CN111596187A - Practical generator stator winding end corona detection method - Google Patents
Practical generator stator winding end corona detection method Download PDFInfo
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- CN111596187A CN111596187A CN202010595878.XA CN202010595878A CN111596187A CN 111596187 A CN111596187 A CN 111596187A CN 202010595878 A CN202010595878 A CN 202010595878A CN 111596187 A CN111596187 A CN 111596187A
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- 238000004804 winding Methods 0.000 title claims abstract description 54
- 238000001514 detection method Methods 0.000 title claims abstract description 34
- 238000012360 testing method Methods 0.000 claims abstract description 40
- 238000000034 method Methods 0.000 claims abstract description 31
- 238000011179 visual inspection Methods 0.000 claims abstract description 12
- 238000003384 imaging method Methods 0.000 claims abstract description 10
- 238000012423 maintenance Methods 0.000 claims abstract description 9
- 238000003851 corona treatment Methods 0.000 claims abstract description 8
- 230000008569 process Effects 0.000 claims description 14
- 230000002159 abnormal effect Effects 0.000 claims description 9
- 238000002474 experimental method Methods 0.000 claims description 8
- 230000008859 change Effects 0.000 claims description 6
- 230000003321 amplification Effects 0.000 claims description 3
- 230000015556 catabolic process Effects 0.000 claims description 3
- 238000012790 confirmation Methods 0.000 claims description 3
- 238000007689 inspection Methods 0.000 claims description 3
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 2
- 230000008901 benefit Effects 0.000 abstract description 4
- 238000004445 quantitative analysis Methods 0.000 abstract description 2
- 238000004451 qualitative analysis Methods 0.000 abstract 1
- 230000000007 visual effect Effects 0.000 description 4
- 230000005684 electric field Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 241000180177 Listrocephalos corona Species 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1218—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing using optical methods; using charged particle, e.g. electron, beams or X-rays
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/34—Testing dynamo-electric machines
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- Testing Relating To Insulation (AREA)
- Tests Of Circuit Breakers, Generators, And Electric Motors (AREA)
Abstract
The invention discloses a practical generator stator winding end corona detection method, which comprises the following steps: when the generator stator winding end is observed to generate corona under a darkroom, an ultraviolet imager is used for obtaining a corona discharge picture with stable corona discharge position and a number Nc1 of corona discharge photons, the ultraviolet imager is used for observing the corona discharge picture and the number Nc of discharge photons of each position of the generator stator winding end under a specified test voltage, and when the number Nc of photons of a position of the end is more than the number Nc1 of the corona discharge photons, the position is required to be subjected to anti-corona treatment in the current maintenance. The practical generator stator winding end corona detection method organically combines a darkroom visual inspection method for qualitative analysis and an ultraviolet imaging method for quantitative analysis, has the advantages of simplicity, high practicability, high operability and the like, and is suitable for wide popularization in the industry.
Description
Technical Field
The application relates to the technical field of corona detection, in particular to a practical corona detection method for a stator winding end portion of a generator.
Background
It is known that air is ionized when the local electric field strength in the air exceeds the ionizing electric field of the air, resulting in a self-sustaining glow discharge which is accompanied by a glow, a light spot or a thin luminescent layer in the dark, and by a hissing sound, i.e. corona.
The corona prevention layer at the end part of the generator stator winding, the position of the notch of the stator wire rod, the uneven electric field distribution parts between the winding and the end part pressing plate, the pressing ring and the pressing finger, the end part supporting ring, the periphery of the binding rope and the like often generate corona when the generator normally works. The generator can cause the corrosion of the insulating layer at the end part of the generator under the long-term action of corona, the long-term service life of the generator is influenced, and the insulating corrosion can cause the short-circuit hidden trouble of the generator winding, so that the corona detection is carried out on the generator with the corona phenomenon by a generator stator winding end part corona detection method, and the specific treatment is carried out on the part for detecting the corona.
