CN113945804A - Alternating current transmission line fault direction judging method - Google Patents

Alternating current transmission line fault direction judging method Download PDF

Info

Publication number
CN113945804A
CN113945804A CN202111262461.2A CN202111262461A CN113945804A CN 113945804 A CN113945804 A CN 113945804A CN 202111262461 A CN202111262461 A CN 202111262461A CN 113945804 A CN113945804 A CN 113945804A
Authority
CN
China
Prior art keywords
voltage
phase
variation
protection installation
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.)
Granted
Application number
CN202111262461.2A
Other languages
Chinese (zh)
Other versions
CN113945804B (en
Inventor
文明浩
陈玉
王玉玺
王祯
马睿智
韩珂
钱堃
王幸主
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.)
Huazhong University of Science and Technology
Original Assignee
Huazhong 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 Huazhong University of Science and Technology filed Critical Huazhong University of Science and Technology
Priority to CN202111262461.2A priority Critical patent/CN113945804B/en
Publication of CN113945804A publication Critical patent/CN113945804A/en
Application granted granted Critical
Publication of CN113945804B publication Critical patent/CN113945804B/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
    • Y—GENERAL 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers
    • Y—GENERAL 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
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS 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
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

The invention belongs to the field of relay protection of power systems, and particularly relates to a method for judging the fault direction of an alternating current transmission line, which comprises the following steps: processing three-phase voltage and three-phase current collected at the protection installation position of the alternating current transmission line through a low-pass filter, wherein the cut-off frequency of the low-pass filter is selected according to the distance of a setting point; calculating the voltage of the setting point, the voltage variation of the setting point and the differential variation of the voltage of the setting point by using the three-phase voltage and the three-phase current which are subjected to low-pass filtering; calculating voltage variation and voltage differential variation of the protection installation position by using the voltage of the protection installation position subjected to low-pass filtering; judging whether the absolute value of the voltage at the protection installation position at the fault moment is greater than a threshold value, and if so, comparing the voltage variation with the setting point voltage variation to determine the fault direction; and if not, comparing the variation of the voltage differential with the variation of the setting point voltage differential to determine the fault direction. The method is suitable for different power electronic power supplies, and has the advantages of simple algorithm and clear setting basis.

