Configuration type selection method for converter transformer valve side oil immersed electric contact component

Abstract

The invention discloses a configuration and model selection method for a converter transformer valve side oil immersed electric contact part. The method comprises the following steps: establishing an electric-thermal coupling simulation model of the electric contact part; obtaining convection heat dissipation coefficients of the plug-in structure under different working conditions, and fitting an empirical expression; selecting the configuration number of the electric contact parts, combining with a convection heat dissipation coefficient empirical expression, and adopting electric-thermal coupling simulation calculation to obtain the operating temperatures of the plug-in structure under different load currents; according to the highest and lowest operation temperatures of the plugging structure, calculating thermal expansion displacement of electric contact of the ammeter, and based on historical operation current data, evaluating wear frequency of an electric contact part; and determining the configuration number of the electric contact parts according to the thermal expansion displacement and the maximum operating temperature of the electric contact parts, and selecting the type of the electric contact part of which the wear resistance of the coating meets the condition according to the thermal expansion displacement and the wear frequency of the electric contact parts. The method is of great significance in eliminating serious potential safety hazards in the ultra-high voltage transmission project.

Description

Technical Field

[0001] The present invention relates to the technical field of configuration and selection of key flow-guiding components of electric power equipment, and in particular to a configuration and selection method for oil-immersed electric contact components on the valve side of a converter transformer. Background Art

[0002] Oil-immersed electrical connection components are key current-carrying connections between the lead-out wires of the valve-side windings of UHV converter transformers and the valve-side bushings. As the "main artery" and "experimental field" of domestic UHV DC transmission, the earliest converter stations in the western region have recently experienced excessive DC resistance values ​​on the valve side of converter transformers due to the degradation of oil-immersed strap contacts, causing a total of 6 bipolar high-end converter transformers to be shut down for 3 months, resulting in significant economic losses. At present, 1,344 valve-side bushings in the domestic UHV DC converter stations in operation use the same strap connection structure. As the operating time increases, the continuous degradation of oil-immersed electrical connections will pose a serious safety hazard to UHV transmission projects.

[0003] At present, the electrical connections in the UHV converter transformer valve side riser area in the UHV DC transmission project of the State Grid Corporation system adopt various types and technical routes of structures, and there are also great differences in the application methods. The design method of the oil-immersed electrical connection components is directly determined by the transformer and bushing manufacturers. The recent frequent failures indicate that the existing electrical connection components in the converter transformer valve side riser area lack scientific selection and configuration methods.

[0004] Research shows that: interface wear is the cause of the deterioration of electrical contact components; when the micro-displacement is less than 20μm, the contact resistance of the electrical contact components remains relatively stable; when the oil temperature exceeds 80°, the electrical contact components may corrode under long-term conditions. How to configure and select the oil-immersed electrical contact components on the valve side of the converter transformer to meet the above requirements, ensure that the contact resistance of the electrical contact components remains relatively stable, and avoid corrosion at the operating temperature.

[0005] In view of this, this patent application is filed. Summary of the invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer, based on the historical operating data of the valve side current, to obtain the minimum and maximum operating currents and current fluctuation frequency (expansion wear frequency) of the plug-in structure. The operating temperature and thermal expansion displacement of the plug-in structure under different load currents are obtained by simulation, and the configuration quantity and model of the electrical contact components are determined according to the maximum operating temperature, maximum thermal expansion distance and expansion wear frequency calculated by the electrothermal simulation, so as to meet the requirements of the oil-immersed electrical contact components on the valve side of the converter transformer in terms of wear resistance and operating temperature.

[0007] The object of the present invention is to provide a configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer, comprising:

[0008] Establish an electrical-thermal coupling simulation model for electrical contact components;

[0009] Obtain the convection heat dissipation coefficient of the plug-in structure under different working conditions and fit the empirical expression;

[0010] The number of electrical contact components is selected, and the operating temperature of the plug-in structure under different load currents is obtained by combining the empirical expression of the convection heat dissipation coefficient and using electrical-thermal coupling simulation calculation;

[0011] Calculate the thermal expansion displacement of the strap electrical contact according to the highest and lowest operating temperatures of the plug-in structure, and evaluate the wear frequency of the electrical contact components based on historical current data;

[0012] According to the thermal expansion displacement and the maximum operating temperature of the electrical contact components, the number of electrical contact components is adjusted until the requirements are met;

[0013] According to the thermal expansion displacement and wear frequency of the electrical contact parts, select the electrical contact part model whose coating wear resistance meets the requirements.

