CN108594044B - Generator-side circuit breaker ground capacitor fault identification method and device - Google Patents
Generator-side circuit breaker ground capacitor fault identification method and device Download PDFInfo
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- CN108594044B CN108594044B CN201810465993.8A CN201810465993A CN108594044B CN 108594044 B CN108594044 B CN 108594044B CN 201810465993 A CN201810465993 A CN 201810465993A CN 108594044 B CN108594044 B CN 108594044B
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Abstract
The invention discloses a method and a device for identifying faults of a ground capacitor of a generator-end breaker, wherein the method comprises the following steps: collecting the voltage of the stator side at the generator end; setting the lowest phase of the voltage to earth voltage as a fault phase according to a voltage acquisition result, and calculating the voltage to earth voltage of the fault, the zero sequence voltage of a stator side voltage generator stator to earth and the electromotive force of the fault phase; setting a phase difference threshold range, and comparing the phase relation between the fault phase electromotive force and the stator-to-ground zero sequence voltage: if the phase difference of the fault phase electromotive force leading stator to the ground zero sequence voltage is within the range of the phase difference threshold value, the fault is judged to be the fault of the ground capacitor of the circuit breaker at the machine end, otherwise, the fault is the fault of the ground capacitor of the circuit breaker at the non-machine end. The invention can reliably identify the fault type when the ground fault occurs to the ground capacitor of the extreme circuit breaker of the generator, reduce the fault troubleshooting range of users and improve the fault troubleshooting efficiency.
Description
Technical Field
The invention relates to the technical field of relay protection of a power system, in particular to a method and a device for identifying faults of a ground capacitor of a generator-end circuit breaker.
Background
The large-scale generator generally adopts a mode that a neutral point is grounded and becomes grounded, and R is satisfiedN≤XCWherein R isNFor converting the grounding into a resistance value, X, converted from a secondary load resistance to a primary oneCThe capacitive reactance is the generator stator winding to the ground. For the machine set meeting the above conditions, no matter the stator single-phase grounding and machine end occurThe PT primary winding turn-to-turn short circuit or the ground capacitor fault of the terminal circuit breaker meets the condition that the voltage of the stator winding fault is lowest relative to the ground voltage. However, there is no method for reliably identifying the fault of the ground capacitor of the generator-side circuit breaker, and a user has a wide search range and consumes much time when searching for a fault point, so there is a need to research a method and a device for correctly identifying the fault of the ground capacitor of the generator-side circuit breaker.
Disclosure of Invention
The invention aims to provide a method and a device for identifying faults of a ground capacitor of a generator-end circuit breaker, which can reliably identify the fault type when the ground capacitor of the generator-end circuit breaker has ground faults, reduce the fault troubleshooting range of a user and improve the fault troubleshooting efficiency.
The technical scheme adopted by the invention is as follows: a generator end circuit breaker-to-ground capacitor fault identification method comprises the following steps:
s1, collecting the voltage of the stator side at the generator end;
s2, setting the lowest phase of the voltage to ground as a fault phase according to the voltage acquisition result of S1, and calculating the voltage to ground of the fault, the zero sequence voltage of the stator-to-ground of the voltage generator at the stator side and the electromotive force of the fault phase;
s3, setting a phase difference threshold range; and according to the calculation result of S2, comparing the phase relation between the fault phase electromotive force and the stator-to-ground zero sequence voltage: if the phase difference of the fault phase electromotive force leading stator to the ground zero sequence voltage is within the range of the phase difference threshold value, the fault is judged to be the fault of the ground capacitor of the circuit breaker at the machine end, otherwise, the fault is the fault of the ground capacitor of the circuit breaker at the non-machine end.
Further, the method also comprises S4, and according to the judgment result of S3, when the fault type is the ground capacitor fault of the generator-side circuit breaker, the protection device is controlled to act on an alarm or trip after a set time delay t.
Preferably, in S4, the set delay time t is a value within a range of 0.1 to 10S.
Preferably, in S2, the stator-side voltage generator stator-to-ground zero-sequence voltage is a generator terminal PT open-delta zero-sequence voltage.
