CN113241743B - Longitudinal differential protection method for multi-terminal hybrid direct current transmission line - Google Patents
Longitudinal differential protection method for multi-terminal hybrid direct current transmission line Download PDFInfo
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- CN113241743B CN113241743B CN202110617492.9A CN202110617492A CN113241743B CN 113241743 B CN113241743 B CN 113241743B CN 202110617492 A CN202110617492 A CN 202110617492A CN 113241743 B CN113241743 B CN 113241743B
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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 longitudinal differential protection method of a multi-terminal hybrid direct current transmission line, which comprises the following steps: collecting transient current linear module components of faults at two ends of each line; calculating the integral value of line mode components of fault transient currents at two ends of each line within 20 ms; calculating the sum of integrated values of the transient current linear modular components of faults at the two ends of each line in 20 ms; calculating the 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 larger than the setting value, generating faults in the line area, and performing corresponding protection actions; if the sum of the integral values is smaller than the setting value, the line area is out of order, and the corresponding protection is not operated. According to the invention, only the line mode component of the fault transient current at two ends of the line is calculated and integrated within 20ms, so that 20ms fault criterion delay is provided, and compared with the traditional differential protection, the action time of the protection is greatly reduced; the method has the advantages of strong transition resistance, strong anti-interference capability and lower communication requirement.
Description
Technical Field
The application relates to the technical field of relay protection, in particular to a longitudinal differential protection method of a multi-terminal hybrid direct current transmission line.
Background
With the development of high-voltage direct current, multi-terminal hybrid direct current transmission combines the advantages of flexible direct current and conventional direct current transmission, and more conventional direct current engineering has the need of upgrading and reconstruction. The multi-terminal hybrid direct current transmission power supply distance is long, the probability of faults of the direct current line is greatly increased, the rapid detection of faults of the direct current line and the isolation of the fault line are important points of research on multi-terminal hybrid direct current line protection, and the multi-terminal hybrid direct current transmission system is also a problem to be solved urgently.
At present, protection adopted by a multi-terminal hybrid direct current transmission system mainly comprises traveling wave protection and longitudinal current differential protection, and when the traveling wave protection is in high-resistance grounding or fault position far away from the protection installation position, the protection has a refusal action condition; the current differential protection requires an operation time to be operated after the occurrence of a fault, and cannot exert its function.
Therefore, the longitudinal differential protection method for the multi-terminal hybrid direct current transmission line, which has 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-terminal hybrid direct current transmission line, which greatly reduces the action time of protection compared with the traditional differential protection.
The technical scheme adopted by the application is as follows:
the invention provides a longitudinal differential protection method of a multi-terminal hybrid direct current transmission line, which comprises the following steps:
collecting transient current linear module components of faults at two ends of each line;
calculating the integral value of line mode components of fault transient currents at two ends of each line within 20 ms;
calculating the sum of integrated values of the transient current linear modular components of faults at the two ends of each line in 20 ms;
calculating the setting value of each line protection;
comparing the sum of the integral values with the setting value, if the sum of the integral values is larger than the setting value, generating faults in the line area, and performing corresponding protection actions;
if the sum of the integral values is smaller than the setting value, the line area is out of order, and the corresponding protection is not operated.
Further, collecting transient current modulus components of faults at two ends, comprising:
and respectively collecting transient current linear modulus components of faults at two ends of the line L1 and the line L2.
Further, calculating a line mode component integrated value of fault transient currents at two ends of the line within 20ms comprises:
the line mode components of the fault transient currents at both ends of the line L1 and the line L2 are calculated respectively and integrated within 20 ms.
Further, calculating a sum of integrated values of line modulus components of fault transient currents at two ends of the line at 20ms includes:
calculating the sum of integral values of the fault transient current linear mode components at the two ends of the line L1 and the line L2 in 20ms respectively, wherein the sum of integral values of the fault transient current linear mode components at the two ends of the line L1 in 20ms is recorded as delta S 1 The sum of the integrated values of the line modulus components of the transient current of faults at the two ends of the line L2 in 20ms is delta S 2 。
Further, calculating a setting value of line protection includes:
calculating the setting value delta of the protection of the line L1 set1 And the setting value delta of the line L2 protection set2 。
Further, comparing the sum of the integral values with the setting value, if the sum of the integral values is larger than the setting value, generating faults in the line area, and performing corresponding protection actions; if the sum of the integral values is smaller than the setting value, the line area is out of order, and the corresponding protection is not operated, including:
will delta S 1 And delta set1 Comparing, judging the faults inside and outside the area of the line L1, if delta S 1 ≥Δ set1 If a fault occurs in the area of the line L1, the line L1 is protected, otherwise, if DeltaS 1 ＜Δ set1 When the circuit L1 fails outside the area, the corresponding protection does not act; and
will delta S 2 And delta set2 Comparing, judging the faults inside and outside the L2 area of the line, if delta S 2 ≥Δ set2 When the fault occurs in the line L2 area; conversely, if DeltaS 2 ＜Δ set2 And if the fault occurs outside the area of the line L2, the corresponding protection does not act.
