CN109521391B - Device and method for detecting turn-to-turn short circuit fault of generator voltage transformer winding - Google Patents
Device and method for detecting turn-to-turn short circuit fault of generator voltage transformer winding Download PDFInfo
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- CN109521391B CN109521391B CN201910060779.9A CN201910060779A CN109521391B CN 109521391 B CN109521391 B CN 109521391B CN 201910060779 A CN201910060779 A CN 201910060779A CN 109521391 B CN109521391 B CN 109521391B
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating
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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
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
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Abstract
The invention relates to a device and a method for detecting turn-to-turn short circuit faults of a generator voltage transformer winding, and the technical scheme is that the device comprises a variable frequency signal generator, a double-channel variable frequency signal measuring device and a computer, wherein the signal output end of the variable frequency signal generator is connected with one detection end of the double-channel variable frequency signal measuring device, and the output end of the double-channel variable frequency signal measuring device is connected with the input end of the computer.
Description
Technical Field
The invention relates to a device and a method for testing turn-to-turn short circuit faults of a generator outlet side voltage transformer (PT) winding in the power industry, in particular to a device and a method for detecting turn-to-turn short circuit faults of the generator outlet PT winding by adopting frequency conversion signal generation and measurement analysis technology.
Background
The voltage transformer at the outlet side of the generator plays an important role in measuring the outlet voltage of the generator, measuring the electric quantity of the outlet and providing voltage signals for relay protection, and once the generator fails, the safety and stability operation of the unit is seriously affected, and even the unit is not scheduled to stop. In recent years, power generation enterprises in the power industry repeatedly generate unplanned outage events of the generator caused by turn-to-turn short circuit insulation defects of the PT winding at the outlet of the generator, and at present, a method and a device for conveniently, effectively and sensitively detecting the turn-to-turn short circuit faults of the PT winding at the outlet of the generator are still lacking.
In the current field test, three methods for detecting turn-to-turn short circuit faults of a PT winding at an outlet of a generator are mainly a direct current resistance test method, a transformation ratio test method and an idle current test method, and the three methods mainly have the following defects:
1) The detection sensitivity of the direct current resistance method is low. The voltage level of the primary winding of the generator outlet PT has a certain difference according to the different capacities of the generator set, and the number of turns of the primary winding is mostly more than 10000 turns in the range of 15-27 kV. In the initial stage of the occurrence of the turn-to-turn short circuit fault of the primary winding, only a few turns to tens of turns can be short-circuited, the direct current resistance change rate in the state is small, and the direct current resistance change rate of the short circuit is not more than three thousandths by taking short circuit 30 turns as an example, and the change rate of the degree is smaller than the normal allowable test error range of a direct current resistance test instrument, so that the turn-to-turn short circuit fault is difficult to find and confirm. Only when the turn-to-turn short circuit fault continuously develops to a more serious subsequent stage, the direct current resistance change rate exceeds two percent or more than three percent, and the fault of the equipment can be confirmed through the test.
2) The detection sensitivity of the transformation ratio test method is low. Similar to the direct current resistance method test, when the number of short-circuit turns of the turn-to-turn short-circuit fault is only several turns to several tens of turns, the change of the result of the transformation ratio test is very small, and basically no more than three thousandths of the result of the transformation ratio test is smaller than the normal allowable test error of a transformation ratio test instrument, so that the turn-to-turn short-circuit fault of the equipment cannot be effectively found and confirmed.
3) The no-load current test can find the turn-to-turn short circuit fault of the equipment more sensitively. When the inter-turn short circuit fault of a few turns to a few tens turns exists in the generator outlet PT, when an idle current method is adopted for testing, the idle current applied to one secondary winding of the equipment is obviously increased, and the inter-turn short circuit fault of the equipment can be found and confirmed by comparing historical idle current data. However, because the equipment required by no-load current test is inconvenient to carry, the equipment is difficult to wire from the secondary winding in a narrow space in the PT cabinet after being installed in place, and the historical data of the equipment is sometimes incomplete, and the like, the method is also less adopted in the field.
