CN113241743A - Pilot differential protection method of multi-end hybrid direct-current transmission line - Google Patents
Pilot differential protection method of multi-end hybrid direct-current transmission line Download PDFInfo
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- CN113241743A CN113241743A CN202110617492.9A CN202110617492A CN113241743A CN 113241743 A CN113241743 A CN 113241743A CN 202110617492 A CN202110617492 A CN 202110617492A CN 113241743 A CN113241743 A CN 113241743A
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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
- H02H7/268—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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- 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
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The invention relates to a pilot differential protection method of a multi-end hybrid direct-current transmission line, which comprises the following steps of: collecting the line mode components of fault transient current at two ends of each line; calculating an integral value of line mode components of fault transient currents at two ends of each line within 20 ms; calculating the sum of the integral values of the mode components of the fault transient current lines at the two ends of each line in 20 ms; calculating a setting value of each line protection; comparing the sum of the integral values with a setting value, if the sum of the integral values is greater than the setting value, generating a fault in the line area, and performing corresponding protection action; if the sum of the integral values is smaller than the setting value, a fault occurs outside the line area, and corresponding protection does not act. The invention only needs to calculate the line mode component integral value of the fault transient current at two ends of the line within 20ms, so that the 20ms fault criterion delay is realized, and the action time of the protection is greatly reduced compared with the traditional differential protection; the method has the advantages of strong transition resistance, strong anti-interference capability and low communication requirement.
Description
Technical Field
The application relates to the technical field of relay protection, in particular to a pilot differential protection method of a multi-end hybrid direct-current transmission line.
Background
With the development of high-voltage direct current, the advantages of flexible direct current and conventional direct current transmission are combined in multi-terminal hybrid direct current transmission, and more conventional direct current projects have the requirements of upgrading and reconstruction. The multi-terminal hybrid direct-current transmission power supply distance is long, the probability of the direct-current line breaking down is greatly increased, and the rapid detection of the direct-current line failure and the isolation of the broken line are the key points of the research on the protection of the multi-terminal hybrid direct-current line and are the problems to be solved urgently by the multi-terminal hybrid direct-current transmission system.
At present, the protection adopted by a multi-terminal hybrid direct-current power transmission system is mainly traveling wave protection and pilot current differential protection, and when the traveling wave protection is in high-resistance grounding or the fault position is far away from the protection installation position, the protection has the condition of failure; the current differential protection needs to be operated after a failure occurs, and cannot be operated.
Therefore, the method for longitudinal differential protection of the multi-terminal hybrid direct-current transmission line, which has a good protection effect and short protection action time, is a main problem to be solved at present.
Disclosure of Invention
The application provides a longitudinal differential protection method of a multi-end hybrid direct-current transmission line, and compared with the traditional differential protection, the action time of protection is greatly reduced.
The technical scheme adopted by the application is as follows:
the invention provides a pilot differential protection method of a multi-end hybrid direct-current transmission line, which comprises the following steps of:
collecting the line mode components of fault transient current at two ends of each line;
calculating an integral value of line mode components of fault transient currents at two ends of each line within 20 ms;
calculating the sum of the integral values of the mode components of the fault transient current lines at the two ends of each line in 20 ms;
calculating a setting value of each line protection;
comparing the sum of the integral values with the setting value, and if the sum of the integral values is greater than the setting value, generating a fault in the line area and correspondingly protecting the line area;
if the sum of the integral values is smaller than the setting value, a fault occurs outside the line area, and corresponding protection does not act.
Further, gather both ends trouble transient state current line modulus component, include:
and fault transient current line mode components at two ends of the line L1 and the line L2 are respectively collected.
Further, calculating the line mode component integral value of the fault transient current at the two ends of the line within 20ms comprises the following steps:
the line mode components of the fault transient currents across lines L1 and L2 are calculated as integrated values within 20ms, respectively.
