CN113049639A - Distribution transformer winding material testing system and method - Google Patents
Distribution transformer winding material testing system and method Download PDFInfo
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- CN113049639A CN113049639A CN202110229457.XA CN202110229457A CN113049639A CN 113049639 A CN113049639 A CN 113049639A CN 202110229457 A CN202110229457 A CN 202110229457A CN 113049639 A CN113049639 A CN 113049639A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/041—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body
Abstract
The invention provides a distribution transformer winding material testing system and a method, the system comprises a temperature regulating device, a direct current resistance testing device, a temperature acquisition device, a transformer to be tested and a testing transformer, the output current of the testing transformer is quickly heated, the temperature of each part of the transformer to be tested is balanced by the temperature regulating device, the balance temperature is continuously regulated, the resistance values of high and low voltage windings are obtained by the direct current resistance testing device, the actual resistance ratio changing relation with the temperature under different balance temperatures and reference temperatures is obtained by calculation, and the actual resistance ratio changing relation with the temperature corresponding to a standard material is compared to detect the winding material. The invention judges the winding material of the transformer by utilizing the different trend of the resistance ratio of the copper and the aluminum at different temperatures along with the temperature change, improves the accuracy of the nondestructive testing method, and simultaneously leads the transformer to quickly reach the equilibrium temperature through the heating at different stages, thereby improving the testing efficiency.
Description
Technical Field
The invention relates to the field of distribution transformer winding material detection, in particular to a distribution transformer winding material testing system and method.
Background
In the production of the current distribution transformer, for reducing cost, some enterprises adopt aluminum wires with stronger economical efficiency to replace copper wires as conductor materials. First, the two materials are used as conductive materials, and in principle, the difference is mainly the difference in conductivity, copper wire has higher conductivity than aluminum wire, and the power loss of copper wire is lower, which finally results in the difference in quality of power consumption of users. Second, the price of copper wire per unit is about twice as much as that of aluminum wire from a cost point of view. In addition, copper wire has higher thermal conductivity than aluminum wire. The copper wire is advantageous over the aluminum wire in safety in the case of long-term use. According to the performances of all aspects of the material, the distribution transformer is relatively hidden in the phenomenon of replacing copper with aluminum, after production is finished, the distribution transformer is difficult to identify through the appearance of a finished product and a wiring terminal, as long as the design is reasonable, the test items specified by the existing standards are difficult to find, and if the distribution transformer is subjected to disassembly inspection through a hanging core, the whole transformer is damaged, so that the development difficulty is high, and the distribution transformer is uneconomical.
The detection methods commonly used at present include the following methods:
1. the material of a transformer winding is judged through the volume of the body and the density of the body, the oil-immersed transformer can be identified by utilizing the volume of the oil tank and the oil quality, the identification method utilizes data of a single sample as a judgment basis, tighter theoretical derivation is lacked, the reliability of an identification result is poor, and certain limitations are realized.
2. Identifying the material of the transformer winding by X-ray; the identification and discrimination method is complex in operation and poor in final actual measurement result due to the influence of scattered rays.
3. Identifying the winding material of the transformer by a thermoelectric effect method; the method is used for testing the oil-immersed transformer, and the mode is limited by a heating mode when oil is changed, and core hanging treatment is still needed during identification.
Disclosure of Invention
The invention provides a distribution transformer winding material testing system and a method, because the resistance ratios of copper and aluminum at different temperatures have different variation relations, the winding material of a transformer is judged according to the relation between the reference resistance ratio of the copper and aluminum material and the temperature variation by comparing the ratio of the resistance at different temperatures and the resistance at a reference temperature through measurement and calculation.
The invention provides a distribution transformer winding material testing system, which comprises a temperature regulating device, a direct-current resistance testing device, a temperature collecting device, a transformer to be tested and a testing transformer, wherein the temperature regulating device is used for regulating the temperature of a winding of the distribution transformer;
the transformer to be tested is arranged in the temperature regulating device, the winding of the transformer to be tested is respectively connected with the direct current resistance testing device and the temperature collecting device, and the testing transformer is connected with the transformer to be tested to rapidly heat up the transformer to be tested.
