Oil paper insulation deterioration evaluation device and method for vehicle-mounted transformer

Abstract

The invention discloses an oil paper insulation deterioration evaluation device and method for a vehicle-mounted transformer. The device comprises an upper computer, a switch, an operation overvoltage generation module, a test cavity, a high-frequency current sensor, a voltage divider and a signal acquisition device, the operation overvoltage generation module applies an operation overvoltage waveform to the pin electrode in the test cavity through the high-voltage coaxial cable, so that the oil paper insulation sample generates electrical response under the simulated impact condition; the high-frequency current sensor is used for monitoring loss characteristics of an oil paper insulation sample, the voltage divider is used for monitoring strength characteristics of two ends of the oil paper insulation sample, acquired signals are uploaded to the upper computer through the signal acquisition device to be processed and analyzed, and the upper computer combines the strength characteristics, the loss characteristics and the amplitude of an operation overvoltage waveform. The oil paper insulation degradation evaluation factor is calculated based on the preset model, continuous quantitative evaluation of the oil paper insulation state is achieved, and the insulation state recognition precision and evaluation reliability of the vehicle-mounted transformer in the actual operation environment are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer insulation performance evaluation, and particularly relates to a device and method for evaluating oil-paper insulation degradation of a vehicle-mounted transformer. BACKGROUND

[0002] Electric locomotives and motor trains rely on vehicle-mounted transformers during high-speed operation to achieve high-voltage power conversion and distribution in the traction power supply system. Therefore, the reliability of the vehicle-mounted transformer as a key power transmission and transformation device in the locomotive vehicle is directly related to the safety and stability of the entire power supply system. Currently, the vehicle-mounted transformer generally adopts an oil-paper composite insulation structure, which, however, often faces the combined effects of complex electromagnetic environments and mechanical stress conditions during long-term service. For example, factors such as local electric field concentration, winding structure deformation, and inherent vibration can all cause the gradual degradation of oil-paper insulation performance, thereby increasing the risk of breakdown.

[0003] In addition, during the operation of the traction power supply system, frequent switching operations can easily produce operating overvoltage surges. Compared with lightning overvoltage, this type of overvoltage has the characteristics of strong repetition and hidden effects. This type of overvoltage has a more significant impact on the oil-paper insulation structure, which can cause accelerated insulation aging or even local breakdown in a short period of time, thereby forming potential power supply failure hazards and seriously threatening the safe operation of the locomotive vehicle.

[0004] Existing evaluation methods for the insulation state of transformers are mainly based on the degradation mechanism and test model under power frequency voltage or lightning surge environment, and have not systematically considered the insulation degradation process caused by operating overvoltage factors, making it difficult to accurately reflect the oil-paper insulation state of the vehicle-mounted transformer under actual traction power supply conditions. In particular, in the traction scene of high-frequency switching and large load fluctuation, operating overvoltage has become one of the key factors affecting the service life of oil-paper insulation, and the traditional evaluation method has not established a corresponding response mechanism, resulting in a certain degree of deviation and lag in the evaluation results.

[0005] Therefore, it is urgent to propose a technical solution that can truly simulate the operating overvoltage action condition and effectively evaluate the oil-paper insulation degradation of the vehicle-mounted transformer, so as to realize accurate judgment and risk identification of the insulation performance state and ensure the stable operation of the traction power supply system of electric locomotives and motor trains.

[0006] This section aims to provide background or context for the embodiments of the application stated in the claims. The description herein is not admitted to be prior art merely because it is included in this section. SUMMARY

[0007] The oil-paper insulation deterioration evaluation device of the vehicle-mounted transformer can accurately obtain the deterioration characteristic parameters of the oil-paper insulation under the operating overvoltage condition, realizes continuous quantitative evaluation of the oil-paper insulation state, and improves the insulation state recognition accuracy and evaluation reliability of the vehicle-mounted transformer in the actual operation environment.

[0008] The oil-paper insulation deterioration evaluation device of the vehicle-mounted transformer comprises:

[0009] The host computer 1, the switch 2, the operating overvoltage generation module 3, the test cavity 4, the high-frequency current sensor 7, the voltage divider 8 and the signal acquisition device 10;

[0010] The host computer 1 is connected with the switch 2, and the switch 2 is respectively connected with the operating overvoltage generation module 3 and the signal acquisition device 10;

[0011] The operating overvoltage generation module 3 is connected with the wiring terminal at the top of the test cavity 4 through a first high-voltage coaxial cable 91, and is used for outputting an operating overvoltage waveform to the needle electrode 5 inside the test cavity 4;

[0012] The outgoing line at the bottom of the test cavity 4 is connected with the ground after passing through the high-frequency current sensor 7, and the high-frequency current sensor 7 is used for monitoring the loss characteristic of the oil-paper insulation sample 6 inside the test cavity 4;

[0013] The wiring terminal at the top of the test cavity 4 is connected with the wiring terminal at the top of the voltage divider 8 through a second high-voltage coaxial cable 92, and the outgoing line at the bottom of the test cavity 4 is connected with the bottom terminal post of the voltage divider 8, and the voltage divider 8 is used for monitoring the strength characteristic between the two ends of the oil-paper insulation sample 6;

[0014] The middle terminal post and the bottom terminal post of the voltage divider 8 are connected with the signal acquisition device 10, and the signal output end of the high-frequency current sensor 7 is connected with the signal acquisition device 10;

[0015] The host computer 1 is used for determining an oil-paper insulation deterioration evaluation factor according to the strength characteristic, the amplitude U of the operating overvoltage waveform and the loss characteristic, so as to perform oil-paper insulation deterioration evaluation of the vehicle-mounted transformer.

[0016] In an embodiment, the host computer 1 is specifically used for:

[0017] determining a loss characteristic evaluation factor theoretical calculation value of the oil-paper insulation sample 6 according to the strength characteristic, the amplitude of the operating overvoltage waveform and a pre-established operating overvoltage loss characteristic theoretical model;

[0018] performing parameter optimization processing on the loss characteristic evaluation factor theoretical calculation value based on the loss characteristic, to obtain an optimized loss characteristic.