As another specific embodiment, in S2, the stator-to-ground zero-sequence voltage of the stator-side voltage generator is the self-generated zero-sequence voltage at the generator terminal PT.
Preferably, the generator terminal PT self-generates zero sequence voltage
Is as follows;
wherein the content of the first and second substances,
for the voltage of the generator terminal a relative to ground,
to the voltage of the generator terminal B with respect to ground,
and the voltage of the generator terminal C is relatively grounded.
Preferably, the generator fault phase electromotive force
Is as follows;
wherein the content of the first and second substances,
in order for a generator fault to be at voltage relative to ground,
is the generator stator to ground zero sequence voltage.
Preferably, in S3, the phase difference threshold range is 90-180 degrees.
The invention also discloses a generator end circuit breaker ground capacitor fault recognition device, which comprises:
the sampling module is used for collecting the voltage of the stator side at the generator end;
the calculation module is used for setting the lowest phase of the voltage to earth as a fault phase according to a voltage acquisition result of the stator side at the generator end, and calculating the voltage to earth of the fault, the voltage to earth zero sequence voltage of the generator stator at the stator side and the electromotive force of the fault phase;
the fault identification module is used for setting a phase difference threshold range; and according to the calculation result of S2, comparing the phase relation between the fault phase electromotive force and the stator-to-ground zero sequence voltage: if the phase difference of the fault phase electromotive force leading stator to the ground zero sequence voltage is within the range of the phase difference threshold value, the fault is judged to be the fault of the ground capacitor of the circuit breaker at the machine end, otherwise, the fault is the fault of the ground capacitor of the circuit breaker at the non-machine end.
Further, the generator-side circuit breaker ground capacitor fault recognition device further comprises a protection action control module, and the protection action control module controls the protection device to act on alarming or tripping after a set time delay t when the fault type is the ground capacitor fault of the generator-side circuit breaker according to the judgment result of the fault recognition module.
Advantageous effects
The method can judge and identify the ground fault of the generator end circuit breaker to the ground capacitor reliably, reduce the fault troubleshooting range of users and improve the fault troubleshooting efficiency by calculating the voltage of the fault phase to ground, the voltage of the generator stator to the ground zero sequence and the power generator fault phase electromotive force and further taking the phase relation of the fault phase electromotive force and the stator to the ground zero sequence voltage as a criterion.
Drawings
Fig. 1 is a schematic diagram of the phase relationship between the fault phase electromotive force and the stator-to-ground zero sequence voltage under three fault conditions.
FIG. 2 is a schematic diagram of the structure of the device of the present invention.
Detailed Description
The following further description is made in conjunction with the accompanying drawings and the specific embodiments.
Theoretical analysis shows that for a large generator set adopting a mode that a neutral point is grounded through grounding, the condition that the voltage of a stator winding fault is lowest relative to the ground voltage is met no matter stator single-phase grounding, a terminal PT primary winding turn-to-turn short circuit or a terminal circuit breaker to ground capacitor fault occurs.
The invention obtains the following results through research: measuring the voltage of the generator terminal stator side by using a protection device, determining the lowest phase to the ground voltage as a fault phase, and calculating the fault phase to ground voltage, the generator stator to ground zero sequence voltage and the generator fault phase electromotive force: when the stator of the generator is grounded in a single phase or the primary winding of the terminal PT is in turn-to-turn short circuit, the phase difference between the fault phase electromotive force and the stator to the ground zero sequence voltage is 180 DEG and 270 DEG; when the generator-end circuit breaker fails to work, the phase difference between the fault phase electromotive force and the stator-to-ground zero sequence voltage is 90-180 degrees. Therefore, the phase relation between the fault phase electromotive force and the stator-to-ground zero sequence voltage is taken as a criterion to reliably identify the fault of the generator terminal circuit breaker-to-ground capacitor.
