Method for calculating overheating coefficient under condition of local blockage of air duct of dry-type traction transformer

Abstract

The invention discloses a method for calculating an overheating coefficient under local blockage of an air duct of a dry type traction transformer. Comprising the following steps: establishing an overheating test platform under the condition of local blockage of the air duct of the dry-type traction transformer; carrying out a test under the condition of no blockage of the air duct and obtaining related data; carrying out a test under the condition of local blockage of the air duct and obtaining related data; calculating an overheating correction coefficient; and evaluating the influence degree of the air duct local blockage fault on the thermal state of the dry-type traction transformer based on the overheating coefficient under the condition of dry-type traction transformer air duct local blockage. The method has the beneficial effects that the capability of the dry-type traction transformer winding for resisting the air duct blockage fault risk is effectively evaluated, and a new method is provided for rationality judgment of a design scheme of a cylindrical winding cooled by train running air; therefore, technical support is provided for optimization design of a winding heat dissipation structure, improvement of cooling performance and improvement of the space structure utilization rate.

Description

Technical Field

[0001] The invention relates to the field of online detection and fault diagnosis of electrical insulation, and in particular to a method for calculating an overheating coefficient of a dry-type traction transformer when an air duct is partially blocked. Background Art

[0002] The cooling channel is an indispensable structure in the traction transformer of the EMU, and even in all transformers. It is used to allow the cooling medium to circulate in it, and transfer the heat generated during the operation of the transformer to the external environment by natural or forced convection during the flow process. The most widely used type of traction transformer in the EMU is the oil-immersed transformer, whose cooling channel is the horizontal and vertical oil channel between the windings enclosed in the oil tank. The insulating oil, as its cooling medium, circulates in the closed oil channel driven by the oil pump, and is difficult to be affected by foreign objects from the outside, and the probability of oil channel blockage is low. As an emerging equipment in the context of lightweight on-board electrical equipment of the EMU, the dry-type traction transformer has eliminated components such as insulating oil, oil tank, and radiator, achieving a significant weight reduction of the traction transformer, and is the development direction of the traction transformer of the EMU in the future. However, the dry-type traction transformer uses the running air generated by the relative movement of the EMU with the air for cooling. During operation, the air duct open to the external environment is more likely to be blocked by foreign objects, dust, etc. In order to ensure the safe operation of EMUs and avoid the adverse effects of partial blockage of the air duct on the normal operation of the traction transformer, it is necessary to conduct an investigation on the overheating characteristics of the transformer under different degrees of partial blockage of the air duct before the transformer heat dissipation design and operation. Compared with the oil-immersed traction transformers that have been maturely used for decades, dry-type traction transformers have less experience in cooling design, and lack an evaluation method that can consider the degree of influence of local air duct blockage failures on the thermal characteristics of dry-type traction transformers and the magnitude of overheating risks during the process of increasing number of air duct blockages. Therefore, it is necessary to propose a calculation method for the overheating coefficient of dry-type traction transformers under partial blockage of the air duct, to achieve an effective evaluation of the ability of dry-type traction transformer windings to resist the risk of air duct blockage failures, and to provide a new method for judging the rationality of the design scheme of cylindrical windings cooled by train running air, thereby providing technical support for the optimization design of winding heat dissipation structure, improvement of cooling performance and improvement of space structure utilization. Summary of the invention

[0003] In view of the above technical problems, the purpose of the present invention is to propose a method for calculating the overheating coefficient of a dry-type traction transformer under partial blockage of the air duct, which can effectively judge the influence of the partial blockage of the air duct on the thermal characteristics of the dry-type traction transformer and the size of the overheating risk.

