CN106602523A - Zero-sequence current differential phase selection element - Google Patents
Zero-sequence current differential phase selection element Download PDFInfo
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- CN106602523A CN106602523A CN201510665416.XA CN201510665416A CN106602523A CN 106602523 A CN106602523 A CN 106602523A CN 201510665416 A CN201510665416 A CN 201510665416A CN 106602523 A CN106602523 A CN 106602523A
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- 238000004088 simulation Methods 0.000 description 13
- 238000010586 diagram Methods 0.000 description 10
- 230000009471 action Effects 0.000 description 7
- 230000005540 biological transmission Effects 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 230000016507 interphase Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
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Classifications
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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
- H02H7/267—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 parallel lines and wires
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- Emergency Protection Circuit Devices (AREA)
Abstract
The invention relates to a zero-sequence current differential phase selection element, which comprises a phase selection criterion I, a phase selection criterion II and a phase selection criterion III, wherein the phase selection criterion I is used for distinguishing a single-phase ground fault phase from a two-phase ground fault phase; the phase selection criterion II is used for distinguishing a single-phase ground fault phase from a two-phase metallic ground fault phase; the phase selection criterion III is used for preventing external three-phase short circuit unbalanced zero sequence; and the phase selection criterion I, the phase selection criterion II and the phase selection criterion III output via an AND gate, and output the single-phase ground fault phase. The zero-sequence current differential phase selection element provided by the technical scheme of the invention has sensitivity higher than zero-sequence differential protection, is not affected by load current, can select the fault phase precisely in the case of a single-phase high resistance ground fault, cooperates with zero-sequence differential protection in use, can realize zero-sequence differential protection phase selection tripping in the case of the single-phase high resistance ground fault, and prevents the occurrence of three-phase tripping condition upon minor faults.
Description
The technical field is as follows:
the invention relates to the field of relay protection of power systems, in particular to a zero-sequence current differential phase selection element.
Background art:
the zero-sequence current differential protection is an important transmission line protection, and is used for cutting off a single-phase high-resistance grounding fault of a transmission line, but the zero-sequence current differential protection does not have a phase selection function and needs a phase selection element to be matched with the phase selection element to realize phase-splitting tripping.
In order to solve the problems, the invention provides a phase selection element for zero-sequence current differential protection.
The invention content is as follows:
the invention aims to provide a zero-sequence current differential phase selection element which can realize zero-difference protection phase selection tripping in single-phase high-resistance earth fault and prevent the occurrence of three-phase tripping in slight fault of zero-difference protection.
In order to achieve the purpose, the invention adopts the following technical scheme: a zero sequence current differential phase selection element comprises a phase selection criterion I for distinguishing a single-phase earth fault phase from a two-phase earth fault phase, a phase selection criterion II for distinguishing a single-phase earth fault phase from a two-phase metallic earth fault phase and a phase selection criterion III for preventing three-phase short circuit unbalance zero sequence outside a region; and the output of the AND gate among the phase selection criterion I, the phase selection criterion II and the phase selection criterion III outputs a single-phase earth fault phase.
And the phase selection criterion I is determined by utilizing the amplitude relation of the negative sequence differential current and the zero sequence differential current.
The phase selection criterion I is determined by the following formula:
wherein,is composed ofThe negative-sequence current is conducted on the two sides of the phase line, is a zero sequence current at two sides of the line,
and the phase selection criterion II is determined by utilizing the phase relation between the positive sequence differential current and the negative sequence differential current.
The phase selection criterion II is determined by the following formula:
wherein,is composed ofPositive sequence current on two sides of phase line
The phase selection criterion III is determined by a low braking coefficient differential criterion.
The phase selection criterion III is determined by the following formula:
wherein, the first and second guide rollers are arranged in a row,are respectively two sides of the circuitThe phase current is supplied to the phase current,is composed ofThe corresponding current phasor is calculated from the current phasor,is composed ofCorresponding current phasor (if
When a single-phase earth fault occurs, the fault phaseMeeting the phase selection criterion I; when the two-phase ground fault occurs, the fault state of the two-phase ground fault occurs,the phase selection criterion I is not fulfilled.
When a single-phase earth fault occurs, the fault phaseMeeting the phase selection criterion II; non-faulted phases when two phases are metallically earthedThe phase selection criterion II is not satisfied.
And when the criteria I, II and III are all met, outputting a single-phase earth fault phase.
Compared with the closest prior art, the technical scheme provided by the invention has the following excellent effects
1. The sensitivity of the zero-difference protection phase selection element provided by the technical scheme of the invention is higher than that of zero-sequence current differential protection, the zero-difference protection phase selection element is not influenced by load current, and a fault phase can still be accurately selected when a single-phase high-resistance earth fault occurs and is matched with the zero-difference protection for use;
2. the technical scheme of the invention can more reliably protect the important power transmission line and is used for removing the single-phase high-resistance grounding fault of the power transmission line;
3. the technical scheme of the invention improves the action performance of zero-sequence current differential protection of the line.
