Nondestructive detection and determination method for main insulation aging degree of motor train unit traction transformer

Abstract

The present application relates to the field of nondestructive testing of vehicle-mounted traction transformer, and discloses a nondestructive testing and judging method for the aging degree of main insulation of EMU traction transformer, comprising the following steps: S1, selecting transformers with different mileages as testing samples; S2, testing LCR testing parameters of the transformers with different mileages; S3, judging the aging degree of main insulation of the transformers according to the LCR testing parameters. The present application fills the vacancy of the method for testing and judging the main insulation of EMU traction transformer, and compared with the traditional testing method, the present application can realize nondestructive measurement of the aging degree of main insulation of EMU traction transformer. Compared with the dielectric parameter testing method under single frequency, the present application contains more information, and according to the analysis of LCR spectral characteristics, the data evaluation system of the aging degree of main insulation of traction transformer can be improved, and the present application can better serve the train maintenance.

Description

Technical Field

[0001] This invention relates to the field of non-destructive testing of vehicle-mounted traction transformers, specifically to a method for non-destructive testing and determination of the aging degree of the main insulation of EMU traction transformers. Background Technology

[0002] The electrical system of high-speed trains is a crucial component, and its power supply reliability and safety are of paramount importance to the safe and stable operation of the train. The traction transformer is one of the heavier and larger single electrical devices in a high-speed train, undertaking the vital tasks of voltage conversion and power distribution. Its operational condition directly affects the safe and efficient operation of the high-speed train. However, due to the wide operating range of the train sets, the traction transformers operate in harsh environments such as alternating high and low temperatures and vibrations for extended periods. As a result, problems can arise in the internal insulation and mechanical structure of the traction transformer, easily leading to malfunctions. If these malfunctions are not detected in time, they can further deteriorate under electrical, mechanical, and chemical influences, causing train shutdowns or even more serious accidents. This is extremely detrimental to the normal operation of the entire railway system and the safety of personnel. Therefore, it is urgent to conduct condition monitoring and assessment of the insulation of high-speed train traction transformers.

[0003] Currently, the maintenance of traction transformers for high-speed trains mainly relies on traditional offline testing methods. These methods determine the operating status of the traction transformer insulation based on data such as dissolved gases in the oil and the oil's physical and chemical properties (conductivity, furfural, electrical strength, moisture, and dielectric loss). However, the testing methods and data are limited, resulting in a small amount of information that cannot be extracted. This approach fails to provide a comprehensive and accurate assessment of the traction transformer's health status and does not take into account factors such as the transformer's operating time and mileage, thus hindering the detection and evaluation of its condition throughout its entire life cycle.

[0004] Due to its advantages such as being non-destructive and reliable, containing rich insulation information, and being easy to conduct on-site testing, the LCR dielectric spectrum method has been widely used in many fields at home and abroad. However, there has been little research on insulation testing of vehicle-mounted traction transformers. Summary of the Invention

[0005] This invention provides a non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer. The method measures the aging state of the traction transformer insulation based on the LCR spectrum. By scanning the LCR spectrum of the traction transformer at multiple frequencies, the spectral curves of each parameter are obtained, and the characteristic parameters that best reflect the aging degree of the traction transformer insulation are extracted. After comprehensive analysis, the aging degree of the traction transformer is determined.

[0006] This invention is achieved through the following technical solution:

[0007] A non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer includes the following steps:

[0008] S1. Select transformers with different mileages as test samples;

[0009] S2. Detect the LCR test parameters of the transformer at different mileages;

[0010] S3. Determine the degree of aging of the main insulation of the transformer based on the LCR test parameters.

[0011] In this technical solution, the LCR tester is used to analyze the spectral characteristics of the test sample. The LCR spectrum is the characteristic change of dielectric parameters at multiple frequencies. Compared with the dielectric parameter test method at a single frequency, it contains more information. Based on the LCR spectrum characteristic analysis, a comprehensive and accurate assessment can be carried out without damaging the transformer. This improves the data assessment system for the aging degree of the main insulation of the traction transformer, better serves the maintenance of EMU trains, optimizes the maintenance procedures for EMU traction transformers, and ultimately achieves the goal of condition-based maintenance.

[0012] As an optimization, the transformer is a traction transformer.

