CN109193578A - DC power transmission line fast protection method based on wavefront Generalized Logistic Function Fitting - Google Patents

DC power transmission line fast protection method based on wavefront Generalized Logistic Function Fitting Download PDF

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Publication number
CN109193578A
CN109193578A CN201810917241.0A CN201810917241A CN109193578A CN 109193578 A CN109193578 A CN 109193578A CN 201810917241 A CN201810917241 A CN 201810917241A CN 109193578 A CN109193578 A CN 109193578A
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China
Prior art keywords
wavefront
protection
transmission line
power transmission
logistic function
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CN201810917241.0A
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CN109193578B (en
Inventor
宋国兵
张晨浩
韩伟
李程昊
刘超
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State Grid Corp of China SGCC
Xian Jiaotong University
Electric Power Research Institute of State Grid Henan Electric Power Co Ltd
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State Grid Corp of China SGCC
Xian Jiaotong University
Electric Power Research Institute of State Grid Henan Electric Power Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/265—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured making use of travelling wave theory
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Locating Faults (AREA)

Abstract

The present invention discloses a kind of DC power transmission line fast protection method based on wavefront Generalized Logistic Function Fitting, comprising the following steps: 1) measures DC power transmission line head end and protect installation place electric current, calculating current zero _exit simultaneously takes absolute value；2) wavefront before identifying, protection starting；3) to carrying out reflected wave identification in traveling wave wavefront T time section, the data window length that adaptively selected protection calculates；4) the traveling wave wavefront obtained using Generalized Logistic Function Fitting obtains the index coefficient k of natural logrithm, distinguishes internal fault external fault according to protection discrimination principles.What guard method proposed by the present invention utilized is the fault message that traveling wave wavefront includes; fault distance and transition resistance size are portrayed using the coefficient that Generalized Logistic Function Fitting obtains; with rapidity, reliability, high resistive fault, which occurs, for route distal end still can correctly be acted.

