CN100363750C - Method for judging generator PT line failure - Google Patents
Method for judging generator PT line failure Download PDFInfo
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- CN100363750C CN100363750C CNB2005101230957A CN200510123095A CN100363750C CN 100363750 C CN100363750 C CN 100363750C CN B2005101230957 A CNB2005101230957 A CN B2005101230957A CN 200510123095 A CN200510123095 A CN 200510123095A CN 100363750 C CN100363750 C CN 100363750C
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Abstract
The present invention relates to a judgment method of a generator voltage measuring transformer (PT), particularly to a wire breakage judgment method of the generator voltage measuring transformer (PT). The judgment method comprises an existing first criterion and an existing second criterion and can judge all the wire breakage fault combination of two groups of PTs of generators particularly under the conditions of small PT measuring value, large rotor current and normal stator current. When wires of three phases of two groups of PTs break simultaneously, the measured three-phase voltage values of two groups of PTs are zero without negative sequence components, and the first criterion and the second criterion are in a failure state; when the rotor current is large and more than the corresponding preset value of the generator, the measured values of two groups of PTs are low and less than the corresponding preset value of the generator; consequently, the present invention has the judgment result that three phases of the outlet of the generator are in short circuit or wires of two groups of PTs are broken. The two conditions have the difference of the variation of the measuring value of the stator current; when the short-circuit condition happens, the measuring value of the stator current is increased.
Description
Technical field
The present invention relates to a kind of generator voltage measuring transformer (PT) determination methods, promptly generator voltage measuring transformer PT broken string determination methods can be judged the disconnection fault combination that two groups of PT of generator are all, and can distinguish PT broken string and generator outlet short circuit.
Background technology
The correct judgement of generator machine end PT broken string, concerning machine end PT as extremely important the excitation system of control benchmark.At present, the conventional method of judging generator machine end PT broken string is mainly two PT relative methods, usually generator machine end all is provided with two groups of PT, control device is accepted two groups of PT voltages simultaneously, under the normal condition, the measured value of two groups of PT equates, compares two groups of PT voltage measuring values, when one group of PT measured value descends suddenly, judge that then disconnection fault takes place this PT.This method is very effective to single group PT broken string, but when two groups of PT break simultaneously, just can not correctly judge the PT broken string; In addition, can not judge the difference of two groups of PT broken strings and generator outlet short circuit.
Summary of the invention
The present invention seeks to: in order to solve the deficiency that conventional PT broken string determination methods is distinguished with short circuit at judgement that two groups of PT break simultaneously and broken string, the present invention proposes a kind of new PT broken string determination methods, two groups of PT carry out complete detection to generator machine end, and combine with generator unit stator electric current and rotor current, correct all combinations of judging two groups of PT broken strings of generator: single group PT broken string, two groups of single-phase (A of PT, B, C) or two-phase breaks simultaneously, two groups of three-phases break simultaneously.The disconnection fault combination that two groups of PT of generator are all can be judged, and PT broken string and generator outlet short circuit can be distinguished.
Technical solution of the present invention is: three kinds of criterions are set in the methods of the invention, and any criterion satisfies can be judged as the PT broken string, and can not be judged as the PT broken string to the generator short circuit situation by mistake.
Method for judging generator PT line failure: first kind of criterion is that two groups of PT measured values compare, consistent with conventional method, when having only one group of PT that broken string takes place, this group PT measured value can descend suddenly, and another group PT measurement simultaneously remains unchanged, when generator outlet is short-circuited, two groups of PT can reduce simultaneously, therefore, this method is very effective to single group PT broken string, and the generator outlet short circuit can not be judged as the PT broken string by mistake.
