A method for evaluating the deterioration state of composite outer-rod insulators considering extreme cold snap environments

Abstract

The present invention provides a method for evaluating the degradation state of a composite outer insulator under an extreme cold snap environment, including building a test platform. First, control signals are sent to the temperature control terminal and the environmental humidity regulator by operating the upper computer to simulate and realize the extreme cold snap environment. Then, the upper computer controls the power frequency voltage controller to perform a constant voltage boost process on the composite insulator specimen. Secondly, the power frequency test current of the composite outer insulator specimen is calculated. Finally, after algorithm optimization, the degradation state evaluation factor of the composite outer insulator is calculated and the degradation state of the composite outer insulator is evaluated. The beneficial effect of the present invention lies in providing a method for evaluating the degradation state of a composite outer insulator under an extreme cold snap environment and building a test platform, providing a solid foundation for the evaluation of the degradation state of composite insulators under an extreme cold snap environment, and providing an important guarantee for the safety and stability of the power system.

Description

Technical Field

[0001] The present invention belongs to the field of insulator degradation state evaluation, and particularly relates to a method for evaluating the degradation state of composite outer sheath insulators considering extreme cold snap environments. Background Art

[0002] In the power system, as an important device for electrical insulation and mechanical support between different live conductors and between live conductors and the ground, composite insulators have been widely used in transmission lines with different voltage levels due to their many advantages such as light weight, good pollution flashover resistance, and high mechanical strength. Composite insulators will be affected by various factors during operation. Especially under complex environmental factors, phenomena such as insulator pulverization, cracking, and flashover of unknown cause will occur over time. The degradation of composite insulators is closely related to the operating environment. Especially in harsh environments such as high cold and humidity, the degradation of insulators is often more serious. Therefore, the degradation problem of composite insulators under the influence of outdoor harsh environments must be highly concerned, and it is necessary to timely detect the degradation problem of composite insulators and take relevant measures.

[0003] The present invention comprehensively considers the operating duration and applied voltage of composite insulators under extreme cold snap environments, and finally obtains an evaluation factor for the degradation state of composite outer sheath insulators, which is of great significance for evaluating the degradation state of insulators. Summary of the Invention

[0004] A method for evaluating the degradation state of composite outer sheath insulators considering extreme cold snap environments is characterized in that, first, a test evaluation platform is built, and the platform includes: a host computer, a power frequency voltage controller, a power frequency voltage generator, a high-voltage coaxial cable, a switch, a high-precision voltage divider, a high-voltage test electrode I, a high-voltage test electrode II, a climate simulation test chamber, a composite outer sheath insulator test sample, a current test coil, a grounding grid, a humidity controller, a humidifier I, a humidifier II, a total temperature control terminal, an ambient temperature regulator, an experimental data acquisition unit, a grounding device I, and a grounding device II;

[0005] The host computer is connected to the input end of the power frequency voltage controller, the output end of the power frequency voltage controller is connected to the input end of the power frequency voltage generator, the output end of the power frequency voltage generator is connected to the right end of the switch through a high-voltage coaxial cable, the left end of the switch is connected to the input end of the high-precision voltage divider, the input end of the high-precision voltage divider is connected to the high-voltage test electrode I, the high-voltage test electrode I is connected to the upper end of the composite outer sheath insulator test sample, the lower end of the composite outer sheath insulator test sample is connected to the high-voltage test electrode II, the high-voltage test electrode II is connected to the grounding grid, and the current test coil is sleeved between the high-voltage test electrode II and the grounding grid;

[0006] The signal terminals of the high-precision voltage divider and the current test coil are connected to the input terminal of the experimental data collection unit, and the output terminal of the experimental data collection unit is connected to the host computer;

[0007] The grounding terminal of the power frequency voltage generator is connected to the first grounding device, and the grounding terminal of the high-precision voltage divider is connected to the second grounding device;

[0008] The input terminal of the humidity controller is connected to the host computer, the output terminals of the humidity controller are connected to the first humidifier and the second humidifier, the input terminal of the total temperature control terminal is connected to the host computer, and the output terminal of the total temperature control terminal is connected to the ambient temperature regulator;

[0009] The composite outer insulator test sample, the first humidifier, the second humidifier, the ambient temperature regulator, the first high-voltage test electrode, and the second high-voltage test electrode are all placed inside the climate simulation test chamber;

[0010] A method for evaluating the deterioration state of a composite outer insulator considering extreme cold snap environments includes the following steps:

[0011] S1: Send a control signal to the total temperature control terminal through the host computer to make the ambient temperature regulator cool down the climate simulation test chamber, and keep this temperature when the temperature drops to T; then send a control signal to the humidity controller through the host computer to make the first humidifier and the second humidifier humidify the environment of the climate simulation test chamber, and keep the humidity at w through the humidity controller;

