CN106771765A - A kind of multidimensional parameter appraisal procedure of operating composite insulator degree of aging - Google Patents

Abstract

A multi-dimensional parameter evaluation method for the aging degree of a composite insulator in operation. The method first measures the hardness, hydrophobicity, surface defect area, and Si-O-Si group correspondence of the high-temperature vulcanized silicone rubber sample of the shed of the target composite insulator. Infrared absorption peak value, trap charge and flashover voltage; then quantify the measured data, and score the aging degree of the processed characteristic parameters; then weight and sum the scores of each characteristic parameter to obtain the characterization The comprehensive characteristic quantity of the aging degree of the composite insulator; finally, the aging degree of the insulator is determined according to the corresponding relationship between the comprehensive characteristic quantity and the aging degree grade. The invention combines the microscopic electrical characteristics, microscopic physical and chemical characteristics and macroscopic characteristics of the shed material of the composite insulator, and realizes the comprehensive evaluation of the aging degree of the composite insulator. This method avoids the one-sidedness of traditional evaluation methods, thereby ensuring the accuracy of evaluation results.

Description

A multi-dimensional parameter evaluation method for the aging degree of composite insulators in operation

technical field

The invention relates to a method capable of accurately evaluating the aging degree of a composite insulator in operation, and belongs to the technical field of insulators.

Background technique

At present, most of the poles and towers of high-voltage transmission lines are insulated from the lines by composite insulators, and the shed and sheath of composite insulators are generally made of high-temperature vulcanized silicone rubber. During the long-term hanging network operation, high-temperature vulcanized silicone rubber is affected by high-intensity electric fields and light, heat, rain, pollution, etc. in the environment, and serious aging problems will occur. In order to ensure the reliable operation of high-voltage transmission lines, it is necessary to detect the aging degree of composite insulators.

There are many methods for detecting the aging degree of silicone rubber composite insulators, such as analyzing the aging degree of the insulator according to the physical properties of the material (such as material appearance, hydrophobicity, equivalent salt density, gray density, thermal weight, etc.); Analyze the aging degree of insulators based on microscopic physical and chemical characteristics; analyze the aging degree of insulators according to the electrical characteristics of materials (such as flashover voltage, leakage current, thermal stimulation current, etc.); analyze the aging degree of insulators based on the dielectric properties and resistance properties of materials. Most of these methods are evaluated based on a single aging index, resulting in a certain one-sidedness in the evaluation results. For example, the invention patent with application number 201210386969.8 discloses a method for evaluating the operating state of composite insulators, which uses the test results of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermal stimulation current measurement (TSC) The composite insulator is evaluated from a microscopic point of view, and the weight of each parameter is optimized based on the BP neural network algorithm. Finally, the operating state of the composite insulator is calculated, but it does not consider the influence of the macroscopic properties of the material on the aging state.

The macroscopic properties of insulating materials are of great significance to the detection of aging. The data of composite insulators operated by the State Grid Corporation of China show that the aging of insulator silicone rubber is mainly manifested in the decrease of surface hydrophobicity and increase of hardness, which in turn affects the pollution flashover resistance of insulators. Therefore, when evaluating the aging degree of composite insulators, it is one-sided to only analyze the microscopic properties of the material, and it is necessary to take the macroscopic properties of the material into consideration. On the one hand, as an important indicator of the pollution flashover resistance performance of composite insulators, hydrophobicity can directly represent the aging degree of materials. As one of the important standards to measure the electrical properties of silicone rubber, flashover voltage is the embodiment of the macroscopic electrical properties of insulating materials, while the hardness reflects the macroscopic mechanical properties of materials. On the other hand, changes in the microscopic properties of the material will lead to changes in the macroscopic properties, and the macroscopic properties can more intuitively reflect the aging state of the material. Therefore, it is necessary to find a method that can combine the microscopic electrical properties and microscopic physical and chemical properties of composite insulator shed materials with the macroscopic properties of the material to achieve accurate assessment of the aging degree of composite insulators.