[0013] As an optimization, the specific implementation steps of step S2 include:

[0014] S2.1 Connect the LCR tester to each winding of the transformer;

[0015] S2.2 Detect the frequency domain dielectric spectrum parameters of each winding of the transformer using the LCR tester.

[0016] As an optimization, the frequency domain dielectric spectrum parameters include inductance spectrum L, capacitance spectrum C, resistance spectrum R, phase spectrum PHASE, loss spectrum D, and impedance spectrum Z.

[0017] As an optimization, the transformer windings include the high-voltage winding, traction winding, auxiliary winding, and excitation winding.

[0018] As an optimization, the LCR tester's housing is grounded before testing.

[0019] As an optimization, the LCR tester outputs a test frequency range of 20Hz to 5MHz.

[0020] As an optimization, in step 3, the LCR test parameter used to determine the aging degree of the main insulation of the transformer is the impedance spectrum of the transformer.

[0021] As an optimization, the traction transformer is a traction transformer for CRH5 / CRH380B type EMU trains.

[0022] As an optimization, step 3, which involves determining the degree of aging of the main insulation of the transformer based on the LCR test parameters, includes the following specific steps:

[0023] S3.1 Obtain the frequency domain impedance curves of the high-voltage winding, traction winding, auxiliary winding and excitation winding of the transformer at different mileages before and after maintenance.

[0024] S3.2 Select the frequency band where the frequency domain impedance curve shows a peak as the characteristic parameter for determining the degree of aging of the transformer's main insulation;

[0025] S3.3. Compare the peak value of the impedance curve after maintenance with the peak value of the impedance curve before maintenance to obtain the degree of aging of the transformer's main insulation.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] This invention fills the gap in the detection and judgment methods for the main insulation of traction transformers in high-speed trains. Compared with traditional testing methods, this invention can achieve non-destructive measurement of the aging degree of the main insulation of traction transformers in high-speed trains. Compared with the dielectric parameter testing method at a single frequency, this invention contains more information. Based on the LCR spectrum characteristic analysis, it can improve the data evaluation system for the aging degree of the main insulation of traction transformers, better serve train maintenance, and have certain reference value for optimizing the high-level maintenance process of high-speed trains, ultimately achieving the goal of condition-based maintenance. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0029] Figure 1 This is a flowchart of a non-destructive testing and determination method for the aging degree of the main insulation of a traction transformer for a high-speed train, as described in this invention.

[0030] Figure 2 This is a schematic diagram illustrating the detection principle for the aging degree of the main insulation of a high-speed train traction transformer.

[0031] Figure 3 Diagram showing the main insulation structure and LCR test sequence of the traction transformer for high-speed trains;

[0032] Figure 4 A simplified schematic diagram of the on-site testing of the main insulation of the traction transformer for a high-speed train (taking the high-voltage winding AX as an example);

[0033] Figure 5 shows the frequency domain dielectric spectrum of the high-voltage winding AX of the traction transformer before repair at different operating mileages of the EMU.

[0034] Figure 6 shows the frequency domain dielectric spectrum of the high-voltage winding AX of the traction transformer after repair at different operating mileages of the EMU.

[0035] Figure 7 This is a comparison of the frequency domain dielectric spectra of the high-voltage winding AX of the traction transformer of a high-speed train before and after repair.

[0036] The attached diagram shows the markings and corresponding component names:

[0037] 1-LCR tester, 2-connecting cable and clamp, 3-traction transformer. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0039] Example 1

[0040] like Figure 1 As shown, a non-destructive testing and assessment method for the aging degree of the main insulation of a high-speed train traction transformer is presented. This technical solution utilizes an LCR (Liquid Crystal Count) meter to analyze the spectral characteristics of the test sample. The LCR spectrum represents the characteristic changes of dielectric parameters at multiple frequencies, containing more information than single-frequency dielectric parameter testing. Based on LCR spectrum analysis, a comprehensive and accurate assessment can be performed without damaging the transformer, thus improving the data assessment system for the aging degree of the traction transformer's main insulation, better serving high-speed train maintenance, optimizing high-speed train traction transformer maintenance procedures, and ultimately achieving the goal of condition-based maintenance. The specific steps include the following:

[0041] S1. Select transformers with different mileages as test samples; in this embodiment, the transformer is a traction transformer.