[0004] The technical solution for achieving the purpose of the present invention is as follows:

[0005] Step 1: Establish an overheating test platform for dry-type traction transformers with partial blockage of air duct

[0006] The overheating test platform of the dry-type traction transformer under partial blockage of the air duct comprises: an outer cylindrical winding (1), an inner cylindrical winding (2), a stay (3), a suspension steel cable (4), an outer cylindrical winding head end lead wire (5), an outer cylindrical winding terminal lead wire (6), an inner cylindrical winding head end lead wire (7), an inner cylindrical winding terminal lead wire (8), a short-circuit wire (9), an air duct wind speed sensor (10), an incoming wind speed sensor (11), an incoming temperature sensor (12), a top thermal imager (13), a bottom thermal imager (14), a data acquisition device (15), a DC adjustable power supply (16), an adjustable speed axial flow fan (17), and a top plate (18);

[0007] The winding part of the test platform is composed of an outer cylindrical winding (1) and an inner cylindrical winding (2) in a set, wherein the outer cylindrical winding (1) is on the outside and the inner cylindrical winding (2) is on the inside, and the center lines of the two are mutually coincident, and both have a length of L, in meters; a stay (3) is installed between the outer cylindrical winding (1) and the inner cylindrical winding (2) to achieve mutual fixation and position constraint of the outer cylindrical winding (1) and the inner cylindrical winding (2), and the total number of stays is recorded as N, where N is ≥ 4; the winding part of the test platform is suspended in the air of the test site by a suspension steel cable (4) whose end is fixed to a top plate (18), and the center lines of the outer cylindrical winding (1) and the inner cylindrical winding (2) are kept parallel to the ground ; The lead wire (5) at the head end of the outer cylindrical winding is connected to the negative output terminal of the DC adjustable power supply (16), the lead wire (7) at the head end of the inner cylindrical winding is connected to the positive output terminal of the DC adjustable power supply (16), and the lead wire (6) at the end of the outer cylindrical winding and the lead wire (8) at the end of the inner cylindrical winding are connected via a short-circuit wire (9); the area enclosed by the outer cylindrical winding (1), the inner cylindrical winding (2) and the struts (3) constitutes an air duct, and the number of the air duct wind speed sensors (10) is the same as the number of the struts (3), both of which are N; an air duct wind speed sensor (10) is placed in each air duct, and all the air duct wind speed sensors (10) are connected to the data acquisition device (15), and the number of the air duct wind speed sensors (10) is recorded as N as , N as≥3; the incoming wind speed sensor (11) and the incoming flow temperature sensor (12) are both installed in the hollow area of ​​the inner cylindrical winding (2), and all the incoming wind speed sensors (11) and the incoming flow temperature sensors (12) are connected to the data acquisition device (15); the top thermal imager (13) and the bottom thermal imager (14) are respectively installed directly above and directly below the outer cylindrical winding (1), and their shooting angles can completely cover the upper and lower surfaces of the outer cylindrical winding (1), and the top thermal imager (13) and the bottom thermal imager (14) are both connected to the data acquisition device (15); the centerline height of the adjustable speed axial flow fan (17) is consistent with the centerline height of the outer cylindrical winding (1) and the inner cylindrical winding (2), and is placed on the air duct side of the winding part of the test platform, and the airflow direction is perpendicular to the end faces of the outer cylindrical winding (1) and the inner cylindrical winding (2);

[0008] Step 2: Conduct tests without air duct blockage and obtain relevant data

[0009] Start the adjustable speed axial flow fan (17), and adjust the speed of the adjustable speed axial flow fan (17) until the average wind speed measured by all incoming wind speed sensors (11) reaches v ave , v ave ≥5m / s; start the DC adjustable power supply (16) and apply the rated loss value of the winding to the large diameter cylindrical winding (1) and the small diameter cylindrical winding (2) at the same time, recorded as P loss , in units of W; the temperature data of all incoming flow temperature sensors (12) are obtained through a data acquisition device (15), and the average value thereof is recorded as T a_ave ; The wind speed data of all wind duct wind speed sensors (10) are obtained through the data acquisition device (15), and the average value is recorded as v duct_ave_0 ; The infrared image of the surface temperature of the outer cylindrical winding (1) taken by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​therein are extracted, which are respectively recorded as T max 0 and T min 0, when the fluctuation of both is less than 2℃ / h, it is recorded as the final result when the air duct is not blocked;

