CN108445384B - On-line monitoring and evaluating method for operating state of converter transformer on-load tap-changer - Google Patents
On-line monitoring and evaluating method for operating state of converter transformer on-load tap-changer Download PDFInfo
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- CN108445384B CN108445384B CN201810444374.0A CN201810444374A CN108445384B CN 108445384 B CN108445384 B CN 108445384B CN 201810444374 A CN201810444374 A CN 201810444374A CN 108445384 B CN108445384 B CN 108445384B
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- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000012544 monitoring process Methods 0.000 title claims abstract description 20
- 230000008569 process Effects 0.000 claims abstract description 25
- 238000011084 recovery Methods 0.000 claims abstract description 19
- 238000012545 processing Methods 0.000 claims abstract description 4
- 230000008859 change Effects 0.000 claims description 13
- 238000011208 chromatographic data Methods 0.000 claims description 7
- 238000004458 analytical method Methods 0.000 claims description 6
- 238000012806 monitoring device Methods 0.000 claims description 4
- 238000001914 filtration Methods 0.000 claims description 3
- 238000012423 maintenance Methods 0.000 abstract description 7
- 238000004587 chromatography analysis Methods 0.000 description 5
- HSFWRNGVRCDJHI-UHFFFAOYSA-N Acetylene Chemical compound C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 238000004804 winding Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 238000005206 flow analysis Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035772 mutation Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000010079 rubber tapping Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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
- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
- G01R31/3271—Testing of circuit interrupters, switches or circuit-breakers of high voltage or medium voltage devices
- G01R31/3275—Fault detection or status indication
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Abstract
An on-line monitoring and evaluating method for the operating state of a converter transformer on-load tap-changer comprises the following specific steps: step 1, monitoring load voltage and current waveforms of a converter transformer on-load tap-changer switching process, oil flow speed of an oil flow relay in the switching process and an oil chromatogram of a switch independent oil chamber of the on-load tap-changer; step 2, calculating and processing the monitored load voltage and current waveforms in the switching process of the on-load tap-changer, and analyzing whether the on-load tap-changer is normal in switching-off current, recovery voltage, arcing time and the like; step 3, analyzing the monitored oil flow velocity of the relay in the switching process of the on-load tap-changer, and judging whether the oil flow velocity is in a reasonable range; the advantage is, realizes real time monitoring, and accurate judgement avoids unnecessary maintenance, improves maintenance efficiency.
Description
Technical Field
The invention relates to the technical field of transformer maintenance, in particular to an online monitoring and evaluation method for the running state of a converter transformer on-load tap-changer.
Background
An On-load Tap Changer (OLTC) is a core component of a transformer for completing On-load voltage regulation, and the performance state of the On-load Tap Changer is directly related to the safe operation of an On-load voltage regulation transformer. According to relevant data statistics, the on-load tap-changer fault caused by the on-load tap-changer fault accounts for about 40% of the total fault.
The on-load tap-changer for the converter transformer is connected to the midpoint of a side winding of the converter transformer, the voltage regulating level is more than 30, a positive and negative voltage regulating mode is needed, and the on-load tap-changer is at a higher insulation level under the influence of oscillation voltage of a suspension end of the voltage regulating winding at a middle tapping position. When a network side winding of the converter transformer is connected with a 550kV alternating current system, the level voltage of the on-load tap-changer is close to the limit.
The voltage of the converter transformer is adjusted frequently during operation, the maximum voltage can reach 1 ten thousand times per year, and the on-load tap-changer is required to meet the requirements of less maintenance or no maintenance after more operation times. The current cut off when the on-load tap-changer of the converter transformer is switched is not an alternating-current sine wave waveform but a square wave with a steeper waveform, and the recovery voltage between contacts after the main contact cuts off the square wave current is also a square wave waveform with a steeper waveform, so that the insulating medium can be required to recover the insulating strength quickly to achieve quick arc blowout and prevent the electric arc from reigniting.
The converter transformer has complex operation condition, the on-load tap-changer thereof has great difference with the on-load tap-changer of the common power transformer, and the operation condition is more severe. Therefore, the on-load tap-changer state on-line monitoring of the converter transformer is carried out, and the method has important significance for reducing on-load tap-changer faults and ensuring the safe operation of the converter transformer.
Disclosure of Invention
The invention aims to solve the technical problem of providing an on-line monitoring method for the operating state of an on-load tap-changer of a converter transformer, which realizes the timely and accurate judgment of the operating state of the on-load tap-changer of the converter transformer by monitoring the voltage and current waveforms, the oil flow speed in an oil flow relay pipeline and the oil chromatogram in a transfer switch oil chamber of the on-load tap-changer in real time in the action process of the on-load tap-changer of the converter transformer.