Second kind of criterion is: occur negative sequence component and (generator zero load or stator current do not have negative sequence component in measuring) during PT measures, this criterion is primarily aimed at two groups of single-phase or two-phase while disconnection faults of PT, for three-phase symmetric voltage or electric current, under the normal condition, negative sequence component can not appear, but when three-phase asymmetric (one mutually or two-phase increase or reduce), negative sequence component can appear in measured value, as two groups of PT during single-phase simultaneously or two-phase broken string, negative sequence component can appear in the voltage measurement, because generator unit stator normally moves, therefore its stator current negative sequence component can not occur in measuring, but when single-phase or line to line fault occurring, stator current negative sequence component will occur in measuring, therefore, this criterion can distinguish short-circuit and the PT broken string, when the generator outlet short circuit, excitation controlling device can correctly be controlled, and can not be judged as the PT broken string by mistake.
The third criterion is: this criterion is primarily aimed at two groups of PT three-phases and breaks simultaneously, and it all is zero that two groups of PT three-phase voltages are measured, and does not also have negative sequence component, and first kind and second kind of criterion all lost efficacy.Under the normal condition, generator unit stator voltage and rotor current are associated, if when rotor current is big, two groups of PT measured values are very low, have only two kinds of possibilities, generator outlet generation three-phase shortcircuit, otherwise all broken strings take place in two groups of PT, and the difference of two kinds of situations is the variation of stator current measured value, when being short-circuited, the stator current measured value can increase, and like this, just can correctly judge two groups of heterogeneous broken strings of PT homophase.
When the PT measured value is very little and rotor current is big and stator current is normal, when two groups of PT three-phases break simultaneously, two groups of PT three-phase voltage measurements all are zero or are close to zero, there is not negative sequence component yet, first kind and second kind of equal invalid state of criterion: then when rotor current is big and greater than certain definite value, set definite value accordingly with generator, two groups of PT measured values are very low (less than certain definite value, set definite value accordingly with generator), various capacity differences, the set end voltage difference, power factor 0.8, the generator that rated exciting current 1000A is different, each definite value is also inequality, the setting of definite value is fully according in the prior art comprehensive parameters of generator being set, and is not special setting of the present invention); Then occur as judging: generator outlet generation three-phase shortcircuit, or two groups of whole broken strings of PT generation, the difference of two kinds of situations is the variation of stator current measured value, when being short-circuited, the stator current measured value can increase; Thereby correctly judge two groups of heterogeneous broken strings of PT homophase.
The invention has the beneficial effects as follows: new PT broken string determination methods, by complete detection generator voltage, stator current and rotor current, according under various PT broken strings and short-circuit conditions, the different variation combinations of generator voltage, stator current and rotor current, the various PT disconnection faults of correct judgement, and can correctly distinguish PT broken string and generator outlet short circuit, for the generator excitation control device provides correct control benchmark, guarantee the normal safe operation of generator.Comprehensive and the perfect method that the present invention judges for generator PT line failure in fact.
Description of drawings
Fig. 1 is a logic theory block diagram of the present invention
Embodiment
PT1 is the 1st a group of PT measured value among Fig. 1, and PT2 is the 2nd a group of PT measured value, and IF is the rotor current measured value, and IG is the stator current measured value, a, b, c, d, e, f, g is a setting parameter, adjusts according to generator parameter, for example at certain generator (set end voltage 10.5KV, capacity 125MVA, power factor 0.8, rated exciting current 1000A), a then, b, c, d, e, f, the g definite value is respectively: 1KV, 8KV, 2KV, 1KA, 0.5KV, 300A, 10KA.Setting valve choose with reference to existing P T breaking protection the time parameter.
Logic diagram has illustrated the logic determines process of the inventive method among Fig. 1.