Description

Alternating current transmission line fault direction judging method
Technical Field
The invention belongs to the field of relay protection of power systems, and particularly relates to a method for judging the fault direction of an alternating current transmission line.
Background
The rapid development of clean energy power generation is an important way for realizing the purposes of carbon peak reaching and carbon neutralization, and a new energy power generation system represented by wind power and photovoltaic is widely applied to a power grid. The wind power and photovoltaic new energy power generation system is connected with a power grid through a power electronic converter, is a typical power electronic power supply, and has a fault characteristic which is obviously different from that of a traditional alternating current synchronous machine power supply.
The conventional relay protection principle is based on the power failure characteristic of an alternating current synchronous machine, and the performance is degraded when the relay protection principle is applied to a power electronic power supply access system, so that the judgment of the failure direction of an alternating current line accessed by a power electronic power supply is difficult, and a method for judging the failure direction of the alternating current line adapted to the power electronic power supply access is urgently needed to be developed.
Disclosure of Invention
Aiming at the defects and the improvement requirements of the prior art, the invention provides a method for judging the fault direction of an alternating current transmission line, and aims to solve the technical problem that the fault direction of an alternating current line of a power electronic power supply access system is difficult to judge in the prior art.
In order to achieve the above object, according to an aspect of the present invention, there is provided an alternating current transmission line fault direction determining method, including:
s1, carrying out low-pass filtering processing on the three-phase voltage and the three-phase current collected at the protection installation position of the alternating-current transmission line through a low-pass filter, wherein the cut-off frequency of the low-pass filter is selected according to the distance of a setting point;
s2, based on the alternating current transmission line model, calculating the set point voltage, the set point voltage variation and the set point voltage differential variation by using the three-phase voltage and the three-phase current subjected to the low-pass filtering; when the fault type is a single-phase fault, determining the single-phase voltage of the phase from the three-phase voltages subjected to the low-pass filtering, and when the fault type is a phase fault, calculating the phase-to-phase voltage of the phase according to the three-phase voltages subjected to the low-pass filtering; calculating a voltage variation and a voltage differential variation at the protection installation site by using the single-phase voltage or the inter-phase voltage;
s3, judging whether the absolute value of the single-phase voltage or the interphase voltage is larger than a threshold value at the fault moment, if so, comparing the voltage variation of the protection installation position with the voltage variation of the setting point to determine the fault direction; if not, comparing the variation of the voltage differential at the protection installation position with the variation of the voltage differential at the set point to determine the fault direction.
Further, in S2, the method for calculating the set point voltage includes:
useti(t)＝g[ui(t),ii(t)]
where, i ═ a, b, c, ab, bc, ac respectively represent a phase, b phase, c phase, ab phase, bc phase and ac phase, t is the current time, u is the current timeseti(t) is the set point voltage, ui(t) and ii(t) is the low pass filtered voltage and current at the protection installation, g [ u [ ]i(t),ii(t)]Is ui(t) and iiAnd (t) a function for calculating a set point voltage according to the alternating current transmission line model and the line parameters thereof.
Further, in S2, the method for calculating the voltage variation at the protection installation location includes:
u1i(t)＝ui(t)-ui(t0)
where, i ═ a, b, c, ab, bc, ac respectively represent a phase, b phase, c phase, ab phase, bc phase and ac phase, t is the current time0To the moment of failure, u1i(t) protective installation Voltage variation, uiIs a passingThe low pass filter process protects the installation site voltage.
Further, in S2, the method for calculating the set-point voltage variation amount is:
u2i(t)＝useti(t)-useti(t0)
where, i ═ a, b, c, ab, bc, ac respectively represent a phase, b phase, c phase, ab phase, bc phase and ac phase, t is the current time0To the moment of failure, u2i(t) is the set point voltage variation, usetiAnd (t) is the setting point voltage at the time t.
Further, in S2, the variation of the voltage differential at the protection installation is:
Figure BDA0003326240320000031
where, i ═ a, b, c, ab, bc, ac respectively represent a phase, b phase, c phase, ab phase, bc phase and ac phase, t is the current time0To the moment of failure, u3i(t) is a variation of a voltage differential at the protection installation,
Figure BDA0003326240320000032
the voltage differential of the protection installation after the low-pass filtering process.
Further, in S2, the change amount of the set point voltage differential is:
Figure BDA0003326240320000033
where, i ═ a, b, c, ab, bc, ac respectively represent a phase, b phase, c phase, ab phase, bc phase and ac phase, t is the current time0To the moment of failure, u4i(t) is a variation of the set point voltage differential,
Figure BDA0003326240320000034
is the setting point voltage differential.
Further, in S3, the comparing the voltage variation at the protection installation site with the setting point voltage variation to determine a fault direction includes:
the single-phase voltage or the inter-phase voltage at the protection installation position is positive and larger than a threshold value at the fault moment, if the voltage variation at the protection installation position is larger than the voltage variation at the set point, the forward fault is considered to occur, and if the voltage variation at the protection installation position is smaller than the voltage variation at the set point, the reverse fault is considered to occur; and at the fault moment, the single-phase voltage or the inter-phase voltage at the protection installation position is negative, the absolute value of the single-phase voltage or the inter-phase voltage is greater than a threshold value, if the voltage variation at the protection installation position is smaller than the voltage variation at the set point, the forward fault is considered to occur, and if the voltage variation at the protection installation position is greater than the voltage variation at the set point, the reverse fault is considered to occur.
Further, in S3, the comparing the variation of the differential voltage at the protection installation site with the variation of the differential voltage at the setpoint to determine the fault direction may be implemented as follows:
the single-phase voltage or the interphase voltage absolute value at the protection installation position is smaller than a threshold value at the fault moment, the differential of the single-phase voltage or the interphase voltage at the protection installation position is positive, if the variation of the voltage differential at the protection installation position is larger than the variation of the voltage differential at the set point, a forward fault is considered to occur, and if the variation of the voltage differential at the protection installation position is smaller than the variation of the voltage differential at the set point, a reverse fault is considered to occur; and the absolute value of the single-phase voltage or the inter-phase voltage at the protection installation position is smaller than a threshold value at the fault moment, the differential of the single-phase voltage or the inter-phase voltage at the protection installation position is negative, if the voltage variation at the protection installation position is smaller than the voltage variation at the set point, the forward fault is considered to occur, and if the voltage variation at the protection installation position is larger than the voltage variation at the set point, the reverse fault is considered to occur.
Further, the cut-off frequency of the low-pass filter is selected according to the following formula:
1-2πf·l/2v·cot(2πf·l/2v)≤0.05；
where f denotes the low pass filter cut-off frequency, l denotes the set point distance, and v denotes the propagation velocity of light in vacuum.
The invention also provides a computer-readable storage medium, which is characterized by comprising a stored computer program, wherein when the computer program is executed by a processor, the computer program controls equipment where the storage medium is located to execute the method for judging the fault direction of the alternating current transmission line.
Generally, by the above technical solution conceived by the present invention, the following beneficial effects can be obtained:
(1) the fault direction is judged by using the fault electric quantity propagation characteristic of the AC line, and is irrelevant to the power supply characteristic. The invention judges the fault direction by comparing the voltage variation of the protection installation position and the voltage variation of the setting point or the voltage differential variation of the protection installation position and the voltage differential variation of the setting point by utilizing the rule that the voltage instantaneous value of lower frequency is approximately linearly distributed along the alternating current line, and is irrelevant to the power supply characteristic. Therefore, the method can be suitable for judging the fault direction of different types of power electronic power supply access systems, and has the advantages of simple algorithm and clear setting basis.
(2) In order to solve the problem that the fault direction is difficult to judge when the zero-crossing point fault occurs, the fault direction is judged by comparing the voltage differential variation at the protection installation position with the voltage differential variation at the setting point. Because the voltage of the alternating current system is alternating current quantity which changes according to a sine rule, the voltage differential corresponding to the voltage zero crossing point moment reaches the peak value, namely the voltage differential changes to the maximum when the voltage zero crossing point moment fails, the problem that the fault direction is difficult to judge when the voltage zero crossing point fails is solved by judging the fault direction by using the voltage differential changes.
(3) The invention can accurately judge the fault direction to be used as a directional element for longitudinal direction protection, can realize the longitudinal direction protection function of the power electronic power supply access system, and judges whether an in-zone fault occurs or not based on the fault direction information at two sides of the protected element.
(4) The fault time t represents a certain time after the fault, t is the current time, and is generally selected to be several milliseconds (within about 5 ms) after the fault, and the fault time t can be estimated according to the length of a general alternating current line and the corresponding low-pass filtering cut-off frequencyCalculating the approximate range, t0Indicating the moment of occurrence of the fault.
Drawings
Fig. 1 is a schematic structural diagram of a power electronic power supply access system according to an embodiment of the present invention;
fig. 2 is a result of determining a forward direction fault of a doubly-fed wind farm power access system according to an embodiment of the present invention, where (a) is an a-phase voltage processed by digital low-pass filtering at a protection installation location; (b) for protecting voltage variation u at installationa1(t) and set point voltage variation ua2(t)；
