A method for evaluating insulation aging status of dry-type transformers

Abstract

The present invention discloses a method for assessing the insulation aging status of a dry-type transformer, comprising the following steps: establishing a dry-type transformer aging status assessment device capable of timely measuring and recording the surface temperature rise of the dry-type transformer's low-voltage winding insulation material, thereby calculating the average temperature rise of the dry-type transformer insulation material; then establishing a relationship between the average temperature rise of the dry-type transformer insulation material and operating time, ultimately obtaining a thermal aging index of the dry-type transformer insulation material, thereby assessing the aging status of the dry-type transformer insulation material. The present invention utilizes the dry-type transformer insulation aging status assessment method to help transformer maintenance personnel understand the dry-type transformer insulation aging status, thereby formulating a reasonable transformer maintenance plan, reducing the manpower and material resources required for transformer maintenance, improving economic efficiency, and ensuring the safe and stable operation of dry-type on-board traction transformers.

Description

Technical Field

[0001] The invention relates to a method for evaluating the insulation aging state of a dry-type transformer, and belongs to the field of online monitoring and fault diagnosis of electrical insulation. Technical Background

[0002] Compared to oil-immersed transformers, dry-type transformers eliminate the insulating oil, effectively preventing transformer fires and other accidents. Common dry-type transformers are insulated using epoxy resin. During operation, heat generated by the windings is transferred to the external environment through the epoxy resin. The epoxy resin's thermal conductivity and insulation properties are crucial for the proper functioning of dry-type transformers. During operation, the epoxy resin is exposed to high temperatures for extended periods, which accelerates its aging. Epoxy resin aging deteriorates, potentially leading to short circuits or burnouts during operation. Therefore, accurate and timely assessment of dry-type transformer insulation aging is crucial. Accurate assessment of dry-type transformer insulation aging helps transformer maintenance personnel understand the aging status of dry-type transformers and develop appropriate maintenance plans, reducing maintenance costs and improving efficiency while ensuring the safe and stable operation of dry-type on-board traction transformers. Summary of the Invention

[0003] In view of the above technical problems, the purpose of the present invention is to propose a method for evaluating the insulation aging status of a dry-type transformer, which can realize a rapid and accurate evaluation of the insulation aging status of a dry-type on-board traction transformer.

[0004] The technical solutions for implementing the present invention are as follows:

[0005] The first step is to arrange the aging status assessment device for the dry-type transformer to be evaluated.

[0006] The aging state evaluation device comprises a temperature sensor A (1), a temperature sensor B (2), a temperature sensor C (3), an air thermometer (4), and a computing terminal (5), wherein the temperature sensor A (1) is arranged on the epoxy resin surface at the outlet of the air duct of the intermediate phase low-voltage winding of the dry-type transformer, the temperature sensor B (2) is arranged on the middle epoxy resin surface of the air duct of the intermediate phase low-voltage winding of the dry-type transformer, and the temperature sensor C (3) is arranged on the epoxy resin surface at the inlet of the air duct of the intermediate phase low-voltage winding of the dry-type transformer;

[0007] The second step is to record the measured values of the arranged temperature sensors

[0008] During the operation of the dry-type transformer, the temperatures of temperature sensor A (1), temperature sensor B (2), temperature sensor C (3), and air thermometer (4) are recorded every time Δt, and a total of n temperature points are recorded. The corresponding time points are recorded as t i , the value of temperature sensor A(1) is recorded as T Ai The value of temperature sensor B(2) is recorded as T Bi , the value of temperature sensor C(3) is recorded as T Ci , the value of the air thermometer (4) is recorded as T i , where i = 1, 2, 3, ..., n;

[0009] The third step is to calculate the average temperature rise of the insulation material of the dry-type transformer

[0010]

[0011] Where λ is the thermal conductivity of the insulation material of the dry-type transformer;

[0012] The fourth step is to calculate the average temperature rise T of the insulation material of the dry-type transformer i and running time t to establish a polynomial

[0013]

[0014] Step 5: Calculate the relationship between the average temperature rise of the insulation material of the dry-type transformer and the operating time

[0015]

[0016] in, Indicates the average temperature rise of the insulating material corresponding to a certain moment t;

[0017] Step 6: Calculate the thermal aging index δ of the insulation material of the dry-type transformer

[0018]

[0019] Among them, T max It is the maximum allowable temperature rise of the insulation material of dry-type transformer;

[0020] Step 7: Evaluate the aging status of the dry-type transformer insulation material

[0021] If the thermal aging index of the dry-type transformer insulation material δ is ≥0.98, it means that the dry-type transformer insulation material is already in an aging state; if δ is <0.98, it means that the dry-type transformer insulation material has not yet aged.