Further, the integrated value of the line mode component of the fault transient current at the two ends of the line L1 and the line L2 in 20ms is calculated respectively, and the formula is as follows:
p in the formula 1 、P 2 、P 3 、P 4 Integration of current modulus components of each end in 20ms for protection 1, protection 2, protection 3 and protection 4 respectively, i 1 (t)、i 2 (t) the current linear mode components, i of the two ends of the line L1 measured by the protection 1 and protection 2 measuring devices 3 (t)、i 4 (t) protecting 3 and 4 the current linear mode components at two ends of the line L2 measured by the measuring device;
the protection 1 and the protection 2 are respectively arranged at two ends of the line L1, the protection 3 and the protection 4 are respectively arranged at two ends of the line L2, and the corresponding protection action results are that the corresponding quick isolating switch is pulled open.
Further, the sum of integrated values of the transient current linear components at the two ends of the line L1 and the line L2 at 20ms is calculated respectively, and the calculation formula is as follows:
further, the setting value delta of the line L1 protection set1 And the setting value delta of the line L2 protection set2 The calculation formula of (2) is as follows:
Δ set1 ＝k rel t w I set1
Δ set2 ＝k rel t w I set2
k in rel ＝1.2、t w ＝20ms、I set1 ＝0.1I L1.1 、I set2 ＝0.1I L2.1 ；I L1.1 、I L2.1 The current modulus components during normal operation of lines L1 and L2, respectively.
The technical scheme of the application has the following beneficial effects:
according to the longitudinal differential protection method for the multi-terminal hybrid direct current transmission line, only the line mode component of fault transient current at two ends of the line is calculated to integrate value within 20ms, so that 20ms fault criterion delay is achieved, and compared with the traditional differential protection, the action time of the protection is greatly reduced;
the method has the advantages of strong transition resistance, strong anti-interference capability and lower communication requirement.
Drawings
In order to more clearly illustrate the technical solutions of the present application, the drawings that are needed in the embodiments will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.
Fig. 1 is a flowchart of a longitudinal differential protection method of a multi-terminal hybrid dc transmission line according to an embodiment of the present invention;
fig. 2 is a multi-terminal hybrid dc power transmission topological diagram of a longitudinal differential protection method for a multi-terminal hybrid dc power transmission line according to an embodiment of the present invention (protection devices are installed on each section of line, protection 1 and protection 2 are installed at the end-to-end ends of line L1, and protection 3 and protection 4 are installed at the end-to-end ends of line L2).
Detailed Description
Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The embodiments described in the examples below do not represent all embodiments consistent with the present application. Merely as examples of systems and methods consistent with some aspects of the present application as detailed in the claims.
See fig. 1 and 2.
The longitudinal differential protection method of the multi-terminal hybrid direct current transmission line comprises the following steps:
s01: collecting transient current linear module components of faults at two ends of each line;
in this embodiment, the transient current linear mode components of the faults at the two ends of the line L1 and the line L2 are collected respectively.
S02: calculating the integral value of line mode components of fault transient currents at two ends of each line within 20 ms;
in this embodiment, the line mode component of the fault transient current across line L1 and line L2 is calculated as an integrated value within 20ms, respectively.
The calculation formula is as follows:
p in the formula 1 、P 2 、P 3 、P 4 Integration of current modulus components of each end in 20ms for protection 1, protection 2, protection 3 and protection 4 respectively, i 1 (t)、i 2 (t) the current linear mode components, i of the two ends of the line L1 measured by the protection 1 and protection 2 measuring devices 3 (t)、i 4 (t) protecting 3 and 4 the current linear mode components at two ends of the line L2 measured by the measuring device;
the protection 1 and the protection 2 are respectively arranged at two ends of the line L1, the protection 3 and the protection 4 are respectively arranged at two ends of the line L2, and the corresponding protection action results are that the corresponding quick isolating switch is pulled open.