[0019] determining an oil-paper insulation deterioration evaluation factor according to the strength characteristic and the optimized loss characteristic;

[0020] evaluating according to the oil-paper insulation deterioration evaluation factor and a preset interval to obtain an evaluation result.

[0021] In an embodiment, the operating overvoltage generating module 3 comprises a power supply device 31, a switch 32, an adjusting impedance 33, a first voltage boosting transformer 34, a second voltage boosting transformer 35, and a discharge sphere gap 36.

[0022] The power supply device 31, the switch 32, the adjusting impedance 33, the first voltage boosting transformer 34, the second voltage boosting transformer 35, and the discharge sphere gap 36 are connected in series, the power supply device 31 is connected to the switch 2, and the discharge sphere gap 36 is connected to the first high-voltage coaxial cable 91.

[0023] In an embodiment, the needle electrode 5 is fixed at the center of the test cavity 4, and the oil-paper insulation sample 6 is placed at the bottom of the test cavity 4.

[0024] In an embodiment, the device further comprises a first grounding device 41, and the first voltage boosting transformer 34 and the second voltage boosting transformer 35 are both connected to the first grounding device 41.

[0025] In an embodiment, the device further comprises a second grounding device 42, and the bottom outlet of the test cavity 4 is connected to the second grounding device 42.

[0026] In an embodiment, the operating overvoltage generating module 3 is specifically configured to generate an operating overvoltage waveform with a preset amplitude, and transmit the operating overvoltage waveform to the needle electrode 5 inside the test cavity 4 through the first high-voltage coaxial cable 91, so as to apply the operating overvoltage waveform to the oil-paper insulation sample 6.

[0027] In an embodiment, the signal collecting device 10 is configured to receive the strength characteristic output by the voltage divider 8 and the loss characteristic output by the high-frequency current sensor 7 respectively, and transmit the strength characteristic and the loss characteristic to the switch 2, and the switch 2 is configured to transmit the strength characteristic and the loss characteristic collected by the signal collecting device 10 to the upper computer 1.

[0028] The embodiment of the present application also provides an oil-paper insulation deterioration evaluation method of a vehicle-mounted transformer, which is used for accurately obtaining a deterioration characteristic parameter of oil-paper insulation under an operating overvoltage condition, realizing continuous quantitative evaluation of the state of oil-paper insulation, and improving the insulation state recognition precision and evaluation reliability of the vehicle-mounted transformer in an actual operation environment.

[0029] The assessment method for the deterioration of the oil-paper insulation of the vehicle-mounted transformer includes:

[0030] The control operation overvoltage generation module 3 outputs the operation overvoltage waveform to the needle electrode 5;

[0031] The strength characteristics at both ends of the oil-paper insulation sample 6 are monitored by the voltage divider 8, and the loss characteristics of the oil-paper insulation sample 6 are monitored by the high-frequency current sensor 7.

[0032] The theoretically calculated value of the loss characteristic evaluation factor of the oil-paper insulation sample 6 is determined based on the intensity characteristics, the amplitude of the switching overvoltage waveform, and the pre-established theoretical model of switching overvoltage loss characteristics.

[0033] Based on the loss characteristics, the theoretically calculated values ​​of the loss characteristic evaluation factors are optimized to obtain the optimized loss characteristics.

[0034] The degradation assessment factors for oil-paper insulation are determined based on the strength characteristics and the optimized loss characteristics.

[0035] The evaluation results are obtained by evaluating the deterioration assessment factors and preset ranges of the paper insulation.

[0036] In one embodiment, the step of optimizing the theoretically calculated values ​​of the loss feature evaluation factors based on the loss features to obtain optimized loss features includes:

[0037] Based on the preset initial error coefficients, the loss characteristics, and the theoretically calculated values ​​of the loss characteristic evaluation factors, the theoretical model of the operating overvoltage loss characteristics is recursively optimized to obtain the optimized error coefficients.

[0038] The optimized loss characteristics are determined based on the optimized error coefficients.

[0039] In one embodiment, the recursive parameter optimization process performed on the theoretical model of the switching overvoltage loss characteristics based on the preset initial error coefficients, the loss characteristics, and the theoretically calculated values ​​of the loss characteristic evaluation factors to obtain the optimized error coefficients includes:

[0040] A fitness function is constructed based on the initial error coefficients, and the first fitness function value corresponding to the initial error coefficients is obtained;

[0041] Candidate error coefficients were determined using a natural heuristic search method.

[0042] Based on the candidate error coefficients and the fitness function, the second fitness function value corresponding to the candidate error coefficients is obtained;

[0043] If the first fitness function value is less than or equal to the second fitness function value, the initial error coefficient is used as the optimized error coefficient;

[0044] If the first fitness function value is greater than the second fitness function value, the candidate error coefficient is used as the optimized error coefficient;

[0045] The above steps are executed iteratively until the preset termination condition is met, and the optimized error coefficient is obtained.

[0046] This invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described method for assessing the deterioration of the oil-paper insulation of vehicle-mounted transformers.