Contents of the invention

The purpose of the present invention is to provide a multi-dimensional parameter evaluation method for the aging degree of composite insulators in operation to more accurately evaluate the aging degree of silicone rubber to ensure the normal operation of high-voltage transmission lines.

Problem described in the present invention is solved with following technical scheme:

A multi-dimensional parameter evaluation method for the aging degree of a composite insulator in operation. The method first measures the hardness, hydrophobicity, surface defect area, and Si-O-Si group correspondence of the high-temperature vulcanized silicone rubber sample of the target composite insulator shed Infrared absorption peak value, trap charge and flashover voltage; then quantify the measured data, and score the aging degree of the processed characteristic parameters; then weight and sum the scores of each characteristic parameter to obtain the characterization The comprehensive characteristic quantity of the aging degree of the composite insulator; finally, the aging degree of the insulator is determined according to the corresponding relationship between the comprehensive characteristic quantity and the aging degree grade.

The multi-dimensional parameter evaluation method for the aging degree of composite insulators in operation above includes the following steps:

a. Determine the characteristic quantity:

Six characteristic parameters are selected as the characteristic quantities to evaluate the aging degree of composite insulators, which are hardness, hydrophobicity, surface defect area, infrared absorption peak corresponding to Si-O-Si group, trap charge and flashover voltage. Among them, hydrophobicity The water property is represented by the static contact angle, and the surface defect area is the sum of the crack area and the precipitate area;

b. Use a slicer to cut a disc-shaped high-temperature vulcanized silicone rubber sample from the surface of the shed of the target composite insulator;

c. Use Shore hardness tester, scanning electron microscope, Fourier transform infrared spectrometer, thermal stimulation current measuring instrument and finger electrode to measure the hardness, surface defect area and Si-O-Si group of high-temperature vulcanized silicone rubber samples respectively The corresponding infrared absorption peak, trap charge and flashover voltage, and the hydrophobicity of the sample is measured by the static contact angle method;

d. Quantify the original characteristic quantity: first, normalize the characteristic parameters measured by various methods, and the normalization treatment formula of the surface defect area is: The normalization formula of the remaining characteristic parameters is: Then, according to each normalized characteristic parameter value, the aging degree of the target composite insulator is scored, and the aging degree score corresponding to each characteristic parameter is obtained;

e. Evaluate the aging degree of the sample: set the weight of each characteristic parameter, carry out weighted summation of the aging degree scores corresponding to the six characteristic parameters of the sample, and obtain the comprehensive characteristic quantity representing the aging degree of the composite insulator, and finally according to the comprehensive The corresponding relationship between the size of the characteristic quantity and the aging degree grade determines the aging degree of the target insulator.

The multi-dimensional parameter evaluation method for the aging degree of composite insulators in operation above can also be evaluated by neural network when evaluating the aging degree of samples. The specific method is as follows:

Collect multiple high-temperature vulcanized silicone rubber samples with known aging degrees, obtain the normalized characteristic parameter values of the samples, form a training sample set, use the training sample set to train the BP neural network, and then use the trained BP neural network to perform high-temperature vulcanization The aging degree of the silicone rubber samples was evaluated.

The multi-dimensional parameter evaluation method for the aging degree of composite insulators in the above operation, the weight of each characteristic parameter is set as: hardness: 0.2, hydrophobicity: 0.4, surface defect area: 0.4, infrared absorption peak corresponding to Si-O-Si group : 0.6, trap charge: 1, flashover voltage: 0.4.

The multi-dimensional parameter evaluation method for the aging degree of composite insulators in operation above, according to each normalized characteristic parameter value, the specific method of scoring the aging degree of the target composite insulator is as follows:

The value range of each normalized characteristic parameter is divided into multiple intervals, each interval is given a value, the higher the aging degree of the insulator, the larger the corresponding value; the interval of a certain normalized characteristic parameter value The given value is the aging degree score corresponding to the characteristic parameter.

The multi-dimensional parameter evaluation method for the aging degree of composite insulators in operation above, there are two types of disc-shaped high-temperature vulcanized silicone rubber samples. The diameter of the sample used in the characteristic parameters is 20mm and the thickness is 3mm.