Further, calculating the sum of the integral values of the fault transient current line modulus components at the two ends of the line in 20ms comprises the following steps:
respectively calculating the sum of the 20ms integral values of the fault transient current linear modulus components at the two ends of the line L1 and the line L2, wherein the sum of the 20ms integral values of the fault transient current linear modulus components at the two ends of the line L1 is recorded as deltaS1The sum of the 20ms integral values of the fault transient current line modulus components across line L2 is Δ S2。
Further, calculating a setting value of the line protection, comprising:
calculating a setting value delta of the L1 protection of the lineset1Setting value delta of and line L2 protectionset2。
Further, comparing the sum of the integral values with the setting value, and if the sum of the integral values is greater than the setting value, generating a fault in a line area and correspondingly protecting the line area; if the sum of the integral values is smaller than the setting value, a fault occurs outside the line area, and corresponding protection does not act, and the method comprises the following steps:
will be Delta S1And deltaset1Comparing, judging the fault inside and outside the L1 area, if delta S1≥Δset1If the fault occurs in the line L1 zone, the line L1 performs the protection action, otherwise, if Δ S1＜Δset1When the fault occurs, the fault occurs outside the L1 area, and the corresponding protection does not act; and
will be Delta S2And deltaset2Comparing, judging the fault inside and outside the L2 area, if delta S2≥Δset2If so, a fault occurs in the line L2 area; on the contrary, if Δ S2＜Δset2If so, a fault occurs outside the zone of the line L2, and the corresponding protection does not act.
Further, the line mode components of the fault transient currents at the two ends of the line L1 and the line L2 are respectively calculated to be integrated values within 20ms, and the formula is as follows:
in the formula P1、P2、P3、P4Integral of each end current linear modulus component within 20ms, i, for protection 1, protection 2, protection 3 and protection 4 respectively1(t)、i2(t) i.e. the current line mode component i at the two ends of the line L1 measured by the protection 1, protection 2 measuring device3(t)、i4(t) the current line mode components at the two ends of the line L2 measured by the protection 3 and protection 4 measuring devices;
wherein, protection 1 and protection 2 are respectively arranged at two ends of the line L1, protection 3 and protection 4 are respectively arranged at two ends of the line L2, and the corresponding protection action result is to pull open the corresponding fast disconnecting switch.
Further, the sum of the integral values of the line modulus components of the fault transient current at the two ends of the line L1 and the line L2 in 20ms is calculated respectively, and the calculation formula is as follows:
further, the setting value delta of the line L1 protectionset1Setting value delta of and line L2 protectionset2The calculation formula of (2) is as follows:
Δset1＝kreltwIset1
Δset2＝kreltwIset2
in the formula krel＝1.2、tw＝20ms、Iset1＝0.1IL1.1、Iset2＝0.1IL2.1；IL1.1、IL2.1The current line mode components for normal operation of line L1 and line L2, respectively.
The technical scheme of the application has the following beneficial effects:
according to the pilot differential protection method for the multi-terminal hybrid direct-current transmission line, the 20ms fault criterion delay is achieved only by calculating the line-mode component integral value of the fault transient current at two ends of the line within 20ms, and compared with the traditional differential protection, the action time of protection is greatly shortened;
the method has the advantages of strong transition resistance, strong anti-interference capability and low communication requirement.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a pilot differential protection method for a multi-terminal hybrid dc transmission line according to an embodiment of the present invention;
fig. 2 is a multi-terminal hybrid dc transmission topological diagram of a pilot differential protection method for a multi-terminal hybrid dc transmission line according to an embodiment of the present invention (each line is provided with a protection device, protection 1 and protection 2 are provided at the first and last ends of a line L1, and protection 3 and protection 4 are provided at the first and last ends of a line L2).
Detailed Description
Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following examples do not represent all embodiments consistent with the present application. But merely as exemplifications of systems and methods consistent with certain aspects of the application, as recited in the claims.
See fig. 1 and 2.
The application provides a longitudinal differential protection method of a multi-end hybrid direct-current transmission line, which comprises the following steps:
s01: collecting the line mode components of fault transient current at two ends of each line;
in the present embodiment, the line modulus components of the fault transient current at both ends of the line L1 and the line L2 are collected respectively.
S02: calculating an integral value of line mode components of fault transient currents at two ends of each line within 20 ms;
in the present embodiment, the line mode components of the fault transient currents across line L1 and line L2 are calculated as integrated values within 20ms, respectively.