Claims (1)
1. method for judging generator PT line failure: it is characterized in that determination methods comprises three kinds of criterions:
First kind of criterion is: two groups of PT voltage measuring values relatively, when having only one group of PT that broken string takes place, this group PT voltage measuring value descends suddenly, and another group PT voltage measuring value remains unchanged simultaneously, when generator outlet was short-circuited, two groups of PT voltage measuring values reduced simultaneously;
Second kind of criterion is: occur not having negative sequence component in the measurement of negative sequence component and generator zero load or stator current in the PT voltage measuring value, this is at two groups of single-phase or two-phase while disconnection faults of PT, as two groups of PT during single-phase simultaneously or two-phase broken string, negative sequence component appears in the voltage measurement, when generator unit stator normally moved, stator current negative sequence component do not occur in measuring; When single-phase or line to line fault occurring, stator current negative sequence component just occurs in measuring; This criterion can distinguish short-circuit and the PT broken string; When the generator outlet short circuit, excitation controlling device can correctly be controlled, and does not judge the broken string into PT by accident;
The third criterion is: when the PT voltage measuring value is very little and rotor current is big and stator current is normal, when two groups of PT three-phases break simultaneously, it all is zero that two groups of PT three-phase voltages are measured, there is not negative sequence component yet, first kind and second kind of equal invalid state of criterion: then when rotor current is big and when setting definite value accordingly with generator, two groups of PT voltage measuring values are very low and less than setting definite value accordingly with generator; Then occur as judging: generator outlet generation three-phase shortcircuit, or all broken strings take place in two groups of PT; The difference of two kinds of situations is the variation of stator current measured value, and when being short-circuited, the stator current measured value increases; Thereby judge two groups of heterogeneous broken strings of PT homophase.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2005101230957A CN100363750C (en) | 2005-12-15 | 2005-12-15 | Method for judging generator PT line failure |
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| CNB2005101230957A CN100363750C (en) | 2005-12-15 | 2005-12-15 | Method for judging generator PT line failure |
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| CN1790039A CN1790039A (en) | 2006-06-21 |
| CN100363750C true CN100363750C (en) | 2008-01-23 |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103091595B (en) * | 2012-07-23 | 2015-09-02 | 南京南瑞继保电气有限公司 | The method of discrimination that a kind of generator terminal voltage mutual inductor once breaks |
| CN102890222B (en) * | 2012-10-17 | 2014-12-17 | 南京国电南自美卓控制系统有限公司 | Method for judging breaking of PT (potential transformer) in fast switch |
| CN104035001B (en) * | 2014-06-25 | 2016-03-16 | 国家电网公司 | A kind of detection method of voltage transformer disconnection |
| CN104297625A (en) * | 2014-11-07 | 2015-01-21 | 安徽马钢自动化信息技术有限公司 | PT wire breakage diagnosis system and method |
| CN109541469B (en) * | 2019-01-09 | 2021-09-17 | 中国长江电力股份有限公司 | PT disconnection judging method for generator excitation system |
| CN110703096B (en) * | 2019-10-29 | 2022-05-27 | 江苏瑞奇海力科技有限公司 | Motor working state detection method, device, equipment and storage medium |
| CN110880890B (en) * | 2019-11-05 | 2021-10-26 | 武汉武水电气技术有限责任公司 | Low pressure hydraulic generator protection system |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07170798A (en) * | 1993-12-16 | 1995-07-04 | Hitachi Ltd | Abnormality diagnositic method for exciting equipment for synchronous machine |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07170798A (en) * | 1993-12-16 | 1995-07-04 | Hitachi Ltd | Abnormality diagnositic method for exciting equipment for synchronous machine |
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Owner name: NANJING NANRUIJUBAO ENGINEERING TECHNOLOGY CO., L Free format text: FORMER OWNER: NANRUI JIBAO ELECTRIC CO., LTD. Effective date: 20080627 |
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Effective date of registration: 20080627 Address after: Zip Road, Jiangning District, Jiangsu, Nanjing: 211100 Co-patentee after: Nanrui Relay Protection Electricity Co., Ltd., Nanjing Patentee after: Nanjing Nan relic Engineering Technology Co., Ltd. Address before: Zip Road, Jiangning District, Jiangsu, Nanjing: 211100 Patentee before: Nanrui Relay Protection Electricity Co., Ltd., Nanjing |