[0010] Step 3: Conduct tests on partial blockage of the air duct and obtain relevant data

[0011] Randomly select one of the N air ducts as the first air duct to be blocked, and number it as air duct No. 1. The remaining air ducts are named air duct No. 2, air duct No. 3, ..., air duct No. N in clockwise direction;

[0012] The end of the No. 1 air duct is blocked so that the airflow generated by the adjustable speed axial flow fan (17) cannot enter the interior of the No. 1 air duct; the wind speed data of all the wind speed sensors (10) in the air ducts are obtained through the data acquisition device (15), and the average value thereof is recorded as v duct_ave_1 ; The infrared image of the surface temperature of the outer cylindrical winding (1) taken by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​therein are extracted, which are respectively recorded as T max_1 and T min_1 , when the fluctuation of both is less than 2℃ / h, it is recorded as the final result under the condition of blockage of air duct No. 1;

[0013] Continue to block the end of the No. 2 air duct so that the airflow generated by the adjustable speed axial flow fan (17) cannot enter the interior of the No. 1 and No. 2 air ducts; obtain the wind speed data of all the air duct wind speed sensors (10) through the data acquisition device (15), and record the average value as v duct_ave_2 ; The infrared image of the surface temperature of the outer cylindrical winding (1) taken by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​therein are extracted, which are respectively recorded as T max_2 and T min_2 , when the fluctuation degree of both is less than 2℃ / h, it is recorded as the final result when both No. 1 and No. 2 air ducts are blocked;

[0014] Repeat the above operation, gradually and sequentially increase the number of blocked air ducts under the premise that the test conditions remain unchanged, until the end of the (N-1) air duct is blocked, at which time the airflow generated by the adjustable speed axial flow fan (17) cannot enter the interior of the No. 1, No. 2, ..., (N-1) air ducts; obtain the wind speed data of all the air duct wind speed sensors (10) through the data acquisition device (15), and record the average value as v duct_ave_(N-1) ; The infrared image of the surface temperature of the outer cylindrical winding (1) taken by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​therein are extracted, which are respectively recorded as T max_(N-1) and T min_(N-1) , when the fluctuations of both are less than 2℃ / h, they are recorded as the final results when the No. 1, No. 2, ..., (N-1) air ducts are all blocked;

[0015] Step 4: Calculate the overheat correction factor k pd

[0016]

[0017] Step 5: Calculate the overheating coefficient S of the dry-type traction transformer under partial blockage of the air duct pd

[0018]

[0019] Step 6: Based on S pd Evaluation of the impact of partial air duct blockage on the thermal state of dry-type traction transformers

[0020] If S pd <0.6, the local blockage of the air duct has little impact on the thermal state of the dry-type traction transformer, and the risk of overheating is low when local blockage occurs. This design can meet the engineering requirements. pd ≥0.6, the local blockage fault of the air duct has a greater impact on the thermal state of the dry-type traction transformer. When local blockage occurs, the risk of overheating is high. This design scheme needs further improvement.

[0021] The beneficial effect of the present invention is that a method for calculating the overheat coefficient of a dry-type traction transformer under partial blockage of the air duct has the following advantages:

[0022] 1) The present invention proposes for the first time to consider the influence of local air duct blockage failure on the thermal characteristics of dry-type traction transformers and the magnitude of overheating risk in the process of gradually increasing number of air duct blockages, which can effectively evaluate the ability of dry-type traction transformer windings to resist the risk of air duct blockage failures, and provide a new method for judging the rationality of the design scheme of cylindrical windings cooled by train running air, thereby providing technical support for the optimal design of winding heat dissipation structure, improvement of cooling performance and improvement of space structure utilization;

[0023] 2) Compared with the blindness and repetitiveness of traditional transformer winding air duct blockage fault simulation test and air duct blockage fault resistance risk assessment, the method proposed in the present invention can effectively improve the work efficiency of the transformer winding structure design and verification stage and reduce the consumption of manpower and material resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention relates to a flow chart of a method for calculating an overheating coefficient of a dry-type traction transformer when the air duct is partially blocked;

[0025] Figure 2 The invention discloses a structural schematic diagram of an overheating test platform for a dry-type traction transformer under partial blockage of an air duct. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and specific implementation processes. It should be emphasized that the specific implementation cases described herein are only used to explain the present invention and do not limit the scope of the present invention and its claims.