The calculation formula is as follows:
in the formula P1、P2、P3、P4Integral of each end current linear modulus component within 20ms, i, for protection 1, protection 2, protection 3 and protection 4 respectively1(t)、i2(t) i.e. the current line mode component i at the two ends of the line L1 measured by the protection 1, protection 2 measuring device3(t)、i4(t) the current line mode components at the two ends of the line L2 measured by the protection 3 and protection 4 measuring devices;
wherein, protection 1 and protection 2 are respectively arranged at two ends of the line L1, protection 3 and protection 4 are respectively arranged at two ends of the line L2, and the corresponding protection action result is to pull open the corresponding fast disconnecting switch.
S03: calculating the sum of the integral values of the mode components of the fault transient current lines at the two ends of each line in 20 ms;
in the present embodiment, the sum of the 20ms integral values of the fault transient current line mode components across the lines L1 and L2 is calculated, respectively, wherein the sum of the 20ms integral values of the fault transient current line mode components across the lines L1 is Δ S1The sum of the 20ms integral values of the fault transient current line modulus components across line L2 is Δ S2。
The calculation formula is as follows:
s04: calculating a setting value of each line protection;
in the present embodiment, the setting value Δ of the line L1 protection is calculatedset1Setting value delta of and line L2 protectionset2Wherein, isset1、Δset2The method is a setting value protected by a line L1 and a line L2, and has a physical meaning that an integral value of 0.1 time of a difference value of current line modulus components at two ends of the line in 20ms is obtained during normal operation.
Setting value delta of line L1 protectionset1Setting value delta of and line L2 protectionset2The calculation formula of (2) is as follows:
Δset1＝kreltwIset1
Δset2＝kreltwIset2
in the formula krel＝1.2、tw＝20ms、Iset1＝0.1IL1.1、Iset2＝0.1IL2.1；IL1.1、IL2.1Line L1 and line L2 are normal, respectivelyThe runtime current line modulus component.
S05: comparing the sum of the integral values with a setting value, if the sum of the integral values is greater than the setting value, generating a fault in a line area, correspondingly protecting, and informing other converter stations through communication; if the sum of the integral values is smaller than the setting value, a fault occurs outside the line area, and corresponding protection does not act.
In this embodiment, Δ S1And deltaset1Comparing, judging the fault inside and outside the L1 area, if delta S1≥Δset1If the fault occurs in the line L1 zone, the line L1 performs the protection action, otherwise, if Δ S1＜Δset1When the fault occurs, the fault occurs outside the L1 area, and the corresponding protection does not act;
will be Delta S2And deltaset2Comparing, judging the fault inside and outside the L2 area, if delta S2≥Δset2If so, a fault occurs in the line L2 area; on the contrary, if Δ S2＜Δset2If so, a fault occurs outside the zone of the line L2, and the corresponding protection does not act.
Compared with the prior art, the invention has the following advantages:
(1) the method of the invention has absolute selectivity, can effectively prevent the problem of protection maloperation caused by reverse direction faults, and specifically comprises the following steps: when a certain line fails, the protection of the failed line should operate correctly, and the non-failed line does not operate, for example, when the line L2 fails, the protection of the line L2 will operate, and the protection of the line L1 will not operate;
(2) the method only needs 20ms fault criterion delay, and greatly reduces the action time of protection compared with the traditional differential protection;
(3) the method has the advantages of strong transition resistance, strong anti-interference capability and low communication requirement, and specifically comprises the following steps: when the high resistance is grounded, the protection can still act correctly. Anti-interference: when the fault occurs, interference factors such as noise exist in the collected fault signal, and the protection method is high in interference resistance. Furthermore, pilot protection is adopted, electrical information interaction at two ends of a line is needed, and the requirement on information interaction synchronism is low.
The embodiments provided in the present application are only a few examples of the general concept of the present application, and do not limit the scope of the present application. Any other embodiments extended according to the scheme of the present application without inventive efforts will be within the scope of protection of the present application for a person skilled in the art.
Claims (9)
1. A pilot differential protection method of a multi-terminal hybrid direct-current transmission line is characterized by comprising the following steps:
collecting the line mode components of fault transient current at two ends of each line;
calculating an integral value of line mode components of fault transient currents at two ends of each line within 20 ms;
calculating the sum of the integral values of the mode components of the fault transient current lines at the two ends of each line in 20 ms;
calculating a setting value of each line protection;
comparing the sum of the integral values with the setting value, and if the sum of the integral values is greater than the setting value, generating a fault in the line area and correspondingly protecting the line area; and
if the sum of the integral values is smaller than the setting value, a fault occurs outside the line area, and corresponding protection does not act.
