Method and device for measuring finished-product resistance of autotransformer

Abstract

A method and device for measuring the finished-product resistance of an autotransformer. The magnitude of a test current output by a direct-current resistance tester (4) is selected, the accuracy of a test result is ensured, the test efficiency is improved, a direct-current resistance value of a common coil (1) is automatically calculated on the basis of the direct-current resistance tester (4), without the need for further conversion. In addition, when direct-current resistance measurement is performed, a same test current flow through two ends of a series coil (2) and two ends of the common coil (1), but the test current does not flow through a voltage regulating coil (3), therefore, a voltage clip at the voltage regulating coil (3) indirectly measures a voltage value on a connecting line between the common coil (1) and the series coil (2) by means of the voltage regulating coil (3), and the direct-current resistance of coils such as the series coil (2) and the common coil (1) can be accurately measured. The problems that during a finished-product direct-current resistance testing process of an oil-immersed autotransformer, direct-current resistance testing and conversion of a common winding, a series winding and a voltage regulating winding are complex and a testing result is inaccurate. The device is simple, has flexible operation and high testing and measurement efficiency, and can provide sufficiently accurate direct-current resistance test data, so as to facilitate analysis and determination of product quality. The present invention is suitable for indirect measurement of coil direct-current resistance in various self-coupled oil-immersed power transformers.

Description

Method and device for measuring finished product resistance of autotransformer TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of electronic device measurement, and in particular to a method and device for measuring finished product resistance of an autotransformer. BACKGROUND

[0002] In modern power grid construction, oil-immersed autotransformers are often used to reduce the procurement cost of power transmission and transformation equipment and to improve the power transmission capacity per unit weight. Such transformers are particularly suitable for high-voltage power grid systems that require direct grounding, as they have the significant advantages of low loss, light weight, small size, and low cost. Therefore, autotransformers are increasingly used in ultra-high voltage and extra-high voltage power grids, especially in the rapid expansion of power grids in China.

[0003] However, the design and application of autotransformers vary in different regions due to differences in power grid backgrounds and design principles. For example, some autotransformers have a field winding designed on a side limb, while others have only a field winding arranged on a main limb. These design differences affect the voltage regulation function and efficiency of the transformer in operation. In the case of oil-immersed transformers, it is not possible to directly measure the resistance of the field winding, the common winding, and the series winding separately in the finished product state, which poses a challenge for calculating the load loss under rated current conditions. In addition, it is difficult to analyze and determine whether there is a problem with the resistance of each contact point, thereby increasing the uncertainty of fault analysis.

[0004] Therefore, it is particularly important to develop an effective autotransformer winding DC resistance measurement technology, which will directly affect the accuracy of test data and the stable operation of the power grid. Analysis of the contact resistance of the high-voltage and medium-voltage side windings and the polarity tap lead is also crucial to ensure the reliability of the power system.

[0005] SUMMARY

[0006] Embodiments of the present application provide a method and device for measuring finished product resistance of an autotransformer. The technical solution is as follows:

[0007] According to one aspect of the present application, a device for measuring finished product resistance of an autotransformer is provided, which is suitable for an oil-immersed autotransformer with medium-voltage line-end voltage regulation. The device comprises:

[0008] a low-voltage winding, a common winding 1, a series winding 2, a field winding 3, and a DC resistance tester 4 and a measurement host, wherein the low-voltage winding, the common winding 1, the series winding 2, and the field winding 3 are arranged in order from inside to outside on the core.

[0009] The series coil 2 is connected in series on one side of the common coil 1, wherein the connection point of the series coil 2 and the common coil 1 is recorded as a common winding voltage actual test point, and the common winding voltage actual test point is a voltage collection point for indirectly obtaining the common winding resistance value; and the voltage regulating coil 3 is connected to the common winding voltage actual test point.

[0010] The DC resistance tester 4 is provided with a current clamp group and a voltage clamp group with variable working positions, and the current clamp group and the voltage clamp group are respectively used for measuring voltage measurement values and current measurement values of each winding coil on the high-voltage side of the oil-immersed autotransformer, and each winding coil refers to the common coil 1, the series coil 2 and the voltage regulating coil 3.

[0011] The measurement host is connected with the DC resistance tester 4, and the measurement host is used for controlling the position movement of the current clamp group and the voltage clamp group and controlling the DC resistance tester 4 to generate a measurement current, and the DC resistance tester 4 is used for obtaining and determining the DC resistance value of each winding coil according to the voltage measurement value and the current measurement value.