[0027] Step 1: Establish an overheating test platform for dry-type traction transformers with partial blockage of air duct

[0028] The overheating test platform of the dry-type traction transformer under partial blockage of the air duct comprises: an outer cylindrical winding (1), an inner cylindrical winding (2), a stay (3), a suspension steel cable (4), an outer cylindrical winding head end lead wire (5), an outer cylindrical winding terminal lead wire (6), an inner cylindrical winding head end lead wire (7), an inner cylindrical winding terminal lead wire (8), a short-circuit wire (9), an air duct wind speed sensor (10), an incoming wind speed sensor (11), an incoming temperature sensor (12), a top thermal imager (13), a bottom thermal imager (14), a data acquisition device (15), a DC adjustable power supply (16), an adjustable speed axial flow fan (17), and a top plate (18);

[0029] The winding part of the test platform is composed of an outer cylindrical winding (1) and an inner cylindrical winding (2) in a set, the outer cylindrical winding (1) is on the outside, and the inner cylindrical winding (2) is on the inside, the center lines of the two are overlapped, and the length is L=0.8m; the ends of the outer cylindrical winding (1) and the inner cylindrical winding (2) are aligned; a support bar (3) is installed between the outer cylindrical winding (1) and the inner cylindrical winding (2) to achieve mutual fixation and position constraint of the outer cylindrical winding (1) and the inner cylindrical winding (2), and the total number of the support bars is recorded as N, and in this embodiment N=4; the winding part of the test platform is suspended in the air of the test site by a suspension steel cable (4) whose end is fixed to the top plate (18), and the center lines of the outer cylindrical winding (1) and the inner cylindrical winding (2) are kept parallel to the ground; the outer The lead wire (5) at the head end of the side cylindrical winding is connected to the negative output terminal of the DC adjustable power supply (16), the lead wire (7) at the head end of the inner cylindrical winding is connected to the positive output terminal of the DC adjustable power supply (16), and the lead wire (6) at the end of the outer cylindrical winding and the lead wire (8) at the end of the inner cylindrical winding are connected via a short-circuit wire (9), so that the coils of the two windings are connected in series and finally connected to the output end of the DC adjustable power supply (16); the area surrounded by the outer cylindrical winding (1), the inner cylindrical winding (2) and the support bar (3) constitutes an air duct, and the number of the air duct wind speed sensor (10) is the same as the number of the support bars (3), both of which are N=4; an air duct wind speed sensor (10) is placed in each air duct, and all the air duct wind speed sensors (10) are connected to the data acquisition device (15), and the number of the air duct wind speed sensors (10) is recorded as N as In this embodiment, N as=3; the incoming wind speed sensor (11) and the incoming flow temperature sensor (12) are both installed in the hollow area of ​​the inner cylindrical winding (2), and all the incoming wind speed sensors (11) and the incoming flow temperature sensors (12) are connected to the data acquisition device (15); the top thermal imager (13) and the bottom thermal imager (14) are respectively installed directly above and directly below the outer cylindrical winding (1), and their shooting angles can completely cover the upper and lower surfaces of the outer cylindrical winding (1), and the top thermal imager (13) and the bottom thermal imager (14) are both connected to the data acquisition device (15); the centerline height of the adjustable speed axial flow fan (17) is consistent with the centerline height of the outer cylindrical winding (1) and the inner cylindrical winding (2), and is placed on the air duct side of the winding part of the test platform, and the airflow direction is perpendicular to the end faces of the outer cylindrical winding (1) and the inner cylindrical winding (2);