Disclosure of Invention
Aiming at the situation, the invention aims to overcome the defects of the prior art, and provides a device and a method for detecting turn-to-turn short circuit faults of a generator voltage transformer winding, which can effectively solve the problems of low sensitivity and low accuracy of field test.
The technical scheme of the invention is as follows:
the utility model provides a detection device of generator voltage transformer winding turn-to-turn short circuit trouble, includes frequency conversion signal generator, binary channels frequency conversion signal measuring device and computer, wherein:
frequency conversion signal generator: the device is used for outputting a sine wave alternating current voltage signal with continuously adjustable and changeable frequency and is used as a signal source of a voltage transformer winding at the outlet side of the generator to be tested;
double-channel variable frequency signal measuring device: the device is used for simultaneously measuring signal voltages of a signal input end and an output end of a winding of a voltage transformer at the outlet side of the generator to be measured under different frequency signal sources;
and (3) a computer: the method comprises the steps of outputting signal voltages acquired by a dual-channel variable-frequency signal measuring device under different frequency signal sources through a formula K (f) =20lg (Vo/Vi), wherein f is frequency; vi is the input signal voltage of the head end of the winding of the voltage transformer at the outlet side of the generator to be tested; vo is the output signal voltage of the tail end of the winding of the voltage transformer at the outlet side of the generator to be tested; the characteristic curve is used as a judging reference of whether the turn-to-turn of the generator outlet side voltage transformer winding is short-circuited or not;
k (f) is characteristic data at a frequency f, frequency values are used as abscissa, characteristic data values are used as ordinate, and corresponding characteristic data at all frequencies are drawn into a continuous curve, wherein the curve is the characteristic curve of the voltage transformer winding at the outlet side of the generator to be tested;
the signal output end of the variable frequency signal generator is connected with one detection end of the double-channel variable frequency signal measuring device, the signal output end is used as the signal input end of the voltage transformer winding at the outlet side of the generator to be measured, the other detection end of the double-channel variable frequency signal measuring device is used as the signal output end of the voltage transformer winding at the outlet side of the generator to be measured, and the output end of the double-channel variable frequency signal measuring device is connected with the input end of the computer.
A method for detecting turn-to-turn short circuit faults of a generator outlet side voltage transformer winding comprises the following steps:
1. confirming state of outlet voltage transformer of generator to be tested
The outlet voltage transformer of the generator to be tested is in a non-running power failure state, the safety of the primary winding of the voltage transformer is taken down, and an obvious physical disconnection point is ensured between the voltage transformer and other possibly electrified equipment;
2. confirming device frequency conversion signal generation and measurement function state is normal
Shorting the signal input end and the signal output end of the detection device, setting the frequency lower limit, the frequency upper limit and the frequency variation step length of the variable frequency signal, then starting the device to perform self-checking test of the variable frequency signal generation and measurement function, wherein the characteristic curve output by the computer is a horizontal straight line which is kept unchanged and has no attenuation;
3. data acquisition
The method comprises the steps that a signal input end of a detection device is connected to the head end of a primary winding of a voltage transformer at the outlet side of a generator to be detected through a lead, a signal output end of the detection device is connected to the tail end of the primary winding of the voltage transformer at the outlet side of the generator to be detected through a lead, a starting device is used for generating and measuring variable frequency signals, a computer records characteristic data K (f) processed by each corresponding measuring signal under each frequency through a formula K (f) =20lg (Vo/Vi), the frequency value is taken as an abscissa, the characteristic data value is taken as an ordinate, and the corresponding characteristic data under all frequencies are drawn into a continuous curve, wherein the curve is the characteristic curve of the voltage transformer at the outlet side of the generator to be detected;
4. data processing
Analyzing the characteristic curve result of the voltage transformer winding at the outlet side of the generator to be tested:
a. when the tested voltage transformer has a past historical characteristic curve, comparing the characteristic curve collected at this time with the historical characteristic curve, and when the characteristic curve changes, judging that the inter-turn short circuit defect of the winding occurs in the voltage transformer, wherein the characteristic curve changes into the number, the position or the amplitude of the peaks and the valleys of the characteristic curve to be obviously different;
b. when the tested voltage transformer has no past historical characteristic curve, confirming whether three-phase equipment of the generator outlet voltage transformer A, B, C is equipment of the same model parameter and the same manufacturing plant, if so (most of the equipment are equipment), the characteristic curves among the voltage transformer equipment of the same model parameter and the voltage transformer equipment of the same manufacturing plant are very similar or similar, so that the characteristic curves of the three-phase equipment can be used for mutual comparison, and if the characteristic curves among the mutually compared equipment change at the moment, the turn-to-turn short circuit defect of windings can be judged to occur inside the voltage transformer; the characteristic curve changes into the number, position or amplitude of the wave crest and the wave trough of the characteristic curve;
5. and repeatedly measuring equipment for judging that the inter-turn short circuit defect of the winding exists in the voltage transformer, and confirming that the test process and the test result are not abnormal.