At present, detailed descriptions are given to a generator end corona detection method in industry standards, specifically a darkroom visual detection method and an ultraviolet imaging method. The visual inspection method in the darkroom is to find the bright corona part at the end part of the stator winding by naked eyes in a dark darkroom, and the accuracy of the corona is greatly influenced due to different eyesight and different observation angles of each person, so that the evaluation of the detection result of the visual inspection method in the darkroom is inaccurate. The ultraviolet imaging method is characterized in that the corona at the end part of the stator winding is quantitatively observed by an ultraviolet imager, the corona strength is judged by using the photon number, then the observed photon number is compared with a calibrated 'AND' grid line 'to judge whether the corona prevention treatment is carried out during the maintenance, but the' AND 'grid line' is independently calibrated, so that a special laboratory and equipment without partial discharge are required to be arranged on site, and the ultraviolet imagers of different manufacturers and the generator stator windings of different manufacturers are required to be re-calibrated each time in a matching and combining manner, so that the field calibration work is very complicated.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a practical generator stator end corona detection method, which solves the problems of inaccuracy of a darkroom visual detection method and calibration and grid line complexity of an ultraviolet imaging method, and greatly improves the detection efficiency. In order to solve the above technical problems, a specific embodiment of the present invention provides a practical generator stator end corona detection method, in which an ultraviolet imager is used to record the number of corona photons when a generator stator winding end corona test is performed by a darkroom visual inspection method, then the ultraviolet imager is used to quantitatively detect the number of photons for the generator stator winding end, and when the number of photons detected at a certain position of the end exceeds the number of corona photons, it is determined that the maintenance needs to perform anti-corona treatment on the certain position, and the specific basic steps are as follows:
lifting the generator rotor out of the chamber by combining with a generator overhaul machine, arranging at least three observation points at the end part of the generator in the darkroom by adopting a darkroom visual inspection method, and observing the end part of the generator simultaneously, wherein at least two observation results are consistent and effective, and the generator should stay for at least 10min under the observed dim light condition;
before the test, the observation point is arranged in a darkroom, or is arranged in a stator hall of the generator and keeps a position with enough safe distance with a stator winding and the end part of the generator to perform the test, before the test, the distance, the angle and the temperature and humidity information between the ultraviolet imager and the end part of the stator winding are recorded, and the parameter setting of the ultraviolet imager is adjusted;
during testing, power frequency resonance or other testing equipment is adopted to enable the power frequency voltage applied to the stator winding of the generator to reach a first stage and a second stage, in the boosting process of any detection stage, when the applied voltage reaches 75% of the highest test voltage, the voltage is applied in a segmented mode by 5% of the highest test voltage, the boosting process is gentle, and once a serious discharge phenomenon occurs, the voltage is immediately reduced and the inspection is stopped;
during the first or second phase, after confirmation of at least two observation points when the appearance of corona characteristics such as bright spots or sparks around the stator winding ends or the stator bars is found, the corona-initiated number of photons Nc1 is observed with an ultraviolet imager.
And finally, performing a corona test on the end winding of the generator stator by using an ultraviolet imaging method, and judging that the maintenance needs to perform anti-corona treatment on a certain part when the number of photons detected by the certain part exceeds the number of the corona-initiating photons in the test process.
Further, the observation point keeps enough safe distance with the pressure winding, just the observation point is in the darkroom, or, is umbrella type evenly distributed setting in the generator tip hall, can observe whole generator tip at different angles, should begin to appear when corona through two observation points at least when arbitrary observation point confirms to measure with the ultraviolet appearance again after the corona to avoid interfering.
Further, the recorded information of the distance, the angle and the temperature and humidity between the ultraviolet imager and the end part of the stator winding before observation provides comparison for a subsequent corona test;
the number of photons detected by the ultraviolet imager is the number of photons of the real photon number at the end part of the generator after air attenuation and gain amplification by the ultraviolet imager, and the number of photons cannot be equal to the real photon number, but the number of photons detected by the ultraviolet imager in unit time has a change rule and a statistical rule which are consistent with the discharge of the charged equipment, and the real photon number can be calculated according to the change rule and the statistical rule.
Further, during the experiment, the abnormal condition is eliminated before the experiment is carried out when the abnormal condition occurs in the first stage or the second stage, the generator corona test is often carried out along with the voltage withstand test, and the breakdown of the insulating layer of the stator winding or other abnormal conditions can occur in the voltage withstand process.
Further, the highest power frequency voltage in the first stage is 1.1Un/√ 3, and the highest power frequency voltage in the second stage is 1.1 Un.
Has the advantages that: the invention provides a practical generator stator end corona detection method, when a darkroom visual inspection method is used for carrying out a corona test on a generator stator winding end, an ultraviolet imager is used for recording the number of corona-forming photons, then the ultraviolet imager is used for carrying out quantitative detection on the number of photons on the generator stator winding end, when the number of photons detected at a certain part of the end exceeds the number of corona-forming photons, the part needs to be subjected to anti-corona treatment for the maintenance, the advantage that the darkroom visual inspection method is convenient to operate and implement is organically combined with the advantage that the ultraviolet imaging method can carry out quantitative analysis, the difficult process of calibrating 'and grid lines' in the ultraviolet imaging method is replaced by the simple process of judging and grid lines in the darkroom visual inspection method, and the quantitative and qualitative perfect combination ensures that the method is simple to operate and high in practicability.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without inventive efforts.
FIG. 1 is a flow chart of the steps of a method for practical generator stator tip corona detection;
FIG. 2 is a schematic view of a practical generator stator tip corona detection method in view of the point of view.
