An Evaluation Method for the Anti-Flashover Performance of Insulating Materials for Dry-Type Distribution Transformers

Abstract

The present invention discloses an evaluation method for the anti-fouling flashover performance of insulating materials used in dry-type distribution transformers. This method obtains multiple fouling flashover factors of the materials under the treatment of configured contaminated liquid by building a test platform and making test material samples, obtains the comprehensive factors of the fouling flashover temperature rise and leakage current of the materials, determines the anti-fouling flashover performance evaluation coefficient of the materials, and finally evaluates the anti-fouling flashover performance of the materials. By using this evaluation method, the present invention can quickly judge the anti-fouling flashover performance of insulating materials used in dry-type distribution transformers, provides a basis for the evaluation and selection of insulating materials, and improves the safety and economy of dry-type distribution transformers.

Description

Technical Field

[0001] The present invention belongs to the field of online monitoring and fault diagnosis of electrical insulation, and more specifically, relates to a method for evaluating the anti-pollution flashover performance of insulating materials for dry-type distribution transformers. Technical Background

[0002] At present, the number of distribution transformers in operation in China has reached tens of millions, and dry-type distribution transformers occupy a significant share among them. The reliable operation of dry-type distribution transformers meets the electricity demand of users and ensures the normal operation of the power grid. However, with the continuous improvement of power levels and the increasing complexity and severity of environmental conditions, higher requirements are also put forward for dry-type distribution transformers. Especially in some areas with severe haze and humid environment, the insulation level of its insulation structure is greatly reduced, and wet flashover and pollution flashover are prone to occur, and even large leakage current is generated under the working voltage, which destroys the insulation and causes structural damage. The occurrence of various accidents may cause the transformer to be broken down and burned, destroying the stable and safe operation of the power grid and causing economic losses. Therefore, it is necessary to evaluate the anti-pollution flashover performance of the insulation material of the dry-type distribution transformer to see whether its insulation can meet the requirements. Therefore, there is an urgent need for an evaluation method for the anti-pollution flashover performance of the insulation material for dry-type distribution transformers, to evaluate its anti-pollution flashover performance, and then to provide guidance on the production and selection of insulation materials for dry-type distribution transformers under some specific environments. 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 anti-pollution flashover performance of insulating materials for dry-type distribution transformers, which can be used to perform good evaluation and then select suitable insulating materials.

[0004] The technical solution for implementing the present invention is as follows:

[0005] Step 1: Build the test platform and make test material samples

[0006] A test platform is constructed, characterized in that it comprises a controllable power supply (1), a first electrode (2), a second electrode (3), a heating plate (4), an insulating support frame (5), a dirty liquid tank (6), a pipeline (7), a peristaltic pump (8), a dropper (9), dirty liquid drops (10), an infrared imager (11), a sample (12), a leakage current measuring device (13), and a computer terminal (14); the first electrode (2), the second electrode (3), and the heating plate (4) are controlled by the controllable power supply (1); the dirty liquid in the dirty liquid tank (6) is controlled by the peristaltic pump (8) to pass through the pipeline (7) and the dropper (9) to form dirty liquid drops (10); the sample (12) is placed on the insulating support frame (5); the infrared imager (11) and the leakage current measuring device (13) both monitor the real-time status of the sample and send the measured data to the computer terminal (14); a plurality of test material samples of the same specifications and sizes are prepared;

[0007] Step 2: Record the normal operation data of the dry-type distribution transformer and configure the contaminated liquid

[0008] Obtain the average temperature suffered by the insulating material used in the dry-type distribution transformer during operation according to the operation record of the dry-type distribution transformer, denoted as T, with the unit of K; at the same time, record the average conductivity value of the contaminated liquid suffered by the insulating material used in the dry-type distribution transformer, denoted as K, with the unit of S / m; configure the contaminated liquid with the same conductivity as the recorded data and load it into the contaminated liquid tank for preparation; the distance between the dropper nozzle and the sample is 5 mm, and adjust the peristaltic pump so that it can drip the contaminated liquid droplets on the sample at a flow rate of 0.5 mL / min;