[0047] The device and method for evaluating the degradation of oil-paper insulation of vehicle-mounted transformers provided in this invention integrate an overvoltage generation module, a test chamber, a high-frequency current sensor, a voltage divider, and a signal acquisition device. Combined with information processing and communication control via a host computer and a switch, it enables real-time monitoring and quantitative evaluation of the degradation state of oil-paper insulation under overvoltage conditions. This evaluation device can simulate typical switching overvoltage impact scenarios in traction power supply systems. The overvoltage generation module outputs an impact waveform with actual transient characteristics, which is then applied to the oil-paper insulation sample within the test chamber, effectively simulating the electrical response process of the insulation material under high-voltage transients. During the test, the voltage divider precisely divides the high-voltage signal applied across the oil-paper insulation sample, extracting the intensity characteristics characterizing the applied voltage stress. The high-frequency current sensor monitors the high-frequency current response during the discharge process in real time, extracting loss characteristics related to insulation loss, thus ensuring the comprehensiveness and accuracy of the test data. The signal acquisition device synchronously acquires the aforementioned voltage and current characteristic signals and uploads them to the host computer for processing and analysis. Based on the amplitude, intensity characteristics, and loss characteristics of operational overvoltage, the host computer constructs an assessment factor for the degradation of oil-paper insulation, enabling continuous quantitative assessment of oil-paper insulation from initial aging to the failure boundary. Compared to existing technologies that primarily rely on assessment methods based on power frequency or lightning strike environments, the assessment device of this invention can more realistically reflect the impact of operational overvoltage on insulation degradation, significantly improving the accuracy and applicability of oil-paper insulation assessment. This helps to identify the insulation failure risk of on-board transformers in advance, thereby enhancing the safety and reliability of the traction power supply system. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0049] Figure 1 This is a schematic diagram of the structure of the vehicle-mounted transformer oil-paper insulation degradation assessment device in an embodiment of the present invention;

[0050] Figure 2 This is a flowchart illustrating the method for assessing the deterioration of the oil-paper insulation of an on-board transformer according to an embodiment of the present invention.

[0051] Figure 3 This is a flowchart illustrating the method for assessing the deterioration of the oil-paper insulation of a vehicle-mounted transformer in another embodiment of the present invention.

[0052] Figure 4 This is a flowchart illustrating the method for assessing the deterioration of the oil-paper insulation of a vehicle-mounted transformer in another embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0054] The information collected in the technical solution of this application is information and data authorized by the user or fully authorized by all parties. The collection, storage, use, processing, transmission, provision, disclosure and application of the relevant data all comply with the relevant laws, regulations and standards of the relevant countries and regions, necessary confidentiality measures have been taken, and they do not violate public order and good morals. Corresponding operation portals are provided for users to choose to authorize or refuse.

[0055] Provide users with corresponding operation entry points, allowing them to choose to agree to or reject the automated decision results; if the user chooses to reject, the process will proceed to the expert decision-making process.

[0056] To address the technical problem of accurately assessing the condition of oil-paper insulation in onboard transformers of electric locomotives or EMUs under switching overvoltage conditions, this invention provides a device and method for assessing the deterioration of oil-paper insulation in onboard transformers. This invention addresses the shortcomings of existing oil-paper insulation deterioration assessment techniques, which primarily rely on power frequency voltage or lightning impulse tests and are insufficient to effectively characterize the continuous and insidious damage caused by switching overvoltages to the performance of oil-paper insulation. Instead, it constructs an oil-paper insulation deterioration assessment device that can simulate the conditions of switching overvoltages. This device simultaneously collects the strength and loss characteristics of oil-paper insulation samples under different switching overvoltage amplitudes, thereby constructing a theoretical model of the switching overvoltage loss characteristics. Subsequently, a natural heuristic optimization algorithm is used to iteratively optimize the error coefficients in this model, obtaining the optimal loss response index that can realistically characterize the deterioration behavior of oil-paper insulation. Based on the optimization results, an insulation deterioration assessment factor in the form of a normalized ratio of strength characteristics and optimized loss characteristics is further constructed, achieving continuous quantitative determination of oil-paper insulation from early deterioration to the critical failure state. This invention significantly improves the accuracy of assessing the condition of oil-paper insulation in onboard transformers under actual operating conditions.

[0057] like Figure 1 As shown, the device for assessing the deterioration of the oil-paper insulation of an on-board transformer includes: a host computer 1, a switch 2, an overvoltage generation module 3, a test chamber 4, a high-frequency current sensor 7, a voltage divider 8, and a signal acquisition device 10.

[0058] The overvoltage generation module 3 is connected to the terminal on the top of the test chamber 4 via a high-voltage coaxial cable 91, and is used to output the overvoltage waveform to the needle electrode 5 inside the test chamber 4.

[0059] The bottom lead of test chamber 4 passes through high-frequency current sensor 7 and is then grounded. High-frequency current sensor 7 is used to monitor the loss characteristic N of the oil-paper insulation sample 6 inside test chamber 4. T .

[0060] The terminal at the top of the test chamber 4 is connected to the terminal at the top of the voltage divider 8 via a high-voltage coaxial cable 92. The bottom wire of the test chamber 4 is connected to the bottom terminal of the voltage divider 8. The voltage divider 8 is used to monitor the strength characteristics A at both ends of the oil-paper insulation sample 6.

[0061] The middle and bottom terminals of the voltage divider 8 are connected to the signal acquisition device 10, and the signal output terminal of the high-frequency current sensor 7 is connected to the signal acquisition device 10.

[0062] The host computer 1 is connected to the switch 2, and the switch 2 is connected to the overvoltage generation module 3 and the signal acquisition device 10 respectively.

[0063] The host computer 1 is used to determine the intensity characteristic A, the amplitude U of the overvoltage waveform, and the loss characteristic N. T The degradation assessment factor ζ of the oil-paper insulation was determined to assess the degradation of the oil-paper insulation of the vehicle-mounted transformer.