Heating for a period of time by adjusting the temperature of the temperature regulating device, so that the temperature of each part of the transformer to be measured is balanced; the direct current resistance testing device is used for testing direct current resistance values of high-voltage windings and low-voltage windings of the transformer to be tested, and the temperature collecting device is used for testing actual heating temperatures of the top layer and the bottom layer of the transformer to be tested and the high-voltage windings and the low-voltage windings of the transformer.
Furthermore, the low-voltage winding end of the test transformer is connected with a power supply, and the high-voltage winding end of the test transformer is connected with the high-voltage winding end of the transformer to be tested.
The test transformer is connected with a winding of the transformer to be tested, the winding resistor is directly heated by electrifying the test power supply, the temperature of a test point of the transformer to be tested is quickly increased, and the time for reaching the predicted initial temperature adjustment is reduced.
Furthermore, the test transformer can adjust output current, and the output current is adjusted according to the voltage grade and the capacity specification of the transformer to be tested.
The test transformer can adjust output current as the device that promotes the transformer test point temperature that awaits measuring fast, can be applicable to the measurement of the transformer that awaits measuring of the different specifications that will detect promptly, can adjust suitable current output simultaneously, can heat up the transformer that awaits measuring fast when guaranteeing not to harm the transformer.
Furthermore, the direct current resistance testing device is connected with any two winding end points of a high-voltage winding end and a low-voltage winding end of the transformer to be tested, and the winding end points of the high-voltage winding end and the low-voltage winding end correspond to each other.
The direct current resistance testing device is connected with the two corresponding winding ends, and is used for measuring the resistance values of the two ends of the corresponding high-voltage and low-voltage groups and calculating the resistance ratio at the temperature.
Furthermore, the temperature acquisition device is connected with any two winding end points of the high-voltage winding end and the low-voltage winding end of the transformer to be detected for temperature detection.
In order to make the resistance ratio more accurate with the change relation of temperature, because the temperature balance of each point of the transformer to be measured needs to be ensured when measuring the resistance, and because the temperature is quickly raised by utilizing the test transformer, the temperature of each point has difference after the temperature is raised, and the accuracy of the change relation of the resistance ratio and the temperature is influenced.
The invention provides a method for testing the material of a distribution transformer winding based on the test system, which tests the material of the winding based on the relation that the resistance ratio changes along with the temperature;
the method specifically comprises the following steps:
s1: rapidly heating the transformer to be tested through the test transformer;
s2: the transformer to be measured is heated at constant temperature through a temperature regulating device, so that the temperature at each part is balanced;
s3: after the temperature is balanced, the temperature regulating device is regulated to heat, the resistance values of the high-voltage group and the low-voltage group of the transformer at different balancing temperatures are obtained, and the resistance ratio of the resistance values to the resistance value at the reference temperature is calculated;
s4: and obtaining the change relation between the resistance ratio and the temperature according to the obtained resistance ratios at different temperatures, comparing the change relation with the relation between the reference resistance ratio obtained at the same temperature balance node and the reference temperature and the temperature change, and judging the winding material of the transformer.
Further, in step S1, the rapid heating is performed to reach a final temperature higher than the initial temperature value when the temperature is to be controlled.
After the rapid heating is finished, the initial temperature is regulated and controlled by the temperature regulation and control device, so that the floating temperature can rapidly reach the required initial temperature value.
Further, in step S3, the reference temperature is a cold temperature value or any balance temperature value of the transformer to be measured.
The optimal balance temperature is achieved at the cold temperature, the obtained resistance ratio is accurate, and meanwhile the cold temperature is used as the reference temperature, so that the resistance ratio of too many subsequent adjusted temperature values is avoided.
Further, in step S4, the reference resistance ratio is an average value of the resistance ratios corresponding to the copper material and the aluminum material, and the calculation formula is as follows:
wherein, KCuDenotes the resistance ratio, K, of copper materialAlDenotes the resistance ratio, t, of the aluminum material2Denotes different equilibrium temperatures, t1Indicating the reference temperature.
The invention has the following beneficial effects:
1. the testing method of the invention firstly adopts an electric heating mode to heat the transformer, then adopts an oven to heat the transformer so that the temperature of each temperature test point of the transformer reaches the balance, then tests the direct current resistance of the winding of each temperature point, utilizes the difference of the resistance coefficients of copper and aluminum at different temperatures to judge the winding material of the transformer, has high material judgment accuracy and no damage to a sample, greatly reduces the time used in the temperature balance state by two parts of quick heating and temperature regulation heating, and improves the detection efficiency.