[0009] Step 3: Obtain the multiple pollution flashover factors of the material

[0010] Take four samples and respectively conduct the contaminated liquid dripping treatment for 1 h, 2 h, 3 h, and 4 h. After the contaminated liquid dripping treatment of each sample is completed, start the heating plate until the sample temperature rises to T, with the floating error not exceeding 1 K; control the electrode to boost the voltage at a speed of 0.2 kV / s per second until the sample undergoes pollution flashover. After the pollution flashover occurs, zero the electrode voltage and then boost the voltage again at the same rate until the sample undergoes pollution flashover again. Repeat this process ten times; record the voltage value at the time of each pollution flashover, denoted as V n,m , with the unit of kV, where n = 1, 2, 3, 4 represents the time of the contaminated liquid dripping treatment of the sample, and m = 1, 2, 3 ··· 10 represents the number of times of flashover of the sample at this time; obtain the multiple pollution flashover factor S through formula (1) z ;

[0011]

[0012] Step 4: Obtain the comprehensive factor of pollution flashover temperature rise and leakage current of the material

[0013] After the tenth sample flashover is completed, turn off the power supply and stop pressurizing the electrode; through the record of the computer terminal, view the real-time state of the material during the whole test process, and record the overall temperature imaging of the sample one second before each flashover, where the maximum temperature is denoted as T n,m , the minimum temperature is denoted as T n,m ’, both with the unit of K. The area ratio of the temperature region exceeding T + 40 K in the overall temperature of the sample to the overall region is denoted as P n,m , and at the same time record the leakage current generated by the sample one second before each flashover, denoted as I n,m , with the unit of A, where n = 1, 2, 3, 4 represents the time of the contaminated liquid dripping treatment of the sample, and m = 1, 2, 3 ··· 10 represents the number of times of flashover of the sample at this time. Obtain the comprehensive factor X of pollution flashover temperature rise and leakage current of the material through formula (2) z ;

[0014]

[0015] Step 5: Determine the anti-fouling flashover performance evaluation coefficient of the material

[0016] Determine the anti-fouling flashover performance evaluation coefficient X of the material through formula (3) z ;

[0017]

[0018] Step 6: Evaluate the anti-fouling flashover performance of the material

[0019] Evaluate the anti-fouling flashover performance of the material. If 0 ≤ X z ≤ 0.5, it indicates that the anti-fouling flashover performance of the material is good; if 0.5 < X z ≤ 1, it indicates that the anti-fouling flashover performance of the material is average; if 1 < X z , it indicates that the anti-fouling flashover performance of the material is poor.

[0020] The beneficial effects of the present invention are as follows: By building a test platform and comprehensively considering the influence of factors such as the sewage treatment time, voltage repeated impact, and environmental temperature on the insulating material for dry-type distribution transformers, an evaluation method for the anti-fouling flashover performance is provided, which can quickly judge its anti-fouling flashover performance, provides a basis for the evaluation and selection of insulating materials, and improves the safety, economy, and reliability of the operation of dry-type distribution transformers. Description of the Drawings

[0021] Figure 1 It represents the built test platform.

[0022] Figure 2 It represents a flowchart of an evaluation method for the anti-fouling flashover performance of an insulating material for dry-type distribution transformers. Detailed Embodiments

[0023] The present invention will be further described below in conjunction with the drawings and the specific implementation process. It should be emphasized that the specific implementation cases described here are only used to explain the present invention and do not limit the scope of the concept of the present invention and its claims; for the convenience of description, some components in the drawings will be omitted and the sizes will change, which does not represent the sizes of the actual products; for those skilled in the art, the omission of some well-known structures and their descriptions in the drawings can be understood.