[0012] S2: Keep the environmental conditions in the climate simulation test chamber unchanged, close the switch, send a control signal to the power frequency voltage controller through the host computer to make the power frequency voltage generator perform a constant voltage boost on the composite outer insulator test sample, boost the voltage by ΔU every Δt time, and perform a total of N voltage boosts. Record the time t and the voltage U of the power frequency voltage generator at this time after each voltage boost 1 , and then measure the voltage U of the composite outer insulator test sample at this time by the high-precision voltage divider and the current test coil 2 and the current I c , and return them to the host computer through the experimental data collection unit, and then disconnect the switch;

[0013] S3: Obtain the calculated value I of the power frequency test current of the composite outer insulator test sample through the following formula i :

[0014]

[0015] In formula (1), t is the duration of the simulated environment, U 2 is the voltage measured at both ends of the test sample, g is the error coefficient, and p is the integration variable;

[0016] S4: Use an optimization algorithm to perform optimization modeling on formula (1) to obtain the g value that minimizes the error. The specific steps are as follows: k The value, and the specific steps are as follows:

[0017] 1) Randomly generate an initial solution δ, and calculate the objective function f(δ):

[0018]

[0019] In formula (2), f(δ) represents the objective function, I cm is the measured value of the mth power frequency current, and I im is the calculated value of the mth power frequency current, and N is the number of tests;

[0020] 2) Generate a perturbed new solution δ', and calculate the objective function Δf = f(δ) - f(δ'); if Δf ≥ 0, accept the new solution, otherwise, obtain the new solution according to the probability acceptance criterion;

[0021] 3) Determine whether the iteration number is reached. If it is reached, go to step 4); otherwise, go to step 2);

[0022] 4) Determine whether the termination condition is satisfied. If it is satisfied, end the operation and output the optimal solution; otherwise, reset the iteration number and go to step 2);

[0023] S5: Substitute the g obtained in S4 k into formula (1) to obtain the calculation formula for the power frequency test current I' of the optimized ZnO varistor: i Calculation formula:

[0024]

[0025] S6: Calculate the deterioration state evaluation factor α of the composite outer sheath insulator based on the optimized power frequency test current I': i Calculation formula:

[0026]

[0027] In formula (4), I i ' is the optimized power frequency test current, and N is the number of tests;

[0028] S7: Evaluate based on the deterioration state evaluation factor α of the composite outer sheath insulator obtained in the above steps. When α ∈ (0, 1], it indicates that the composite outer sheath insulator has no deterioration; when α ∈ (1, 2], it indicates that the composite outer sheath insulator has slight deterioration; when α ∈ (2, +∞), it indicates that the composite outer sheath insulator has serious deterioration.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1) A method for evaluating the degradation state of composite outer-rod insulators considering extreme cold snap environments is provided, and a test platform is built, which can simulate the extreme cold snap environment more realistically;

[0031] 2) The whole process is operated through a host computer, which is safe and convenient;

[0032] 3) The degradation state of composite outer-rod insulators can be evaluated more accurately through the degradation state evaluation factors of composite outer-rod insulators. Description of the Drawings

[0033] Figure 1 It is a schematic structural diagram of the present invention. Detailed Embodiment

[0034] A method for evaluating the degradation state of composite outer-rod insulators considering extreme cold snap environments is characterized in that a test and evaluation platform is first built, and the platform includes: a host computer (1), a power frequency voltage controller (2), a power frequency voltage generator (3), a high-voltage coaxial cable (4), a switch (5), a high-precision voltage divider (6), a high-voltage test electrode one (71), a high-voltage test electrode two (72), a climate simulation test chamber (8), a composite outer-rod insulator test sample (9), a current test coil (10), a grounding grid (11), a humidity controller (12), a humidifier one (131), a humidifier two (132), a temperature control terminal (14), an ambient temperature regulator (15), an experimental data acquisition unit (16), a grounding device one (171), and a grounding device two (172);

[0035] The host computer (1) is connected to the input end of the power frequency voltage controller (2), the output end of the power frequency voltage controller (2) is connected to the input end of the power frequency voltage generator (3), the output end of the power frequency voltage generator (3) is connected to the right end of the switch (5) through the high-voltage coaxial cable (4), the left end of the switch (5) is connected to the input end of the high-precision voltage divider (6), the input end of the high-precision voltage divider (6) is connected to the high-voltage test electrode one (71), the high-voltage test electrode one (71) is connected to the upper end of the composite outer-rod insulator test sample (9), the lower end of the composite outer-rod insulator test sample (9) is connected to the high-voltage test electrode two (72), the high-voltage test electrode two (72) is connected to the grounding grid (11), and the current test coil (10) is sleeved between the high-voltage test electrode two (72) and the grounding grid (11);

[0036] The signal ends of the high-precision voltage divider (6) and the current test coil (10) are connected to the input end of the experimental data collection unit (16), and the output end of the experimental data collection unit (16) is connected to the host computer (1);

[0037] The grounding terminal of the industrial frequency voltage generator (3) is connected to the first grounding device (171), and the grounding terminal of the high-precision voltage divider (6) is connected to the second grounding device (172).