The invention is realized by the following technical scheme:
an on-line monitoring and evaluating method for the operating state of a converter transformer on-load tap-changer comprises the following specific steps:
step 1, monitoring load voltage and current waveforms in a switching process of an on-load tap-changer of a converter transformer, oil flow speed in an oil flow relay pipeline in the switching process and an oil chromatogram of an independent oil chamber of the on-load tap-changer;
step 2, calculating and processing the monitored load voltage and current waveforms in the switching process of the on-load tap-changer, and analyzing whether the on-load tap-changer is normal in switching-off current, recovery voltage change rate, switching-off time sequence, arcing time and the like;
step 3, analyzing the monitored oil flow velocity of the relay in the switching process of the on-load tap-changer, and judging whether the oil flow velocity is in a reasonable range;
and 5, evaluating whether the operating state of the on-load tap-changer is normal or not.
As an improvement of the above scheme, the load voltage and current waveforms of the on-load tap-changer switching process described in step 1 are extracted from the converter station wave recording system.
As an improvement of the above scheme, the oil chromatogram of the independent oil chamber of the diverter switch of the on-load tap-changer in the step 1 is obtained by additionally installing an oil chromatogram online monitoring device in the oil chamber of the diverter switch of the on-load tap-changer, and analyzing the characteristic gas and the moisture content in the oil by taking an oil sample through a pipeline of an online oil filtering device of the on-load tap-changer.
As an improvement of the above scheme, the on-off current, the recovery voltage change rate and the on-off time sequence of the on-load tap-changer in the step 2 should meet the technical requirements; the arcing time should be within 12 ms.
The invention has the following beneficial effects:
1. real-time monitoring and accurate judgment are realized, redundant maintenance is avoided, and maintenance efficiency is improved.
2. The safe operation of the converter transformer is ensured.
Drawings
Fig. 1 is a block diagram of an on-load tap changer on-line monitoring system of a converter transformer.
Fig. 2 is a process flow of on-load tap-changer status evaluation of a converter transformer.
Fig. 3 is a schematic diagram of the structure of an on-load tap-changer of a converter transformer.
Fig. 4 voltage at switching of an on-load tap changer.
Fig. 5 current waveforms at switching of an on-load tap changer.
FIG. 6 change curve of tap changer oil chromatogram with switching times
Detailed Description
Example 1
As shown in fig. 1 and 2, an online monitoring and evaluating method for an operation state of a converter transformer on-load tap changer includes the following specific steps:
step 1, monitoring load voltage and current waveforms of a converter transformer on-load tap-changer switching process, oil flow speed of an oil flow relay in the switching process and an oil chromatogram of a switch independent oil chamber of the on-load tap-changer;
step 2, calculating and processing the monitored load voltage and current waveforms in the switching process of the on-load tap-changer, and analyzing whether the on-load tap-changer is normal in switching-off current, recovery voltage change rate, switching-off time sequence, arcing time and the like;
step 3, analyzing the monitored oil flow velocity of the relay in the switching process of the on-load tap-changer, and judging whether the oil flow velocity is in a reasonable range;
and 5, evaluating whether the operating state of the on-load tap-changer is normal or not.
Example 2
The method for monitoring and evaluating the on-load tap-changer of one converter transformer in a certain converter station comprises the following steps:
1. acquisition of on-line monitoring quantity
1.1 acquisition of Voltage and Current waveforms at on-load tap-changer switching
And extracting the load voltage and current waveforms in the switching process of the on-load tap-changer through a converter station wave recording system. The voltage and current waveforms of a certain on-load tap-changer of a certain converter transformer at a certain switching time are shown in fig. 4 and 5.
1.2 acquisition of Relay oil flow at on-load tap-changer switching
The flow rate monitoring device is additionally arranged in the on-load tap-changer oil flow relay pipeline shown in fig. 3, so that the flow rate of oil flowing through the oil flow relay during on-load tap-changing can be monitored. The flow velocity range measured by the oil flow sensor in the switching process of the tap changer is as follows: 0.3m/s to 0.6 m/s.
1.3 acquisition of on-load tap-changer diverter switch oil chromatogram
An oil chromatography online monitoring device is additionally arranged in a transfer switch oil chamber of the on-load tap-changer shown in fig. 3, and an oil sample is taken through an online oil filtering device pipeline of the on-load tap-changer for analysis, so that the content of characteristic gases such as C2H2, C2H4 and H2 and the content of water in the analyzed oil are determined. After the on-load tap-changer of the converter transformer is switched for 35000 times, the chromatographic value of the insulating oil in the oil chamber of the switch is shown in table 1:
TABLE 1 diverter switch oil chromatogram data
2. On-load tap-changer condition assessment
2.1 Voltage and Current waveform analysis
And calculating rated voltage and pole current of the on-load tap-changer according to the load voltage and current waveforms during the switching of the tap-changer.