S03: calculating the sum of integrated values of the transient current linear modular components of faults at the two ends of each line in 20 ms;
in the present embodiment, the sum of the integrated values of the fault transient current linear mode components at the two ends of the line L1 and the line L2 at 20ms is calculated, respectively, wherein the sum of the integrated values of the fault transient current linear mode components at the two ends of the line L1 at 20ms is Δs 1 The sum of the integrated values of the line modulus components of the transient current of faults at the two ends of the line L2 in 20ms is delta S 2 。
The calculation formula is as follows:
s04: calculating the setting value of each line protection;
in the present embodiment, the setting value Δ of the line L1 protection is calculated set1 And the setting value delta of the line L2 protection set2 Wherein delta is set1 、Δ set2 The physical meaning is the integral value of 0.1 times of the difference value of the current modulus components at the two ends of the line within 20ms in normal operation.
Setting value delta of line L1 protection set1 And the setting value delta of the line L2 protection set2 The calculation formula of (2) is as follows:
Δ set1 ＝k rel t w I set1
Δ set2 ＝k rel t w I set2
k in rel ＝1.2、t w ＝20ms、I set1 ＝0.1I L1.1 、I set2 ＝0.1I L2.1 ；I L1.1 、I L2.1 The current modulus components during normal operation of lines L1 and L2, respectively.
S05: comparing the sum of the integral values with a setting value, if the sum of the integral values is larger than the setting value, generating faults in the line area, and informing other converter stations through communication according to corresponding protection actions; if the sum of the integral values is smaller than the setting value, the line area is out of order, and the corresponding protection is not operated.
In the present embodiment, ΔS is 1 And delta set1 Comparing, judging the faults inside and outside the area of the line L1, if delta S 1 ≥Δ set1 If a fault occurs in the area of the line L1, the line L1 is protected, otherwise, if DeltaS 1 ＜Δ set1 When the circuit L1 fails outside the area, the corresponding protection does not act;
will delta S 2 And delta set2 Comparing, judging the faults inside and outside the L2 area of the line, if delta S 2 ≥Δ set2 When the fault occurs in the line L2 area; conversely, if DeltaS 2 ＜Δ set2 When the line L2 fails, the corresponding protection is not movedAnd (3) doing so.
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 misoperation caused by reverse fault, and is concretely as follows: when a certain line fails, the protection of the failed line should act correctly, and the non-failed line does not act, for example, when the line L2 fails, the protection of the line L2 acts, and the protection of the line L1 does not act;
(2) The method only needs 20ms fault criterion delay, and compared with the traditional differential protection, the method greatly reduces the action time of the protection;
(3) The method of the invention has strong transitional resistance capability, strong anti-interference capability and lower communication requirement, and specifically: the protection can still act correctly when the high resistance is grounded. Anti-interference: when in fault, the fault signal is collected and has noise and other interference factors, and the protection method has strong interference resistance. Furthermore, because the longitudinal protection is adopted, the electric information interaction at the two ends of the line is required, and the requirement on the information interaction synchronism is low.
The foregoing detailed description of the embodiments is merely illustrative of the general principles of the present application and should not be taken in any way as limiting the scope of the invention. Any other embodiments developed in accordance with the present application without inventive effort are within the scope of the present application for those skilled in the art.
Claims (9)
1. A longitudinal differential protection method of a multi-terminal hybrid direct current transmission line is characterized by comprising the following steps:
collecting transient current linear module components of faults at two ends of each line;
calculating the integral value of line mode components of fault transient currents at two ends of each line within 20 ms;
calculating the sum of integrated values of the transient current linear modular components of faults at the two ends of each line in 20 ms;
calculating the setting value of each line protection;
comparing the sum of the integral values with the setting value, if the sum of the integral values is larger than the setting value, generating faults in the line area, and performing corresponding protection actions; and
if the sum of the integral values is smaller than the setting value, the line area is out of order, and the corresponding protection is not operated.
2. The method for longitudinal differential protection of a multi-terminal hybrid direct current transmission line according to claim 1, wherein collecting transient current linear mode components of faults at both ends comprises:
and respectively collecting transient current linear modulus components of faults at two ends of the line L1 and the line L2.
3. The method for longitudinal differential protection of a multi-terminal hybrid direct current transmission line according to claim 2, wherein calculating the line mode component of the fault transient current at both ends of the line integrates the value within 20ms, comprises:
the line mode components of the fault transient currents at both ends of the line L1 and the line L2 are calculated respectively and integrated within 20 ms.