[0038] The input end of the humidity controller (12) is connected to the host computer (1), the output end of the humidity controller (12) is connected to the first humidifier (131) and the second humidifier (132), the input end of the total temperature control terminal (14) is connected to the host computer (1), and the output end of the total temperature control terminal (14) is connected to the ambient temperature regulator (15).

[0039] The composite insulator sample (9), the first humidifier (131), the second humidifier (132), the ambient temperature regulator (15), the high-voltage test electrode one (71), and the high-voltage test electrode two (72) are all placed inside the climate simulation test chamber (8).

[0040] A method for evaluating the degradation state of a composite insulator under extreme cold snap environments includes the following steps:

[0041] S1: Send a control signal to the total temperature control terminal (14) through the host computer (1) to make the ambient temperature regulator (15) cool down the climate simulation test chamber (8). When the temperature drops to T, maintain this temperature. Subsequently, send a control signal to the humidity controller (12) through the host computer (1) to make the first humidifier (131) and the second humidifier (132) humidify the environment of the climate simulation test chamber (8), and maintain the humidity at w through the humidity controller (12).

[0042] S2: Keep the environmental conditions in the climate simulation test chamber (8) unchanged. Close the switch (5), and send a control signal to the industrial frequency voltage controller (2) through the host computer (1) to make the industrial frequency voltage generator (3) perform a constant voltage boost on the composite insulator sample (9). Boost the voltage by ΔU every Δt time, and perform a total of N voltage boosts. Record the time t and the voltage U of the industrial frequency voltage generator at this time after each voltage boost. 1 Then, measure the voltage U 2 and current I c of the composite insulator sample (9) at this time by the high-precision voltage divider (6) and the current test coil (10), and return them to the host computer (1) through the experimental data collection unit (16). Disconnect the switch (5).

[0043] S3: Obtain the calculated value I of the industrial frequency test current of the composite insulator sample (9) through the following formula i :

[0044]

[0045] In formula (1), t is the duration of the simulated environment, U2 To measure the voltage across the test sample, g is the error coefficient, and p is the integration variable;

[0046] S4: Use an optimization algorithm to optimize the modeling of formula (1) to obtain the g value that minimizes the error. The specific steps are as follows: k The value, and the specific steps are as follows:

[0047] 1) Randomly generate an initial solution δ and calculate the objective function f(δ):

[0048]

[0049] In formula (2), f(δ) represents the objective function, I cm is the measured value of the mth power frequency current, I im is the calculated value of the mth power frequency current, and N is the number of tests;

[0050] 2) Generate a perturbed new solution δ' and calculate the objective function Δf = f(δ) - f(δ'); if Δf ≥ 0, accept the new solution, otherwise, obtain the new solution according to the probability acceptance criterion;

[0051] 3) Determine whether the iteration number has been reached. If it has, go to step 4), otherwise, go to step 2);

[0052] 4) Determine whether the termination condition is satisfied. If it is, end the operation and output the optimal solution, otherwise, reset the iteration number and go to step 2);

[0053] S5: Substitute the g obtained in S4 k into formula (1) to obtain the calculation formula for the power frequency test current I' of the optimized ZnO varistor: i ' Calculation formula:

[0054]

[0055] S6: Calculate the deterioration state evaluation factor α of the composite outer insulator based on the optimized power frequency test current I' i ':

[0056]

[0057] In formula (4), I i ' is the optimized power frequency test current, and N is the number of tests;

[0058] S7: Evaluate based on the deterioration state evaluation factor α of the composite outer insulator obtained from the above steps. When α ∈ (0, 1], it indicates that the composite outer insulator has no deterioration; when α ∈ (1, 2], it indicates that the composite outer insulator has slight deterioration; when α ∈ (2, +∞), it indicates that the composite outer insulator has serious deterioration.