Description

DC power transmission line based on wavefront Generalized Logistic Function Fitting is quickly protected Method
Technical field
The invention belongs to field of relay protection in power, in particular to a kind of DC power transmission line fast protection method.
Background technique
Direct current transportation has many advantages, such as high-transmission capacity, flexible power control and remote transmission, at present electric system Customary DC and flexible direct current are widely used in transmission of electricity.After DC line breaks down, trouble duration is shorter More be conducive to the raising of Transmission Lines power and the enhancing of power system transient stability, wherein Zhangbei County's flexible direct current is defeated Electricity proposes the requirement of 3ms to the relay protection outlet time, and direct current transportation, which is quickly protected, becomes the emphasis studied at present.
Existing DC engineering relay protective plan is mostly provided by ABB and SIEMENS, main protection configuration traveling-wave protection and electricity Sudden Changing Rate protection is pressed, back-up protection configures under-voltage protection and longitudinal difference protection.Traveling-wave protection quick action, but there are route hairs Tripping problem when raw distal end high resistive fault.
Summary of the invention
The purpose of the present invention is to provide a kind of DC power transmission line based on wavefront Generalized Logistic Function Fitting is fast Fast guard method, to solve the above technical problems.The failure distortion step wave measured at protection measurements is known as wavefront, and wavefront includes Fault message abundant；The present invention improves the performance of existing traveling-wave protection, meets requirement of the DC line to relay protection.This hair Bright to pass through the theory analysis dispersion of fault traveling wave on the transmission line first, sum up: 1) fault traveling wave wavefront shape changes Degree is related with fault distance, and transition resistance only influences wavefront amplitude, does not influence wavefront variation degree；2) protection head end measures Thus the conclusion for the quantic that there is electric current natural exponential function to be added constructs zero mould electric current of Generalized Logistic Function Fitting Wavefront realizes the extraction of fault distance information.The starting differentiation protected and oneself are realized using the method for wavelet modulus maxima Adapt to the long selection of data window.
What guard method proposed by the present invention utilized is the fault message that traveling wave wavefront includes, and utilizes Generalized Logistic letter The coefficient that number fitting obtains portrays fault distance and transition resistance size.It is fast that simulating, verifying shows that proposed protection philosophy has Speed, reliability, high resistive fault, which occurs, for route distal end still can correctly act.
In order to achieve the above objectives, the present invention adopts the following technical scheme:
DC power transmission line fast protection method based on wavefront Generalized Logistic Function Fitting, comprising the following steps:
1) measurement DC power transmission line head end protects installation place electric current, and calculating current zero _exit simultaneously takes absolute value；
2) wavefront before identifying, protection starting；
3) to carrying out reflected wave identification in traveling wave wavefront T time section, the data window length that adaptively selected protection calculates；
4) the traveling wave wavefront obtained using Generalized Logistic Function Fitting obtains the index coefficient k of natural logrithm, according to Discrimination principles are protected to distinguish internal fault external fault.
Further, in step 1): measurement DC power transmission line route head end protects installation place electric current, is calculated as follows out Electric current zero _exit:
Wherein, Ip、In、I0、I1Anode, cathodal current and calculated zero mould, a mould for respectively installation place being protected to measure Electric current；And to electric current zero _exit I0It takes absolute value.
Further, in step 2): carrying out singularity to electric current zero _exit using the method for wavelet modulus maxima Detection carries out the identification of wave head using the result of quadratic spline wavelet scale five, when:
Wmax≥Wset (6)
Protection starting；Wherein, WmaxIt is the modulus maximum of zero mould current traveling wave as a result, threshold value WsetTake 2.5kA.
Further, in step 3): if starting element actuation time is t0, it protects and following 1ms data is sampled, Singular values standard form is carried out with 1ms data of the wavelet transformation to sampling again, if | W2max|≥W2set, back wave reaches in 1ms, Write down time t at this time1, the data window of calculating is protected to become T=t at this time1-t0If back wave is not detected in 1ms, data Window is T=1ms；Wherein, W2maxThe modulus maximum of zero mould current traveling wave is as a result, threshold value W when differentiating for second2setTake 0.5kA.
Further, in step 4): construction Generalized Logistic function:
Wherein a, b, k are coefficient to be asked；K is used to characterize the degree of traveling wave wavefront dispersion, and a, b have codetermined the width of function Value characterizes the amplitude of traveling wave wavefront, the i.e. size of transition resistance with A:
The zero mould fault current absolute value measured is protected for route head end, its fitting coefficient k is obtained and carries out protection differentiation, Protection criteria are as follows:
k≥kset=krelk0 (5)
K in formula0It is reliable to be for the fitting coefficient of the zero mould current absolute value obtained when most serious failure outside DC line area Number krel=1.16.
Compared with the existing technology, the invention has the following advantages:
What guard method proposed by the present invention utilized is the fault message that traveling wave wavefront includes, and utilizes Generalized Logistic letter The coefficient that number fitting obtains portrays fault distance and transition resistance size.It is fast that simulating, verifying shows that proposed protection philosophy has Speed, reliability, high resistive fault, which occurs, for route distal end still can correctly act.