Fig. 3 is a result of determining when a reverse fault occurs in a doubly-fed wind farm power access system according to an embodiment of the present invention, where (a) a phase voltage at a protection installation location is subjected to digital low-pass filtering; (b) for protecting voltage variation u at installationa1(t) and set point voltage variation ua2(t)；
Fig. 4 is a result of determining a forward direction fault of a photovoltaic power access system according to an embodiment of the present invention, where (a) is an a-phase voltage processed by digital low-pass filtering at a protection installation location; (b) for protecting differential voltage variation u at installationa3(t) and the set point voltage differential variation ua4(t)；
Fig. 5 is a result of determining that a photovoltaic power access system fails in the opposite direction according to an embodiment of the present invention, where (a) is an a-phase voltage subjected to digital low-pass filtering at a protection installation location; (b) for protecting differential voltage variation u at installationa3(t) and the set point voltage differential variation ua4(t)；
Fig. 6 is a result of determining that a forward direction fault occurs in a power access system of a dc converter station according to an embodiment of the present invention, where (a) is an a-phase voltage that is subjected to digital low-pass filtering at a protection installation location; (b) for protecting voltage variation u at installationa3(t) and the set point voltage differential variation ua4(t)；
Fig. 7 is a result of determining that a power access system of a dc converter station has a reverse fault according to an embodiment of the present invention, where (a) is an a-phase voltage processed by digital low-pass filtering at a protection installation location; (b) is composed ofProtection installation voltage variation ua3(t) and the set point voltage differential variation ua4(t)。
The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:
the protection circuit comprises a power electronic power supply 1, a line bus on the same side 2, a relay protection device 3, a protected line 4, a bus on the opposite side 5 and a power supply on the opposite side 6.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and 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. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention provides an alternating current transmission line fault direction judging method suitable for power electronic power supply access, aiming at the problem that the fault direction of an alternating current line of a power electronic power supply access system is difficult to judge.
In the embodiment of the invention, the three-phase voltage and the three-phase current collected at the protection installation position of the alternating current line are processed by a low-pass filter; calculating a setting point voltage by using three-phase voltage and three-phase current at the protection installation part after low-pass filtering and combining an alternating current circuit model; calculating the voltage variation of the protection installation position by using the voltage of the protection installation position subjected to low-pass filtering; calculating the voltage variation of the setting point by using the voltage of the setting point; calculating the differential of the voltage at the protection installation position by using the voltage at the protection installation position subjected to low-pass filtering, and then calculating the variation of the differential at the protection installation position; calculating the differential of the voltage of the setting point by using the voltage of the setting point, and then calculating the variation of the differential of the voltage of the setting point; if the absolute value of the voltage at the protection installation position at the fault moment is larger than a threshold value, comparing the voltage variation at the protection installation position with the voltage variation at the setting point to determine the fault direction; and if the absolute value of the voltage at the protection installation position at the fault moment is smaller than the threshold value, comparing the variation of the voltage differential at the protection installation position with the variation of the voltage differential at the setting point to determine the fault direction. The provided fault direction judging method can be suitable for different power electronic power supplies, the algorithm is simple, and the setting basis is clear.
For further explanation, the method for judging the fault direction of the ac power transmission line adapted to the power electronic power source access provided by the present invention is described in detail below with reference to the accompanying drawings and specific examples:
the specific embodiment is described by taking a typical power electronic power supply access system as an example, and as shown in fig. 1, the structure of the typical power electronic power supply access system includes: power electronic power supply 1, this side circuit generating line 2, relay protection device 3 is protected circuit 4, offside generating line 5, offside power 6, power electronic power supply 1 links to each other with this side circuit generating line 2, and this side circuit generating line 2 links to each other with relay protection device 3, relay protection device 3 with by protection circuit 4 link to each other, by protection circuit 4 with offside generating line 5 link to each other, offside generating line 5 links to each other with offside power 6.
By adopting the system, the method for judging the fault direction of the alternating current transmission line adapting to the access of the power electronic power supply is implemented according to the following steps:
step 1: processing the three-phase voltage and the three-phase current collected at the protection installation position of the alternating current line by a low-pass filter;
step 2: calculating a setting point voltage by using three-phase voltage and three-phase current at the protection installation part after low-pass filtering and combining an alternating current circuit model;