The multi-dimensional parameter evaluation method for the aging degree of composite insulators in the above operation, when using the Shore hardness tester to measure the hardness of high-temperature vulcanized silicone rubber samples, stack two high-temperature vulcanized silicone rubber samples and measure them 5 times. The median value of the value is used as the hardness value of the high temperature vulcanized silicone rubber sample.

In the multi-dimensional parameter evaluation method for the aging degree of composite insulators in operation, the discharge end of the finger electrode is semicircular, and its radius is 8mm. When using the finger electrode to measure the flashover voltage of the high-temperature vulcanized silicone rubber sample, two The distance between the finger-shaped electrodes is 10mm. The prepared sample is placed in the center of the two finger-shaped electrodes, and a voltage is applied between the two finger-shaped electrodes. The gradient of the applied voltage is 1kV. The flashover voltage of each sample is measured five times, with an interval of 10 minutes between two adjacent measurements, and the average value of the five measurements is taken as the flashover voltage of the high-temperature vulcanized silicone rubber sample.

The invention combines the microscopic electrical characteristics, microscopic physical and chemical characteristics and macroscopic characteristics of the shed material of the composite insulator, and realizes the comprehensive evaluation of the aging degree of the composite insulator. This method avoids the one-sidedness of traditional evaluation methods, thereby ensuring the accuracy of evaluation results.

Description of drawings

Figure 1 is a structural diagram of the BP neural network.

detailed description

The present invention will be further described below in conjunction with accompanying drawing.

This method evaluates the aging degree of operating composite insulators by comprehensively considering various aging evaluation methods according to different weights. It can not only combine the microscopic properties and macroscopic properties of materials to consider the aging degree of materials, but also give quantitative discrimination results to ensure the accuracy of the assessment results. The feature of this patent is that according to the internal relationship between them and the different degrees of influence on aging, the six aging rating indicators are divided into different weights to comprehensively evaluate the aging degree of insulators, and it is suitable for evaluating various operating composite insulators. BP neural network model. The limitations of single factor evaluation index to evaluate composite insulators are:

Hardness index: Hardness is the macroscopic physical property of silicone rubber materials. During the operation of silicone rubber, the surface is affected by aging factors, and the material will first undergo excessive cross-linking and hardening, which will increase the hardness. Halo aging causes the chemical bonds of the material to be continuously interrupted, and the nitric acid continues to corrode the surface of the material, causing cracks and pulverization on the surface of the material, resulting in a decrease in hardness. It is difficult to distinguish the aging state of the material.

Hydrophobicity: The main factor affecting the performance of composite insulators is the loss of hydrophobicity, and the destruction of hydrophobicity is an important feature of insulator aging. The hydrophobicity of the surface of the material is due to the fact that the non-polar group of the side chain of the silicone rubber shields the strong polarity of the main chain, which enhances the hydrophobicity of the surface of the material. As the service life of the composite insulator increases, the side chain methyl group If it is interrupted, the hydrophobicity will decrease, but at the same time, small LMW molecules will be generated, and LMW will migrate to the surface of the material, making the hydrophobicity relatively increase. Therefore, the hydrophobicity cannot accurately evaluate the aging state of the material.

SEM: Scanning electron microscope is suitable for observing the surface morphology changes of materials. The test results can characterize the physical defects on the surface of silicone rubber materials. It can qualitatively analyze the aging status of materials, and is greatly affected by subjective judgments, so it is difficult to give accurate quantitative evaluation results.

FTIR: Fourier transform infrared spectroscopy test is suitable for analyzing the change of chemical structure on the surface of materials. The test results can only characterize the chemical structure defects on the surface of silicone rubber materials. During the operation of composite insulators, the impact of discharge particles will cause the chemical bonds of materials to break down. Breakage and generation of active groups are manifested in FTIR as the decrease of characteristic groups such as methyl groups and Si-O-Si groups, and the increase of -OH active groups. However, it cannot characterize the physical defects of materials caused by mechanical effects such as physical impact.