[0024] Step 1: Build a test platform and make test material samples

[0025] Build a test platform, which is characterized by including a controllable power supply (1), a first electrode (2), a second electrode (3), a heating plate (4), an insulating support frame (5), a sewage tank (6), a pipeline (7), a peristaltic pump (8), a dropper (9), sewage droplets (10), an infrared imager (11), a sample (12), a leakage current measuring device (13), and a computer terminal (14); control the first electrode (2), the second electrode (3), and the heating plate (4) through the controllable power supply (1), control the sewage in the sewage tank (6) to form sewage droplets (10) through the pipeline (7) and the dropper (9) by the peristaltic pump (8), place the sample (12) on the insulating support frame (5), both the infrared imager (11) and the leakage current measuring device (13) monitor the real-time state of the sample, and send the measured data to the computer terminal (14); make several test material samples of the same specification size, the sample is 0.3 m long, 0.2 m wide, and 0.01 m high.

[0026] Step 2: Record the normal operation data of the dry-type distribution transformer and configure the sewage

[0027] Obtain the average temperature suffered by the insulating material used in the dry-type distribution transformer during operation according to the operation record of the dry-type distribution transformer, denoted as T, and its value is 400 K; at the same time, record the average conductivity of the sewage suffered by the insulating material used in the dry-type distribution transformer, denoted as K, and its value is 0.15 S / m; configure the sewage with the same conductivity value as the recorded data and load it into the sewage tank for preparation; the dropper mouth is 5 mm away from the specimen, and adjust the peristaltic pump so that it can drip sewage droplets on the sample at a flow rate of 0.5 mL / min.

[0028] Step 3: Obtain the multiple pollution flashover factors of the material

[0029] Take four samples and respectively carry out sewage dripping treatment for 1 h, 2 h, 3 h, and 4 h. After the sewage dripping treatment of each sample is completed, start the heating plate until the sample temperature rises to 400 K, with the floating error not exceeding 1 K; control the electrode to boost the voltage at a speed of 0.2 kV / s per second until the sample undergoes pollution flashover. After the pollution flashover occurs, zero the electrode voltage and then boost the voltage again at the same rate until the sample undergoes pollution flashover again. Repeat this process ten times; record the voltage value at the time of each pollution flashover, denoted as V n,m , with the unit of kV, where n = 1, 2, 3, 4, representing the time of sewage dripping treatment of the sample, and m = 1, 2, 3 ··· 10, representing the number of times of flashover of the sample at this time; obtain the multiple pollution flashover factor S through formula (1) z ;

[0030]

[0031] Step 4: Obtain the comprehensive factors of pollution flashover temperature rise and leakage current of the material

[0032] After the tenth sample flashover ends, turn off the power supply and stop applying voltage to the electrode; through the records on the computer terminal, check the real-time state of the material during the whole test process, and record the overall temperature imaging of the sample one second before each flashover. The maximum temperature is denoted as T n,m , and the minimum temperature is denoted as T n,m ’, both in the unit of K. The area ratio of the temperature region exceeding 440K in the overall temperature of the sample to the overall area is denoted as P n,m , and at the same time record the leakage current generated by the sample one second before each flashover, denoted as I n,m , in the unit of A, where n = 1, 2, 3, 4 represents the time when the sample is treated with the contaminated solution, and m = 1, 2, 3 ··· 10 represents the number of the flashover that occurs to the sample at this time. The comprehensive factor X of the flashover temperature rise and leakage current of the material is obtained through formula (2) z ;

[0033]

[0034] Step 5: Determine the anti-fouling flashover performance evaluation coefficient of the material

[0035] Determine the anti-fouling flashover performance evaluation coefficient X of the material through formula (3) z ;

[0036]

[0037] Step 6: Evaluate the anti-fouling flashover performance of the material

[0038] The calculated anti-fouling flashover performance evaluation coefficient of the material is 0.38, and the anti-fouling flashover performance of this material is good.