[0012] Optionally, the current clamp group includes a first tester current clamp 5 and a second tester current clamp 6; and the voltage clamp group includes a first tester voltage clamp 7 and a second tester voltage clamp 8.

[0013] Optionally, the common coil 1 and the series coil 2 form a high-voltage winding in series, and the voltage regulating coil 3 and the common coil 1 form a medium-voltage winding.

[0014] In the high-voltage winding, a first wire end of the common coil 1 is recorded as a wire end X, a second wire end of the common coil 1 is recorded as a wire end A'', a first wire end of the series coil 2 is recorded as a wire end A, and a second wire end of the series coil 2 is recorded as a wire end A'.

[0015] In the medium-voltage winding, a connection end of the voltage regulating coil 3 is recorded as a wire end Am.

[0016] Optionally, the first tester current clamp 5 and the first tester voltage clamp 7 are clamped at the wire end X.

[0017] Optionally, the second tester current clamp 6 is clamped at the wire end A.

[0018] Optionally, the second tester voltage clamp 8 is clamped at the wire end Am.

[0019] Optionally, in the oil-immersed self-coupled power transformer, each coil lead is led out through a bushing, the line end X is an air connection terminal of a neutral point bushing, the line end A is an air connection terminal of a high-voltage bushing, and the line end Am is an air connection terminal of a medium-voltage bushing.

[0020] In another aspect, a self-coupled transformer finished product resistance measurement method is provided, which is used in any of the self-coupled transformer finished product resistance measurement devices described above, and the method comprises:

[0021] The measurement host controls the DC resistance tester 4 to generate the measurement current and apply the test current to the first line end of the common coil 1 and the series coil 2 through the current clip set;

[0022] The measurement host controls the voltage clip set to be clamped at the first line end of the common coil 1 and the connection end of the voltage regulating coil 3 and collects corresponding voltage measurement values;

[0023] The DC resistance tester 4 acquires the voltage measurement values and the current measurement values and determines the DC resistance values of each winding coil;

[0024] The measurement host acquires the DC resistance values of each winding coil and stores them.

[0025] In the embodiment of the present application, a self-coupling transformer finished product resistance measuring device and method thereof are provided. The device comprises a low-voltage coil, a common coil, a series coil, a voltage regulating coil, a direct current resistance tester, and a measuring host. The direct current resistance tester is provided with a current clamp group and a voltage clamp group with variable working positions. The current clamp group and the voltage clamp group are respectively used for measuring the voltage measurement value and the current measurement value of each winding coil on the high-voltage side of the oil-immersed self-coupling power transformer. The position movement of the current clamp group and the voltage clamp group is controlled by the measuring host, and the measuring current is generated by the direct current resistance tester. The direct current resistance value of each winding coil is determined according to the voltage measurement value and the current measurement value obtained by the direct current resistance tester. The size of the output test current of the direct current resistance tester is selected, which helps to ensure the accuracy of the test results and improve the test efficiency. The direct current resistance value of the common coil is automatically calculated based on the direct current resistance tester, and there is no need for further conversion. In addition, during the direct current resistance measurement, the same test current flows through the series coil and the common coil, while the voltage regulating coil does not flow through the test current. The voltage clamp at the voltage regulating coil indirectly measures the voltage value on the connection line between the common coil and the series coil by means of the voltage regulating coil, so that the direct current resistance of the series coil, the common coil and other coils can be accurately measured. The direct current resistance test and conversion of the common winding, the series winding and the voltage regulating winding in the oil-immersed self-coupling power transformer during the finished product direct current resistance test are complicated, and the test results are not accurate. The device of the present application is simple, flexible to operate, high in test measurement efficiency, and can provide accurate direct current resistance test data for the analysis and judgment of product quality. It is suitable for the indirect measurement of the direct current resistance of the coil in various self-coupling oil-immersed power transformers. BRIEF DESCRIPTION OF DRAWINGS

[0026] Fig. 1 is a structural schematic diagram of a self-coupling transformer finished product resistance measuring device provided by an illustrative embodiment of the present application;

[0027] Fig. 2 is a flow chart of a self-coupling transformer finished product resistance measuring method provided by an illustrative embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0029] In this paper, "a plurality of" refers to two or more. The association relationship of the associated objects is described as "and / or", which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. The character " / " generally represents an "or" relationship between the front and rear associated objects.