[0064] The vehicle-mounted transformer oil-paper insulation degradation assessment device provided in this invention integrates an overvoltage generation module, a test chamber, a high-frequency current sensor, a voltage divider, and a signal acquisition device. Combined with information processing and communication control via a host computer and switch, it enables real-time monitoring and quantitative assessment of the degradation state of the vehicle-mounted transformer oil-paper insulation under overvoltage conditions. This assessment device can simulate typical switching overvoltage impact scenarios in traction power supply systems. The overvoltage generation module outputs an impact waveform with actual transient characteristics, which is then applied to the oil-paper insulation sample within the test chamber, effectively simulating the electrical response process of the insulation material under high-voltage transient action. During the test, the voltage divider precisely divides the high-voltage signal applied across the oil-paper insulation sample, extracting the intensity characteristics characterizing the applied voltage stress. The high-frequency current sensor monitors the high-frequency current response during the discharge process in real time, extracting loss characteristics related to insulation loss, thus ensuring the comprehensiveness and accuracy of the test data. The signal acquisition device synchronously acquires the aforementioned voltage and current characteristic signals and uploads them to the host computer for processing and analysis. Based on the amplitude, intensity characteristics, and loss characteristics of operational overvoltage, the host computer constructs an assessment factor for the degradation of oil-paper insulation, enabling continuous quantitative assessment of oil-paper insulation from initial aging to the failure boundary. Compared to existing technologies that primarily rely on assessment methods based on power frequency or lightning strike environments, the assessment device of this invention can more realistically reflect the impact of operational overvoltage on insulation degradation, significantly improving the accuracy and applicability of oil-paper insulation assessment. This helps to identify the insulation failure risk of on-board transformers in advance, thereby enhancing the safety and reliability of the traction power supply system.

[0065] In one embodiment, such as Figure 1 As shown, the overvoltage generation module 3 includes: a power supply device 31, a switch 32, an adjustable impedance 33, a step-up transformer 34, a step-up transformer 35, and a discharge ball gap 36.

[0066] The power supply unit 31, switch 32, regulating impedance 33, step-up transformer 34, step-up transformer 35 and discharge ball gap 36 are connected in series. The power supply unit 31 is connected to the switch 2 and the discharge ball gap 36 is connected to the high-voltage coaxial cable 91.

[0067] Specifically, the input terminal of the power supply device 31 is connected to the switch 2, and the output terminal of the power supply device 31 is connected to the input terminal of the switch 32. The output terminal of the switch 32 is connected to the input terminal of the step-up transformer 34 via the adjustable impedance 33. The output terminal of the step-up transformer 34 is connected to the input terminal of the step-up transformer 35, and the output terminal of the step-up transformer 35 is connected to the input terminal of the discharge sphere gap 36. The output terminal of the discharge sphere gap 36 is connected to the terminal block at the top of the test chamber 4 via a high-voltage coaxial cable 91.

[0068] Furthermore, the power supply unit 31 provides initial electrical energy to the overvoltage generation module 3 and has adjustable output voltage. The power supply unit 31 can output different voltage levels according to the control commands of the host computer 1 to drive the subsequent step-up transformers 34 and 35 to boost the voltage, thereby providing the necessary voltage conditions for the breakdown discharge of the discharge ball gap 36.

[0069] When switch 32 receives a control command from host computer 1 and closes, power supply unit 31 begins to output current. This current first passes through regulating impedance 33, which is used to adjust the inrush current characteristics and limit the voltage rise rate. The current regulated by regulating impedance 33 is sequentially input to step-up transformers 34 and 35, and the voltage is gradually increased to the set voltage level through cascading step-up. The boosted voltage signal is applied to discharge gap 36. When the voltage across discharge gap 36 exceeds its breakdown voltage threshold, the air in the gap is broken down, thereby generating a one-time strong pulse discharge, forming an impulse waveform with operational overvoltage characteristics. This operational overvoltage waveform has typical characteristics such as step rise, steep fall, and narrow pulse width, which can simulate the transient overvoltage impulse behavior caused by switch operation in the traction power supply system.

[0070] In one embodiment, such as Figure 1 As shown, the oil-paper insulation degradation assessment device also includes a grounding device 41. The grounding terminals of both the step-up transformer 34 and the step-up transformer 35 are connected to the grounding device 41.

[0071] In one embodiment, such as Figure 1 As shown, the test chamber 4 includes: a needle electrode 5 and an oil paper insulating sample 6.

[0072] The needle electrode 5 is fixed at the center of the test chamber 4. The distance between the needle electrode 5 and the oil-paper insulation sample 6 can be set according to specific working conditions. For example, the needle electrode 5 is about 1 mm away from the top of the oil-paper insulation sample 6. The oil-paper insulation sample 6 is placed at the bottom of the test chamber 4.

[0073] In one embodiment, the overvoltage generation module 3 is specifically used to generate an overvoltage waveform with a preset amplitude, and transmit the overvoltage waveform to the needle electrode 5 inside the test chamber 4 via a high-voltage coaxial cable 91, so as to apply the overvoltage waveform to the oil-paper insulation sample 6.

[0074] Specifically, when the voltage across the discharge gap 36 exceeds its breakdown voltage threshold, the gap discharge generates an operational overvoltage impulse waveform, which is output to the test chamber 4 via the high-voltage coaxial cable 91. The needle electrode 5 is fixedly installed at the center of the top of the test chamber 4 and connected to the terminal of the test chamber 4. The tip of the needle electrode 5 faces the bottom of the test chamber 4, directly opposite the oil-paper insulation sample 6 placed at the bottom of the test chamber 4.

[0075] The overvoltage waveform is input to the test chamber 4 via a high-voltage coaxial cable 91 and applied to the needle electrode 5 inside the chamber. Due to the pointed structure of the needle electrode 5, a strong local electric field can be formed at its tip. When the applied voltage reaches a certain amplitude, electric field breakdown occurs within the tiny gap between the tip of the needle electrode 5 and the oil-paper insulation sample 6, thus forming a discharge channel. This achieves the instantaneous loading of the overvoltage waveform onto the oil-paper insulation sample 6. This loading process effectively simulates the transient overvoltage impact caused by the switching operation of the traction power supply system during actual transformer operation, helping to reproduce the electrical response behavior of oil-paper insulation under real operating conditions.

[0076] In one embodiment, such as Figure 1 As shown, the oil-paper insulation degradation assessment device also includes a grounding device 42, which is connected to the bottom of the test chamber 4.