[0030] Step 2: Conduct tests without air duct blockage and obtain relevant data

[0031] Start the adjustable speed axial flow fan (17), and adjust the speed of the adjustable speed axial flow fan (17) until the average wind speed measured by all incoming wind speed sensors (11) reaches v ave , v ave =6.00m / s; start the DC adjustable power supply (16) and apply the rated loss value of the winding to the large diameter cylindrical winding (1) and the small diameter cylindrical winding (2) at the same time, recorded as P loss =735.00W; obtain the temperature data of all incoming flow temperature sensors (12) through the data acquisition device (15), and record the average value as T a_ave =17.62℃; obtain the wind speed data of all wind duct wind speed sensors (10) through the data acquisition device (15), and record the average value as v duct_ave_0 =5.34 m / s; the infrared image of the surface temperature of the outer cylindrical winding (1) obtained by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​therein are extracted, which are respectively recorded as T max_0 and T min_0 When the fluctuation of both is less than 2℃ / h, it is recorded as the final result when the air duct is not blocked, T max_0 and T min_0 The final results were 52.94℃ and 33.07℃ respectively;

[0032] Step 3: Conduct tests on partial blockage of the air duct and obtain relevant data

[0033] Randomly select one of the four air ducts as the first air duct to be blocked, and number it as air duct No. 1. The remaining air ducts are named air duct No. 2, air duct No. 3 and air duct No. 4 in clockwise direction;

[0034] The end of air duct No. 1 is blocked so that the airflow generated by the adjustable speed axial flow fan (17) cannot enter the interior of air duct No. 1; the wind speed data of the wind speed sensors (10) of all unblocked air ducts are obtained through the data acquisition device (15), and the average value thereof is recorded as v duct_ave_1 =5.42 m / s; the infrared image of the surface temperature of the outer cylindrical winding (1) obtained by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​therein are extracted, which are respectively recorded as T max_1 and T min_1 When the fluctuation of both is less than 2℃ / h, it is recorded as the final result under the condition of blockage of air duct No. 1, T max_1 and T min_1 The final results were 54.56℃ and 33.85℃ respectively;

[0035] Continue to block the end of the No. 2 air duct so that the airflow generated by the adjustable speed axial flow fan (17) cannot enter the interior of the No. 1 and No. 2 air ducts; obtain the wind speed data of the wind speed sensors (10) of all unblocked air ducts through the data acquisition device (15), and record the average value as v duct_ave_2 =5.57m / s; the infrared image of the surface temperature of the outer cylindrical winding (1) obtained by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​therein are extracted, which are respectively recorded as T max_2 and T min_2 When the fluctuation of both is less than 2℃ / h, it is recorded as the final result when both No. 1 and No. 2 air ducts are blocked, T max_2 and T min_2 The final results were 57.82℃ and 35.11℃ respectively;

[0036] Continue to block the end of the No. 3 air duct so that the airflow generated by the adjustable speed axial flow fan (17) cannot enter the interior of the No. 1, No. 2, and No. 3 air ducts; obtain the wind speed data of the wind speed sensors (10) of all unblocked air ducts through the data acquisition device (15), and record the average value as v duct_ave_3 =5.94 m / s; the infrared image of the surface temperature of the outer cylindrical winding (1) obtained by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​therein are extracted, which are respectively recorded as T max_3 and T min_3 When the fluctuations of both are less than 2℃ / h, they are recorded as the final result when the No. 1, No. 2, and No. 3 air ducts are all blocked, T max_3 and T min_3The final results were 63.17℃ and 39.24℃ respectively;

[0037] Step 4: Substitute the v obtained in steps 2 and 3 duct_ave_0 、v duct_ave_1 、v duct_ave_2 、v duct_ave_3 、v ave Substitute into the following formula to calculate the overheat correction factor k pd , we get k pd =0.1635;

[0038]

[0039] Step 5: Combine the temperature data obtained in steps 2 and 3 with the k obtained in step 4. pd Substitute the following formula to calculate the overheating coefficient S of the dry-type traction transformer when the air duct is partially blocked pd , get S pd =0.1190;