The characteristic curve changes, specifically, compared with the number of peaks and troughs of a history characteristic curve, the number of the collected characteristic curve is increased by 1 or more, or the frequency positions corresponding to the peaks and the troughs change by more than 100Hz, or the amplitude values corresponding to the peaks and the troughs change by more than 15 db; or a combination of the three.
The invention has novel and unique structure, simple and reasonable detection method, small volume of instrument and equipment, and convenient and fast wiring from the primary winding of the equipment in the aspect of test, can effectively detect the turn-to-turn short circuit fault of the PT winding of the outlet of the generator in the field, can accurately detect the short circuit fault under the condition of very low ratio of the short circuit turns, has high test sensitivity and high accuracy, can simply, effectively and intuitively detect the turn-to-turn short circuit fault of the PT winding of the outlet of the generator by using the technology, can discover hidden defects in the equipment as soon as possible, and can prevent the occurrence of unplanned shutdown events of the generator caused by the turn-to-turn short circuit insulation defect of the PT winding of the outlet of the generator, thereby having good social benefit and economic benefit.
Drawings
FIG. 1 is a schematic diagram of the structure of the detecting device of the present invention.
Fig. 2 is an equivalent structural diagram of the generator outlet PT winding.
Fig. 3 is a diagram of an equivalent network of generator outlet PT windings.
FIG. 4 is a graph showing the comparison of characteristic curves of actual detection by the detection method of the present invention.
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to examples.
The invention relates to a device for detecting turn-to-turn short circuit faults of a generator voltage transformer winding, which comprises a variable frequency signal generator, a double-channel variable frequency signal measuring device and a computer, wherein:
frequency conversion signal generator: the device is used for outputting a sine wave alternating current voltage signal with continuously adjustable and changeable frequency and is used as a signal source of a voltage transformer winding at the outlet side of the generator to be tested;
double-channel variable frequency signal measuring device: the device is used for simultaneously measuring signal voltages of a signal input end and an output end of a winding of a voltage transformer at the outlet side of the generator to be measured under different frequency signal sources;
and (3) a computer: the method comprises the steps of outputting signal voltages acquired by a dual-channel variable-frequency signal measuring device under different frequency signal sources through a formula K (f) =20lg (Vo/Vi), wherein f is frequency; vi is the input signal voltage of the head end of the winding of the voltage transformer at the outlet side of the generator to be tested; vo is the output signal voltage of the tail end of the winding of the voltage transformer at the outlet side of the generator to be tested; the characteristic curve is used as a judging reference of whether the turn-to-turn of the generator outlet side voltage transformer winding is short-circuited or not;
k (f) is characteristic data at a frequency f, frequency values are used as abscissa, characteristic data values are used as ordinate, and corresponding characteristic data at all frequencies are drawn into a continuous curve, wherein the curve is the characteristic curve of the voltage transformer winding at the outlet side of the generator to be tested;
the signal output end of the variable frequency signal generator is connected with one detection end of the double-channel variable frequency signal measuring device, the signal output end is used as the signal input end of the voltage transformer winding at the outlet side of the generator to be measured, the other detection end of the double-channel variable frequency signal measuring device is used as the signal output end of the voltage transformer winding at the outlet side of the generator to be measured, and the output end of the double-channel variable frequency signal measuring device is connected with the input end of the computer.