TSC: Thermally stimulated current test is the microscopic electrical properties of materials. It can reflect the characteristics of traps caused by material physical and chemical defects. These traps can trap carriers and accumulate them, distorting the local field strength, causing flashover on the surface of solid media, and aggravating the aging performance of materials. Although the TSC test can reflect the physical and chemical defects of the material, the repeatability of the TSC test is very poor. Different (contact barrier, electrode area, impurity contamination, interface state), then the number and distribution of injected carriers may be different under the same conditions, and the filling of traps is also different, resulting in the distribution of trap charges and the internal electric field The difference of the thermal stimulation process caused by it is also different. On the other hand, the thermal history experienced by the material and the absorbed moisture, impurities, etc. will change its physical or chemical structure, and then change the trap state. Therefore, the aging state of service composite insulators cannot be evaluated only by TSC testing technology.

Flashover voltage: As one of the important standards to measure the electrical performance of silicone rubber, flashover voltage is the embodiment of the macroscopic electrical properties of insulating materials. However, due to the influence of the environment and the surface state of the material, the dispersion and error of the test results are uniform. Larger, it is only used as a means to evaluate the aging state of composite insulators, which loses the true accuracy of the test.

Therefore, when judging the aging state of composite insulators, if the above six methods are used to comprehensively evaluate the aging degree of materials according to a certain weight, it will be an effective means with high accuracy.

The specific content of the multi-dimensional parameter evaluation method for the aging degree of composite insulators in operation will be described in detail below with examples.

1. Determine the characteristic quantity: the hardness of the sample is characterized by Shore hardness, the hydrophobicity is characterized by the static contact angle, the surface defect area is the sum of the crack area and the precipitate area, and the Si- The absorption peak corresponding to the O-Si group, because the trap charge can more quantitatively reflect the trap characteristics of the material, the thermally stimulated current (TSC) is determined to use the trap charge as a characteristic quantity.

2. Sample collection: Use a slicer to cut out a disc-shaped high-temperature vulcanized silicone rubber sample from the surface of the shed shed of the composite insulator to be evaluated that has been run on the hanging net, with a diameter of 20mm and a thickness of 3mm.

3. Hardness test: The hardness tester is a Shore hardness tester. The thickness of two pieces of silicone rubber is superimposed to 6 mm, and then the hardness is tested 5 times, and the median of the 5 measurement results is taken.

4. Test of surface defect area and infrared absorption peak: Use scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) to analyze the physical and chemical structure of silicone rubber materials, and observe its surface morphology and Si-O-Si groups peak change.

5. Hydrophobic test: The static contact angle method is used to measure the hydrophobic angle, and each sample is measured 5 times, and the average value is taken.

6. Thermally stimulated current (TSC) test: Use a special slicer to slice the circular sample to obtain a circular thin slice sample with a diameter of 20 mm and a thickness of 1.3 mm for the TSC test, and test the trap through thermally stimulated current technology amount of charge.

7. Flashover test along the surface: use finger electrodes, the electrode radius is 8mm, and the distance between electrodes is 10mm. Put the prepared sample into the center of the finger electrode and apply a voltage to it with a gradient of 1kV. The creepage flashover voltage is measured during the voltage application. Each sample is subjected to 5 flashover tests with an interval of 10 minutes between each test, and the flashover voltage is the average value of 5 times.

8. Quantify the original characteristic quantity: the units of the measured result parameters of each test method are inconsistent, and the values of different parameters are quite different. One treatment. The normalization formula for surface defect area is: The normalization formula of the remaining characteristic parameters is: Then score each feature quantity according to the aging degree scoring information given in Table 1.