The arc current, the recovery voltage and the recovery voltage change rate of the main contact and the transition contact of the transfer switch are calculated according to the following formula:
main contact:
arc current I ═ Iload
Recovery voltage UR＝RIload
Recovery voltage rate of change
Transition contact:
arc current:
voltage recovery: u shapeR＝RIload+Ustep
Recovery voltage change rate:
according to the voltage and current waveforms of fig. 4 and 5, the arc current, the recovery voltage and the recovery voltage change rate during the tap switch switching are calculated by using the above formula, and compared with the allowable value of the tap switch characteristic parameter, whether the tap switch switching is abnormal or not is judged.
Through calculation, the arc current, the recovery voltage and the recovery voltage change rate of the main contact and the transition contact are all smaller than the allowable value of the tap switch when the tap switch is switched.
According to the voltage and current waveforms of fig. 5, the on-off time sequence of each contact in the switching process of the tap changer is normal, the arcing time is within 12ms, and the requirement of 1.2/2f is met.
2.2 Relay oil flow analysis
When the on-load tap-changer is switched, the flow velocity value measured by the oil flow sensor is smaller than the alarm pressure (1.5m/s) of the oil flow relay, and the arc energy in the switching process is in a normal range.
2.3 oil chromatography
The arc-cutting of the diverter switch during operation generates energy causing the insulating oil to break down, generating gas, among which acetylene is the most interesting. According to table 1, the tap changer had an acetylene content of 2.48ppm after 35000 switchings, which was less than the manufacturer control value. Fig. 6 shows a graph plotting a change curve from the chromatographic values after 5000 times, 10000 times, 20000 times, and 35000 times of the tap changer operation.
The curve trend shows that the insulating oil chromatogram of the switch oil chamber of the tap switch has no mutation, the chromatographic value is positively correlated with the switching times, and no abnormity can be judged.
As shown in table 2, the comparative oil chromatography analysis was performed on other 5 on-load tap changers of the same type, and it was found that the oil chromatography content was close when the switching times were close. The on-load tap-changer is also proved to be in a normal operation state.
TABLE 2 chromatographic data of change-over switch oil for on-load tap-changers of the same type
3. On-load tap-changer condition assessment
According to the comprehensive analysis of the arc current, the recovery voltage and the change rate of the recovery voltage, the on-off time sequence, the arcing time, the flow rate of the relay oil flow and the chromatographic analysis of the diverter switch oil in the switching process of the diverter switch, the on-load diverter switch is normal in operation state.
The above detailed description is specific to possible embodiments of the present invention, and the embodiments are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the scope of the present invention are intended to be included within the scope of the present invention.
Claims (3)
1. An on-line monitoring and evaluating method for the operating state of a converter transformer on-load tap-changer is characterized by comprising the following specific steps:
step 1, monitoring load voltage and current waveforms in a switching process of an on-load tap-changer of a converter transformer, oil flow speed in an oil flow relay pipeline in the switching process and an oil chromatogram of an independent oil chamber of the on-load tap-changer;
step 2, calculating and processing the monitored load voltage and current waveforms in the switching process of the on-load tap-changer, and analyzing whether the on-load tap-changer is normal in switching-off current, recovery voltage change rate, switching-off time sequence, arcing time and the like; the on-off current, the recovery voltage change rate and the on-off time sequence of the on-load tap-changer meet the technical requirements and are smaller than an allowable value; the arcing time is within 12 ms;
step 3, analyzing the monitored oil flow velocity of the relay in the switching process of the on-load tap-changer, and judging whether the oil flow velocity is in a reasonable range;
step 4, drawing a relation curve between oil chromatographic data and switching times according to the monitored oil chromatographic data of the oil chamber of the switch, analyzing whether the oil chromatogram is abnormally increased, and performing transverse comparison analysis between on-load tap-changers of the same type;
and 5, evaluating whether the operating state of the on-load tap-changer is normal or not.
2. The method as claimed in claim 1, wherein the load voltage and current waveforms of the on-load tap-changer switching process in step 1 are extracted from a converter station wave recording system.
3. The on-line monitoring and evaluating method for the operating state of the converter transformer on-load tap-changer according to claim 1, characterized in that the oil chromatogram of the independent oil chamber of the diverter switch of the on-load tap-changer in the step 1 is obtained by adding an oil chromatogram on-line monitoring device to the oil chamber of the diverter switch of the on-load tap-changer and analyzing the characteristic gas and moisture content in the oil by taking an oil sample through the pipeline of the on-load tap-changer on-load oil filtering device.
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