Detailed description of the invention
Fig. 1 is the schematic diagram of ± 400kV flexible HVDC transmission system；
Fig. 2 is the fitting result before zero mould current wave；
Fig. 3 is protection result；
Fig. 4 is guard method flow chart.
Specific embodiment
The present invention will be further explained below with reference to the attached drawings:
The present invention is based on the Dispersion Analysis to fault traveling wave on the transmission line, sum up: 1) fault traveling wave wavefront shape Variation degree is related with fault distance, and transition resistance only influences wavefront amplitude, does not influence wavefront variation degree；2) protection head end is surveyed The conclusion for the quantic that there is the electric current obtained natural exponential function to be added.And DC transmission system model is built on PSCAD. Fig. 1 is ± 400kV flexible HVDC transmission system；Fig. 2 is the fitting result before zero mould current wave.It can be seen that broad sense The Logistic Function Fitting result degree of approximation is higher, and fitting coefficient can react fault distance and transition resistance information.Fig. 3 is protection As a result, Fig. 4 is protection flow chart.It can be seen that 1) identical transition resistance when, fault distance is remoter, and k is smaller；Transition resistance Increase so that A is substantially reduced；2) when direct current system breaks down, under the setting valve of protection setting, troubles inside the sample space is protected just Positive motion is made, and external area error protection is reliably failure to actuate, and for the failure of remote high transition resistance, protection remains to act.
Shown in please referring to Fig.1 to Fig.4, the present invention proposes that a kind of direct current based on wavefront Generalized Logistic Function Fitting is defeated Electric line fast protection method, comprising the following steps:
1) measurement DC power transmission line route head end protects installation place electric current, and electric current zero _exit is calculated as follows out；
Wherein, Ip、In、I0、I1Anode, cathodal current and calculated zero mould, a mould for respectively installation place being protected to measure Electric current.And to I0It takes absolute value.
2) Singularity Detection is carried out to zero mould electric current using the method for wavelet modulus maxima (WTMM), the present invention utilizes The result of quadratic spline wavelet scale five carries out the identification of wave head, and threshold value W is arrangedsetNoise jamming is avoided, when:
Wmax≥Wset (10)
Protection starting.Wherein, WmaxIt is the modulus maximum of zero mould current traveling wave as a result, threshold value W of the present inventionsetTake 2.5kA.
3) if starting element actuation time is t0, protection samples following 1ms data, again with wavelet transformation pair The 1ms data of sampling carry out singular values standard form, if | W2max|≥W2set, back wave reaches in 1ms, writes down time t at this time1, The data window that protection calculates becomes T=t at this time1-t0If back wave is not detected in 1ms, data window T=1ms.Wherein, W2maxThe modulus maximum of zero mould current traveling wave is as a result, threshold value W of the present invention when differentiating for second2setTake 0.5kA.
4) Generalized Logistic function is constructed:
Wherein a, b, k are coefficient to be asked.K is used to characterize the degree of traveling wave wavefront dispersion, and a, b have codetermined the width of function Value characterizes the amplitude of traveling wave wavefront, the i.e. size of transition resistance with A:
The zero mould fault current absolute value measured is protected for route head end, its fitting coefficient k is obtained and carries out protection differentiation, Protection criteria are as follows:
k≥kset=krelk0 (5)
K in formula0For the fitting coefficient of the zero mould current absolute value obtained when most serious failure outside DC line area, krelFor Safety factor, the present invention take 1.16.The remoter k of fault distance is smaller, external area error since there are k obviously to become smaller for boundary element, because It is troubles inside the sample space, protection act that this, which meets Protection criteria (5),.
Simulating, verifying:
The flexible HVDC transmission system of the very bipolar wiring of ± 400kV as shown in Figure 1 is built on PSCAD, converter station is Full-bridge MMC, DC line are frequency variable parameter model, and parameter is default value, line length 500km, route both ends smoothing reactor For 100mH.In simulating, verifying, sample frequency 200kHz, WsetTake 2.5kA, W2setTake 0.5kA, ksetTake 0.25；It utilizes Curve Fitting Tool carries out the fitting of Logistic function to zero mould current data of failure in Matlab, and when calculating Take the domain of zero mould current dataWherein x is zero mould current sampling data serial number.
To DC line overall length every 50km by closely to remote setting positive electrode fault, transition resistance is set as 0 Ω, 50 Ω, 100 Ω, 150 Ω, 200 Ω, and metallicity failure f is occurred with cathode 250km3For verify cathode failure.External area error is provided with just Failure f on the outside of to smoothing reactor1With failure f on the outside of reversed smoothing reactor2.Failure occurs in 1s.Table 1, table 2, table 3, table 4, Table 5 protects result when route different distance, transition resistance failure is set forth.
When can be seen that 1) identical transition resistance, fault distance is remoter, and k is smaller；The increase of transition resistance is so that A is significant Reduce；2) when direct current system breaks down, under the setting valve of protection setting, troubles inside the sample space protection is correct to be acted, event outside area Barrier protection is reliably failure to actuate, and for the failure of remote high transition resistance, protection remains to act.In conclusion the protection proposed Principle is effective.
1 route different distance error protection result (0 Ω transition resistance) of table
2 route different distance error protection result (50 Ω transition resistance) of table
3 route different distance error protection result (100 Ω transition resistance) of table
4 route different distance error protection result (150 Ω transition resistance) of table
5 route different distance error protection result (200 Ω transition resistance) of table