[0042] The test samples for this invention were selected as prototypes of the traction transformers of CRH5 / CRH380B EMUs before and after repair, with mileage of 2.4 million kilometers (level 4 repair) and 4.8 million kilometers (level 5 repair). Before the test, the prototypes were divided into 6 groups and named according to the traction transformer model: XCH000000-BHN-058, XCH000000-BHN-493, XCH000000-BHN-618, XCH000000-BHN-625, XCH000000-BHN-042, and XCH000000-BHX-201. The specific prototype categories and numbers are shown in Table 1.

[0043] Table 1. Prototype of Traction Transformer for CRH380B EMU

[0044] Maintenance Category Operating mileage (10,000 kilometers) Transformer model 5-1 Pre-repair 480 XCH000000-BHN-058 5-1 Pre-repair 480 XCH000000-BHN-493 4-1 Pre-repair 240 XCH000000-BHN-618 4-1 Pre-repair 240 XCH000000-BHN-625 5-1 after revision 480 XCH000000-BHN-042 5-1 after revision 480 XCH000000-BHX-201

[0045] Although the characteristic parameters are not compared before and after the repair of the same traction transformer, the traction transformers mentioned above belong to the CRH5 / CRH380B category, and their parameter changes after operation are similar. Therefore, comparing the parameters before and after repair of the same type of traction transformer is authentic and reliable.

[0046] S2. Detect the LCR test parameters of the transformer at different mileages; in this embodiment, the specific implementation steps of step S2 include:

[0047] S2.1 Connect the LCR tester to each winding of the transformer;

[0048] S2.2 Detect the frequency domain dielectric spectrum parameters of each winding of the transformer using the LCR tester, that is, detect the impedance spectrum curves of each winding of the transformer at different frequencies.

[0049] Specifically, firstly, the LCR meter was calibrated under operating conditions of 20Hz~5MHz and 1V before testing. Secondly, based on the site conditions, the LCR meter 1, along with connecting wires and clamps 2, was used to perform frequency domain dielectric spectrum testing on each winding of the EMU traction transformer 3. The spectrum of inductance L, capacitance C, resistance R, phase angle PHASE, loss D, and impedance Z of each winding of the traction transformer were tested respectively. Finally, through analysis, it was found that the impedance spectrum implicitly contains information on resistance, inductance, capacitance, phase angle, and loss parameters, and that the phase angle and loss parameters are easily interfered with by other operating equipment on site during the testing process. Therefore, the impedance spectrum—the characteristic parameter that best reflects the aging degree of the main insulation of the traction transformer—was selected as an effective characterization parameter for the aging of the main insulation of the traction transformer.

[0050] like Figure 2 , 4 As shown, the instruments required for the experiment are as follows:

[0051] LCR Tester 1: Equipped with a display panel, test frequency 20Hz~5MHz, measurement drive level 10mV~2V, basic measurement accuracy 0.1%, model: TH-2826, Changzhou Tonghui Electronics Co., Ltd. The LCR tester casing is grounded, and an additional grounding wire for the LCR testing equipment is added to avoid the influence of external interference on the main insulation impedance spectrum of the traction transformer and to avoid interference from other factors. Of course, other models of LCR testers can also be selected. The tester model in this embodiment is not the only tester model in this determination method.

[0052] Connecting wire and clamp 2: used to connect the LCR measuring instrument 1 and the windings of the test sample traction transformer 3, so that the LCR measuring instrument 1 and the windings of the traction transformer used as the test sample are reliably connected.

[0053] In this embodiment, the windings of the traction transformer include the high-voltage winding, traction winding, auxiliary winding, and excitation winding.

[0054] S3. Determine the degree of aging of the main insulation of the transformer based on the LCR test parameters. In general, the determination of the degree of aging of the main insulation of the test sample is as follows: Based on the LCR test results, obtain the LCR spectrum curves at different frequencies, extract the characteristic parameters that best reflect the degree of aging of the main insulation of the traction transformer, and compare them with the corresponding characteristic spectrum curves of each winding of the traction transformer before and after repair at different operating mileages to determine the degree of aging of the main insulation of the traction transformer.

[0055] like Figure 3 As shown, the test sequence for each winding of traction transformer 3 is ①, ②, ③, ④, ⑤, ⑥, ⑦. Of course, this test sequence is not the only possible sequence; other test sequences are also acceptable.