Table 1 Aging degree scoring information

9. Evaluate the aging degree of the sample: According to the relationship between the microscopic electrical characteristics and the macroscopic characteristics, the importance of each aging characteristic is different, so its weight in the aging evaluation is different. The microscopic physical and chemical properties determine the macroscopic physical and electrical properties. In view of this, the weighted sum of the measured results of the microscopic physical and chemical properties, that is, the results of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) is initially positioned as 1. The generation of particles and the formation of defects such as cracks can be observed in SEM, and the changes in the chemical structure of materials are reflected in FTIR. Considering that FTIR is easy to quantify, and the large particles observed in SEM images, molecular bond breakage and new bond generation can be found in FTIR test results, so the weight of FTIR test results is greater than that of SEM. Preliminarily set the weights of FTIR test results and SEM test results to 0.6 and 0.4. The main reason for the change of hardness is the content of aluminum hydroxide, etc.; the change of hydrophobicity is jointly affected by microscopic physical properties and microchemical properties, that is, the results of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) are jointly affected, due to The chemical structure in FTIR is based on the Si-O-Si group peak, so the weight setting of hydrophobicity is smaller than that of FTIR test results. Hydrophobicity affects the flashover voltage along the surface. Considering the weight of hydrophobicity test results is 0.4, the weight of flashover voltage is 0.4, and the weight of hardness is 0.2. The reason for the deepening of the trap energy level in TSC is the increase of internal defects, that is, the formation of cracks and the generation of new chemical groups, and the changes in the chemical structure in FTIR can not all cause the deepening of the trap energy level, so the TSC test results are weighted Set to roughly equal to the sum of SEM and FTIR, considering the weight of TSC test results as 1.

The aging degree scores corresponding to the six characteristic parameters of the sample are weighted and summed to obtain the comprehensive characteristic quantity representing the aging degree of the composite insulator, and the aging degree of the target insulator is determined according to the corresponding relationship between the comprehensive characteristic quantity and the aging degree grade .

The aging degree of the sample can also be evaluated using the BP neural network shown in Figure 1. The specific steps are:

a.BP neural network training:

1) To create a neural network in Matlab, you can use the newff function to create a network or create a network on the Network/Datamanager interface.

2) Assign sample feature quantities x1 to x6 and sample output quantity y as input and output.

3) Setting model parameters: the neural network is a three-layer network: input layer-hidden layer-output layer, the selection of the number of neurons in the hidden layer is generally obtained through continuous improvement, and is determined by comprehensive consideration of comparison errors and input results. Therefore, 10 neurons are selected, so 10 neurons in the hidden layer are selected, and the weight of the hidden layer is randomly set by the system. The initial weight is a random number between (-1, 1). In neural networks, the activation function used by neurons must be derivable everywhere. Most designers choose to use Sigmoid functions, where tansig' and 'purline' functions can be used. The maximum number of training times is set to 5000, and the error precision is set to 10 ^-2 .

Store the trained BP neural network for easy calling when testing samples.

The aging characteristics of more than ten strings of composite insulators in a certain area were measured, and the test results of TSC, FTIR, SEM, hydrophobicity, hardness, and flashover voltage were quantified and scored. The results were: 2, 3, 2, 1, 1 and 1, input the sample characteristic parameters x1~x6 (2, 3, 2, 1, 1, 1) into the trained BP neural network, and obtain the corresponding output y=10, so it can be judged that the sample is The moderately aged sample is in line with the subjective judgment result of the sample.

Claims (8)

1. a kind of multidimensional parameter appraisal procedure of operating composite insulator degree of aging, it is characterized in that, methods described is first Measure hardness, hydrophobicity, surface defect area, the Si-O-Si of the high-temperature silicon disulfide rubber sample of target composite insulator umbrella skirt The corresponding infrared absorption peaks of group, trapped charge amount and flashover voltage；Then surveyed data are carried out with quantification treatment, and to place Characteristic parameter after reason carries out the marking of degree of aging；The score value to each characteristic parameter is weighted summation again, obtains characterizing again Close the comprehensive features of the Ageing of Insulators degree；The corresponding relation of size and degree of aging grade finally according to comprehensive features Determine the degree of aging of insulator.