[0030] Please refer to Fig. 1, which shows a structural schematic diagram of the self-coupling transformer finished product resistance measuring device provided by one illustrative embodiment of the present application.

[0031] In the present application, the self-coupling power transformer is oil-immersed, and the oil-immersed transformer is characterized by a closed oil tank shell outside and contact and / or invisible internal connection leads when becoming a finished product.

[0032] The device is suitable for oil-immersed self-coupling power transformers with medium-voltage line end voltage regulation, and the device comprises a low-voltage coil, a common coil 1, a series coil 2, a voltage regulation coil 3, a direct current resistance tester 4, and a measuring host. Next, the connection relationship and the role of each component are described.

[0033] The low-voltage coil, the common coil 1, the series coil 2, and the voltage regulation coil 3 are sequentially arranged from inside to outside on the core. The series coil 2 is connected in series on one side of the common coil 1, wherein the connection point of the series coil 2 and the common coil 1 is recorded as the common winding voltage actual test point, and the common winding voltage actual test point is the voltage collection point for indirectly obtaining the common winding resistance value; the voltage regulation coil 3 is connected to the common winding voltage actual test point.

[0034] The direct current resistance tester 4 is provided with a current clamp group and a voltage clamp group with variable working positions, and the current clamp group and the voltage clamp group are respectively used for measuring the voltage measurement value and the current measurement value of each winding coil on the high-voltage side of the oil-immersed self-coupling power transformer, and each winding coil refers to the common coil 1, the series coil 2, and the voltage regulation coil 3.

[0035] The measuring host is connected with the direct current resistance tester 4, and the measuring host is used for controlling the position movement of the current clamp group and the voltage clamp group and controlling the direct current resistance tester 4 to generate a measurement current, and the direct current resistance tester 4 is used for obtaining and determining the direct current resistance value of each winding coil according to the voltage measurement value and the current measurement value. Among them, the test current is also equal to the current value when calculating the resistance value, that is, the value of the test current is the current measurement value.

[0036] Further, as shown in Fig. 1, considering the number and type of test windings, the current clamp group comprises a first tester current clamp 5 and a second tester current clamp 6; and the voltage clamp group comprises a first tester voltage clamp 7 and a second tester voltage clamp 8.

[0037] Among them, the common coil 1 and the series coil 2 form a high-voltage winding in series, and the voltage regulation coil 3 and the common coil 1 form a medium-voltage winding. In the high-voltage winding, the first line end of the common coil 1 is recorded as the line end X, the second line end of the common coil 1 is recorded as the line end A”, the first line end of the series coil 2 is recorded as the line end A, and the second line end of the series coil 2 is recorded as the line end A’; in the medium-voltage winding, the connection end of the voltage regulation coil 3 is recorded as the line end Am.

[0038] Wherein, the first tester current clamp 5 and the first tester voltage clamp 7 are clamped at the line end X, the second tester current clamp 6 is clamped at the line end A, and the second tester voltage clamp 8 is clamped at the line end Am.

[0039] Further, in the oil-immersed autotransformer, each coil lead is led out through a bushing, the line end X is the air terminal of the neutral-point bushing, the line end A is the air terminal of the high-voltage bushing, and the line end Am is the air terminal of the medium-voltage bushing.

[0040] In the embodiment of the present application, a kind of autotransformer finished product resistance measuring device is provided, the device includes low-voltage coil, common coil, series coil, voltage regulating coil and direct current resistance tester and measurement host, direct current resistance tester is equipped with the current clamp group and voltage clamp group of variable working position, current clamp group and voltage clamp group are respectively used to measure the voltage measurement value and current measurement value of each winding coil of high-voltage side of oil-immersed autotransformer, the position movement of current clamp group and voltage clamp group is controlled by measurement host and the measurement current generated by direct current resistance tester, the direct current resistance value of each winding coil is determined by direct current resistance tester and according to voltage measurement value and current measurement value.It is helpful to guarantee the accuracy of test result and improve test efficiency by selecting the size of the test current output by direct current resistance tester, and the direct current resistance value of common coil is automatically calculated based on direct current resistance tester, without further conversion.In addition, when direct current resistance is measured, the same test current flows through series coil and common coil, and the voltage clamp at voltage regulating coil does not flow through test current, so the voltage value on the connection line between common coil and series coil is indirectly measured by voltage regulating coil, and the direct current resistance of series coil and common coil can be accurately measured;The direct current resistance of common winding, series winding and voltage regulating winding in the finished product direct current resistance test process of oil-immersed autotransformer is tested and converted complicatedly, and the test result is not accurate, and the problems are solved.The device of the present application is simple, flexible to operate, high in test efficiency, and can provide accurate direct current resistance test data for product quality analysis and judgment;It is suitable for indirect measurement of direct current resistance of coil in various oil-immersed power transformers connected in autotransformer mode.