[0014] In an optional embodiment, the process of establishing the electrical-thermal coupling simulation model of the electrical contact component is:

[0015] The compression-current-contact resistance mapping relationship of the electrical contact components under different compression and current conditions is obtained, and the empirical expression is obtained by fitting; the contact resistance of the electrical contact components is calculated according to the operating current and the geometric parameters of the plug-in structure, and the convection heat dissipation coefficient h is preliminarily set within a reasonable range, and the electric-thermal coupling simulation model of the electrical contact components is established.

[0016] In an optional embodiment, the process of obtaining the convection heat dissipation coefficient of the plug-in structure under different working conditions is:

[0017] Under different operating current and oil temperature conditions, the operating temperature of the plug, socket and electrical contact parts was measured using an operating temperature test platform. Combined with electrical-thermal coupling simulation, the convection heat dissipation coefficient of the plug structure under various working conditions was obtained, and an empirical expression was fitted.

[0018] In an optional embodiment, in the process of obtaining the convection heat dissipation coefficient h of the plug structure, based on the operating temperatures of the plug, socket and electrical contact components measured in the experiment, the convection heat dissipation coefficient h is continuously adjusted through parameter optimization until the error requirement range is met.

[0019] In an optional embodiment, the operating temperature test platform includes an oil chamber, a heating ring, a high current generator, a thermocouple, and a data acquisition device;

[0020] The oil chamber is used to carry insulating oil;

[0021] The heating ring is located in the oil chamber and is used for heating to increase the oil temperature;

[0022] The high current generator is connected to the plug-in structure to provide operating current to the plug-in structure;

[0023] The data acquisition interface of the data acquisition device is connected to the armored thermocouple to collect the test temperature of the plug-in structure measured by the thermocouple.

[0024] In an optional embodiment, the number of electrical contact components to be configured is preliminarily determined based on the rated operating current of the converter transformer valve side.

[0025] In an optional embodiment, based on the convective heat dissipation coefficient of the plug-in structure and the empirical expression of the contact resistance of the electrical contact component, an electrothermal coupling model is used to calculate the operating temperature of the plug-in structure at the highest and lowest load currents.

[0026] In an optional embodiment, the highest and lowest operating temperatures of the plug-in structure are introduced into a static simulation model to calculate the thermal expansion displacement of the electrical contact of the watch strap.

[0027] In an optional embodiment, the wear frequency of the electrical contact components is evaluated based on the thermal expansion displacement of the band electrical contact and combined with historical operating statistics of the valve side current.

[0028] In an optional embodiment, based on the criteria that the maximum operating temperature of the electrical contact component is lower than 80° C. and the operating life is greater than 30 years, electrical contact components that meet the standards are selected and reasonably configured.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] 1. A configuration selection method for oil-immersed electrical contact components on the valve side of a converter transformer provided in an embodiment of the present invention obtains the convective heat dissipation coefficient of the plug-in structure and the contact resistance of the electrical contact components under different working conditions through experiments, and obtains corresponding empirical expressions by fitting. Based on the above two empirical expressions, the operating temperature of the plug-in structure under the highest and lowest load currents is obtained by electrothermal coupling simulation, and the maximum thermal expansion displacement and the number of wear times of the electrical contact components are evaluated. Then, according to the set maximum operating temperature, limit thermal expansion distance, and maximum operating life criteria, the configuration quantity and model of the electrical contact components are determined to meet the requirements of wear resistance and operating temperature of the oil-immersed electrical contact components on the valve side of the converter transformer.

[0031] 2. In view of the serious safety hazards posed by the deterioration of oil-immersed electrical connection components in UHV power transmission projects, and the current lack of scientific selection and configuration methods for electrical contact components, the present invention proposes for the first time a configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer, which is of great significance for eliminating serious safety hazards in UHV power transmission projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0033] Figure 1 It is a flow chart of the configuration and selection method of the oil-immersed electric contact components on the valve side of the converter transformer of the present invention.

[0034] Figure 2 It is a structural diagram of the contact resistance test platform.

[0035] Figure 3 It is the measurement and fitting curve of the electrical contact component compression-contact resistance under different operating currents.