2. The pilot differential protection method of the multi-terminal hybrid direct-current transmission line according to claim 1, wherein the collecting transient current line mode components of the faults at both terminals comprises:
and fault transient current line mode components at two ends of the line L1 and the line L2 are respectively collected.
3. The pilot differential protection method of the multi-terminal hybrid direct-current transmission line according to claim 1, wherein calculating an integral value of line-mode components of fault transient currents at two terminals of the line within 20ms comprises:
the line mode components of the fault transient currents across lines L1 and L2 are calculated as integrated values within 20ms, respectively.
4. The pilot differential protection method of the multi-terminal hybrid direct-current transmission line according to claim 1, wherein calculating the sum of the 20ms integral values of the transient current line modulus components of the fault at the two terminals of the line comprises:
respectively calculating the sum of the 20ms integral values of the fault transient current linear modulus components at the two ends of the line L1 and the line L2, wherein the sum of the 20ms integral values of the fault transient current linear modulus components at the two ends of the line L1 is recorded as deltaS1The sum of the 20ms integral values of the fault transient current line modulus components across line L2 is Δ S2。
5. The pilot differential protection method of the multi-terminal hybrid direct-current transmission line according to claim 1, wherein calculating the setting value of the line protection comprises:
calculating a setting value delta of the L1 protection of the lineset1Setting value delta of and line L2 protectionset2。
6. The longitudinal differential protection method of the multi-terminal hybrid direct-current transmission line according to claim 1, wherein the sum of the integrated values is compared with the setting value, and if the sum of the integrated values is greater than the setting value, a fault occurs in a line area, and corresponding protection action is performed; if the sum of the integral values is smaller than the setting value, a fault occurs outside the line area, and corresponding protection does not act, and the method comprises the following steps:
will be Delta S1And deltaset1Comparing, judging the fault inside and outside the L1 area, if delta S1≥Δset1If the fault occurs in the line L1 zone, the line L1 performs the protection action, otherwise, if Δ S1＜Δset1When the fault occurs, the fault occurs outside the L1 area, and the corresponding protection does not act;
will be Delta S2And deltaset2Comparing, judging the fault inside and outside the L2 area, if delta S2≥Δset2If so, a fault occurs in the line L2 area; on the contrary, if Δ S2＜Δset2If so, a fault occurs outside the zone of the line L2, and the corresponding protection does not act.
7. The pilot differential protection method for the multi-terminal hybrid direct-current transmission line according to claim 3, wherein the line-mode components of the fault transient currents on the two ends of the line L1 and the line L2 are respectively calculated to be integrated within 20ms, and the formula is as follows:
in the formula P1、P2、P3、P4Integral of each end current linear modulus component within 20ms, i, for protection 1, protection 2, protection 3 and protection 4 respectively1(t)、i2(t) i.e. the current line mode component i at the two ends of the line L1 measured by the protection 1, protection 2 measuring device3(t)、i4(t) the current line mode components at the two ends of the line L2 measured by the protection 3 and protection 4 measuring devices;
wherein, protection 1 and protection 2 are respectively arranged at two ends of the line L1, protection 3 and protection 4 are respectively arranged at two ends of the line L2, and the corresponding protection action result is to pull open the corresponding fast disconnecting switch.
8. The pilot differential protection method for the multi-terminal hybrid direct-current transmission line according to claim 4, wherein the sum of the 20ms integral values of the mode components of the fault transient current lines at the two ends of the line L1 and the line L2 is calculated respectively, and the calculation formula is as follows:
9. the longitudinal differential protection method of the multi-terminal hybrid direct-current transmission line according to claim 5, wherein the setting value delta of the line L1 protectionset1Setting value delta of and line L2 protectionset2The calculation formula of (2) is as follows:
Δset1＝kreltwIset1
Δset2＝kreltwIset2
in the formula krel＝1.2、tw＝20ms、Iset1＝0.1IL1.1、Iset2＝0.1IL2.1；IL1.1、IL2.1The current line mode components for normal operation of line L1 and line L2, respectively.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114062846A (en) * | 2021-11-12 | 2022-02-18 | 昆明理工大学 | Alternating current transmission line protection method and system |
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