2. the multidimensional parameter appraisal procedure of a kind of operating composite insulator degree of aging according to claim 1, its It is characterized in that the described method comprises the following steps：

A. characteristic quantity is determined：

Six characteristic parameters are selected as the characteristic quantity of evaluating combined the Ageing of Insulators degree, respectively hardness, hydrophobicity, surface Defect area, the corresponding infrared absorption peaks of Si-O-Si groups, trapped charge amount and flashover voltage, wherein, hydrophobicity is by static state Contact angle represents that surface defect area is crackle area and precipitate area sum；

B. wafer type high-temperature silicon disulfide rubber sample is cut from target composite insulator umbrella skirt surface using food slicer；

C. Shore durometer, ESEM, FTIR spectrum analyzer, thermally stimulated current measuring instrument and finger-type electrode are utilized Respectively the measurement hardness of high-temperature silicon disulfide rubber sample, surface defect area, the corresponding infrared absorption peaks of Si-O-Si groups, Trapped charge amount and flashover voltage, and the hydrophobicity of sample is measured using Static Contact horn cupping；

D. primitive character amount is quantified：The characteristic parameter measured by various methods is normalized first, wherein, surface lacks Fall into area normalized formula be： Remaining is special The normalized formula for levying parameter is： So Afterwards according to each normalized characteristic parameter value, the marking of degree of aging is carried out to target composite insulator, obtain special with each Levy the corresponding degree of aging score value of parameter；

E. sample degree of aging is assessed：The weight of each characteristic parameter is set, to aging corresponding to six characteristic parameters of sample Degree score value is weighted summation, obtains characterizing the comprehensive features of composite insulator degree of aging, finally according to comprehensive characteristics The size of amount judges the degree of aging of target insulator with the corresponding relation of degree of aging grade.

3. the multidimensional parameter appraisal procedure of a kind of operating composite insulator degree of aging according to claim 2, its It is characterized in, when assessing the degree of aging of sample, it is also possible to be estimated using neutral net, specific method is：

High-temperature silicon disulfide rubber sample known to the multiple degree of agings of collection, obtains the normalization characteristic value of consult volume of sample, composition Training sample set, is trained using training sample set pair BP neural network, then using the BP neural network of training to high temperature The degree of aging of sulphurated siliastic sample is estimated.

4. the multidimensional parameter appraisal procedure of a kind of operating composite insulator degree of aging according to claim 2, its It is characterized in that the weight setting of each characteristic parameter is：Hardness：0.2, hydrophobicity：0.4, surface defect area：0.4, Si-O-Si base The corresponding infrared absorption peaks of group：0.6, trapped charge amount：1, flashover voltage：0.4.

5. the multidimensional parameter appraisal procedure of a kind of operating composite insulator degree of aging according to claim 4, its It is characterized in, according to each normalized characteristic parameter value, the specific method of degree of aging marking to be carried out to target composite insulator For：

The span of every kind of normalization characteristic parameter is divided into multiple intervals, each interval gives a numerical value, insulator Degree of aging is higher, and corresponding numerical value is also bigger；Interval given numerical value is this feature where certain normalization characteristic value of consult volume Degree of aging score value corresponding to parameter.

6. the multidimensional parameter appraisal procedure of a kind of operating composite insulator degree of aging according to claim 5, its It is characterized in that the specification of the wafer type high-temperature silicon disulfide rubber sample has two kinds, and sample used is straight during measurement trapped charge amount Footpath is 20mm, thick 1.3mm, a diameter of 20mm of sample used during measurement further feature parameter, and thickness is 3mm.

7. the multidimensional parameter appraisal procedure of a kind of operating composite insulator degree of aging according to claim 6, its It is characterized in, when measuring the hardness of high-temperature silicon disulfide rubber sample using Shore durometer, by two panels high-temperature silicon disulfide rubber sample After stacking measure 5 times, using 5 medians of measured value as high-temperature silicon disulfide rubber sample hardness number.

8. the multidimensional parameter appraisal procedure of a kind of operating composite insulator degree of aging according to claim 7, its It is characterized in that the discharge end of the finger-type electrode is semicircle, and its radius is 8mm, using finger-type electrode measurement high-temperature vulcanized silicon rubber During the flashover voltage of glue sample, two finger-type interelectrode distances are 10mm, and the sample that will be prepared is placed on two finger-type electrodes center, The applied voltage between two finger-type electrodes, the gradient of applied voltage is 1kV, to the edge flashing of sample during applied voltage Voltage is measured, and every sample carries out 5 measurements of flashover voltage, and 10min is spaced between adjacent measurement twice, by 5 surveys The average value of value as high-temperature silicon disulfide rubber sample flashover voltage.