[0040]

[0041] Step 6: Based on S pd Evaluation of the impact of partial air duct blockage on the thermal state of dry-type traction transformers

[0042] If S pd <0.6, the local blockage of the air duct has little impact on the thermal state of the dry-type traction transformer, and the risk of overheating is low when local blockage occurs. This design can meet the engineering requirements. pd ≥0.6, the local blockage fault of the air duct has a greater impact on the thermal state of the dry-type traction transformer. When local blockage occurs, the risk of overheating is high. This design scheme needs further improvement.

Claims

1. A method for calculating the overheat coefficient of a dry-type traction transformer under partial blockage of the air duct, characterized in that: The following steps are involved: Step 1: Establish an overheating test platform for dry-type traction transformers with partial blockage of air duct The overheating test platform of the dry-type traction transformer under partial blockage of the air duct comprises: an outer cylindrical winding (1), an inner cylindrical winding (2), a stay (3), a suspension steel cable (4), an outer cylindrical winding head end lead wire (5), an outer cylindrical winding terminal lead wire (6), an inner cylindrical winding head end lead wire (7), an inner cylindrical winding terminal lead wire (8), a short-circuit wire (9), an air duct wind speed sensor (10), an incoming wind speed sensor (11), an incoming temperature sensor (12), a top thermal imager (13), a bottom thermal imager (14), a data acquisition device (15), a DC adjustable power supply (16), an adjustable speed axial flow fan (17), and a top plate (18); The winding part of the test platform is composed of an outer cylindrical winding (1) and an inner cylindrical winding (2) in a set, wherein the outer cylindrical winding (1) is on the outside and the inner cylindrical winding (2) is on the inside, and the center lines of the two are mutually coincident, and both have a length of L, in meters; a stay (3) is installed between the outer cylindrical winding (1) and the inner cylindrical winding (2) to achieve mutual fixation and position constraint of the outer cylindrical winding (1) and the inner cylindrical winding (2), and the total number of stays is recorded as N, where N is ≥ 4; the winding part of the test platform is suspended in the air of the test site by a suspension steel cable (4) whose end is fixed to a top plate (18), and the center lines of the outer cylindrical winding (1) and the inner cylindrical winding (2) are kept parallel to the ground ; The lead wire (5) at the head end of the outer cylindrical winding is connected to the negative output terminal of the DC adjustable power supply (16), the lead wire (7) at the head end of the inner cylindrical winding is connected to the positive output terminal of the DC adjustable power supply (16), and the lead wire (6) at the end of the outer cylindrical winding and the lead wire (8) at the end of the inner cylindrical winding are connected via a short-circuit wire (9); the area enclosed by the outer cylindrical winding (1), the inner cylindrical winding (2) and the struts (3) constitutes an air duct, and the number of the air duct wind speed sensors (10) is the same as the number of the struts (3), both of which are N; an air duct wind speed sensor (10) is placed in each air duct, and all the air duct wind speed sensors (10) are connected to the data acquisition device (15), and the number of the air duct wind speed sensors (10) is recorded as N as , N as ≥3; the incoming wind speed sensor (11) and the incoming flow temperature sensor (12) are both installed in the hollow area of ​​the inner cylindrical winding (2), and all the incoming wind speed sensors (11) and the incoming flow temperature sensors (12) are connected to the data acquisition device (15); the top thermal imager (13) and the bottom thermal imager (14) are respectively installed directly above and directly below the outer cylindrical winding (1), and their shooting angles can completely cover the upper and lower surfaces of the outer cylindrical winding (1), and the top thermal imager (13) and the bottom thermal imager (14) are both connected to the data acquisition device (15); the centerline height of the adjustable speed axial flow fan (17) is consistent with the centerline height of the outer cylindrical winding (1) and the inner cylindrical winding (2), and is placed on the air duct side of the winding part of the test platform, and the airflow direction is perpendicular to the end faces of the outer cylindrical winding (1) and the inner cylindrical winding (2); Step 2: Conduct tests without air duct blockage and obtain relevant data Start the adjustable speed axial flow fan (17), and adjust the speed of the adjustable speed axial flow fan (17) until the average wind speed measured by all incoming wind speed sensors (11) reaches v ave , v ave ≥5m / s; The DC adjustable power supply (16) is started to apply the rated loss value of the windings, denoted as P, to the large diameter cylindrical winding (1) and the small diameter cylindrical winding (2) at the same time. loss , in units of W; the temperature data of all incoming flow temperature sensors (12) are obtained through a data acquisition device (15), and the average value thereof is recorded as T a_ave ; The wind speed data of all wind duct wind speed sensors (10) are obtained through the data acquisition device (15), and the average value is recorded as v duct_ave_0 ; The infrared image of the surface temperature of the outer cylindrical winding (1) taken by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​thereof are extracted and recorded as T max_0 and T min_0 When the fluctuation of both is less than 2℃ / h, it is recorded as the final result when the air duct is not blocked; Step 3: Conduct tests on partial blockage of the air duct and obtain relevant data Randomly select one of the N air ducts as the first air duct to be blocked, and number it as air duct No.