Claims

1. A method for evaluating the degradation state of composite outer-rod insulators considering extreme cold snap environments It is characterized in that First, a test and evaluation platform is built, and the platform includes: a host computer (1), a power frequency voltage controller (2), a power frequency voltage generator (3), a high-voltage coaxial cable (4), a switch (5), a high-precision voltage divider (6), a first high-voltage test electrode (71), a second high-voltage test electrode (72), a climate simulation test chamber (8), a composite outer-rod insulator test sample (9), a current test coil (10), a grounding grid (11), a humidity controller (12), a first humidifier (131), a second humidifier (132), a total temperature control terminal (14), an ambient temperature regulator (15), an experimental data acquisition unit (16), a first grounding device (171), and a second grounding device (172); The host computer (1) is connected to the input end of the power frequency voltage controller (2), the output end of the power frequency voltage controller (2) is connected to the input end of the power frequency voltage generator (3), the output end of the power frequency voltage generator (3) is connected to the right end of the switch (5) via the high-voltage coaxial cable (4), the left end of the switch (5) is connected to the input end of the high-precision voltage divider (6), the input end of the high-precision voltage divider (6) is connected to the first high-voltage test electrode (71), the first high-voltage test electrode (71) is connected to the upper end of the composite outer-rod insulator test sample (9), the lower end of the composite outer-rod insulator test sample (9) is connected to the second high-voltage test electrode (72), the second high-voltage test electrode (72) is connected to the grounding grid (11), and the current test coil (10) is sleeved between the second high-voltage test electrode (72) and the grounding grid (11); The signal ends of the high-precision voltage divider (6) and the current test coil (10) are connected to the input end of the experimental data collection unit (16), and the output end of the experimental data collection unit (16) is connected to the host computer (1); The grounding end of the power frequency voltage generator (3) is connected to the first grounding device (171), and the grounding end of the high-precision voltage divider (6) is connected to the second grounding device (172); The input end of the humidity controller (12) is connected to the host computer (1), the output end of the humidity controller (12) is connected to the first humidifier (131) and the second humidifier (132), the input end of the total temperature control terminal (14) is connected to the host computer (1), and the output end of the total temperature control terminal (14) is connected to the ambient temperature regulator (15); The composite outer-rod insulator test sample (9), the first humidifier (131), the second humidifier (132), the ambient temperature regulator (15), the first high-voltage test electrode (71), and the second high-voltage test electrode (72) are all placed inside the climate simulation test chamber (8); A method for evaluating the degradation state of composite outer-rod insulators considering extreme cold snap environments includes the following steps: S1: Send a control signal to the temperature control terminal (14) through the host computer (1) to make the environmental temperature regulator (15) cool down the climate simulation test chamber (8), and maintain this temperature when the temperature drops to T; then send a control signal to the humidity controller (12) through the host computer (1) to make the humidifier 1 (131) and the humidifier 2 (132) humidify the environment of the climate simulation test chamber (8), and maintain the humidity at w through the humidity controller (12); S2: Keep the environmental conditions in the climate simulation test chamber (8) unchanged. Close the switch (5), and send a control signal to the power frequency voltage controller (2) through the host computer (1), so that the power frequency voltage generator (3) performs a constant voltage boost on the composite outer insulator test sample (9). Boost the voltage by ΔU every Δt time, and perform a total of N voltage boosts. Record the time t and the voltage U of the power frequency voltage generator at this time after each voltage boost 1 , and then measure the voltage U of the composite outer insulator test sample (9) at this time by the high-precision voltage divider (6) and the current test coil (10) 2 and the power frequency current I c , and return them to the host computer (1) through the experimental data collection unit (16); disconnect the switch (5). S3: Obtain the calculated value I of the power frequency test current of the composite insulator sample (9) through the following formula i : In Equation (1), t is the duration of the simulation environment, U 2 is the voltage measured across the test sample, g is the error coefficient, and p is the integration variable; S4: Use an optimization algorithm to optimize and model formula (1) to obtain the value of g that minimizes the error. The specific steps are as follows: k The value, the specific steps are as follows: 1) Randomly generate the initial solution δ and calculate the objective function f(δ): In formula (2), f(δ) represents the objective function, and I cm is the measured value of the m-th power frequency current, and I im is the calculated value of the m-th power frequency test current, and N is the number of tests; 2) Generate a perturbed new solution δ', and calculate the objective function Δf = f(δ) - f(δ'); if Δf ≥ 0, accept the new solution, otherwise, obtain the new solution according to the probability acceptance criterion; 3) Determine whether the iteration times are reached. If so, go to step 4), otherwise, go to step 2); 4) Determine whether the termination condition is satisfied. If so, end the operation and output the optimal solution, otherwise reset the iteration times and go to step 2); S5: Substitute the g obtained in S4 k into formula (1) to obtain the power frequency test current I of the optimized ZnO varistor i Calculation formula: S6: Based on the optimized power frequency test current I i ' Calculate the deterioration state evaluation factor α of the composite insulator: I in Equation (4) i ' is the optimized power frequency test current, and N is the number of tests; S7: Evaluate based on the degradation state evaluation factor α of the composite outer insulator obtained from the above steps. When α ∈ (0, 1], it indicates that the composite outer insulator has no degradation; when α ∈ (1, 2], it indicates that the composite outer insulator is slightly degraded; when α ∈ (2, +∞), it indicates that the composite outer insulator is severely degraded.

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