[0041] Please refer to Fig. 2, which shows the flow chart of the autotransformer finished product resistance measuring method provided by one illustrative embodiment of the present application. This embodiment takes the method used in the autotransformer finished product resistance measuring device provided by the above-mentioned embodiment as an example for illustration, and the method comprises:

[0042] Step 201: the measurement host controls the direct current resistance tester to generate measurement current and applies test current to the first line end of common coil and series coil through the current clamp group.

[0043] The applied test current is also the same as the current value used when calculating the resistance.

[0044] The formula for calculating the test current is as follows:

[0045] In the formula, I represents the output current of the DC resistance tester during the test, measured in amperes (A), and is usually an integer ending in 0 or 5; N — Rated current of the transformer test side, in A; i0 — No-load current of the transformer test side (per unit), in %; k — Overexcitation coefficient, range (3~10); For k, if the DC resistance of the coil is small, take a larger value, and if it is large, take a smaller value.

[0046] Step 202: The host control voltage clamp group is clamped at the first wire end of the common coil and the connection end of the voltage regulating coil, and the corresponding voltage measurement value is collected.

[0047] Step 203: Obtain and determine the DC resistance value of each winding coil by using a DC resistance tester based on the voltage and current measurement values.

[0048] Here, each winding coil refers to each coil, such as the high-voltage winding.

[0049] Step 204: The measuring host obtains and stores the DC resistance values ​​of each winding coil.

[0050] The result obtained by this measurement method is the DC resistance of the coil turns through which DC current flows and between the coil turns and the voltage clamp, either directly or indirectly. This not only makes the voltage clamp position of the DC resistance tester more flexible and convenient, but also ensures the accuracy of the test results. This invention patent is applicable to the indirect or direct measurement of the coil DC resistance in various autotransformer oil-immersed power transformers.

[0051] In the embodiments of the present application, a self-coupling transformer finished product resistance measurement method is provided, the voltage measurement value and the current measurement value of each winding coil of the high voltage side of the oil-immersed self-coupling power transformer are measured by the current clamp set and the voltage clamp set respectively, the position movement of the current clamp set and the voltage clamp set is measured by the host computer, and the measurement current is generated by controlling the direct current resistance tester, and the direct current resistance value of each winding coil is obtained by the direct current resistance tester according to the voltage measurement value and the current measurement value. The size of the output test current of the direct current resistance tester is selected, which helps to ensure the accuracy of the test result and improve the test efficiency, and the direct current resistance value of the common coil is automatically calculated based on the direct current resistance tester, without the need for further conversion. The apparent feeling of this test method is that the test result seems to include the direct current resistance value of the regulating coil and the connection thereof, and in fact, the creative test method has excluded it, and the reason is that during the direct current resistance measurement, the same test current flows through the series coil and the common coil, and the test current does not flow through the regulating coil, and the voltage clamp clamped at the medium voltage line end Am only indirectly measures the voltage value on the connection line between the common coil and the series coil by means of the regulating coil. The same method can also be used to accurately measure the direct current resistance of the series coil and the common coil; the direct current resistance test and conversion of the common winding, the series winding and the regulating winding of the oil-immersed self-coupling power transformer during the finished product direct current resistance test are solved, the problem of inaccurate test result is solved, the device of the present application is simple, the operation is flexible, the test measurement efficiency is high, and the direct current resistance test data can provide sufficient accurate direct current resistance test data for the analysis and judgment of product quality; and the device is suitable for the indirect measurement of the direct current resistance of the coil of the oil-immersed power transformer connected in various self-coupling modes.

[0052] In summary, the embodiments of the present application can flexibly and accurately measure the direct current resistance of each winding coil of the high voltage side of the oil-immersed self-coupling power transformer with medium voltage line end regulating by changing the working positions of the current clamp and the voltage clamp of the direct current resistance tester. The structure is suitable for the indirect measurement of the direct current resistance of the coil of the oil-immersed power transformer connected in various self-coupling modes. The structure provides theoretical support for the accurate conversion of the load loss of the self-coupling transformer and the fault troubleshooting and analysis of each coil and each connection point of the high voltage side of the self-coupling transformer.