Claims

1. An evaluation method for the anti - pollution flashover performance of insulating materials used in dry - type distribution transformers, characterized in that, it includes the following steps: The first step: Build a test platform and make test material samples; The second step: Record the normal operation data of the dry - type distribution transformer and configure the contaminated liquid; The third step: Obtain the multiple pollution flashover factors of the material; The fourth step: Obtain the comprehensive factors of pollution flashover temperature rise and leakage current of the material; The fifth step: Determine the anti - pollution flashover performance evaluation coefficient of the material; The sixth step: Evaluate the anti - pollution flashover performance of the material; The specific process of the first step is as follows: Build a test platform, which is characterized by including a controllable power supply (1), a first electrode (2), a second electrode (3), a heating plate (4), an insulating support frame (5), a contaminated liquid tank (6), a pipeline (7), a peristaltic pump (8), a dropper (9), a contaminated liquid droplet (10), an infrared imager (11), a sample (12), a leakage current measuring device (13), and a computer terminal (14); Control the first electrode (2), the second electrode (3), and the heating plate (4) through the controllable power supply (1), control the contaminated liquid in the contaminated liquid tank (6) to form contaminated liquid droplets (10) through the pipeline (7) and the dropper (9) by the peristaltic pump (8), place the sample (12) on the insulating support frame (5), and both the infrared imager (11) and the leakage current measuring device (13) monitor the real - time state of the sample and send the measured data to the computer terminal (14); Make several test material samples of the same specification size; The specific process of the second step is as follows: Obtain the average temperature T (unit: K) suffered by the insulating material used in the dry - type distribution transformer during operation according to the operation record of the dry - type distribution transformer; At the same time, record the average conductivity K (unit: S / m) of the contaminated liquid suffered by the insulating material used in the dry - type distribution transformer; Configure the contaminated liquid with the same conductivity as the recorded data and put it into the contaminated liquid tank for preparation; The distance between the dropper mouth and the specimen is 5 mm, and adjust the peristaltic pump so that the contaminated liquid can drip on the sample at a flow rate of 0.5 mL / min; The specific process of the third step is as follows: Take four samples and treat them with the dripping contamination solution for 1 h, 2 h, 3 h, and 4 h respectively. After the treatment of each sample with the dripping contamination solution is completed, start the heating plate until the temperature of the sample rises to T, with the floating error not exceeding 1 K; control the electrode to boost the voltage at a speed of 0.2 kV / s per second until flashover of the sample occurs. After flashover occurs, reset the electrode voltage to zero and then boost the voltage again at the same rate until flashover of the sample occurs again. Repeat this process ten times; record the voltage value at the time of each flashover, denoted as V n,m , with the unit of kV, where n = 1, 2, 3, 4, representing the time of the sample treated with the dripping contamination solution, and m = 1, 2, 3 ··· 10, representing the number of times of flashover of the sample at this time; obtain the multiple flashover factor S through formula (1) z ; The specific process of the fourth step is as follows: After the tenth sample flashover ends, turn off the power supply and stop applying voltage to the electrode; through the records of the computer terminal, view the real-time state of the material during the whole test process, and record the overall temperature imaging of the sample one second before each flashover. The maximum temperature is denoted as T n,m , and the minimum temperature is denoted as T n,m ’. The unit of both is K. The area ratio of the temperature region exceeding T + 40K in the overall sample temperature to the overall area is denoted as P n,m . At the same time, record the leakage current generated by the sample one second before each flashover, denoted as I n,m . The unit is A. Here, n = 1, 2, 3, 4 represents the time when the sample is treated with the contaminated solution, and m = 1, 2, 3 ··· 10 represents the number of the flashover that the sample undergoes at this time. The comprehensive factor X of the pollution flashover temperature rise and leakage current of the material is obtained through formula (2) z ; The specific process of the fifth step is as follows: Determine the anti-fouling flashover performance evaluation coefficient X of the material through formula (3). z ; The specific process of the sixth step is as follows: Evaluate the anti-fouling flashover performance of the material. If 0 ≤ X z ≤ 0.5, it indicates that the anti-fouling flashover performance of the material is good; if 0.5 < X z ≤ 1, it indicates that the anti-fouling flashover performance of the material is average; if 1 < X z , it indicates that the anti-fouling flashover performance of the material is poor.

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