[0036] Figure 4 It is a structural diagram of a plug-in structure operating temperature test platform.

[0037] Figure 5 It is a flow chart for obtaining the empirical expression of the convection heat dissipation coefficient.

[0038] Figure 6 It is the historical operating current data of the converter transformer valve side, where (a) is the operating data trend chart of the load current collected between 2023 and 2024, and (b) is the trend chart of the maximum difference of daily operating current under a certain number of operating days.

[0039] Figure 7 It is the operating temperature of the plug-in structure at 45°C oil temperature and maximum load current.

[0040] Figure 8 It is the operating temperature of the plug-in structure at 45°C oil temperature and minimum load current.

[0041] Fig. 9 It is the calculation result when the thermal expansion displacement of the valve side plug-in structure is the full-load expansion.

[0042] Fig.10 It is the calculation result when the thermal expansion displacement of the valve side plug-in structure is 0.1 times the rated power expansion.

[0043] In the figure, the components represented by each mark are:

[0044] 1-pressing plate; 2-pressing head; 3-band fixing copper ring; 4-micrometer slide; 5-power anode hole; 6-power cathode hole; 7-DC power supply (current source). DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary implementation modes of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0046] Embodiment 1:

[0047] A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer comprises the following steps:

[0048] S101: Establishing an electrical-thermal coupling simulation model of an electrical contact component.

[0049] Specifically, a contact resistance measuring device is used to measure the compression-current-contact resistance mapping relationship of the electrical contact component under different compression and current conditions, and an empirical expression of the contact resistance of the electrical contact component is obtained by fitting. The contact resistance of the electrical contact component is calculated according to the operating current and the geometric parameters of the plug-in structure, and the convection heat dissipation coefficient h is preliminarily set within a reasonable range to establish an electric-thermal coupling simulation model of the electrical contact component.

[0050] The contact resistance measuring device in this embodiment includes a pressing plate 1, a pressing head 2, a copper ring for fixing a strap 3, a micrometer slide 4, a power anode hole 5, a power cathode hole 6, and a DC power supply 7. The structural relationship of the pressing plate 1, the pressing head 2, the copper ring for fixing a strap 3, and the micrometer slide 4 is in accordance with the existing patent "A continuous flow corrosion simulation system for elastic contact fingers" and the application number 2023102450859. Figure 3 The structure arrangement of the pressing plate 22, the pressing head 23, the contact finger 24, the copper ring 25, the copper plate 26, the XY slide table 27, the power anode hole 32, and the power cathode hole 33. The contact resistance measuring device of this embodiment is specifically as follows Figure 1 as shown in .

[0051] During measurement, the compression amount of the electrical connection component is adjusted by rotating the micrometer slide 4; the power supply anode hole 5 and the power supply cathode hole 6 are connected to a high-precision current generator, which can provide a DC current of 0 to 100A for the contact finger to be tested. Before the experiment, firstly embed a single-block pressure head and short-circuit the experimental circuit, and measure the resistance value R1 of the entire circuit after the current is passed. After that, disconnect the power supply, fix the electrical contact component on the strap fixing copper ring 3, rotate the micrometer slide 4 to compress the electrical contact component to the predetermined position, and then pass the current again to measure the circuit resistance value R2. Finally, the resistance measurement value of the electrical contact component to be tested is R=R2-R1. After the contact resistance of the electrical contact component under different compression amounts and operating current conditions is obtained, the contact resistance-compression amount-current mapping relationship of the electrical contact component is obtained, and the empirical expression of the contact resistance of the electrical contact component can be obtained by using the fitting formula, such as Figure 3 According to the operating current and the geometric parameters of the plug-in structure, the contact resistance of the electrical contact component is calculated, the convection heat dissipation coefficient h is preliminarily set within a reasonable range, and the electrical-thermal coupling simulation model of the electrical contact component is established.

[0052] S102: Obtain the convection heat dissipation coefficient h of the plug-in structure under different working conditions, and fit the empirical expression.

[0053] Specifically, the operating temperature of the plug, socket and electrical contact parts is measured under different operating current and oil temperature conditions, and the convection heat dissipation coefficient h is continuously optimized and corrected in combination with electrical-thermal coupling simulation until the error between the measured temperature and the operating temperature is less than or equal to 1%.