Example 1
The method for identifying the fault of the ground capacitor of the generator-side circuit breaker comprises the following steps:
s1, collecting the voltage of the stator side at the generator end;
s2, setting the lowest phase of the voltage to ground as a fault phase according to the voltage acquisition result of S1, and calculating the voltage to ground of the fault, the zero sequence voltage of the stator-to-ground of the voltage generator at the stator side and the electromotive force of the fault phase;
s3, setting a phase difference threshold range; and according to the calculation result of S2, comparing the phase relation between the fault phase electromotive force and the stator-to-ground zero sequence voltage: if the phase difference of the fault phase electromotive force leading stator to the ground zero sequence voltage is within the range of the phase difference threshold value, judging that the fault is a ground capacitor fault of the circuit breaker at the machine end, otherwise, judging that the fault is a ground capacitor fault of the circuit breaker at the non-machine end;
and S4, controlling the protection device to act on alarm or trip after a set time delay t when the fault type is the ground capacitor fault of the generator-side circuit breaker according to the judgment result of S3.
In this embodiment, in S2, the stator-to-ground zero-sequence voltage of the stator-side voltage generator is a generator-end PT open-delta zero-sequence voltage.
Electric potential of generator fault phase
Is as follows;
wherein the content of the first and second substances,
in order for a generator fault to be at voltage relative to ground,
is the generator stator to ground zero sequence voltage.
In S3, the phase difference threshold range is 90-180 degrees. In S4, the set delay t takes a value within the range of 0.1-10S.
Example 2
Unlike embodiment 1, in S2 of this embodiment, the stator-side voltage generator stator-to-ground zero-sequence voltage is the self-generated zero-sequence voltage at the generator terminal PT.
Generator terminal PT self-generating zero sequence voltage
Is as follows;
wherein the content of the first and second substances,
for the voltage of the generator terminal a relative to ground,
to the voltage of the generator terminal B with respect to ground,
and the voltage of the generator terminal C is relatively grounded.
The judgment and identification of the embodiment 1 and the embodiment 2 are based on the reference of fig. 1. Stator grounded zero sequence voltage
The fault phase electromotive force is positioned on a horizontal axis, when the generator stator is grounded in a single phase and the terminal PT primary winding is in turn-to-turn short circuit, the fault phase electromotive force is positioned on a third quadrant, namely the phase difference between the fault phase electromotive force and the stator ground zero sequence voltage is 180 DEG and 270 DEG; when the ground capacitor of the generator-end circuit breaker fails, the fault phase electromotive force is located at the second quadrant, and the phase difference between the fault phase electromotive force and the stator-to-ground zero-sequence voltage is 90-180 degrees. The phase relation between the fault phase electromotive force and the stator-to-ground zero sequence voltage is taken as a criterion, the fault of the generator end circuit breaker to the ground capacitor can be reliably identified, and when the fault is identified as the fault of the generator end circuit breaker to the ground capacitor, the protection acts on alarm or trip after time delay t.
Example 3
Generator end circuit breaker capacitor to ground fault identification equipment includes:
the sampling module is used for collecting the voltage of the stator side at the generator end;
the calculation module is used for setting the lowest phase of the voltage to earth as a fault phase according to a voltage acquisition result of the stator side at the generator end, and calculating the voltage to earth of the fault, the voltage to earth zero sequence voltage of the generator stator at the stator side and the electromotive force of the fault phase;
the fault identification module is used for setting a phase difference threshold range; and according to the calculation result of S2, comparing the phase relation between the fault phase electromotive force and the stator-to-ground zero sequence voltage: if the phase difference of the fault phase electromotive force leading stator to the ground zero sequence voltage is within the range of the phase difference threshold value, the fault is judged to be the fault of the ground capacitor of the circuit breaker at the machine end, otherwise, the fault is the fault of the ground capacitor of the circuit breaker at the non-machine end.
Further, the generator-side circuit breaker ground capacitor fault recognition device further comprises a protection action control module, and the protection action control module controls the protection device to act on alarming or tripping after a set time delay t when the fault type is the ground capacitor fault of the generator-side circuit breaker according to the judgment result of the fault recognition module.
The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention.