and step 3: calculating the voltage variation of the protection installation position by using the voltage of the protection installation position subjected to low-pass filtering;
and 4, step 4: calculating the voltage variation of the setting point by using the voltage of the setting point;
and 5: calculating the differential of the voltage at the protection installation position by using the voltage at the protection installation position subjected to low-pass filtering, and then calculating the variation of the differential of the voltage at the protection installation position;
step 6: calculating the differential of the voltage of the setting point by using the voltage of the setting point, and then calculating the variation of the differential of the voltage of the setting point;
and 7: if the absolute value of the voltage at the protection installation position at the fault moment is larger than a threshold value, comparing the voltage variation at the protection installation position with the voltage variation at the setting point to determine the fault direction;
and 8: and if the absolute value of the voltage at the protection installation position at the fault moment is smaller than the threshold value, comparing the variation of the voltage differential at the protection installation position with the variation of the voltage differential at the setting point to determine the fault direction.
It should be noted that, in the case where the absolute value of the voltage at the protection installation location is equal to the threshold value at the time of the fault, the criterion of the voltage variation or the criterion of the variation of the voltage differential may be adopted.
In the embodiment of the invention, the cut-off frequency of the digital low-pass filter in the step 1 is selected according to the length of the protected line. The invention utilizes the law that the voltage instantaneous value of lower frequency is approximately linearly distributed along the AC line, and the longer the line length is, the lower the cut-off frequency of the low-pass filter is required, so the cut-off frequency of the low-pass filter needs to be selected according to the line length. The specific formula is as follows: 1-2 pi f l/2v cot (2 pi f l/2v) ≦ 0.05, where f represents the low-pass filter cut-off frequency, l represents the set point distance, and v represents the propagation velocity of light in vacuum.
In an embodiment where the line length is 150km, the digital low pass filter cut-off frequency is chosen to be 200 Hz.
In the embodiment of the present invention, in step 2, based on the RL model of the power transmission line, the calculation method of the voltage of the single-phase fixed point specifically includes:
Figure BDA0003326240320000081
wherein t is time; u. ofseta(t)，usetb(t)，usetc(t) are three-phase setting point voltages respectively; u. ofa(t)，ub(t)，uc(t) three-phase voltages at the protection installation part after low-pass filtering are respectively obtained; i.e. ia(t)，ib(t)，ic(t) respectively protecting three-phase currents at the installation position through low-pass filtering; r issIs the unit length self-resistance of the AC line; r ismIs a mutual resistance of unit length of the AC line; lsIs a self-inductance of unit length of the AC line; lmIs a crossMutual inductance per unit length of the flow lines.
In the embodiment of the present invention, in step 3, the method for calculating the voltage variation at the protection installation location includes:
u1i(t)＝ui(t)-ui(t0)
wherein t is the current time, t0Is the fault time (a time before the current time), u1i(t) protective installation Voltage variation, uikAnd (t) is the protection installation voltage processed by the digital low-pass filter.
In the embodiment of the present invention, in step 4, a method for calculating a voltage variation of a setting point includes:
u2i(t)＝useti(t)-useti(t0)
where i ═ a, b, c represent a phase, b phase, c phase, t is the current time, t is0Is a time, u, before the current time2i(t) is the set point voltage variation, usetiAnd (t) is a setting point voltage.
In the embodiment of the present invention, in step 5, the variation of the differential voltage at the protection installation is:
Figure BDA0003326240320000091
wherein t is the current time, t0Is a time, u, before the current time3i(t) is the differential change of the voltage at the protective installation,
Figure BDA0003326240320000092
the voltage differential at the protection installation is processed by a digital low-pass filter.
In the embodiment of the present invention, in step 6, the variation of the set point voltage differential is:
Figure BDA0003326240320000093
wherein t is the current time, t0Is a time, u, before the current time4i(t) is the setting point voltage differential variation,
Figure BDA0003326240320000094
is the setting point voltage differential.
In the embodiment of the present invention, in step 7, the method for determining the fault direction includes:
the absolute value of the voltage at the protection installation position is larger than a threshold value at the fault moment, the voltage at the protection installation position is positive, wherein the threshold value is set to be 0.5 time of the voltage peak value in normal operation, if the voltage variation at the protection installation position is larger than the voltage variation at the set point, a forward fault is considered to occur, and if the voltage variation at the protection installation position is smaller than the voltage variation at the set point, a reverse fault is considered to occur; in the embodiment of the invention, if the voltage variation of the protection installation position is smaller than the voltage variation of the set point, the forward fault is considered to occur, and if the voltage variation of the protection installation position is larger than the voltage variation of the set point, the reverse fault is considered to occur.
In the embodiment of the present invention, in step 8, the method for determining the fault direction includes:
the absolute value of the voltage at the protection installation position at the fault moment is smaller than a threshold value, the differential of the voltage at the protection installation position is positive, wherein the threshold value is set to be 0.5 time of the voltage peak value in normal operation, if the variation of the voltage differential at the protection installation position is larger than the variation of the voltage differential at the setting point, a forward fault is considered to occur, and if the variation of the voltage differential at the protection installation position is smaller than the variation of the voltage differential at the setting point, a reverse fault is considered to occur; and the absolute value of the voltage at the protection installation position at the fault moment is smaller than a threshold value, the differential of the voltage at the protection installation position is negative, wherein the threshold value is set to be 0.5 time of the voltage peak value in normal operation, if the voltage variation at the protection installation position is smaller than the voltage variation at the set point, the forward fault is considered to occur, and if the voltage variation at the protection installation position is larger than the voltage variation at the set point, the reverse fault is considered to occur.
In the embodiment, a-phase grounding short circuit is generated at the outlet of the forward protected line of the relay protection device 3Failure (f in FIG. 1)1A dot). The fault occurrence time is 0.593s, and the power electronic power supply is a double-fed wind power plant power supply. Fig. 2 (a) is a diagram of a-phase voltage subjected to digital low-pass filtering processing at a protection installation site, the absolute value of the voltage at the fault moment is 139.7kV and is greater than 0.5 times of the voltage peak value in normal operation, and the voltage is negative; FIG. 2 (b) is a graph showing the amount of change u in voltage at the protection installation sitea1(t) and set point voltage variation ua2(t) u in the graph (b) in FIG. 2a2(t) is greater than ua1(t), it is thus judged that a forward failure has occurred.
In the embodiment, a-phase grounding short-circuit fault (f in fig. 1) occurs at the outlet of the forward protected line of the relay protection device 32A dot). The fault occurrence time is 0.593s, and the power electronic power supply is a double-fed wind power plant power supply. Fig. 3 (a) is a diagram of a-phase voltage subjected to digital low-pass filtering processing at a protection installation site, the absolute value of the voltage at the fault time is 139.7kV and is greater than 0.5 times of the voltage peak value in normal operation, and the voltage is negative; FIG. 3 (b) is a graph showing the amount of change u in voltage at the protection installation sitea1(t) and set point voltage variation ua2(t) u in the graph (b) in FIG. 3a2(t) less than ua1(t), it is thus judged that a reverse fault has occurred.
In the embodiment, a-phase grounding short-circuit fault (f in fig. 1) occurs at the outlet of the forward protected line of the relay protection device 31A dot). The fault occurrence time is 0.5885s, and the power electronic power supply is a photovoltaic power supply. Fig. 4 (a) is a diagram of a-phase voltage subjected to digital low-pass filtering processing at a protection installation site, the absolute value of the voltage at the fault time is 36.3kV and is less than 0.5 times of the voltage peak value in normal operation, and the voltage differential is negative; FIG. 4 (b) is a graph showing the differential change u of the voltage at the protective mountinga3(t) and the set point voltage differential variation ua4(t) u in the graph (b) in FIG. 4a4(t) is greater than ua3(t), it is thus judged that a forward failure has occurred.
In the present embodiment, the relay protection device 3 is set to generate a-phase grounding short circuit fault at the outlet of the protected line in the opposite direction (f in fig. 1)2A dot). The fault occurrence time is 0.5885s, and the power electronic power supply is a photovoltaic power supply. FIG. 5 (a) is a digital low pass protection installationThe absolute value of the voltage of the filtered a-phase voltage at the fault time is 36.3kV, which is less than 0.5 time of the voltage peak value in normal operation, and the voltage differential is negative; FIG. 5 (b) is a graph showing the differential change u of the voltage at the protective mountinga3(t) and the set point voltage differential variation ua4(t) u in the graph (b) in FIG. 5a4(t) less than ua3(t), it is thus judged that a reverse fault has occurred.
In the embodiment, a-phase grounding short-circuit fault (f in fig. 1) occurs at the outlet of the forward protected line of the relay protection device 31A dot). The time of the fault occurrence is 0.595s, and the power electronic power supply is a direct current converter station power supply. Fig. 6 (a) is a graph of a-phase voltage subjected to digital low-pass filtering processing at a protection installation site, wherein the absolute value of the voltage at the fault time is 345.8kV which is greater than 0.5 times of the peak value of the voltage at normal operation and the voltage is negative; FIG. 6 (b) is a graph showing the amount of change u in voltage at the protective mountinga1(t) and set point voltage variation ua2(t) u in FIG. 6 (b)a2(t) is greater than ua1(t), it is thus judged that a forward failure has occurred.
In the present embodiment, the relay protection device 3 is set to generate a-phase grounding short circuit fault at the outlet of the protected line in the opposite direction (f in fig. 1)2A dot). The time of the fault occurrence is 0.595s, and the power electronic power supply is a direct current converter station power supply. Fig. 7 (a) is a graph of a-phase voltage subjected to digital low-pass filtering processing at a protection installation site, wherein the absolute value of the voltage at the fault time is 345.8kV which is greater than 0.5 times of the peak value of the voltage at normal operation and the voltage is negative; FIG. 7 (b) is a graph showing the amount of change u in voltage at the protective mountinga1(t) and set point voltage variation ua2(t) FIG. 7 (b) FIG. ua2(t) less than ua1(t), it is thus judged that a reverse fault has occurred.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (10)