[0054] The plug-in structure includes a plug, a socket, and an electrical contact component. The plug is fixedly placed in the socket, and the number of electrical contact components can be preliminarily selected based on the rated operating current.

[0055] The operating temperature of the plug, socket and electrical contact parts is measured using the plug structure operating temperature test platform.

[0056] The test platform includes an oil chamber, a heating ring, a high current generator, a thermocouple and a data acquisition device. The oil chamber is used to carry insulating oil; the heating ring in the oil chamber is used to increase the oil temperature and simulate different oil temperature environments; the high current generator is connected to the plug structure to provide the operating current of the electrical contact component; the data acquisition interface of the data acquisition device is connected to the thermocouple to collect and record the test temperature of the socket, plug and electrical contact component measured by the thermocouple. The armored thermocouple is embedded in the electrical contact component by drilling a hole in the electrical contact component to measure the operating temperature of the electrical contact component. The structure of the test platform is as follows: Figure 4As shown. Based on the plug-in structure operating temperature test platform, the flow test of the plug-in structure can be carried out under different oil temperature conditions. In the experiment, a probe-type armored thermocouple is used to measure the stable operating temperature of the plug, socket and electrical contact parts. Based on the test data of the operating temperature of the plug, socket and electrical contact parts measured under different operating currents and oil temperatures, and combined with the above-mentioned electric-thermal coupling simulation model, the convection heat dissipation coefficient of the electrical connection parts and the plug and socket at different oil temperatures is evaluated, and an empirical expression is obtained by fitting. The flow chart for determining the empirical expression of the convection heat dissipation coefficient is shown in the figure. Figure 5 When the error between the actual measured temperature and the calculated temperature is greater than or equal to 1%, it is necessary to return to readjust the convection heat dissipation coefficient h and calculate again.

[0057] S103: Preliminarily determine the number of electrical contact components to be configured based on the rated operating current, and use an electric-thermal coupling simulation calculation in combination with a convection heat dissipation coefficient fitting formula to obtain the operating temperature of the plug-in structure under different load currents.

[0058] Specifically:

[0059] After obtaining the fitting empirical expression of the convective heat dissipation coefficient of the plug-in structure, combined with the aforementioned electro-thermal coupling simulation model, and introducing the configuration number of electrical contact components (preliminarily selected based on the rated operating current), the operating temperature of the plug-in structure under different load currents can be calculated.

[0060] S104: Calculate the thermal expansion displacement of the electrical contact of the watch strap according to the highest and lowest operating temperatures of the plug-in structure, and evaluate the wear frequency of the electrical contact components based on historical operating current data.

[0061] Specifically:

[0062] Based on the rated operating current of the converter transformer valve side, the daily maximum operating current (corresponding to the maximum load current) and the daily minimum current (corresponding to the minimum load current) of the converter transformer valve side are calculated. Figure 6 The operating temperature of the plug-in structure under the maximum and minimum load currents is calculated by using the electric-thermal coupling simulation, as shown in Figure 7 , Figure 8 Then, the highest and lowest operating temperatures of the plug-in structure are obtained from the operating temperatures of the plug-in structure at the maximum and minimum load currents.

[0063] Then the highest and lowest operating temperatures of the plug-in structure are imported into the static simulation model to calculate the thermal expansion displacement of the strap electrical contact, such as Fig. 9 , Fig.10As shown. The wear frequency is evaluated based on the thermal expansion displacement of the band electrical contact obtained above and the historical operating statistical data of the valve side current to evaluate the wear frequency of the electrical contact parts. According to the wear resistance of the electrical contact parts within a certain operating period, when the wear resistance limit is reached, the wear frequency is the maximum wear resistance number.

[0064] S105: adjusting and determining the number of electrical contact components to be configured according to the thermal expansion displacement and the maximum operating temperature of the electrical contact components, and selecting an electrical contact component model whose coating wear resistance meets the requirements according to the thermal expansion displacement and the wear frequency of the electrical contact components.

[0065] As studies have shown: when the micro-displacement is less than 20μm, the contact resistance of the electrical contact components remains relatively stable; when the oil temperature exceeds 80°, the electrical contact components may corrode under long-term conditions. In view of the fact that the operating life of the converter transformer is 30 years, the present invention takes the maximum operating temperature below 80°C, the thermal expansion distance less than 20μm, and the operating life greater than 30 years as the criteria, and finally determines the specific configuration quantity of the electrical contact components and determines the model of the electrical contact components that meet the wear resistance of the coating and meet the 30-year operating conditions.