[0077] In one embodiment, the signal acquisition device 10 is used to receive the intensity characteristic A output by the voltage divider 8 and the loss characteristic N output by the high-frequency current sensor 7, respectively. T And combine the intensity feature A and the loss feature N T The signal is transmitted to switch 2. Switch 2 is used to transfer the intensity feature A and loss feature N acquired by signal acquisition device 10. T Transmitted to host computer 1.

[0078] Specifically, the voltage divider 8 is connected in parallel across the test chamber 4 to collect the high-voltage response signal of the oil-paper insulation sample 6 when subjected to an operational overvoltage impact, and converts the high-voltage response signal into a low-voltage signal after voltage division, and transmits it to the signal acquisition device 10.

[0079] Since the amplitude range of the overvoltage waveform is typically from 10kV to 100kV, direct sampling poses a safety risk. Therefore, voltage divider 8 reduces the high-voltage response signal to a voltage range that the signal acquisition device 10 can safely read through voltage division processing. The signal acquisition device 10 processes the received low-voltage signal and transmits it to the switch 2 as the intensity characteristic A of the voltage stress on the oil-paper insulation.

[0080] The wire exiting the bottom of the test chamber 4 passes through the inside of the annular magnetic core of the high-frequency current sensor 7. The high-frequency current sensor 7 is used to monitor the high-frequency current signal flowing through the oil-paper insulating sample 6 during the discharge process in real time, and transmits the collected high-frequency current signal to the signal acquisition device 10.

[0081] This high-frequency current signal is closely related to the micro-discharge, local breakdown, and conduction state before and after breakdown within the oil-paper insulation, and can serve as an important basis for measuring the degree of degradation of the oil-paper insulation. After processing the high-frequency current signal, the signal acquisition device 10 uses it as a loss feature N representing the insulation loss characteristics. T Transmitted to switch 2.

[0082] In one embodiment, the host computer 1 is specifically used to: determine the theoretically calculated value of the loss characteristic evaluation factor of the oil-paper insulation sample 6 based on the intensity characteristic A, the amplitude U of the switching overvoltage waveform, and the pre-established theoretical model of the switching overvoltage loss characteristics; and based on the loss characteristic N... T The theoretically calculated values ​​of the loss feature evaluation factors are optimized to obtain the optimized loss feature N. ′ Based on the intensity feature A and the optimized loss feature N ′ Determine the degradation assessment factor ζ for oil-paper insulation; conduct an assessment based on the degradation assessment factor ζ and the preset range to obtain the assessment results.

[0083] In this embodiment of the invention, by constructing an oil-paper insulation degradation assessment device comprising an overvoltage generation module, a test chamber, a voltage divider, a high-frequency current sensor, a signal acquisition device, and a host computer, an impact waveform can be accurately applied under typical switching overvoltage conditions in a traction power supply system. Simultaneously, the voltage and current response characteristics of the oil-paper insulation sample during the electrical impact process can be acquired, enabling precise assessment of its insulation state. This assessment device achieves breakdown discharge through a discharge sphere gap, generating an overvoltage waveform with transient characteristics such as a step rise, steep fall, and narrow pulse width. The overvoltage waveform is applied to the oil-paper insulation sample via a needle electrode, creating a localized electric field concentration at the electrode tip, thereby inducing electrical breakdown and causing the oil-paper insulation sample to exhibit electrical response behavior under near-realistic operating conditions. The voltage signal generated during the electrical response process is transformed by the voltage divider and output to the signal acquisition device for extracting intensity characteristics. Simultaneously, the high-frequency current signal is acquired in real-time by a series-connected high-frequency current sensor for extracting loss characteristics. The aforementioned characteristic signals are collected by the signal acquisition device and uploaded to the host computer for processing. Combined with the preset theoretical model of operating overvoltage loss characteristics and the introduction of a parameter optimization mechanism, loss characteristic values ​​that are highly fitted to the actual response are obtained. Finally, an oil-paper insulation deterioration assessment factor based on strength characteristics and loss characteristics is constructed, realizing the quantitative determination of the aging level of oil-paper insulation.

[0084] This invention also provides a method for assessing the deterioration of the oil-paper insulation of a vehicle-mounted transformer, which is applied to the aforementioned assessment device for the deterioration of the oil-paper insulation of the vehicle-mounted transformer, as described in the following embodiments.

[0085] like Figure 2 As shown, the method for assessing the deterioration of paper insulation includes steps 201 to 206.

[0086] Step 201: Control the operation overvoltage generation module 3 to output the operation overvoltage waveform to the needle electrode 5.

[0087] Step 202: Monitor the strength characteristic A at both ends of the oil-paper insulation sample 6 using voltage divider 8, and monitor the loss characteristic N of the oil-paper insulation sample 6 using high-frequency current sensor 7. T .

[0088] Step 203: Determine the theoretically calculated value N of the loss characteristic evaluation factor for oil-paper insulation sample 6 based on the intensity characteristic A, the amplitude U of the switching overvoltage waveform, and the pre-established theoretical model of switching overvoltage loss characteristics. J .

[0089] Step 204: Based on loss feature N T The theoretically calculated values ​​of the loss feature evaluation factors are optimized to obtain the optimized loss feature N. ′ .

[0090] Step 205: Based on the intensity feature A and the optimized loss feature N ′ Determine the assessment factor ζ for the deterioration of oil-paper insulation.

[0091] Step 206: Evaluate according to the oil-paper insulation deterioration assessment factor ζ and the preset range to obtain the evaluation results.