[0056] In this embodiment, step 3, which involves determining the degree of aging of the main insulation of the transformer based on the LCR test parameters, includes the following specific steps:

[0057] S3.1 Obtain the frequency domain impedance curves of the high-voltage winding, traction winding, auxiliary winding and excitation winding of the transformer at different mileages before and after maintenance.

[0058] S3.2 Select the frequency band where the frequency domain impedance curve shows a peak as the characteristic parameter for determining the degree of aging of the transformer's main insulation;

[0059] S3.3. Compare the peak value of the impedance curve after maintenance with the peak value of the impedance curve before maintenance to obtain the degree of aging of the transformer's main insulation.

[0060] Specifically, the test frequency band of 20Hz to 5MHz was selected, and the LCR frequency domain impedance spectrum curves of each winding of the CRH380B traction transformer at different frequencies were obtained (for ease of explanation, the impedance spectrum diagrams of the high voltage winding AX of the traction transformer before and after maintenance at different operating mileages are shown in Figure 5 and Figure 6 respectively).

[0061] By comparing the LCR frequency domain impedance spectrum characteristic curves of the high-voltage winding AX of the traction transformer before repair with the impedance spectrum curves after repair, the aging degree of the high-voltage winding AX of the traction transformer is obtained. Similarly, by comparing the LCR frequency domain impedance spectrum characteristic curves of the traction winding, auxiliary winding and excitation winding of the traction transformer before repair with the impedance spectrum curves after repair, the aging degree of the traction winding, auxiliary winding and excitation winding of the traction transformer is obtained.

[0062] Taking the high-voltage winding AX of the traction transformer of the EMU as an example, Figures 5 and 6 show the impedance spectrum of the traction winding AX at different operating mileages.

[0063] In Figure 5, (a) is the impedance spectrum of the high-voltage winding AX of the traction transformer (XCH000000-BHN-618) that has been in operation for 2.4 million kilometers before maintenance.

[0064] In Figure 5, (b) is the impedance spectrum of the high-voltage winding AX of the traction transformer (XCH000000-BHN-625) that had been in operation for 2.4 million kilometers before maintenance.

[0065] In Figure 5, (c) is the impedance spectrum of the high-voltage winding AX of the traction transformer (XCH000000-BHN-058) that had been in operation for 4.8 million kilometers before maintenance.

[0066] In Figure 5, (d) is the impedance spectrum of the high-voltage winding AX of the traction transformer (XCH000000-BHN-493) that had been in operation for 4.8 million kilometers before maintenance.

[0067] In Figure 6, (a) is the impedance spectrum of the high-voltage winding AX of the traction transformer (XCH000000-BHN-042) after maintenance and operation for 4.8 million kilometers;

[0068] In Figure 6, (b) is the impedance spectrum of the high-voltage winding AX of the traction transformer (XCH000000-BHN-201) after maintenance and 4.8 million kilometers of operation.

[0069] As shown in Figure 5, the frequency domain impedance spectrum curves of the high-voltage windings of the four traction transformers before repair, which had operated for 2.4 million kilometers and 4.8 million kilometers respectively, are similar and not significantly different, especially in the mid-frequency range (10). 2 -10 3The impedance spectrum of the traction transformer becomes more sensitive, exhibiting a peak value. Comparison with the frequency domain impedance spectrum curve of the high-voltage winding of the repaired traction transformer (Figure 6) reveals that as the operating mileage increases, the impedance spectrum value of the traction transformer before repair is lower than that after repair. Therefore, the mid-frequency band (10) is selected. 2 -10 3 As a characteristic parameter of the aging of the high-voltage winding insulation of the traction transformer, it can effectively characterize the degree of deterioration of the main insulation of the traction transformer.

[0070] In order to study the degradation characteristics of the main insulation of traction transformers at different operating mileages, Figure 7 The evolution of the frequency domain impedance spectrum of the high-voltage winding AX of the traction transformer at different operating mileages is presented. As shown in the figure, the frequency domain impedance spectrum value of the high-voltage winding of the traction transformer before repair is lower than that after repair, indicating that as the operating mileage increases, the impedance value of the main insulation of the traction transformer decreases (after traction transformer repair, the mileage of the traction transformer can be considered to be reduced equivalently), decreasing to approximately 2-3 times the original value. This is manifested in the mid-frequency impedance peak gradually decreasing with the degree of aging. Based on this, the aging degree DD1 of the high-voltage winding of the traction transformer is determined as shown in Formula 1.