4. A method of longitudinal differential protection of a multi-terminal hybrid direct current transmission line according to claim 3, wherein calculating the sum of integrated values of the line two-terminal fault transient current modulus components at 20ms comprises:
calculating the sum of integral values of the fault transient current linear mode components at the two ends of the line L1 and the line L2 in 20ms respectively, wherein the sum of integral values of the fault transient current linear mode components at the two ends of the line L1 in 20ms is recorded as delta S 1 The sum of the integrated values of the line modulus components of the transient current of faults at the two ends of the line L2 in 20ms is delta S 2 。
5. The method for longitudinal differential protection of a multi-terminal hybrid direct current transmission line according to claim 4, wherein calculating a setting value of line protection comprises:
calculating the setting value delta of the protection of the line L1 set1 And the setting value delta of the line L2 protection set2 。
6. The longitudinal differential protection method for a multi-terminal hybrid direct current transmission line according to claim 5, wherein the sum of the integral values is compared with the setting value, and if the sum of the integral values is greater than the setting value, a fault occurs in the line area, and a corresponding protection action occurs; if the sum of the integral values is smaller than the setting value, the line area is out of order, and the corresponding protection is not operated, including:
will delta S 1 And delta set1 Comparing, judging the faults inside and outside the area of the line L1, if delta S 1 ≥Δ set1 If a fault occurs in the area of the line L1, the line L1 is protected, otherwise, if DeltaS 1 ＜Δ set1 When the circuit L1 fails outside the area, the corresponding protection does not act;
will delta S 2 And delta set2 Comparing, judging the faults inside and outside the L2 area of the line, if delta S 2 ≥Δ set2 When the fault occurs in the line L2 area; conversely, if DeltaS 2 ＜Δ set2 And if the fault occurs outside the area of the line L2, the corresponding protection does not act.
7. The method for longitudinal differential protection of a multi-terminal hybrid direct current transmission line according to claim 3, wherein the integrated values of the line mode components of the fault transient currents at both ends of the line L1 and the line L2 within 20ms are calculated respectively, and the formula is:
p in the formula 1 、P 2 、P 3 、P 4 Integration of current modulus components of each end in 20ms for protection 1, protection 2, protection 3 and protection 4 respectively, i 1 (t)、i 2 (t) the current linear mode components, i of the two ends of the line L1 measured by the protection 1 and protection 2 measuring devices 3 (t)、i 4 (t) protecting 3 and 4 the current linear mode components at two ends of the line L2 measured by the measuring device;
the protection 1 and the protection 2 are respectively arranged at two ends of the line L1, the protection 3 and the protection 4 are respectively arranged at two ends of the line L2, and the corresponding protection action results are that the corresponding quick isolating switch is pulled open.
8. The longitudinal differential protection method of a multi-terminal hybrid direct current transmission line according to claim 4, wherein the sum of integrated values of transient current linear components at two ends of the line L1 and the line L2 at 20ms is calculated respectively, and the calculation formula is as follows:
9. the method for longitudinal differential protection of a multi-terminal hybrid direct current transmission line according to claim 5, wherein the setting value Δ of the line L1 protection is set1 And the setting value delta of the line L2 protection set2 The calculation formula of (2) is as follows:
Δ set1 ＝k rel t w I set1
Δ set2 ＝k rel t w I set2
k in rel ＝1.2、t w ＝20ms、I set1 ＝0.1I L1.1 、I set2 ＝0.1I L2.1 ；I L1.1 、I L2.1 The current modulus components during normal operation of lines L1 and L2, respectively.
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| CN102510050A (en) * | 2011-11-08 | 2012-06-20 | 西安交通大学 | Pilot protection method for direct current line current abrupt change of multi-terminal direct current transmission system |
| CN108092244A (en) * | 2017-12-15 | 2018-05-29 | 华南理工大学 | A kind of common-tower double-return HVDC transmission line traveling-wave protection method |
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| WO2014121438A1 (en) * | 2013-02-05 | 2014-08-14 | Alstom Technology Ltd. | Method and apparatus for current differential protection for uhvdc transmission line |
| CN110380390B (en) * | 2019-07-22 | 2021-05-14 | 西南交通大学 | High-voltage direct-current transmission line protection method based on traveling wave waveform similarity |
| CN110880778A (en) * | 2019-11-01 | 2020-03-13 | 天津大学 | Improved nonlinear droop control method for multi-terminal flexible direct-current power transmission system |
| CN111463764B (en) * | 2020-05-14 | 2021-02-23 | 山东大学 | Direct-current transmission line protection method based on initial voltage traveling wave frequency domain attenuation rate |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102510050A (en) * | 2011-11-08 | 2012-06-20 | 西安交通大学 | Pilot protection method for direct current line current abrupt change of multi-terminal direct current transmission system |
| CN108092244A (en) * | 2017-12-15 | 2018-05-29 | 华南理工大学 | A kind of common-tower double-return HVDC transmission line traveling-wave protection method |
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