CN107817413B - Method for eliminating influence of short-circuit resistance in transformer low-voltage short-circuit impedance test - Google Patents
Method for eliminating influence of short-circuit resistance in transformer low-voltage short-circuit impedance test Download PDFInfo
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- CN107817413B CN107817413B CN201711005445.9A CN201711005445A CN107817413B CN 107817413 B CN107817413 B CN 107817413B CN 201711005445 A CN201711005445 A CN 201711005445A CN 107817413 B CN107817413 B CN 107817413B
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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
- G01R31/62—Testing of transformers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
The invention relates to a method for eliminating short-circuit resistance influence in a transformer low-voltage short-circuit impedance test. The low-voltage short-circuit impedance tester comprises a first switch used for connecting two ends of the low-voltage side of the transformer and a second switch used for connecting two ends of the low-voltage side of the transformer, wherein the first switch comprises a suspension gear, a current output gear and a current measurement gear, the second switch comprises a suspension gear and a voltage measurement gear, and the low-voltage short-circuit impedance tester is further connected with the high-voltage side of the transformer. The method can eliminate short-circuit resistance influence in a low-voltage short-circuit impedance test.
Description
Technical Field
The invention belongs to the field of electric tests for transformer overhaul in a power system, and particularly relates to a method for eliminating short-circuit resistance influence in a transformer low-voltage short-circuit impedance test.
Background
Transformer low voltage short circuit impedance test wiring as in figure 1 (for example a single phase transformer),
the low voltage side AB of the transformer is short-circuited, a low voltage (generally about 220V) is input from the high voltage side AB, and a current is measured from the high voltage side, thereby calculating a low voltage short-circuit impedance value of the transformer. Its impedance value:
Z=U/I=（X 2 +R 2 ） 1/2
the existing low-voltage short-circuit impedance tester can directly measure the values of the reactance X and the resistance R. Where X determines reactive losses and R determines active losses. The active loss in this test is mainly the no-load loss of the transformer at this voltage and the resistive loss caused by the low-side resistor r.
Ideally, the low-voltage side ab has a short-circuit resistance of 0, but in actual operation, R tends to be large due to poor short-circuit, resulting in large deviation of test results.
Currently, it is common practice to short-circuit the low-voltage side by means of bare copper wire winding. For a transformer with higher voltage level, the influence on the test result is smaller due to the fact that the short circuit impedance value is larger by adopting bare copper wire winding. However, for a transformer with a higher voltage class, since the short-circuit impedance is not large, the total measurement impedance of the additional resistance value of the transformer is large by adopting a direct short-circuit mode of bare copper wires, the measurement data is easy to exceed the standard, and the measurement effect is poor.
The prior art has the defects that:
for a transformer with lower voltage level (smaller capacity), because the short circuit impedance is not large, the total measurement impedance of the additional resistance value of the transformer is large in proportion by adopting a direct short circuit mode of bare copper wires, the measurement data is easy to exceed the standard, and the measurement effect is poor.
Disclosure of Invention
The invention aims to provide a method for eliminating short-circuit resistance influence in a low-voltage short-circuit impedance test of a transformer, which can eliminate short-circuit resistance influence in the low-voltage short-circuit impedance test.
In order to achieve the above purpose, the technical scheme of the invention is as follows: a method for eliminating short-circuit resistance influence in a transformer low-voltage short-circuit impedance test provides a low-voltage short-circuit impedance tester, which comprises a first switch used for connecting two ends of a transformer low-voltage side and a second switch used for connecting two ends of the transformer low-voltage side, wherein the first switch comprises a suspension, a current output and a current measurement gear, the second switch comprises a suspension and a voltage measurement gear, and the low-voltage short-circuit impedance tester is also connected with the transformer high-voltage side; the method is realized as follows:
s1, cutting the first switch and the second switch to be suspended, inputting a voltage U at the high-voltage side of the transformer, and measuring a current I 0 Obtaining the no-load active loss P under the voltage U 0 ；
S2, switching the first switch to a current output gear, switching the second switch to a voltage measurement gear, enabling the high-voltage side of the transformer to be suspended, and measuring the direct-current resistance r of a winding on the high-voltage side of the transformer;
s3, switching the first switch to a current measurement gear, switching the second switch to a suspension gear, inputting voltage U at the high-voltage side of the transformer and measuring input measurement current I, wherein the first switch corresponds to a short circuit; at this time, the first switch measures a current I 1 The method comprises the steps of carrying out a first treatment on the surface of the According to the short-circuit impedance formula:
Z=U/I=（X 2 +R 2 ） 1/2
wherein R is affected by three parts: equivalent resistance r of no-load loss 0 Voltage measuring direct current resistor r and short circuit additional resistor r x
Now get rid of r x Is a function of (1); let the exclusion r x The resistance after the influence is R', the following equation holds true
U 2 / R’= I 1 2 r+P 0
I.e. R' =u 2 /（I 1 2 r+P 0 ）
R' is replaced by R, so that the influence of the short-circuit additional resistor can be eliminated; i.e. z=u/i= (X 2 +R’ 2 ） 1/2 。
Compared with the prior art, the invention has the following beneficial effects:
1. the influence of the additional resistance cannot be eliminated by the existing test method, and the influence of the additional resistance can be completely eliminated by measurement and calculation, so that the accuracy of the test is improved;
2. the method can realize accurate measurement only by connecting the test wire into an instrument, reduces the workload of winding copper wires and improves the working efficiency.