The signal input end, the signal output end and the output end of the double-channel variable frequency signal measuring device can be connected with the wiring terminal, so that wiring is facilitated.
During detection, the common end of the signal output end of the variable frequency signal generator and one detection end of the double-channel variable frequency signal measuring device is connected with the head end of the voltage transformer winding at the outlet side of the generator to be detected, and the other detection end of the double-channel variable frequency signal measuring device is connected with the tail end of the voltage transformer winding at the outlet side of the generator to be detected.
The variable frequency signal generator is a function signal generator.
The dual-channel variable frequency signal measuring device is a dual-channel oscilloscope.
The power input end of the variable frequency signal generator is connected with the computer and shares a power supply with the computer.
The method for detecting the turn-to-turn short circuit fault of the generator outlet side voltage transformer winding of the detection device comprises the following steps:
1. confirming state of outlet voltage transformer of generator to be tested
The outlet voltage transformer of the generator to be tested is in a non-running power failure state, the safety of the primary winding of the voltage transformer is taken down, and an obvious physical disconnection point is ensured between the voltage transformer and other possibly electrified equipment;
2. confirming device frequency conversion signal generation and measurement function state is normal
Shorting the signal input end and the signal output end of the detection device, setting the frequency lower limit, the frequency upper limit and the frequency variation step length of the variable frequency signal, then starting the device to perform self-checking test of the variable frequency signal generation and measurement function, wherein the characteristic curve output by the computer is a horizontal straight line which is kept unchanged and has no attenuation;
3. data acquisition
The generator outlet PT is an electromagnetic voltage transformer, is structurally a step-down transformer with small capacity, small volume and large voltage ratio, has the same basic principle as the transformer and is composed of a primary winding, a secondary winding, an iron core, an outgoing line, an insulating structure and the like. The primary winding is very thin in wire diameter and has more than 10000 turns, is divided into tens of layers to be arranged and is wrapped on the annular iron core, the direct current resistance and the inductance under power frequency are very large, the direct current resistance can reach hundreds of ohms, the power frequency inductance can reach hundreds of henries, and the equivalent structural diagram is shown in figure 2.
According to the equivalent structure diagram of the PT winding of the generator outlet, referring to the equivalent circuit diagram of the transformer equipment in a typical circuit, the PT winding of the generator outlet can be equivalently regarded as a passive linear dual-port network consisting of distributed parameters such as inductance, resistance, capacitance and the like, the inductance, the resistance and the capacitance of a certain length of the winding are respectively L, R and C, and the equivalent network of the winding is shown in figure 3;
the method comprises the steps of continuously adjusting the frequency of a sinusoidal alternating voltage signal applied from the head end of a winding, simultaneously measuring and recording the signal voltage input to the head end of the winding and the output signal voltage transmitted to the tail end of the winding, and obtaining a series of characteristic functions (characteristic data) corresponding to different frequencies through calculation by utilizing the recorded input signal voltage of the head end and the output signal voltage of the tail end:
K(f)＝20lg(Vo/Vi)
f-frequency
Vi-head input signal voltage
Vo-end output signal voltage
And connecting a series of measured and calculated characteristic function values related to frequency by using a smooth curve to obtain the characteristic curve of the generator outlet PT winding in a specific frequency range.
The method comprises the steps that a signal input end of a detection device is connected to the head end of a primary winding of a voltage transformer at the outlet side of a generator to be detected through a lead, a signal output end of the detection device is connected to the tail end of the primary winding of the voltage transformer at the outlet side of the generator to be detected through a lead, a starting device is used for generating and measuring variable frequency signals, a computer records characteristic data K (f) processed by each corresponding measuring signal under each frequency through a formula K (f) =20lg (Vo/Vi), the frequency value is taken as an abscissa, the characteristic data value is taken as an ordinate, and the corresponding characteristic data under all frequencies are drawn into a continuous curve, wherein the curve is the characteristic curve of the voltage transformer at the outlet side of the generator to be detected;
when the winding has no turn-to-turn short circuit, the distribution parameters of inductance, resistance, capacitance and the like of the winding are fixed, the network formed by the winding is also fixed, the variable frequency signal characteristic curve is fixed, when the winding has turn-to-turn short circuit faults of different degrees, the distribution parameters of inductance, resistance, capacitance and the like are changed, the parameters of inductance, capacitance and the like are greatly changed along with the change of frequency, the change of resistance parameters is small, the parameters of an equivalent network of PT equipment are changed, and at the moment, the variable frequency signal characteristic curve is different from the previous characteristic curve even obviously, so that the judgment of the turn-to-turn short circuit faults of the winding of the generator outlet PT is realized.