Drawings
FIG. 1 is a logic diagram of the operation of phase selection components according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a fault line according to an embodiment of the present invention;
fig. 3 is a schematic diagram of sampling values of three-phase currents on two sides of a line MN in embodiment 1 of the present invention;
FIG. 4 is a schematic diagram of a simulation result of criterion I in embodiment 1 of the present invention;
FIG. 5 is a schematic diagram of a simulation result of criterion II in embodiment 1 of the present invention;
FIG. 6 is a schematic diagram of a simulation result of criterion III in embodiment 1 of the present invention;
fig. 7 is a schematic diagram of sampling values of three-phase currents on two sides of a line MN in embodiment 2 of the present invention;
FIG. 8 is a schematic diagram of a simulation result of criterion I in embodiment 2 of the present invention;
FIG. 9 is a schematic diagram of a simulation result of criterion II in embodiment 2 of the present invention;
fig. 10 is a schematic diagram of a simulation result of criterion III in embodiment 2 of the present invention.
Detailed Description
The invention of this example provides a zero sequence current differential phase selection element, which is composed of three parts, as shown in fig. 1:
(1) and distinguishing a single-phase earth fault phase from a two-phase earth fault phase by using the principle that the negative sequence current differential current is similar to the zero sequence current differential current. The phase selection criterion I is as follows:
(2) and distinguishing a single-phase earth fault phase from a two-phase metallic earth fault phase by using the phase relation between the positive sequence differential current and the negative sequence differential current. Phase selection criterion II is as follows:
(3) and a low braking coefficient differential criterion is used for judging three-phase short circuit unbalanced zero-sequence current outside a defense area. The phase selection criterion III is as follows:
and gate output is performed among the criteria I, II and III, and a single-phase earth fault phase is output.
In case of single-phase earth fault, fault phaseWhen the criterion I is met and two-phase high-resistance earth fault is caused,the criterion I is not satisfied.
In case of single-phase earth fault, fault phaseMeeting criterion II, non-faulted phase when two-phase metallic earthingThe criterion II is not satisfied.
With a fault at F1 at the point in the line MN of figure 2, the system voltage class is 1000kV and the line length is 200km, the protection is installed at 1 and 2 in the figure.
(1) Three-phase current at acquisition protection 1 and 2Calculating a difference flow The value is A, B, C. Calculating the positive, negative and zero sequence difference flows respectively
(2) The calculation of the criteria 1 is carried out,
(3) the calculation of the criterion 2 is carried out,
(4) the calculation of the criterion 3 is carried out,wherein
(5) When the criteria I, II and III are simultaneously satisfied, the phase is judged to be a single-phase earth fault phase
(6) Simulation verification:
example 1:
1) phase A via 800 omega transition resistance ground fault
Fig. 3 is sampled values of three-phase currents on two sides of a line MN, and it can be seen that the current change degree is small when a transition resistance fault occurs through 800.
The simulation result of the criterion I is shown in FIG. 4, the criterion 1 utilizes the amplitude relationship between the negative sequence current differential current and the zero sequence differential current, the solid line in the figure is a fixed value curve, the dotted solid line is a three-phase action curve, and thus, the A phase meets the criterion I.
The simulation result of criterion II is shown in fig. 5, and criterion 2 selects a phase using the phase relationship between the positive sequence differential current and the negative sequence differential current, where straight lines in the figure are constant value curves of 45 ° and 75 ° respectively, and a dotted solid line is a three-phase action curve, and it can be seen that phase a satisfies criterion II.
The simulation result of criterion III is shown in FIG. 6, in which the solid line is a braking curve and the dotted solid line is a three-phase action curve, and as shown in the figure, phase A meets criterion III.
And outputting the criteria I, II and III through an AND gate to output a phase A of the single-phase earth fault.
Example 2:
2) BC phase inter-phase fault through 25 omega transition resistance
Fig. 7 shows three-phase current sampling values on two sides of a BC-phase inter-phase fault line MN through a 25 omega transition resistor.
The simulation result of the criterion I is shown in FIG. 8, the criterion 1 utilizes the amplitude relationship between the negative sequence current differential current and the zero sequence differential current, the solid line in the figure is a fixed value curve, the dotted solid line is a three-phase action curve, and therefore, A, B, C three phases do not meet the criterion I.
The simulation result of criterion II is shown in FIG. 9, criterion 2 selects phases by using the phase relation between the positive sequence differential current and the negative sequence differential current, straight lines in the figure are constant value curves of 45 degrees and 75 degrees respectively, a dotted solid line is a three-phase action curve, and B, C phases meet criterion II;
the simulation result of the criterion III is shown in FIG. 10, in which the solid line is a braking curve and the dotted solid line is a three-phase action curve, and as shown in the figure, B, C phases meet the criterion in a part of time period.
