence Current in Non-ground Neutral System
CN109406949B (en) Power distribution network early fault detection method and device based on support vector machine
CN110244192B (en) Electric power overhead line ground fault distance measurement method
CN110007198B (en) Single-phase earth fault starting method
Myint et al. Fault Type Identification Method based on Wavelet Detail Coefficients of Modal Current Components
CN110045232B (en) Method for identifying ground fault phase of neutral point non-effective grounding system
CN111381129B (en) Ground fault line and type identification method and device based on ultralow frequency signal
CN212111734U (en) Grounding fault phase detection system of ITN power supply system
Liu et al. Application of fractal theory in detecting low current faults of power distribution system in coal mines
Liu A Series Arc Fault Location Method for DC Distribution System Using Time Lag of Parallel Capacitor Current Pulses
Liu et al. Single-phase Grounding Fault Line Selection Method Based on the Difference of Electric Energy Information Between the Distribution End and the Load End
CN113189439A (en) Power distribution network single-phase earth fault line selection method based on mutual difference absolute value sum

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