1. The remaining air ducts are named air duct No. 2, air duct No. 3, ..., air duct No. N in clockwise direction; The end of the No. 1 air duct is blocked so that the airflow generated by the adjustable speed axial flow fan (17) cannot enter the interior of the No. 1 air duct; the wind speed data of all the wind speed sensors (10) in the air ducts are obtained through the data acquisition device (15), and the average value thereof is recorded as v duct_ave_1 ; The infrared image of the surface temperature of the outer cylindrical winding (1) taken by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​thereof are extracted and recorded as T max_1 and T min_1 , when the fluctuation of both is less than 2℃ / h, it is recorded as the final result under the condition of blockage of air duct No. 1; Continue to block the end of the No. 2 air duct so that the airflow generated by the adjustable speed axial flow fan (17) cannot enter the interior of the No. 1 and No. 2 air ducts; obtain the wind speed data of all the air duct wind speed sensors (10) through the data acquisition device (15), and record the average value as v duct_ave_2 ; The infrared image of the surface temperature of the outer cylindrical winding (1) taken by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​thereof are extracted and recorded as T max_2 and T min_2 , when the fluctuation degree of both is less than 2℃ / h, it is recorded as the final result when both No. 1 and No. 2 air ducts are blocked; Repeat the above operation, gradually and sequentially increase the number of blocked air ducts under the premise that the test conditions remain unchanged, until the end of the (N-1) air duct is blocked, at which time the airflow generated by the adjustable speed axial flow fan (17) cannot enter the interior of the No. 1, No. 2, ..., (N-1) air ducts; obtain the wind speed data of all the air duct wind speed sensors (10) through the data acquisition device (15), and record the average value as v duct_ave_(N-1) ; The infrared image of the surface temperature of the outer cylindrical winding (1) taken by the top thermal imager (13) and the bottom thermal imager (14) is obtained by the data acquisition device (15), and the maximum and minimum temperature values ​​thereof are extracted and recorded as T max_(N-1) and T min_(N-1) , when the fluctuations of both are less than 2℃ / h, they are recorded as the final results when the No. 1, No. 2, ..., (N-1) air ducts are all blocked; Step 4: Calculate the overheat correction factor k pd Step 5: Calculate the overheating coefficient S of the dry-type traction transformer under partial blockage of the air duct pd Step 6: Based on S pd Evaluation of the impact of partial air duct blockage on the thermal state of dry-type traction transformers If S pd <0.6, the local blockage of the air duct has little impact on the thermal state of the dry-type traction transformer, and the risk of overheating is low when local blockage occurs. This design can meet the engineering requirements. pd ≥0.6, the local blockage fault of the air duct has a greater impact on the thermal state of the dry-type traction transformer. When local blockage occurs, the risk of overheating is high. This design scheme needs further improvement.

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