2. The system comprises an external test transformer, the test transformer is adopted to electrically heat the transformer to be tested, the current output of the test transformer can be adjusted, and the system can be better suitable for testing distribution transformers of various specifications and models.
3. The temperature regulation and control device adopts an electric oven, and the transformer to be tested is arranged in the temperature regulation and control device, so that the temperature of the transformer to be tested can be uniformly raised, and each temperature test point of the transformer can reach a thermal balance state more quickly.
Drawings
FIG. 1 is a schematic view of a system connection structure in electric heating according to the present invention;
FIG. 2 is a schematic diagram of the system connection structure when the oven of the present invention is heated;
FIG. 3 is a graph showing the comparison of the test results of the resistance ratio of the present invention with the temperature change.
Reference numerals: 1-temperature regulation and control device, 2-test transformer, 3-direct current resistance test device, 4-temperature acquisition device, 5-test power supply and 6-transformer to be tested.
Detailed Description
In the following description, technical solutions in the embodiments of the present invention are clearly and completely described, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
temperature regulation and control device 1 adopts the electric heating oven, heats up the heating to 6 high, low voltage winding of transformer to be measured during the test, 6 high, two arbitrary endpoints of low voltage group of transformer to be measured are connected respectively direct current resistance testing arrangement 3 and temperature acquisition device 4, wherein, direct current resistance testing arrangement 3 is including testing current generator and binary channels tester, testing current generator can carry out simultaneous measurement to the high, low voltage resistance of transformer through the binary channels tester, temperature acquisition device 4 includes thermocouple and collection module, the thermocouple distributes in distribution transformer's top, bottom and high, low voltage winding, accurately obtains distribution transformer test point's actual temperature through collection module.
The high-voltage group end of the transformer 6 to be tested is connected with the high-voltage group end of the testing transformer 2, the low-voltage group end of the testing transformer 2 is connected with the testing power supply 5, and the transformer 6 to be tested is rapidly preheated through the output adjustable current.
In the stage of rapidly heating the transformer 6 to be tested by using the testing transformer 2, as shown in fig. 2, each end point of the low-voltage group of the transformer 6 to be tested is short-circuited, and the testing power supply 5 is started to rapidly heat the transformer to be tested through the testing transformer; in the stage of obtaining the resistance parameter under temperature balance by controlling the temperature of the transformer to be tested by using the oven, as shown in fig. 1, each end point of the transformer to be tested is disconnected, and each end point is respectively connected with the direct current resistance testing device and the temperature acquisition device as described above.
Example 2
s1: the low-voltage group end point of the transformer 6 to be tested is in short circuit connection, each end point of the high-voltage group is respectively connected with the high-voltage group end point of the testing transformer 2, the output current of the testing transformer 2 is adjusted according to the specification and the size of the transformer 6 to be tested, and the transformer 6 to be tested is rapidly heated;
and when the temperature of the temperature test point of the transformer 2 to be measured is heated to be higher than the lowest value of the balance temperature required by the resistance to be measured, stopping the output current of the test transformer 2, disconnecting the connection of the low-voltage group end point of the transformer 6 to be measured, and entering a temperature balance adjusting stage.
When the rapid heating is carried out, the final heating temperature is slightly higher than the temperature value of the initial equilibrium temperature, so that the temperature can be rapidly adjusted to be in equilibrium, and the adjusting time is shortened.
S2: an electric oven is adopted to heat the transformer 6 to be tested at constant temperature, the temperature value of the electric oven is adjusted from low to high according to the temperature balance points set for obtaining the resistance value parameters, the temperature difference values of the temperature balance points collected by the resistance value in the embodiment are the same, and the highest temperature is not more than 100 ℃;
the temperature is in the range of 80 to 140 degrees, the relative aging rate of the insulation increases with the increase of the temperature, and in order to avoid the influence of the overhigh temperature on the insulation performance of the transformer, the heating temperature does not exceed 100 degrees in the embodiment.