Detailed Description
The invention provides a practical generator stator end corona detection method, which solves the problems of inaccuracy of a darkroom visual detection method and calibration and grid line complexity of an ultraviolet imaging method, and greatly improves the detection efficiency.
The specific embodiment of the invention provides a practical generator stator end corona detection method, as shown in fig. 1, when a darkroom visual inspection method is used for carrying out a corona test on a generator stator winding end, an ultraviolet imager is used for recording the number of corona starters, then the ultraviolet imager is used for carrying out quantitative detection on the number of the corona starters on the generator stator winding end, when the number of the photons detected at a certain position of the end exceeds the number of the corona starters, the method is judged that the maintenance needs to carry out anti-corona treatment on the certain position, and the specific basic steps are as follows:
lifting the generator rotor out of the chamber by combining with a generator overhaul machine, arranging at least three observation points at the end part of the generator in the darkroom by adopting a darkroom visual inspection method as shown in figure 2, and observing the end part of the generator simultaneously, wherein at least two observation results are consistent and effective and stay for at least 10min under the observed dim light condition;
before the test, the observation point is arranged in a darkroom, or is arranged in a stator hall of the generator and keeps a position with enough safe distance with a stator winding and the end part of the generator to perform the test, before the test, the distance, the angle and the temperature and humidity information between the ultraviolet imager and the end part of the stator winding are recorded, and the parameter setting of the ultraviolet imager is adjusted;
during testing, power frequency resonance or other testing equipment is adopted to enable the power frequency voltage applied to the stator winding of the generator to reach a first stage and a second stage, in the boosting process of any detection stage, when the applied voltage reaches 75% of the highest test voltage, the voltage is applied in a segmented mode by 5% of the highest test voltage, the boosting process is gentle, and once a serious discharge phenomenon occurs, the voltage is immediately reduced and the inspection is stopped;
during the first or second phase, after confirmation of at least two observation points when the appearance of corona characteristics such as bright spots or sparks around the stator winding ends or the stator bars is found, the corona-initiated number of photons Nc1 is observed with an ultraviolet imager.
And finally, performing a corona test on the end winding of the generator stator by using an ultraviolet imaging method, and judging that the maintenance needs to perform anti-corona treatment on a certain part when the number of photons detected by the certain part exceeds the number of the corona-initiating photons in the test process.
And carrying out generator end corona detection on a No. 2 generator of a certain hydropower station. The specific implementation of the invention is carried out according to the following steps:
when the corona generated at the end part of a stator winding of a generator is observed by a visual observation method in a darkroom, an ultraviolet imager is used for obtaining a stable corona discharge picture of a corona-initiating part and the number of corona-initiating photons Nc1, a certain hydropower station No. 2 machine assigns 3 persons to keep at a point in a dark environment at the wind tunnel position at the lower end part of the winding, after the voltage slowly rises until all persons confirm that a bright point or a spark occurs for the first time, the voltage temporarily stays at the voltage point, then the ultraviolet imager is used for observing the number of photons at the point so as to determine the number of photons corresponding to the visible corona light of the first time of naked eyes, and the number of photons is recorded as Nc 1. Since the upper end portion cannot be completely blackened due to the test conditions, the darkroom observation method of the upper end portion is limited, and the lower end portion observation is preferable. However, the upper end darkroom observation method is supplemented by observing the number of the halation photons of each part of the upper end by the ultraviolet imager in combination with the Nc1 data, and when the number of the photons of a certain part of the upper end measured by the ultraviolet imager exceeds Nc1, it indicates that the bright spot or the spark can be seen by the naked eyes of the person at the part under the blackened environment.
The halo and halation can be seen by naked eyes of three persons at the lower end part of the No. 2 machine for the first time, and the maximum photon Nc1 corresponding to the halation part is measured by an ultraviolet imager to be about 1200.
Under the specified voltage, each part of the end part of the stator winding of the generator is measured by an ultraviolet imager, a corona discharge picture and the number Nc of discharge photons are recorded, and a corona onset corona picture and the number of photons are recorded by the ultraviolet imager under the first stage and the second stage of the No. 2 generator of a certain hydropower station.
Comparing the number of photons of each part in the second part with the number of the blooming photons Nc1, and performing anti-blooming treatment on the part when the number of the blooming photons is greater than Nc1
Further, as shown in fig. 2, the observation points are kept at a sufficient safety distance from the pressurized winding, and are uniformly distributed in a dark room or in an umbrella shape in a generator end chamber, so that the whole generator end can be observed at different angles, and when any observation point starts to generate corona, the observation point is confirmed to be corona through at least two observation points, and then the measurement is started by using an ultraviolet instrument, so as to avoid interference.