[0066] S106: If the final determined configuration quantity and model of the electrical contact components cannot meet the wear resistance and maximum operating temperature conditions (for this embodiment, if the micro-displacement is greater than 20μm, or the temperature is greater than 80°C), increase the configuration quantity and return to step S103, and continue with S104 and S105 until the wear resistance and operating temperature requirements are met.

[0067] This is the configuration and selection method for the oil-immersed electrical contact components on the valve side of the converter transformer.

[0068] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer, characterized in that: include: Establish an electrical-thermal coupling simulation model for electrical contact components; Obtain the convection heat dissipation coefficient of the plug-in structure under different working conditions and fit the empirical expression; The number of electrical contact components is selected, and the operating temperature of the plug-in structure under different load currents is obtained by combining the empirical expression of the convection heat dissipation coefficient and using electrical-thermal coupling simulation calculation; Calculate the thermal expansion displacement of the strap electrical contact based on the highest and lowest operating temperatures of the plug-in structure, and evaluate the wear frequency of the electrical contact components based on historical operating current data; The number of electrical contact components to be configured is determined based on the thermal expansion displacement and maximum operating temperature of the electrical contact components. The model of the electrical contact component whose coating wear resistance meets the requirements is selected based on the thermal expansion displacement and wear frequency of the electrical contact components.

2. A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer according to claim 1, characterized in that: The process of establishing the electrical-thermal coupling simulation model of the electrical contact component is as follows: Obtaining the compression-current-contact resistance mapping relationship of the electrical contact component under different compression and current conditions, and fitting to obtain an empirical expression for the contact resistance of the electrical contact component; According to the operating current and the geometric parameters of the plug-in structure, the contact resistance of the electrical contact components is calculated, the convection heat dissipation coefficient h is preliminarily set within a reasonable range, and the electrical-thermal coupling simulation model of the electrical contact components is established.

3. A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer according to claim 1, characterized in that: The process of obtaining the convection heat dissipation coefficient of the plug-in structure under different working conditions is: Under different operating current and oil temperature conditions, the operating temperature of the plug, socket and electrical contact parts was measured using an operating temperature test platform. Combined with electrical-thermal coupling simulation, the convection heat dissipation coefficient of the plug structure under various working conditions was obtained, and an empirical expression was fitted.

4. A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer according to claim 3, characterized in that: In the process of obtaining the convection heat dissipation coefficient h of the plug structure, based on the operating temperatures of the plug, socket and electrical contact components measured in the experiment, the convection heat dissipation coefficient h is continuously adjusted through parameter optimization until the error requirement range is met.

5. A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer according to claim 3, characterized in that: The operating temperature test platform includes an oil chamber, a heating ring, a high current generator, a thermocouple, and a data acquisition device; The oil chamber is used to carry insulating oil; The heating ring is located in the oil chamber and is used for heating to increase the oil temperature; The high current generator is connected to the plug-in structure to provide operating current to the plug-in structure; The data acquisition interface of the data acquisition device is connected to the armored thermocouple to collect the test temperature of the plug-in structure measured by the thermocouple.

6. A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer according to claim 1, characterized in that: The number of electrical contact components to be configured is preliminarily determined based on the rated operating current of the converter transformer valve side.

7. A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer according to claim 1, characterized in that: Based on the empirical expression of the convection heat dissipation coefficient of the plug-in structure and the empirical expression of the contact resistance of the electrical contact components, the operating temperature of the plug-in structure under the highest and lowest load currents is calculated using the electrothermal coupling model to obtain the highest and lowest operating temperatures of the plug-in structure.

8. A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer according to claim 1, characterized in that: The highest and lowest operating temperatures of the plug-in structure are imported into the statics simulation model to calculate the thermal expansion displacement of the electrical contact of the strap.

9. A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer according to claim 1, characterized in that: The wear frequency of the electrical contact parts is evaluated based on the thermal expansion displacement of the strap electrical contact and combined with the historical operating statistics of the valve side current.

10. A configuration and selection method for oil-immersed electrical contact components on the valve side of a converter transformer according to claim 1, characterized in that: With the maximum operating temperature of electrical contact components below 80°C and an operating life of more than 30 years as the criteria, select electrical contact components that meet the standards and configure them reasonably.

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