Drawings
Fig. 1 is a diagram of a transformer low voltage short circuit impedance test.
FIG. 2 is a wiring diagram of the method of the present invention.
Fig. 3 is an enlarged view of a portion P of fig. 2.
Detailed Description
The technical scheme of the invention is specifically described below with reference to fig. 2-3.
The invention provides a method for eliminating short-circuit resistance influence in a transformer low-voltage short-circuit impedance test, which comprises a first switch used for connecting two ends of a transformer low-voltage side and a second switch used for connecting two ends of the transformer low-voltage side, wherein the first switch comprises a suspension, current output and current measurement gear, the second switch comprises a suspension and voltage measurement gear, and the low-voltage short-circuit impedance tester is also connected with the transformer high-voltage side; the method is realized as follows:
s1, cutting the first switch and the second switch to be suspended, inputting a voltage U at the high-voltage side of the transformer, and measuring a current I 0 Obtaining the no-load active loss P under the voltage U 0 ；
S2, switching the first switch to a current output gear, switching the second switch to a voltage measurement gear, enabling the high-voltage side of the transformer to be suspended, and measuring the direct-current resistance r of a winding on the high-voltage side of the transformer;
s3, switching the first switch to a current measurement gear, switching the second switch to a suspension gear, inputting voltage U at the high-voltage side of the transformer and measuring input measurement current I, wherein the first switch corresponds to a short circuit; at this time, the first switch measures a current I 1 The method comprises the steps of carrying out a first treatment on the surface of the According to the short-circuit impedance formula:
Z=U/I=（X 2 +R 2 ） 1/2
wherein R is affected by three parts: equivalent resistance r of no-load loss 0 Voltage measuring direct current resistor r and short circuit additional resistor r x
Now get rid of r x Is a function of (1); let the exclusion r x The resistance after the influence is R', the following equation holds true
U 2 / R’= I 1 2 r+P 0
I.e. R' =u 2 /（I 1 2 r+P 0 ）
R' is replaced by R, so that the influence of the short-circuit additional resistor can be eliminated; i.e. z=u/i= (X 2 +R’ 2 ） 1/2 。
The following are examples of embodiments of the invention.
The invention relates to a method for eliminating short-circuit resistance influence in a transformer low-voltage short-circuit impedance test, wherein wiring diagrams of a low-voltage short-circuit impedance tester are shown in figures 2 and 3, and the test method comprises the following steps:
s1, the switch C, D in FIG. 2 is cut to 1, the voltage U is input at the high-voltage side of the transformer, and the current I is measured 0 Obtaining the no-load active loss P under the voltage U 0 ；
S2, cutting the switch C, D in the figure 2 to 2 positions, suspending the high-voltage side of the transformer, and measuring the direct-current resistance r of the winding on the high-voltage side of the transformer (testing the direct-current resistance of the transformer);
s3, cutting C in FIG. 2 to a 3-current measuring end, wherein C corresponds to a short circuit. D, cutting to 1 position and suspending. Inputting a voltage U at the high-voltage side of the transformer, and measuring an input measurement current I; at this time haveThe measured current at the first switch is I 1 The method comprises the steps of carrying out a first treatment on the surface of the According to the short-circuit impedance formula:
Z=U/I=（X 2 +R 2 ） 1/2
wherein R is affected by three parts: equivalent resistance r of no-load loss 0 Voltage measuring direct current resistor r and short circuit additional resistor r x
Now get rid of r x Is a function of (1); let the exclusion r x The resistance after the influence is R', the following equation holds true
U 2 / R’= I 1 2 r+P 0
I.e. R' =u 2 /（I 1 2 r+P 0 ）
R' is replaced by R, so that the influence of the short-circuit additional resistor can be eliminated; i.e. z=u/i= (X 2 +R’ 2 ） 1/2 。
The above is a preferred embodiment of the present invention, and all changes made according to the technical solution of the present invention belong to the protection scope of the present invention when the generated functional effects do not exceed the scope of the technical solution of the present invention.