Claims (5)

1. the DC power transmission line fast protection method based on wavefront Generalized Logistic Function Fitting, which is characterized in that including Following steps:
1) measurement DC power transmission line head end protects installation place electric current, calculates zero mould electric current and takes absolute value；
2) wavefront before identifying, protection starting；
3) to carrying out reflected wave identification in traveling wave wavefront T time section, the data window length that adaptively selected protection calculates；
4) the traveling wave wavefront obtained using Generalized Logistic Function Fitting obtains the index coefficient k of natural logrithm, according to protection Discrimination principles distinguish internal fault external fault.
2. the quick side of protection of the DC power transmission line according to claim 1 based on wavefront Generalized Logistic Function Fitting Method, which is characterized in that in step 1): measurement DC power transmission line route head end protects installation place electric current, is calculated as follows out zero Mould electric current:
Wherein, Ip、In、I0、I1Anode, cathodal current and calculated zero mould, the mould electric current for respectively installation place being protected to measure； And to zero mould electric current I0It takes absolute value.
3. the quick side of protection of the DC power transmission line according to claim 1 based on wavefront Generalized Logistic Function Fitting Method, which is characterized in that in step 2): Singularity Detection, benefit are carried out to zero mould electric current using the method for wavelet modulus maxima The identification that wave head is carried out with the result of quadratic spline wavelet scale five, when:
Wmax≥Wset (2)
Protection starting；Wherein, WmaxIt is the modulus maximum of zero mould current traveling wave as a result, threshold value WsetTake 2.5kA.
4. the quick side of protection of the DC power transmission line according to claim 1 based on wavefront Generalized Logistic Function Fitting Method, which is characterized in that in step 3): if starting element actuation time is t0, it protects and following 1ms data is sampled, then It is secondary to carry out singular values standard form with 1ms data of the wavelet transformation to sampling, if | W2max|≥W2set, back wave reaches in 1ms, remembers Under time t at this time1, the data window of calculating is protected to become T=t at this time1-t0If back wave is not detected in 1ms, data window For T=1ms；Wherein, W2maxThe modulus maximum of zero mould current traveling wave is as a result, threshold value W when differentiating for second2setTake 0.5kA.
5. the quick side of protection of the DC power transmission line according to claim 1 based on wavefront Generalized Logistic Function Fitting Method, which is characterized in that in step 4): construction Generalized Logistic function:
Wherein a, b, k are coefficient to be asked；K is used to characterize the degree of traveling wave wavefront dispersion, and a, b have codetermined the amplitude of function, The amplitude of traveling wave wavefront, the i.e. size of transition resistance are characterized with A:
The zero mould current absolute value measured is protected for route head end, its fitting coefficient k is obtained and carries out protection differentiation, Protection criteria Are as follows:
k≥kset=krelk0 (5)
K in formula0For the fitting coefficient of the zero mould current absolute value obtained when most serious failure outside DC line area, safety factor krel =1.16.
CN201810917241.0A 2018-08-13 2018-08-13 Rapid protection method for direct-current transmission line based on wave-front generalized Logistic function fitting Active CN109193578B (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110854828A (en) * 2019-12-03 2020-02-28 西安交通大学 Single-ended adaptive traveling wave ultra-high speed protection system and method for dealing with high-resistance fault
CN110912091A (en) * 2019-12-03 2020-03-24 西安交通大学 Single-ended traveling wave ultra-high speed protection system and method for flexible direct current transmission line
CN112083280A (en) * 2020-08-27 2020-12-15 中国南方电网有限责任公司超高压输电公司检修试验中心 Method for identifying fault interval of hybrid multi-terminal direct-current power transmission system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108199356A (en) * 2017-12-29 2018-06-22 西安交通大学 DC power transmission line ultra- high speed protection method based on wavefront information

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108199356A (en) * 2017-12-29 2018-06-22 西安交通大学 DC power transmission line ultra- high speed protection method based on wavefront information

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110854828A (en) * 2019-12-03 2020-02-28 西安交通大学 Single-ended adaptive traveling wave ultra-high speed protection system and method for dealing with high-resistance fault
CN110912091A (en) * 2019-12-03 2020-03-24 西安交通大学 Single-ended traveling wave ultra-high speed protection system and method for flexible direct current transmission line
CN110912091B (en) * 2019-12-03 2020-11-10 西安交通大学 Single-ended traveling wave ultra-high speed protection system and method for flexible direct current transmission line
CN110854828B (en) * 2019-12-03 2021-01-19 西安交通大学 Single-ended adaptive traveling wave ultra-high speed protection system and method for dealing with high-resistance fault
CN112083280A (en) * 2020-08-27 2020-12-15 中国南方电网有限责任公司超高压输电公司检修试验中心 Method for identifying fault interval of hybrid multi-terminal direct-current power transmission system
CN112083280B (en) * 2020-08-27 2022-07-08 中国南方电网有限责任公司超高压输电公司检修试验中心 Method for identifying fault interval of hybrid multi-terminal direct-current power transmission system

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