Further, the recorded information of the distance, the angle and the temperature and humidity between the ultraviolet imager and the end part of the stator winding before observation provides comparison for a subsequent corona test;
the number of photons detected by the ultraviolet imager is the number of photons of the real photon number at the end part of the generator after air attenuation and gain amplification by the ultraviolet imager, and the number of photons cannot be equal to the real photon number, but the number of photons detected by the ultraviolet imager in unit time has a change rule and a statistical rule which are consistent with the discharge of the charged equipment, and the real photon number can be calculated according to the change rule and the statistical rule.
Further, during the experiment, the abnormal condition is eliminated before the experiment is carried out when the abnormal condition occurs in the first stage or the second stage, the generator corona test is often carried out along with the voltage withstand test, and the breakdown of the insulating layer of the stator winding or other abnormal conditions can occur in the voltage withstand process.
Further, the highest power frequency voltage in the first stage is 1.1Un/√ 3, and the highest power frequency voltage in the second stage is 1.1 Un.
Although the present invention has been described in terms of specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention as defined in the appended claims, and such changes and modifications are also encompassed within the scope of the invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (5)
1. The utility model provides a practical generator stator winding end corona detection method which characterized in that records the number of corona-forming photons with ultraviolet imager when using darkroom visual inspection to generator stator winding end corona test, then carries out quantitative detection photon number with ultraviolet imager to generator stator winding end, judges when finding that the number of photons measured at some position of tip exceeds the number of corona-forming photons and need carry out anti-corona treatment to this position for this maintenance, and concrete basic step is as follows:
lifting the generator rotor out of the chamber by combining with a generator overhaul machine, arranging at least three observation points at the end part of the generator in the darkroom by adopting a darkroom visual inspection method, and observing the end part of the generator simultaneously, wherein the observation results of the at least two observation points are consistent and effective, and the generator should stay for at least 10min under the observed dim light condition;
before the test, the observation point is arranged in a darkroom, or is arranged in a stator hall of the generator and keeps a position with enough safe distance with a stator winding and the end part of the generator to perform the test, before the test, the distance, the angle and the temperature and humidity information between the ultraviolet imager and the end part of the stator winding are recorded, and the parameter setting of the ultraviolet imager is adjusted;
during testing, power frequency resonance or other testing equipment is adopted to enable the power frequency voltage applied to the stator winding of the generator to reach a first stage and a second stage, in the boosting process of any detection stage, when the applied voltage reaches 75% of the highest test voltage, the voltage is applied in a segmented mode by 5% of the highest test voltage, the boosting process is gentle, and once a serious discharge phenomenon occurs, the voltage is immediately reduced and the inspection is stopped;
in the first stage or the second stage, when the existence of corona characteristics such as bright spots or sparks at the end part of a stator winding or around a stator bar is found, the corona starting photon number Nc1 is observed by an ultraviolet imager after the confirmation of at least two observation points;
and finally, performing a corona test on the end winding of the generator stator by using an ultraviolet imaging method, and judging that the maintenance needs to perform anti-corona treatment on a certain part when the number of photons detected by the certain part exceeds the number of the corona-initiating photons in the test process.
2. The practical generator stator winding end corona detection method as recited in claim 1, wherein said observation points are located at a safe enough distance from said pressurized winding, and said observation points are located in a dark room or in an umbrella-shaped and evenly distributed manner in said generator end hall, so that the whole generator end can be observed at different angles, and when corona begins to appear at any observation point, the measurement with an ultraviolet instrument is started after the corona is confirmed by at least two observation points, so as to avoid interference.
3. The practical generator stator winding end corona detection method according to claim 1, wherein the distance, angle, temperature and humidity information of the ultraviolet imager and the stator winding end recorded before observation provides comparison for subsequent corona tests;
the number of photons detected by the ultraviolet imager is the number of photons of the real photon number at the end part of the generator after air attenuation and gain amplification by the ultraviolet imager, and the number of photons cannot be equal to the real photon number, but the number of photons detected by the ultraviolet imager in unit time has a change rule and a statistical rule which are consistent with the discharge of the charged equipment, and the real photon number can be calculated according to the change rule and the statistical rule.
4. The practical generator stator winding end corona detection method is characterized in that during experiment, the abnormal condition is eliminated firstly and then the experiment is carried out when the abnormal condition occurs in the first stage or the second stage, the generator corona experiment is usually carried out along with a voltage withstanding experiment, and the breakdown of an insulating layer of a stator winding or other abnormal conditions can occur in the voltage withstanding process.
5. The practical generator stator winding end corona detection method as recited in claim 1, wherein the highest power frequency voltage in the first stage is 1.1Un/√ 3, and the highest power frequency voltage in the second stage is 1.1 Un.
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