Claims (1)
1. A method for eliminating short-circuit resistance influence in a transformer low-voltage short-circuit impedance test is characterized by comprising the following steps: providing a low-voltage short-circuit impedance tester, wherein the low-voltage short-circuit impedance tester comprises a first switch used for connecting two ends of a low-voltage side of a transformer and a second switch used for connecting two ends of the low-voltage side of the transformer, the first switch comprises a suspension, current output and current measurement gears, the second switch comprises a suspension and voltage measurement gears, and the low-voltage short-circuit impedance tester is also connected with the high-voltage side of the transformer; the method is realized as follows:
s1, cutting the first switch and the second switch to be suspended, inputting a voltage U at the high-voltage side of the transformer, and measuring a current I 0 Obtaining the no-load active loss P under the voltage U 0 ；
S2, switching the first switch to a current output gear, switching the second switch to a voltage measurement gear, enabling the high-voltage side of the transformer to be suspended, and measuring the direct-current resistance r of a winding on the high-voltage side of the transformer;
s3, switching the first switch to a current measurement gear, switching the second switch to a suspension gear, inputting voltage U at the high-voltage side of the transformer and measuring input measurement current I, wherein the first switch corresponds to a short circuit; at this time, the first switch measures a current I 1 The method comprises the steps of carrying out a first treatment on the surface of the According to the short-circuit impedance formula:
Z=U/I=（X 2 +R 2 ） 1/2
wherein R is affected by three parts: equivalent resistance r of no-load loss 0 Measuring the direct current resistance r and the short-circuit additional resistance r of the high-voltage side winding of the transformer x
Now get rid of r x Is a function of (1); let the exclusion r x The resistance after the influence is R', the following equation holds true
U 2 / R’= I 1 2 r+P 0
I.e. R' =u 2 /（I 1 2 r+P 0 ）
R' is replaced by R, so that the influence of the short-circuit additional resistor can be eliminated; i.e. z=u/i= (X 2 +R’ 2 ） 1/2 。
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| CN201711005445.9A CN107817413B (en) | 2017-10-25 | 2017-10-25 | Method for eliminating influence of short-circuit resistance in transformer low-voltage short-circuit impedance test |
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| CN107817413B true CN107817413B (en) | 2023-10-17 |
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| CN108693432A (en) * | 2018-04-27 | 2018-10-23 | 国家电网公司 | A kind of tester of deformation of transformer winding |
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| CN107144758A (en) * | 2017-05-25 | 2017-09-08 | 云南电网有限责任公司电力科学研究院 | The test method that a kind of fuel factor influences on transformer anti-short circuit capability |
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- 2017-10-25 CN CN201711005445.9A patent/CN107817413B/en active Active
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| JP2013113710A (en) * | 2011-11-29 | 2013-06-10 | Toyota Industries Corp | Insulation abnormality detection device |
| CN103869202A (en) * | 2012-12-13 | 2014-06-18 | 国家电网公司 | Transformer high-tension side phase-failure detection method and system |
| CN103245834A (en) * | 2013-05-16 | 2013-08-14 | 国家电网公司 | Site testing method for transformer winding deformation low-voltage impedance |
| CN103941136A (en) * | 2013-12-23 | 2014-07-23 | 上海大郡动力控制技术有限公司 | Signal sampling circuit resistor-capacitor component short circuit and open circuit fault diagnosis method |
| CN103901313A (en) * | 2014-03-18 | 2014-07-02 | 常熟理工学院 | Low-voltage circuit breaker main wiring insulation pre-checking device based on piezoelectric ceramic transformer |
| CN103837792A (en) * | 2014-03-21 | 2014-06-04 | 山东电力设备有限公司 | Device and method for detecting short circuit ring of coils of transformers |
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