The criteria I, II and III are output through an AND gate, and the single-phase grounding phase selection output is not satisfied.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and those skilled in the art should understand that although the above embodiments are referred to: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is set forth in the claims below.
Claims (9)
1. A zero sequence current differential phase selection element, characterized by: the method comprises a phase selection criterion I for distinguishing a single-phase earth fault phase from a two-phase high-resistance earth fault phase, a phase selection criterion II for distinguishing a single-phase earth fault phase from a two-phase metallic earth fault phase and a phase selection criterion III for preventing three-phase short circuit unbalance zero sequence outside a region; and the output of the AND gate among the phase selection criterion I, the phase selection criterion II and the phase selection criterion III outputs a single-phase earth fault phase.
2. A zero sequence current differential phase selection element as claimed in claim 1, characterized in that: and the phase selection criterion I is determined by utilizing the amplitude relation of the negative sequence differential current and the zero sequence differential current.
3. A zero sequence current differential phase selection element as claimed in claim 2, characterized in that: the phase selection criterion I is determined by the following formula:
wherein,is composed ofThe negative-sequence current is conducted on the two sides of the phase line, is a zero sequence current at two sides of the line,
4. a zero sequence current differential phase selection element as claimed in claim 1, characterized in that: and the phase selection criterion II is determined by utilizing the phase relation between the positive sequence differential current and the negative sequence differential current.
5. A zero sequence current differential phase selection element as claimed in claim 4, characterized in that: the phase selection criterion II is determined by the following formula:
wherein,is composed ofAnd positive sequence currents are arranged at two sides of the phase line.
6. A zero sequence current differential phase selection element as claimed in claim 1, characterized in that: the phase selection criterion III is determined by a low braking coefficient differential criterion.
7. A zero sequence current differential phase selection element as claimed in claim 6, characterized in that: the phase selection criterion III is determined by the following formula:
wherein,are respectively two sides of the circuitThe phase current is supplied to the phase current,is composed ofThe corresponding current phasor is calculated from the current phasor,is composed ofCorresponding current phasor, ifThen
8. A zero sequence current differential phase selection element as claimed in claim 3, characterized in that: when a single-phase earth fault occurs, the fault phaseMeeting the phase selection criterion I; when the two-phase high-resistance earth fault occurs,the phase selection criterion I is not fulfilled.
9. A zero sequence current differential phase selection element as claimed in claim 5, characterized in that: when a single-phase earth fault occurs, the fault phaseMeeting the phase selection criterion II; non-faulted phases when two phases are metallically earthedThe phase selection criterion II is not satisfied.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110703134A (en) * | 2019-10-15 | 2020-01-17 | 南京国电南自电网自动化有限公司 | Small current grounding line selection and phase selection method based on fault sequence component |
| CN113410823A (en) * | 2021-05-12 | 2021-09-17 | 北京四方继保工程技术有限公司 | Zero-sequence current differential protection phase selection method free from load influence |
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| CN101814730A (en) * | 2009-04-15 | 2010-08-25 | 河南省电力公司 | Fault phase selection method of double transmission line protection on the same pole |
| CN102769279A (en) * | 2012-07-23 | 2012-11-07 | 国电南瑞科技股份有限公司 | High-resistance grounding phase selection method for longitudinal zero-sequence protection of line protection device |
| CN103207346A (en) * | 2013-03-13 | 2013-07-17 | 福建省电力有限公司 | Power transmission line fault phase selection method |
| CN103368151A (en) * | 2013-06-18 | 2013-10-23 | 国家电网公司 | Method of realizing line-to-ground fault phase selection by using sequence voltage phase characteristic |
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2015
- 2015-10-15 CN CN201510665416.XA patent/CN106602523B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101038316A (en) * | 2007-04-23 | 2007-09-19 | 国电南京自动化股份有限公司 | Circuit protection order component phase selectiing method using both end information |
| CN101814730A (en) * | 2009-04-15 | 2010-08-25 | 河南省电力公司 | Fault phase selection method of double transmission line protection on the same pole |
| CN102769279A (en) * | 2012-07-23 | 2012-11-07 | 国电南瑞科技股份有限公司 | High-resistance grounding phase selection method for longitudinal zero-sequence protection of line protection device |
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| CN110703134A (en) * | 2019-10-15 | 2020-01-17 | 南京国电南自电网自动化有限公司 | Small current grounding line selection and phase selection method based on fault sequence component |
| CN110703134B (en) * | 2019-10-15 | 2022-02-15 | 南京国电南自电网自动化有限公司 | Small current grounding line selection and phase selection method based on fault sequence component |
| CN113410823A (en) * | 2021-05-12 | 2021-09-17 | 北京四方继保工程技术有限公司 | Zero-sequence current differential protection phase selection method free from load influence |
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