[0022] The beneficial effects of the present invention are that a method for evaluating the insulation aging status of a dry-type transformer has the following advantages:

[0023] The present invention establishes a dry-type transformer aging status assessment device that can timely measure and record the surface temperature rise of the dry-type transformer's low-voltage winding insulation material, thereby calculating the average temperature rise of the dry-type transformer insulation material. The relationship between the average temperature rise of the dry-type transformer insulation material and operating time can then be established to ultimately obtain the dry-type transformer insulation material thermal aging index, thereby enabling dry-type transformer insulation material aging status assessment. The present invention utilizes this dry-type transformer insulation aging status assessment method to help transformer maintenance personnel understand the dry-type transformer insulation aging status, thereby formulating a reasonable transformer maintenance plan, reducing the manpower and material resources required for transformer maintenance, improving economic efficiency, and ensuring the safe and stable operation of dry-type on-board traction transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It shows a schematic diagram of a dry-type transformer aging status assessment device according to the present invention;

[0025] Figure 2 Shown is a flow chart of the method of the present invention. DETAILED DESCRIPTION

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

[0027] The first step is to arrange the aging status assessment device for the dry-type transformer to be evaluated.

[0028] The aging state evaluation device comprises a temperature sensor A (1), a temperature sensor B (2), a temperature sensor C (3), an air thermometer (4), and a computing terminal (5), wherein the temperature sensor A (1) is arranged on the epoxy resin surface at the outlet of the air duct of the intermediate phase low-voltage winding of the dry-type transformer, the temperature sensor B (2) is arranged on the middle epoxy resin surface of the air duct of the intermediate phase low-voltage winding of the dry-type transformer, and the temperature sensor C (3) is arranged on the epoxy resin surface at the inlet of the air duct of the intermediate phase low-voltage winding of the dry-type transformer;

[0029] The second step is to record the measured values of the arranged temperature sensors

[0030] During the operation of the dry-type transformer, the temperatures of temperature sensor A (1), temperature sensor B (2), temperature sensor C (3), and air thermometer (4) are recorded every 1 hour. A total of 10944 temperature points are recorded, and the corresponding time points are recorded as t i , the value of temperature sensor A(1) is recorded as T Ai The value of temperature sensor B(2) is recorded as T Bi , the value of temperature sensor C(3) is recorded as T Ci, the value of the air thermometer (4) is recorded as T i , where i = 1, 2, 3, ..., 10944;

[0031] The third step is to calculate the average temperature rise of the insulation material of the dry-type transformer

[0032]

[0033] The fourth step is to calculate the average temperature rise of the insulation material of the dry-type transformer and running time t to establish a polynomial

[0034]

[0035] Step 5: Calculate the relationship between the average temperature rise of the insulation material of the dry-type transformer and the operating time

[0036]

[0037] in, Indicates the average temperature rise of the insulating material corresponding to a certain moment t;

[0038] Step 6: Calculate the thermal aging index δ of the insulation material of the dry-type transformer

[0039]

[0040] Step 7: Evaluate the aging status of the dry-type transformer insulation material

[0041] The thermal aging index of the insulation material of the dry-type transformer is δ=0.9865, which means that the insulation material of the dry-type transformer is already in an aging state and the dry-type transformer should be replaced.

Claims

1. A method for evaluating the insulation aging status of a dry-type transformer, characterized in that: The following steps are involved: The first step is to arrange the aging status assessment device for the dry-type transformer to be evaluated. The aging state evaluation device comprises a temperature sensor A (1), a temperature sensor B (2), a temperature sensor C (3), an air thermometer (4), and a computing terminal (5), wherein the temperature sensor A (1) is arranged on the epoxy resin surface at the outlet of the air duct of the intermediate phase low-voltage winding of the dry-type transformer, the temperature sensor B (2) is arranged on the middle epoxy resin surface of the air duct of the intermediate phase low-voltage winding of the dry-type transformer, and the temperature sensor C (3) is arranged on the epoxy resin surface at the inlet of the air duct of the intermediate phase low-voltage winding of the dry-type transformer; The second step is to record the measured values of the arranged temperature sensors During the operation of the dry-type transformer, the temperatures of temperature sensor A (1), temperature sensor B (2), temperature sensor C (3), and air thermometer (4) are recorded every time Δt, and a total of n temperature points are recorded. The corresponding time points are recorded as t i , the value of temperature sensor A(1) is recorded as T Ai The value of temperature sensor B(2) is recorded as T Bi , the value of temperature sensor C(3) is recorded as T Ci , the value of the air thermometer (4) is recorded as T i , where i = 1, 2, 3, ..., n; The third step is to calculate the average temperature rise of the insulation material of the dry-type transformer Where λ is the thermal conductivity of the insulation material of the dry-type transformer; The fourth step is to calculate the average temperature rise of the insulation material of the dry-type transformer and running time t to establish a polynomial Step 5: Calculate the relationship between the average temperature rise of the insulation material of the dry-type transformer and the operating time in, Indicates the average temperature rise of the insulating material corresponding to a certain moment t; Step 6: Calculate the thermal aging index δ of the insulation material of the dry-type transformer Among them, T max It is the maximum allowable temperature rise of the insulation material of dry-type transformer; Step 7: Evaluate the aging status of the dry-type transformer insulation material If the thermal aging index of the dry-type transformer insulation material δ is ≥0.98, it means that the dry-type transformer insulation material is already in an aging state; if δ is <0.98, it means that the dry-type transformer insulation material has not yet aged.

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