1. A method for judging the fault direction of an alternating current transmission line is characterized by comprising the following steps:
s1, carrying out low-pass filtering processing on the three-phase voltage and the three-phase current collected at the protection installation position of the alternating-current transmission line through a low-pass filter, wherein the cut-off frequency of the low-pass filter is selected according to the distance of a setting point;
s2, based on the alternating current transmission line model, calculating the set point voltage, the set point voltage variation and the set point voltage differential variation by using the three-phase voltage and the three-phase current subjected to the low-pass filtering; when the fault type is a single-phase fault, determining the single-phase voltage of the phase from the three-phase voltages subjected to the low-pass filtering, and when the fault type is a phase fault, calculating the phase-to-phase voltage of the phase according to the three-phase voltages subjected to the low-pass filtering; calculating a voltage variation and a voltage differential variation at the protection installation site by using the single-phase voltage or the inter-phase voltage;
s3, judging whether the absolute value of the single-phase voltage or the interphase voltage is larger than a threshold value at the fault moment, if so, comparing the voltage variation of the protection installation position with the voltage variation of the setting point to determine the fault direction; if not, comparing the variation of the voltage differential at the protection installation position with the variation of the voltage differential at the set point to determine the fault direction.
2. The method according to claim 1, wherein in S2, the calculation method of the set point voltage is:
useti(t)＝g[ui(t),ii(t)]
where, i ═ a, b, c, ab, bc, ac respectively represent a phase, b phase, c phase, ab phase, bc phase and ac phase, t is the current time, u is the current timeseti(t) is the set point voltage, ui(t) and ii(t) is the low pass filtered voltage and current at the protection installation, g [ u [ ]i(t),ii(t)]Is ui(t) and iiAnd (t) a function for calculating a set point voltage according to the alternating current transmission line model and the line parameters thereof.
3. The method according to claim 1, wherein in S2, the method for calculating the voltage variation at the protection installation location is:
u1i(t)＝ui(t)-ui(t0)
where, i ═ a, b, c, ab, bc, ac respectively represent a phase, b phase, c phase, ab phase, bc phase and ac phase, t is the current time0To the moment of failure, u1i(t) protective installation Voltage variation, uiAnd (—) is the voltage at the protection installation after the low-pass filtering process.
4. The method according to claim 1, wherein in S2, the method for calculating the variation of the voltage at the fixed point comprises:
u2i(t)＝useti(t)-useti(t0)
where, i ═ a, b, c, ab, bc, ac respectively represent a phase, b phase, c phase, ab phase, bc phase and ac phase, t is the current time0To the moment of failure, useti(t) is the set point voltage variation, usetiAnd (t) is the setting point voltage at the time t.
5. The method according to claim 1, wherein in S2, the variation of the differential voltage at the protection installation is:
Figure FDA0003326240310000021
where, i ═ a, b, c, ab, bc, ac respectively represent a phase, b phase, c phase, ab phase, bc phase and ac phase, t is the current time0To the moment of failure, u3i(t) is a variation of a voltage differential at the protection installation,
Figure FDA0003326240310000022
the voltage differential of the protection installation after the low-pass filtering process.
6. The method according to claim 1, wherein in S2, the variation of the differential of the setting point voltage is:
Figure FDA0003326240310000023
where, i ═ a, b, c, ab, bc, ac respectively represent a phase, b phase, c phase, ab phase, bc phase and ac phase, t is the current time0To the moment of failure, u4i(t) is a variation of the set point voltage differential,
Figure FDA0003326240310000024
is the setting point voltage differential.
7. The method according to claim 1, wherein in S3, the comparing the voltage variation at the protection installation site with the voltage variation at the setting point determines the fault direction, and the specific implementation manner is as follows:
the single-phase voltage or the inter-phase voltage at the protection installation position is positive and larger than a threshold value at the fault moment, if the voltage variation at the protection installation position is larger than the voltage variation at the set point, the forward fault is considered to occur, and if the voltage variation at the protection installation position is smaller than the voltage variation at the set point, the reverse fault is considered to occur; and at the fault moment, the single-phase voltage or the inter-phase voltage at the protection installation position is negative, the absolute value of the single-phase voltage or the inter-phase voltage is greater than a threshold value, if the voltage variation at the protection installation position is smaller than the voltage variation at the set point, the forward fault is considered to occur, and if the voltage variation at the protection installation position is greater than the voltage variation at the set point, the reverse fault is considered to occur.
8. The method according to claim 1, wherein in S3, the comparing the variation of the differential voltage at the protection installation site with the variation of the differential voltage at the setpoint to determine the fault direction is implemented as follows:
the single-phase voltage or the interphase voltage absolute value at the protection installation position is smaller than a threshold value at the fault moment, the differential of the single-phase voltage or the interphase voltage at the protection installation position is positive, if the variation of the voltage differential at the protection installation position is larger than the variation of the voltage differential at the set point, a forward fault is considered to occur, and if the variation of the voltage differential at the protection installation position is smaller than the variation of the voltage differential at the set point, a reverse fault is considered to occur; and the absolute value of the single-phase voltage or the inter-phase voltage at the protection installation position is smaller than a threshold value at the fault moment, the differential of the single-phase voltage or the inter-phase voltage at the protection installation position is negative, if the voltage variation at the protection installation position is smaller than the voltage variation at the set point, the forward fault is considered to occur, and if the voltage variation at the protection installation position is larger than the voltage variation at the set point, the reverse fault is considered to occur.
9. The method according to any one of claims 1 to 8, wherein the cut-off frequency of the low-pass filter is selected according to the following formula:
1-2πf·l/2v·cot(2πf·l/2v)≤0.05；
where f denotes the low pass filter cut-off frequency, l denotes the set point distance, and v denotes the propagation velocity of light in vacuum.
10. A computer-readable storage medium, comprising a stored computer program, wherein when the computer program is executed by a processor, the computer program controls a device on which the storage medium is located to execute a method according to any one of claims 1 to 9.
CN202111262461.2A 2021-10-28 2021-10-28 Alternating current transmission line fault direction judging method Active CN113945804B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111262461.2A CN113945804B (en) 2021-10-28 2021-10-28 Alternating current transmission line fault direction judging method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111262461.2A CN113945804B (en) 2021-10-28 2021-10-28 Alternating current transmission line fault direction judging method