4. Data processing
Analyzing the characteristic curve result of the voltage transformer winding at the outlet side of the generator to be tested:
a. when the tested voltage transformer has a past historical characteristic curve, comparing the characteristic curve collected at this time with the historical characteristic curve, and when the characteristic curve changes, judging that the inter-turn short circuit defect of the winding occurs in the voltage transformer, wherein the characteristic curve changes into the number, the position or the amplitude of the peaks and the valleys of the characteristic curve to be obviously different;
b. when the tested voltage transformer has no past historical characteristic curve, confirming whether three-phase equipment of the generator outlet voltage transformer A, B, C is equipment of the same model parameter and the same manufacturing plant, if so (most of the equipment are equipment), the characteristic curves among the voltage transformer equipment of the same model parameter and the voltage transformer equipment of the same manufacturing plant are very similar or similar, so that the characteristic curves of the three-phase equipment can be used for mutual comparison, and if the characteristic curves among the mutually compared equipment change at the moment, the turn-to-turn short circuit defect of windings can be judged to occur inside the voltage transformer; the characteristic curve changes into the number, position or amplitude of the wave crest and the wave trough of the characteristic curve;
5. and repeatedly measuring equipment for judging that the inter-turn short circuit defect of the winding exists in the voltage transformer, and confirming that the test process and the test result are not abnormal.
The characteristic curve changes, specifically, compared with the number of peaks and troughs of a history characteristic curve, the number of the collected characteristic curve is increased by 1 or more, or the frequency positions corresponding to the peaks and the troughs change by more than 100Hz, or the amplitude values corresponding to the peaks and the troughs change by more than 15 dB; or a combination of the three.
The technology of the invention achieves good effect through practical application, and the specific conditions are as follows:
the HR 1000F type tester developed by Datang China electric power test institute is adopted to carry out comparison tests with the traditional test technologies such as a direct current resistance method, a transformation ratio test method and the like, and the feasibility and the reliability of the method are verified:
(1) The test sample adopts the outlet PT of the JDZX9-20F1 type generator as the test sample, the total turns of the test sample winding is about 13000 turns, and comparison tests are respectively carried out under the conditions of no turn-to-turn short circuit and artificial manufacturing of the turn-to-turn short circuit, wherein the artificial manufacturing of the turn-to-turn short circuit is divided into 3 different working conditions of 5 turns short circuit, 35 turns short circuit and 96 turns short circuit.
(2) According to the traditional testing method, a single-arm bridge and a transformation ratio tester are used for comparison testing under 4 working conditions of no turn-to-turn short circuit and 3 different degrees of turn-to-turn short circuits respectively, and the testing results are shown in table 1.
(3) Secondly, the test under the same 4 working conditions is also carried out on the tested product by using an HR 1000F type tester.
(4) Finally, the sensitivity and the effectiveness of turn-to-turn short circuit faults of the PT equipment winding are analyzed and judged under different working conditions by comparing with a plurality of methods.
Table 1 comparison of test results of the dc resistance method and the transformation ratio test method under four working conditions
It can be seen that: when the traditional direct current resistance method is used for testing, when the number of short-circuit turns is 5 turns and the number of short-circuit turns is 35 turns, the direct current resistance change rate is very small, namely about four parts per million and three thousandths respectively, and whether turn-to-turn short circuit faults exist can not be judged. When the number of short-circuit turns reaches 96 turns, the direct-current resistance change rate is close to one percent, and only data analysis is carefully performed, the change condition of the data can be noticed, and the turn-to-turn short-circuit fault of the sample is suspected.