S3: after the temperature is balanced, that is, the temperatures of the temperature test points are the same, the resistance values of the high voltage group and the low voltage group at the balanced temperature are obtained through the direct current resistance testing device 3, and the resistance ratio of the resistance values of the high voltage group and the low voltage group at the balanced temperature to the resistance value at the reference temperature is calculated, where the reference temperature may be the cold temperature of the transformer to be tested before heating or any balanced temperature value, in this embodiment, the cold temperature of the transformer is used as the reference temperature, and the calculation formula is as follows:
wherein, KnRepresents the ratio of the measured resistance at each equilibrium temperature to the measured resistance at the cold temperature, RtRepresenting the measured resistance, R, of the high-voltage group or the low-voltage group at each equilibrium temperatureTRepresents the measured resistance value at cold temperature.
The cold temperature is used as the reference temperature, so that the temperature obtained by measuring parameters is mostly at a low temperature, the parameters obtained by high temperature are reduced, the measuring accuracy is improved, and the adjustment of the balance temperature is simpler and more convenient.
S4: because the resistance ratios of the copper winding material and the aluminum winding material at different temperatures are in a linear relationship, the change relationship between the resistance ratio and the temperature is obtained according to the obtained resistance ratios at different temperatures, and the change relationship is compared with the relationship between the reference resistance ratio and the temperature, so that the winding material of the transformer is judged;
the reference resistance ratio is obtained as follows:
firstly, respectively obtaining the resistance ratio of standard copper and aluminum winding materials;
the resistance R of the metal increases along with the rise of the temperature t, and the change of the resistance along with the temperature is related as follows:
Rt＝R0(1+αt+βt2+γt3+…)
wherein R istAnd R0Is a resistance value at t degree and 0 degree, alpha, beta and gamma are temperature coefficients of resistance, and alpha>β>And gamma. For metals, beta is generally very small, and when the temperature is not high, the resistance and the temperature are in a linear relation, and the linear relation is as follows:
alpha of copper and aluminum at 20 ℃ temperature coefficient of resistance200.00393, 0.00429, respectively, the product of the resistance coefficient and the resistance at each temperature is a constant value, alpha at 0 DEG C0Comprises the following steps:
when t is 20 ℃ according to the correction coefficient of copper and aluminum,
so that the resistivity alpha of copper and aluminum at 0 ℃ can be respectively obtained00.004265, 0.004671 respectively0Substituting into a linear relation between the resistance and the temperature to obtain:
therefore, the resistance ratio of copper to aluminum at different temperatures is obtained as follows:
wherein, KCuRepresenting the resistance ratio, K, of a standard copper windingAlRepresents the resistance ratio, t, of a standard aluminum material winding2Denotes different equilibrium temperatures, t1Represents a reference temperature; t is t2The selected value is the same as the equilibrium temperature value at the time of measuring the resistance in the above-mentioned step S2 and step S3, t1Selecting the reference temperature value to be the same as the reference temperature value used for measuring the resistance in the step S3;
then, the average value of the copper and aluminum resistance ratios obtained at different temperatures is calculated and obtained respectively, and the calculation formula is as follows:
and finally, comparing the actual resistance ratio and the temperature change relation obtained in the step S3 with the reference resistance ratio and the temperature change relation, and judging the material of the transformer winding.
As shown in fig. 3, a comparison graph of the test results in this embodiment is a relationship between the measured resistance ratio corresponding to the aluminum winding and the temperature, a relationship between the reference resistance ratio and the temperature, and a relationship between the measured resistance ratio corresponding to the copper winding and the temperature, respectively, from top to bottom; if the resistance ratio and the temperature change slope of the actual high-voltage winding and the actual low-voltage winding are larger than the reference resistance ratio and the temperature change slope, the material of the winding of the distribution transformer is aluminum, and if the resistance ratio and the temperature change slope are smaller than the reference resistance ratio and the temperature change slope, the material of the winding is copper.
The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.
Claims (9)
1. A distribution transformer winding material test system is characterized by comprising a temperature regulation and control device, a direct-current resistance test device, a temperature acquisition device, a transformer to be tested and a test transformer;
the transformer to be tested is arranged in the temperature regulating device, the winding of the transformer to be tested is respectively connected with the direct current resistance testing device and the temperature collecting device, and the testing transformer is connected with the transformer to be tested to rapidly heat up the transformer to be tested.
2. The distribution transformer winding material testing system of claim 1, wherein the low voltage winding end of the test transformer is connected to a power source, and the high voltage winding end is connected to the high voltage winding end of the transformer to be tested.