Publications (2)

Publication Number Publication Date
CN113945804A true CN113945804A (en) 2022-01-18
CN113945804B CN113945804B (en) 2022-07-12

Family

ID=79336891

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111262461.2A Active CN113945804B (en) 2021-10-28 2021-10-28 Alternating current transmission line fault direction judging method

Country Status (1)

Country Link
CN (1) CN113945804B (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103972873A (en) * 2014-05-14 2014-08-06 国网上海市电力公司 Method for protecting high-voltage DC three-pole power transmission line
CN104242267A (en) * 2014-09-11 2014-12-24 国家电网公司 Distance protection method for wind power generation transmission line
US20150233976A1 (en) * 2012-10-03 2015-08-20 Abb Technology Ltd Method for sensing a fault in a power system based on travelling wave currents
CN107636921A (en) * 2015-05-05 2018-01-26 Abb瑞士股份有限公司 Method and apparatus for detecting failure in mixed configuration transmission line of electricity
CN108120902A (en) * 2018-01-31 2018-06-05 国网浙江省电力有限公司电力科学研究院 A kind of transmission line malfunction quick discrimination method
US20190094291A1 (en) * 2017-09-22 2019-03-28 Schweitzer Engineering Laboratories, Inc. Distance protection using traveling waves in an electric power delivery system
US20190271730A1 (en) * 2017-01-22 2019-09-05 Abb Schweiz Ag Method and control system for fault direction detection

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150233976A1 (en) * 2012-10-03 2015-08-20 Abb Technology Ltd Method for sensing a fault in a power system based on travelling wave currents
CN103972873A (en) * 2014-05-14 2014-08-06 国网上海市电力公司 Method for protecting high-voltage DC three-pole power transmission line
CN104242267A (en) * 2014-09-11 2014-12-24 国家电网公司 Distance protection method for wind power generation transmission line
CN107636921A (en) * 2015-05-05 2018-01-26 Abb瑞士股份有限公司 Method and apparatus for detecting failure in mixed configuration transmission line of electricity
US20190271730A1 (en) * 2017-01-22 2019-09-05 Abb Schweiz Ag Method and control system for fault direction detection
US20190094291A1 (en) * 2017-09-22 2019-03-28 Schweitzer Engineering Laboratories, Inc. Distance protection using traveling waves in an electric power delivery system
CN108120902A (en) * 2018-01-31 2018-06-05 国网浙江省电力有限公司电力科学研究院 A kind of transmission line malfunction quick discrimination method

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JOE-AIR JIANG 等: "A composite index to adaptively perform fault detection, classification, and direction discrimination for transmission lines", 《2002 IEEE POWER ENGINEERING SOCIETY WINTER MEETING. CONFERENCE PROCEEDINGS》 *
钱国明 等: "基于分布参数模型的突变量距离保护新算法", 《电力系统自动化》 *

Also Published As

Publication number Publication date
CN113945804B (en) 2022-07-12

Similar Documents

Publication Publication Date Title
CN109830978B (en) Control method of wind power flexible-straight system with fault automatic ride-through capability
TWI522767B (en) Photovoltaic power generation system
Afshari et al. A low-voltage ride-through control strategy for three-phase grid-connected PV systems
CN107863780B (en) Fault control method and device for offshore wind power direct current sending-out system
CN109390963B (en) Direct-current voltage preset control method and application of voltage source converter
CN106340895A (en) Two-stage photovoltaic grid connected inverter control system and method
CN109167378B (en) Method and system for evaluating risk of multiple-circuit direct current simultaneous commutation failure
Jia et al. Amplitude comparison based pilot protection for renewable power teed line
CN113945804B (en) Alternating current transmission line fault direction judging method
CN112557961A (en) Method for judging fault of double-fed wind power plant outgoing line
CN112039036A (en) Alternating current line instantaneous value variation distance protection method and system
Ruffing et al. Dynamic internal overcurrent control for undetected DC faults for modular multilevel converters
CN114204525B (en) Pilot protection method for direct-current transmission line and application thereof
Kumar A survey on recent developments of islanding detection techniques
CN105790295A (en) Grid fault non-communication ride-through control method for double-end flexible direct current power transmission system
Bimenyimana et al. Fault Ride-Through (FRT) Behavior in VSC-HVDC as Key Enabler of Transmission Systems Using SCADA Viewer Software
CN113972632B (en) Direct current line pilot direction protection method, device and system
Ma et al. Renewable Energy Integrated HVDC Power System Modeling for Transient Frequency Stability Online Assessment
CN111509759B (en) Method and system for evaluating high-low end mutual influence indexes of multi-feed direct current layered access
KR102678463B1 (en) Control method of switching device for DC power system having power directionality
Yang et al. Research on the Influence of Photovoltaic Grid-connected on the Relay Protection of Distribution Network
CN113363948B (en) Active power distribution network current differential protection method based on positive sequence fault component
Liu et al. Study on Third Harmonic Fault Current Characteristics of Inverter-Based Resources
CN112398138B (en) Voltage reactive coordination control method and system for synchronous phase modulator of high-voltage converter station
CN113804991B (en) Island detection method based on arc tangent synovial frequency shift

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