When the traditional transformation ratio method is used for testing, even if the number of turns of a short circuit reaches 96 turns, the transformation ratio data change is only about two thousandths, whether turn-to-turn short circuit faults exist or instrument testing errors can not be judged at all, and accurate fault judgment can not be carried out.
When the frequency conversion signal generation and measurement analysis technology provided by the invention is adopted for testing, the test result is shown in fig. 4, wherein: curve 1: PT normal state; curve 2: PT short-circuits 5 turns; curve 3: PT is short-circuited for 35 turns; curve 4: PT was shorted 96 turns.
The graph shows that under the working conditions of 3 different-degree inter-turn short circuits, the corresponding characteristic curves are quite obviously different from the characteristic curves of PT equipment in normal non-inter-turn short circuits. Even under the condition of short-circuiting only 5 turns, the change of the characteristic curve is very visual and obvious, the amplitude of the trough of the characteristic curve is changed by more than 15dB, and under the condition of short-circuiting 96 turns, the positions and the amplitudes of the peaks and the troughs are obviously changed, so that the turn-to-turn short-circuit fault of the equipment can be clearly judged. Therefore, by applying the technology, the turn-to-turn short circuit fault of the PT winding at the outlet of the generator can be simply, conveniently, effectively and intuitively detected, the hidden defect inside the equipment can be found out in time, the occurrence of the unplanned shutdown event of the generator caused by the turn-to-turn short circuit insulation defect of the PT winding at the outlet of the generator is prevented, and the method has good social benefit and economic benefit.
Claims (4)
1. The utility model provides a detection device of generator voltage transformer winding turn-to-turn short circuit trouble, its characterized in that includes frequency conversion signal generator, binary channels frequency conversion signal measuring device and computer, wherein:
frequency conversion signal generator: the device is used for outputting a sine wave alternating current voltage signal with continuously adjustable and changeable frequency and is used as a signal source of a voltage transformer winding at the outlet side of the generator to be tested;
double-channel variable frequency signal measuring device: the device is used for simultaneously measuring signal voltages of a signal input end and an output end of a winding of a voltage transformer at the outlet side of the generator to be measured under different frequency signal sources;
and (3) a computer: the method comprises the steps of outputting signal voltages acquired by a dual-channel variable-frequency signal measuring device under different frequency signal sources through a formula K (f) =20lg (Vo/Vi), wherein f is frequency; vi is the input signal voltage of the head end of the winding of the voltage transformer at the outlet side of the generator to be tested; vo is the output signal voltage of the tail end of the winding of the voltage transformer at the outlet side of the generator to be tested; the characteristic curve is used as a judging reference of whether the turn-to-turn of the generator outlet side voltage transformer winding is short-circuited or not;
the signal output end of the variable frequency signal generator is connected with one detection end of the double-channel variable frequency signal measuring device, the signal output end is used as the signal input end of the voltage transformer winding at the outlet side of the generator to be measured, the other detection end of the double-channel variable frequency signal measuring device is used as the signal output end of the voltage transformer winding at the outlet side of the generator to be measured, and the output end of the double-channel variable frequency signal measuring device is connected with the input end of the computer;
the signal output end of the variable frequency signal generator is connected with the public end of one detection end of the two-channel variable frequency signal measuring device and the head end of the voltage transformer winding at the outlet side of the generator to be measured, and the other detection end of the two-channel variable frequency signal measuring device is connected with the tail end of the voltage transformer winding at the outlet side of the generator to be measured;
the variable frequency signal generator is a function signal generator.
2. The device for detecting turn-to-turn short circuit faults of generator voltage transformer windings according to claim 1, wherein the dual-channel variable frequency signal measuring device is a dual-channel oscilloscope.