3. The distribution transformer winding material testing system of claim 2, wherein the test transformer is capable of regulating the output current, the output current being adjusted according to the voltage class and capacity specification of the transformer to be tested.
4. The distribution transformer winding material testing system of claim 1, wherein the dc resistance testing device is connected to any two winding terminals of the high-voltage winding terminal and the low-voltage winding terminal of the transformer to be tested, and the winding terminals of the high-voltage winding terminal and the low-voltage winding terminal correspond to each other.
5. The distribution transformer winding material testing system of claim 1, wherein the temperature acquisition device is connected to any two winding terminals of the high-voltage winding terminal and the low-voltage winding terminal of the transformer to be tested for temperature detection.
6. A method for testing the material of a distribution transformer winding is characterized by comprising the following steps:
s1: rapidly heating the transformer to be tested through the test transformer;
s2: the transformer to be measured is heated at constant temperature through a temperature regulating device, so that the temperature at each part is balanced;
s3: after the temperature is balanced, the temperature regulating device is regulated to heat, the resistance values of the high-voltage group and the low-voltage group of the transformer at different balancing temperatures are obtained, and the resistance ratio of the resistance values to the resistance value at the reference temperature is calculated;
s4: and obtaining the change relation between the resistance ratio and the temperature according to the obtained resistance ratios at different temperatures, comparing the change relation with the relation between the reference resistance ratio obtained at the same temperature balance node and the reference temperature and the temperature change, and judging the winding material of the transformer.
7. The method for testing the winding material of the distribution transformer as claimed in claim 6, wherein in step S1, the final temperature reached by the rapid heating is higher than the initial temperature value when the temperature is to be controlled.
8. The method for testing the winding material of the distribution transformer as claimed in claim 6, wherein in step S3, the reference temperature is a cold temperature value or any balance temperature value of the transformer to be tested.
9. The method for testing the material of the distribution transformer winding according to claim 6, wherein in step S4, the reference resistance ratio is an average value of the resistance ratios respectively corresponding to the copper material and the aluminum material, and the calculation formula is as follows:
wherein, KCuDenotes the resistance ratio, K, of copper materialAlDenotes the resistance ratio, t, of the aluminum material2Denotes different equilibrium temperatures, t1Indicating the reference temperature.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114034742A (en) * | 2021-11-16 | 2022-02-11 | 国网江苏省电力有限公司电力科学研究院 | System and method for detecting conductor material of coiled power cable |
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| CN106771774A (en) * | 2017-01-17 | 2017-05-31 | 山东电力设备有限公司 | It is a kind of while many transformers are carried out with the device of overcurrent test |
| CN209085791U (en) * | 2018-10-17 | 2019-07-09 | 浙江华电器材检测研究所有限公司 | Transformer temperature rise automatic checkout system |
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- 2021-03-02 CN CN202110229457.XA patent/CN113049639A/en active Pending
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| CN106771774A (en) * | 2017-01-17 | 2017-05-31 | 山东电力设备有限公司 | It is a kind of while many transformers are carried out with the device of overcurrent test |
| CN209085791U (en) * | 2018-10-17 | 2019-07-09 | 浙江华电器材检测研究所有限公司 | Transformer temperature rise automatic checkout system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114034742A (en) * | 2021-11-16 | 2022-02-11 | 国网江苏省电力有限公司电力科学研究院 | System and method for detecting conductor material of coiled power cable |
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Address after: No.16, Xingmao street, economic and Technological Development Zone (Longquanyi District), Chengdu, Sichuan 610100 Applicant after: CHENGDU PRODUCTS QUALITY INSPECTION RESEARCH INSTITUTE CO.,LTD. Applicant after: SICHUAN INSTITUTE PRODUCT QUALITY SUPERVISION INSPECTION AND RESEARCH Applicant after: Chengdu Institute of product quality supervision and inspection Address before: No.16, Xingmao street, economic and Technological Development Zone (Longquanyi District), Chengdu, Sichuan 610100 Applicant before: CHENGDU PRODUCTS QUALITY INSPECTION RESEARCH INSTITUTE CO.,LTD. Applicant before: SICHUAN INSTITUTE PRODUCT QUALITY SUPERVISION INSPECTION AND RESEARCH Applicant before: CHENGDU PRODUCT QUALITY SUPERVISION AND INSPECTION INSTITUTE |