[0092] In this embodiment of the invention, a complete and targeted method for assessing the degradation of oil-paper insulation is constructed by combining key steps such as operational overvoltage impact loading, characteristic signal acquisition, theoretical model calculation, and parameter optimization. This method controls the operational overvoltage generation module to output an impact waveform with typical transient characteristics, which is then applied to the needle electrodes within the test chamber. This places the oil-paper insulation sample in an electrical stress environment simulating the operational overvoltage conditions of an actual traction power supply system, significantly enhancing the engineering adaptability and realism of the assessment process. During the impact loading process, the host computer control signal acquisition device acquires the low-voltage signal processed by the voltage divider and the high-frequency current signal monitored by the high-frequency current sensor, respectively. It extracts the strength characteristics reflecting the pressure-bearing capacity of the oil-paper insulation and the loss characteristics characterizing its loss behavior, thereby achieving comprehensive acquisition and characterization of the electrical response characteristics of the oil-paper insulation. Subsequently, by combining the acquired strength characteristics, operational overvoltage amplitude, and a preset loss characteristic theoretical model, the theoretical loss characteristic value is calculated. Using the actually measured loss characteristics as the optimization benchmark, a natural heuristic algorithm is used to optimize the model parameters, obtaining optimized loss characteristic values ​​that better conform to the actual insulation response law. Based on the optimized loss characteristics, a degradation assessment factor for oil-paper insulation is further constructed and combined with a preset risk level range to achieve the classification and risk identification of the aging state of oil-paper insulation. This invention improves the quantitative accuracy and dynamic identification capability of insulation assessment results. Compared with traditional static judgment methods based on power frequency or lightning impact conditions, it has higher assessment accuracy, operational condition adaptability, and early warning foresight.

[0093] like Figure 2 As shown below, each step will be explained in detail, with the host computer 1 being the execution entity.

[0094] Step 201: Control the operation overvoltage generation module 3 to output the operation overvoltage waveform to the needle electrode 5.

[0095] Specifically, when switch 32 is closed, the host computer 1 sends a control command to the overvoltage generation module 3, controlling the overvoltage generation module 3 to generate and output an overvoltage waveform according to the set voltage amplitude. Upon receiving the control command, the overvoltage generation module 3 initiates the voltage output process, progressively increasing the voltage through a step-up transformer, and then discharging through the air gap after the discharge ball gap 36 reaches the breakdown condition, thereby generating an overvoltage impulse waveform with transient characteristics. The overvoltage waveform is transmitted to the needle electrode 5 at the top of the test chamber 4 via a high-voltage coaxial cable 91. The amplitude U of the overvoltage waveform can be set in stages according to test requirements, with an initial setting of 10kV, increasing in 5kV increments, up to a maximum of 100kV. By progressively increasing the overvoltage amplitude U, the response characteristics of the oil-paper insulation sample 6 under different voltage levels can be analyzed.

[0096] Step 202: Monitor the strength characteristic A at both ends of the oil-paper insulation sample 6 using voltage divider 8, and monitor the loss characteristic N of the oil-paper insulation sample 6 using high-frequency current sensor 7. T .

[0097] Specifically, the signal acquisition device 10 receives the low-voltage signal output from the voltage divider 8 and the high-frequency current signal output from the high-frequency current sensor 7, respectively. It processes the received low-voltage signal to extract the strength feature A reflecting the compressive state of the oil-paper insulation, and processes the received high-frequency current signal to extract the loss feature N characterizing the insulation loss behavior. T The host computer 1 receives the intensity feature A and loss feature N extracted by the signal acquisition device 10 through the switch 2. T .

[0098] Step 203: Determine the theoretically calculated value N of the loss characteristic evaluation factor for oil-paper insulation sample 6 based on the intensity characteristic A, the amplitude U of the switching overvoltage waveform, and the pre-established theoretical model of switching overvoltage loss characteristics. J Among them, the theoretical model of the switching overvoltage loss characteristics is the theoretical calculation formula of the switching overvoltage loss characteristics, namely formula (1).

[0099] Specifically, the theoretically calculated value N of the loss characteristic evaluation factor for oil-paper insulation sample 6 is calculated according to formula (1). J .

[0100]

[0101] Where, N J δ is the theoretically calculated value of the loss characteristic evaluation factor for oil-paper insulation sample 6, U is the amplitude of the switching overvoltage waveform in kV, δ is the error coefficient, τ is the integral variable, and e is the natural constant.

[0102] Step 204: Based on loss feature NT The theoretically calculated values ​​of the loss feature evaluation factors are optimized to obtain the optimized loss feature N. ′ .

[0103] In one embodiment, such as Figure 3 As shown, step 204 includes steps 301 and 302.

[0104] Step 301: Based on the preset initial error coefficient δ and loss feature N T Theoretical calculated value N of loss characteristic evaluation factor J The theoretical model of operating overvoltage loss characteristics is recursively optimized to obtain the optimized error coefficient δ0.

[0105] Specifically, the theoretical calculation formula for the loss characteristics of switching overvoltage is recursively optimized to obtain the theoretically calculated value N of the loss characteristic evaluation factor for oil-paper insulation sample 6. J And the measured loss characteristics N T The error coefficient with the smallest error. During parameter optimization, the initial error coefficient δ is used as the variable to be optimized, based on the measured loss characteristics N. T Theoretical calculated value N of loss characteristic evaluation factor J A fitness function is constructed, and iterative calculation is performed using a natural heuristic optimization algorithm. By continuously updating the error coefficients, the theoretically calculated value N of the loss feature evaluation factor is minimized. J The measured loss characteristic N T The error between them was calculated. Finally, the optimized error coefficient δ0 was obtained, which can more accurately characterize the loss response behavior of the oil-paper insulation sample 6 under a specific operating overvoltage amplitude U.

[0106] In one embodiment, such as Figure 4 As shown, step 301 includes steps 401 to 406.

[0107] Step 401: Construct a fitness function based on the initial error coefficient δ, and obtain the first fitness function value f(δ) corresponding to the initial error coefficient δ. Here, the initial error coefficient δ is an initial assumed value of the error coefficient.

[0108]

[0109] Where f(δ) is the fitness function value, N ji N represents the theoretically calculated value of the loss characteristic evaluation factor for the i-th waveform amplitude. Ti is the measured value of the loss characteristic under the i-th waveform amplitude, and n is the corresponding test group number.

[0110] N JiIt is calculated by substituting the initial error coefficient δ into formula (1).

[0111] Step 402: Determine the candidate error coefficients δ′ using a natural heuristic search method.