3. A method for detecting turn-to-turn short circuit faults of a generator outlet side voltage transformer winding by adopting the detection device as claimed in claim 1, which is characterized by comprising the following steps:
1. confirming state of outlet voltage transformer of generator to be tested
The outlet voltage transformer of the generator to be tested is in a non-running power failure state, the safety of the primary winding of the voltage transformer is taken down, and an obvious physical disconnection point is ensured between the voltage transformer and other possibly electrified equipment;
2. confirming device frequency conversion signal generation and measurement function state is normal
Shorting the signal input end and the signal output end of the detection device, setting the frequency lower limit, the frequency upper limit and the frequency variation step length of the variable frequency signal, then starting the device to perform self-checking test of the variable frequency signal generation and measurement function, wherein the characteristic curve output by the computer is a horizontal straight line which is kept unchanged and has no attenuation;
3. data acquisition
The method comprises the steps of connecting a signal input end of a detection device to a head end of a primary winding of a voltage transformer at an outlet side of a generator to be detected through a lead, connecting a signal output end of the detection device to a tail end of the primary winding of the voltage transformer at the outlet side of the generator to be detected through a lead, starting the device to generate and measure variable frequency signals, and recording characteristic data K (f) after processing of each corresponding measurement signal through a formula K (f) =20lg (Vo/Vi) under each frequency by a computer;
4. data processing
Analyzing the characteristic curve result of the voltage transformer winding at the outlet side of the generator to be tested:
a. when the tested voltage transformer has a past historical characteristic curve, comparing the characteristic curve collected at this time with the historical characteristic curve, and when the characteristic curve changes, judging that the inter-turn short circuit defect of the winding occurs in the voltage transformer, wherein the characteristic curve changes into the number, the position or the amplitude of the peaks and the valleys of the characteristic curve to be obviously different;
b. when the tested voltage transformer has no past historical characteristic curve, confirming whether three-phase equipment of the generator outlet voltage transformer A, B, C is equipment of the same model parameter and the same manufacturing plant, if so, the characteristic curves among the voltage transformer equipment of the same model parameter and the voltage transformer equipment of the same manufacturing plant are very similar or similar, so that the characteristic curves of the three-phase equipment can be utilized for mutual comparison, and if the characteristic curves among the mutually compared equipment change at the moment, the turn-to-turn short circuit defect of the winding can be judged to occur inside the voltage transformer; the characteristic curve changes into the number, position or amplitude of the wave crest and the wave trough of the characteristic curve;
5. and repeatedly measuring equipment for judging that the inter-turn short circuit defect of the winding exists in the voltage transformer, and confirming that the test process and the test result are not abnormal.
4. The method for detecting the turn-to-turn short circuit fault of the generator outlet side voltage transformer winding according to claim 3, wherein the characteristic curve changes by 1 or more or the frequency positions corresponding to the peaks and the troughs are changed by more than 100Hz or the amplitude corresponding to the peaks and the troughs is changed by more than 15dB compared with the number of the peaks and the troughs of the characteristic curve acquired at this time after comparison; or a combination of the three.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910060779.9A CN109521391B (en) | 2019-01-23 | 2019-01-23 | Device and method for detecting turn-to-turn short circuit fault of generator voltage transformer winding |
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| CN201910060779.9A CN109521391B (en) | 2019-01-23 | 2019-01-23 | Device and method for detecting turn-to-turn short circuit fault of generator voltage transformer winding |
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| CN109521391A CN109521391A (en) | 2019-03-26 |
| CN109521391B true CN109521391B (en) | 2024-02-09 |
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| CN110456241B (en) * | 2019-08-30 | 2022-02-11 | 国家电网有限公司 | Coil turn-to-turn fault detection method |
| CN110456242A (en) * | 2019-08-30 | 2019-11-15 | 国家电网有限公司 | Coil turn-to-turn insulation detecting method and device |
| CN112526306B (en) * | 2020-11-24 | 2022-11-04 | 中国大唐集团科学技术研究院有限公司火力发电技术研究院 | Generator outlet side voltage transformer insulation state monitoring system |
| CN112834617B (en) * | 2021-01-22 | 2023-07-07 | 中国大唐集团科学技术研究院有限公司华中电力试验研究院 | Circular arc fir type blade root phased array ultrasonic detection method |
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