Claims (7)
1. A generator end circuit breaker ground capacitor fault identification method is characterized by comprising the following steps:
s1, collecting the voltage of the stator side at the generator end;
s2, setting the lowest phase of the voltage to ground as a fault phase according to the voltage acquisition result of S1, and calculating the voltage to ground of the fault phase, the zero sequence voltage of the stator of the generator to ground and the electromotive force of the fault phase; the ground zero-sequence voltage of the generator stator is a triangular zero-sequence voltage of a PT opening at the generator end or a zero-sequence voltage self-generated by the PT at the generator end;
s3, setting a phase difference threshold range; and according to the calculation result of S2, comparing the phase relation between the fault phase electromotive force and the generator stator to the ground zero sequence voltage: if the phase difference of the fault phase electromotive force leading the generator stator to the ground zero sequence voltage is within the range of the phase difference threshold value, judging that the generator-end circuit breaker has a fault to the ground capacitor, otherwise, judging that the generator-end circuit breaker has a fault to the ground capacitor;
the phase difference threshold range is 90-180 degrees.
2. The method as claimed in claim 1, further comprising S4, wherein the control protection device is configured to alarm or trip after a set delay t when the fault type is a ground capacitor fault of the terminal circuit breaker according to the determination result of S3.
3. The method of claim 2, wherein the set delay time t in S4 is in a range of 0.1-10S.
4. According to the rightThe method of claim 1, wherein the generator terminal PT is self-generating zero sequence voltage
Is as follows;
wherein the content of the first and second substances,
for the voltage of the generator terminal a relative to ground,
to the voltage of the generator terminal B with respect to ground,
and the voltage of the generator terminal C is relatively grounded.
5. A method according to claim 1 or 2, characterized in that the generator fault phase electromotive force
Is as follows;
wherein the content of the first and second substances,
in order for a generator fault to be at voltage relative to ground,
is the generator stator to ground zero sequence voltage.
6. A generator end circuit breaker capacitor to ground fault recognition device is characterized by comprising:
the sampling module is used for collecting the voltage of the stator side at the generator end;
the calculation module is used for setting the lowest phase of the voltage to ground as a fault phase according to a voltage acquisition result of the stator side at the generator end, and calculating the voltage to ground of the fault phase, the zero sequence voltage of the stator of the generator to ground and the electromotive force of the fault phase; the ground zero-sequence voltage of the generator stator is a triangular zero-sequence voltage of a PT opening at the generator end or a zero-sequence voltage self-generated by the PT at the generator end;
the fault identification module is used for setting a phase difference threshold range; according to the calculation result of the calculation module, comparing the phase relation between the fault phase electromotive force and the ground zero sequence voltage of the generator stator: if the phase difference of the fault phase electromotive force leading the generator stator to the ground zero sequence voltage is within the range of the phase difference threshold value, judging that the generator-end circuit breaker has a fault to the ground capacitor, otherwise, judging that the generator-end circuit breaker has a fault to the ground capacitor; the phase difference threshold range is 90-180 degrees.
7. The apparatus as claimed in claim 6, wherein the apparatus further comprises a protection operation control module for controlling the protection apparatus to operate in an alarm or trip after a predetermined delay t when the fault type is the ground-to-ground capacitor fault of the generator-side circuit breaker according to the judgment result of the fault identification module.
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| CN102426316A (en) * | 2011-08-25 | 2012-04-25 | 南京南瑞继保电气有限公司 | Method for locating single-phase earth fault of generator stator winding |
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| CN100495055C (en) * | 2007-06-14 | 2009-06-03 | 上海交通大学 | Method for detecting generator stator single-phase earthing fault direction |
| JP2014110714A (en) * | 2012-12-04 | 2014-06-12 | Mitsubishi Electric Corp | Ground fault protection device |
| CN105116279B (en) * | 2015-07-03 | 2017-12-12 | 华中科技大学 | A kind of generator stator single-phase earthing fault accurate positioning method |
| CN106918783B (en) * | 2017-01-23 | 2019-08-09 | 华北电力大学（保定） | The localization method of large salient-pole synchronous generator stator single-phase earthing fault |
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| CN102426316A (en) * | 2011-08-25 | 2012-04-25 | 南京南瑞继保电气有限公司 | Method for locating single-phase earth fault of generator stator winding |
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| 基于电压型故障特征量的发电机机端断路器非全相保护;李荷婷等;《电力系统自动化》;20170110;第41卷(第1期);140-144 * |
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