[0112] For example, natural heuristic search methods include: Simulated Annealing (SA), Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Ant Colony Optimization (ACO), etc., and this invention is not limited thereto.

[0113] If the simulated annealing algorithm is used to determine the candidate error coefficient δ′, first set and initialize various parameters, namely, initialize the initial error coefficient δ (e.g., set to 0.001, 0.01 or other empirical values), the initial temperature T0 (e.g., T0 = 100), the temperature decay coefficient α (e.g., α = 0.95), the termination temperature T, and the maximum number of iterations, etc.

[0114] The candidate error coefficient δ′ for the current iteration is calculated using formula (3).

[0115] δ ′ =δ+ε (3)

[0116] Where, δ ′ δ is the candidate error coefficient, ε is the initial error coefficient, and ε is the disturbance range, which is usually taken as 0.01.

[0117] Step 403: Based on the candidate error coefficients δ′ and the fitness function, obtain the second fitness function value f(δ′) corresponding to the candidate error coefficients δ′. ′ ).

[0118] Specifically, the candidate error coefficient δ′ of the current iteration is substituted into formulas (1) and (2) to calculate the fitness function value f(δ′) corresponding to the candidate error coefficient δ′. ′ ).

[0119] Step 404: If the first fitness function value f(δ) is less than or equal to the second fitness function value f(δ) ′ The initial error coefficient δ is used as the optimized error coefficient δ0.

[0120] Step 405: If the first fitness function value f(δ) is greater than the second fitness function value, the candidate error coefficient δ′ is used as the optimized error coefficient δ0.

[0121] Step 406: Iterate through the above steps until the preset termination condition is met, and obtain the optimized error coefficient δ0.

[0122] For example, if the simulated annealing algorithm is used, the temperature parameter is updated by the temperature decay coefficient α after each iteration. When the initial temperature T0 drops to the termination temperature T or the current iteration round has reached the maximum number of iterations, the optimized error coefficient δ0 is output.

[0123] Step 302: Determine the optimized loss feature N based on the optimized error coefficient δ0. ′ .

[0124] Specifically, the optimized error coefficient δ0 is substituted into formula (1) to calculate the optimized loss feature N. ′ As shown in formula (3).

[0125]

[0126] Where, N ′ The optimized loss characteristics are defined by U, where U is the amplitude of the switching overvoltage waveform in kV, δ0 is the optimized error coefficient, τ is the integral variable, and e is the natural constant.

[0127] Step 205: Based on the intensity feature A and the optimized loss feature N ′ Determine the assessment factor ζ for the deterioration of oil-paper insulation.

[0128] Specifically, the oil-paper insulation degradation assessment factor ζ of the vehicle-mounted transformer is calculated according to formula (4).

[0129]

[0130] Where ζ is the assessment factor for the deterioration of oil-paper insulation, A is the strength characteristic, and N is the strength characteristic. ′ This represents the optimized loss feature.

[0131] Step 206: Evaluate according to the oil-paper insulation deterioration assessment factor ζ and the preset range to obtain the evaluation results.

[0132] Specifically, when the oil-paper insulation degradation assessment factor ζ∈[-∞,0), it indicates that the oil-paper insulation is in the early stage of degradation, and there has been no significant performance degradation. Monitoring personnel can maintain routine inspections without special attention. When the oil-paper insulation degradation assessment factor ζ∈[0,1), it indicates that the oil-paper insulation has entered the middle and late stages of degradation, and the insulation performance has decreased to a certain extent. Monitoring personnel should increase the monitoring frequency and focus on the changing trend of the oil-paper insulation. When the oil-paper insulation degradation assessment factor ζ∈[1,5), it indicates that the oil-paper insulation is in a severely degraded stage, close to the failure threshold. It is recommended that monitoring personnel take timely maintenance or replacement measures to avoid the risk of insulation failure to the operation of the transformer system.

[0133] In this embodiment of the invention, a complete testing process and model optimization mechanism are constructed to achieve quantitative assessment and dynamic analysis of the oil-paper insulation status of on-board transformers. This oil-paper insulation degradation assessment method is tested under simulated operating overvoltage conditions caused by switching operations in an actual traction power supply system. A graded impulse voltage is applied to the oil-paper insulation sample, while simultaneously acquiring low-voltage signals from a voltage divider and current signals from a high-frequency current sensor. Strength features for assessing insulation pressure-bearing capacity and loss features reflecting insulation loss behavior are extracted, respectively. Based on this, the extracted loss features are combined with a preset loss feature theoretical model to construct a fitness function. A natural heuristic optimization algorithm is used to recursively adjust the error coefficients to minimize the error between theoretical and measured values, ultimately obtaining optimized loss features that better conform to actual response patterns. Furthermore, the optimized loss features are fused with the strength features to calculate the insulation degradation assessment factor, and the oil-paper insulation status is graded according to a preset level division interval. This method not only significantly improves the accuracy and reliability of oil-paper insulation performance assessment but also enables dynamic identification and risk warning at different degradation stages.

[0134] This invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described method for assessing the deterioration of the oil-paper insulation of vehicle-mounted transformers.

[0135] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0136] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0137] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0138] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0139] In the description of this specification, the references to terms such as "an embodiment," "a specific embodiment," "some embodiments," "for example," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0140] 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 descriptions are merely specific embodiments 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 within the scope of protection of the present invention.