[0053] The embodiments of the present application also provide a computer readable medium, which stores at least one instruction, and the at least one instruction is loaded and executed by a processor to realize the self-coupling transformer finished product resistance measurement method of the above various embodiments.

[0054] The above description is only optional embodiments of the present application, and does not limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A device for measuring the resistance of a finished product autotransformer, characterised in that it comprises: The device is suitable for oil-immersed self-coupled power transformer with medium voltage terminal voltage regulation, and the device comprises: a low-voltage coil, a common coil (1), a series coil (2), a voltage regulation coil (3), a direct current resistance tester (4), and a measurement host, wherein the low-voltage coil, the common coil (1), the series coil (2), and the voltage regulation coil (3) are sequentially arranged from inside to outside on an iron core; the series coil (2) is connected in series on one side of the common coil (1), wherein a connection point of the series coil (2) and the common coil (1) is recorded as a common winding voltage actual test point, and the common winding voltage actual test point is a voltage collection point for indirectly obtaining a common winding resistance value; the voltage regulation coil (3) is connected to the common winding voltage actual test point; the direct current resistance tester (4) is provided with a current clamp group and a voltage clamp group with variable working positions, the current clamp group and the voltage clamp group are respectively used for measuring voltage measurement values and current measurement values of each winding coil on a high-voltage side of the oil-immersed self-coupled power transformer, and each winding coil refers to the common coil (1), the series coil (2), and the voltage regulation coil (3); the measurement host is connected with the direct current resistance tester (4), the measurement host is used for controlling position movement of the current clamp group and the voltage clamp group and controlling the direct current resistance tester (4) to generate a measurement current, and the direct current resistance tester (4) is used for obtaining and determining direct current resistance values of each winding coil according to the voltage measurement values and the current measurement values.

2. The self-coupled transformer finished product resistance measurement device according to claim 1, wherein the current clamp group comprises a first tester current clamp (5) and a second tester current clamp (6); the voltage clamp group comprises a first tester voltage clamp (7) and a second tester voltage clamp (8).

3. The autotransformer finished resistance measuring device of claim 2, wherein, the common coil (1) and the series coil (2) form a high-voltage winding in series, and the voltage regulation coil (3) and the common coil (1) form a medium-voltage winding; in the high-voltage winding, a first terminal of the common coil (1) is recorded as a terminal X, a second terminal of the common coil (1) is recorded as a terminal A”, a first terminal of the series coil (2) is recorded as a terminal A, and a second terminal of the series coil (2) is recorded as a terminal A’; in the medium-voltage winding, a connection terminal of the voltage regulation coil (3) is recorded as a terminal Am.

4. The autotransformer finished resistance measurement apparatus according to claim 3, characterized in that, the first tester current clamp (5) and the first tester voltage clamp (7) are clamped at the terminal X.

5. The autotransformer finished resistance measurement apparatus according to claim 3, wherein, the second tester current clamp (6) is clamped at the terminal A.

6. The autotransformer finished resistance measurement apparatus according to claim 3, wherein the second tester voltage clamp (8) is clamped at the terminal Am.

7. The autotransformer finished resistance measurement apparatus according to claim 3, wherein in the oil-immersed self-coupled power transformer, each coil lead is led out through a bushing, the terminal X is an air terminal of a neutral point bushing, the terminal A is an air terminal of a high-voltage bushing, and the terminal Am is an air terminal of a medium-voltage bushing.

8. A method of measuring the resistance of a finished autotransformer, characterized in that, The method is used for the self-coupled transformer finished product resistance measurement device according to any one of claims 1 to 7, and the method comprises: The measurement host controls the direct current resistance tester (4) to generate the measurement current and apply the test current to the first wire end of the common coil (1) and the series coil (2) through the current clip set; The measurement host controls the voltage clip set to be clamped at the first wire end of the common coil (1) and the connection end of the voltage regulating coil (3) and collects corresponding voltage measurement values; The direct current resistance values of each winding coil are obtained through the direct current resistance tester (4) and determined according to the voltage measurement values and the current measurement values; The measurement host obtains the direct current resistance values of each winding coil and stores them.

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