[0071]

[0072] In the formula, Z after-max The high-voltage winding of the traction transformer after repair is in the characteristic frequency band 10. 2 -10 3 The maximum peak value, Z before-max The high-voltage winding of the traction transformer before repair was in the characteristic frequency band 10. 2 -10 3 The maximum peak value.

[0073] Example 2

[0074] The above process is the same as in Example 1. The only difference is that the impedance spectrum parameters of the traction winding of the traction transformer are tested, and the LCR tester is connected to the traction winding of the traction transformer. The insulation aging degree of the traction winding of the traction transformer is detected as DD2.

[0075] Example 3

[0076] The above process is the same as in Example 1. The only difference is that the impedance spectrum parameters of the auxiliary winding of the traction transformer are tested. The LCR tester is connected to the auxiliary winding of the traction transformer, and the insulation aging degree of the auxiliary winding of the traction transformer is detected as DD3.

[0077] Example 4

[0078] The above process is the same as in Example 1. The only difference is that the impedance spectrum parameters of the excitation winding of the traction transformer are tested, and the LCR tester is connected to the excitation winding of the traction transformer. The insulation aging degree of the excitation winding of the traction transformer is detected as DD4.

[0079] Therefore, the degree of aging of the main insulation of the traction transformer can be obtained from the aging values ​​of each winding mentioned above.

[0080] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is 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 within the scope of protection of the present invention.

Claims

1. A non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer, characterized in that, Includes the following steps: S1. Select transformers with different mileages as test samples; S2. Detect the LCR test parameters of the transformer at different mileages; S3. Determine the degree of aging of the main insulation of the transformer based on the LCR test parameters; Aging degree of the main insulation of the traction transformer Among them, DD1 is the aging degree of the high-voltage winding of the traction transformer, DD2 is the insulation aging degree of the traction winding of the traction transformer, DD3 is the insulation aging degree of the auxiliary winding of the traction transformer, and DD4 is the insulation aging degree of the excitation winding of the traction transformer.

2. The non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer according to claim 1, characterized in that, The transformer is a traction transformer.

3. The non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer according to claim 1, characterized in that, The specific implementation steps of step S2 include: S2.1 Connect the LCR tester to each winding of the transformer; S2.2 Detect the frequency domain dielectric spectrum parameters of each winding of the transformer using the LCR tester.

4. The non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer according to claim 3, characterized in that, The frequency domain dielectric spectrum parameters include inductance spectrum L, capacitance spectrum C, resistance spectrum R, phase spectrum PHASE, loss spectrum D, and impedance spectrum Z.

5. The non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer according to claim 3, characterized in that, The transformer windings include the high-voltage winding, traction winding, auxiliary winding, and excitation winding.

6. The non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer according to claim 3, characterized in that, Before performing the test, the LCR tester's casing is grounded.

7. A non-destructive testing and determination method for the aging degree of the main insulation of a traction transformer for a high-speed train, as described in any one of claims 3-6, characterized in that... The LCR tester outputs a test frequency range of 20Hz to 5MHz.

8. The non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer according to claim 4, characterized in that, In step 3, the LCR test parameter used to determine the aging degree of the main insulation of the transformer is the impedance spectrum of the transformer.

9. The non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer according to claim 2, characterized in that, The traction transformer is a traction transformer for CRH5 / CRH380B type EMU trains.

10. A non-destructive testing and determination method for the aging degree of the main insulation of a high-speed train traction transformer according to claim 5, characterized in that, Step 3, the specific steps for determining the aging degree of the main insulation of the transformer based on the LCR test parameters, are as follows: S3.1 Obtain the frequency domain impedance curves of the high-voltage winding, traction winding, auxiliary winding and excitation winding of the transformer at different mileages before and after maintenance. S3.2 Select the frequency band where the frequency domain impedance curve shows a peak as the characteristic parameter for determining the degree of aging of the transformer's main insulation; S3.

3. Compare the peak value of the impedance curve after maintenance with the peak value of the impedance curve before maintenance to obtain the degree of aging of the transformer's main insulation.

Images