Claims

1. A device for assessing the deterioration of oil-paper insulation in vehicle-mounted transformers, characterized in that, include: The host computer (1), the switch (2), the operation overvoltage generation module (3), the test chamber (4), the high-frequency current sensor (7), the voltage divider (8) and the signal acquisition device (10); The host computer (1) is connected to the switch (2), and the switch (2) is connected to the operation overvoltage generation module (3) and the signal acquisition device (10) respectively. The operation overvoltage generating module (3) is connected to the terminal on the top of the test chamber (4) via the first high-voltage coaxial cable (91) and is used to output the operation overvoltage waveform to the needle electrode (5) inside the test chamber (4); The bottom wire of the test cavity (4) passes through the high-frequency current sensor (7) and is grounded; the high-frequency current sensor (7) is used to monitor the loss characteristics of the oil-paper insulation sample (6) inside the test cavity (4); The terminal at the top of the test chamber (4) is connected to the terminal at the top of the voltage divider (8) via a second high-voltage coaxial cable (92). The bottom wire of the test chamber (4) is connected to the bottom terminal of the voltage divider (8). The voltage divider (8) is used to monitor the strength characteristics at both ends of the oil-paper insulation sample (6). The middle and bottom terminals of the voltage divider (8) are connected to the signal acquisition device (10), and the signal output terminal of the high-frequency current sensor (7) is connected to the signal acquisition device (10). The host computer (1) is used to determine the oil-paper insulation degradation assessment factor based on the strength characteristics, the amplitude U of the operating overvoltage waveform and the loss characteristics, so as to conduct an assessment of the oil-paper insulation degradation of the vehicle-mounted transformer.

2. The apparatus according to claim 1, characterized in that, The host computer (1) is specifically used for: The theoretically calculated value of the loss characteristic evaluation factor of the oil-paper insulation sample (6) is determined based on the intensity characteristics, the amplitude of the switching overvoltage waveform, and the pre-established theoretical model of switching overvoltage loss characteristics. Based on the loss characteristics, the theoretically calculated values ​​of the loss characteristic evaluation factors are optimized to obtain the optimized loss characteristics. The degradation assessment factors for oil-paper insulation are determined based on the strength characteristics and the optimized loss characteristics. The evaluation results are obtained by evaluating the deterioration assessment factors and preset ranges of the paper insulation.

3. The apparatus according to claim 1, characterized in that, The overvoltage generation module (3) includes: a power supply (31), a switch (32), an adjustable impedance (33), a first step-up transformer (34), a second step-up transformer (35), and a discharge ball gap (36); The power supply device (31), the switch (32), the adjustable impedance (33), the first step-up transformer (34), the second step-up transformer (35), and the discharge ball gap (36) are connected in series. The power supply device (31) is connected to the switch (2), and the discharge ball gap (36) is connected to the first high-voltage coaxial cable (91).

4. The apparatus according to claim 1, characterized in that, The needle electrode (5) is fixed at the center of the test cavity (4), and the oil paper insulation sample (6) is placed at the bottom of the test cavity (4).

5. The apparatus according to claim 3, characterized in that, The device further includes: a first grounding device (41); the first step-up transformer (34) and the second step-up transformer (35) are both connected to the first grounding device (41).

6. The apparatus according to claim 1, characterized in that, The device further includes: a second grounding device (42); the bottom wire of the test cavity (4) is connected to the second grounding device (42).

7. The apparatus according to claim 3, characterized in that, The overvoltage generation module (3) is specifically used to generate an overvoltage waveform with a preset amplitude, and transmit the overvoltage waveform to the needle electrode (5) inside the test cavity (4) through the first high-voltage coaxial cable (91) to apply the overvoltage waveform to the oil paper insulation sample (6).

8. The apparatus according to claim 7, characterized in that, The signal acquisition device (10) is used to receive the intensity characteristics output by the voltage divider (8) and the loss characteristics output by the high-frequency current sensor (7), and transmit the intensity characteristics and the loss characteristics to the switch (2). The switch (2) is used to transmit the intensity characteristics and the loss characteristics acquired by the signal acquisition device (10) to the host computer (1).

9. A method for assessing the deterioration of oil-paper insulation in a vehicle-mounted transformer, applied to the apparatus described in claim 1, characterized in that, include: The control operation overvoltage generation module (3) outputs the operation overvoltage waveform to the needle electrode (5); The strength characteristics at both ends of the oil-paper insulation sample (6) are monitored by the voltage divider (8), and the loss characteristics of the oil-paper insulation sample (6) are monitored by the high-frequency current sensor (7). The theoretically calculated value of the loss characteristic evaluation factor of the oil-paper insulation sample (6) is determined based on the intensity characteristics, the amplitude of the switching overvoltage waveform, and the pre-established theoretical model of switching overvoltage loss characteristics. Based on the loss characteristics, the theoretically calculated values ​​of the loss characteristic evaluation factors are optimized to obtain the optimized loss characteristics. The degradation assessment factors for oil-paper insulation are determined based on the strength characteristics and the optimized loss characteristics. The evaluation results are obtained by evaluating the deterioration assessment factors and preset ranges of the paper insulation.

10. The method according to claim 9, characterized in that, The optimized loss features are obtained by performing parameter optimization on the theoretically calculated values ​​of the loss feature evaluation factors based on the loss features, including: Based on the preset initial error coefficients, the loss characteristics, and the theoretically calculated values ​​of the loss characteristic evaluation factors, the theoretical model of the operating overvoltage loss characteristics is recursively optimized to obtain the optimized error coefficients. The optimized loss characteristics are determined based on the optimized error coefficients.

11. The method according to claim 10, characterized in that, The theoretical model of switching overvoltage loss characteristics is recursively optimized based on the preset initial error coefficients, the loss characteristics, and the theoretically calculated values ​​of the loss characteristic evaluation factors to obtain the optimized error coefficients, including: A fitness function is constructed based on the initial error coefficients, and the first fitness function value corresponding to the initial error coefficients is obtained; Candidate error coefficients were determined using a natural heuristic search method. Based on the candidate error coefficients and the fitness function, the second fitness function value corresponding to the candidate error coefficients is obtained; If the first fitness function value is less than or equal to the second fitness function value, the initial error coefficient is used as the optimized error coefficient; If the first fitness function value is greater than the second fitness function value, the candidate error coefficient is used as the optimized error coefficient; The above steps are executed iteratively until the preset termination condition is met, and the optimized error coefficient is obtained.

12. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the method of any one of claims 9 to 11.

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