Method and system for estimating moisture state of oil paper insulation sample of power equipment

Abstract

The invention provides a power equipment oil paper insulation sample moisture state estimation method and system, and belongs to the field of insulation performance monitoring and management.The method comprises the steps that the water content corresponding relation between oil and paper in the heating / cooling process is obtained based on an Oommen curve, and a heating and cooling asymmetric kinetic equation is obtained based on fitting of the water content corresponding relation between the oil and the paper; a core kinetic equation is constructed based on a kinetic equation with asymmetrical temperature rise and temperature drop, a temperature-dependent time constant equation and a rate-dependent equation. And substituting the temperature change at different moments and the water content change of the insulating oil into a core kinetic equation for calculation to obtain the water content in the insulating paper. And a technical support is provided for moisture state evaluation and equipment life management of the oil paper insulation system.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of insulation performance monitoring and management, and particularly relates to a moisture state estimation method and system for oil-paper insulation samples of power equipment. BACKGROUND

[0002] During long-term service, the oil-paper insulation system inevitably suffers from the combined action of heat, electricity, mechanics and chemistry, among which the introduction of moisture is considered as one of the key factors to accelerate the aging of oil-paper insulation, reduce the dielectric strength and thermal stability thereof. Therefore, the evaluation of the moisture state of oil-paper insulation is of great significance to ensure the safe and stable operation of key power equipment such as transformers.

[0003] However, the existing evaluation of the moisture state of oil-paper insulation usually only considers static balance, calculates the moisture in paper by using the oil-paper water balance curve, but assumes that the oil-paper system is always in thermodynamic equilibrium, ignoring the non-equilibrium effect and hysteresis phenomenon when the temperature changes rapidly. Or a single curve is used without distinguishing between the heating and cooling processes, but the water distribution between oil and paper has obvious hysteresis and heating-cooling asymmetry. At the same time, in actual transformer operation, frequent temperature fluctuations caused by load and cooling conditions cannot be accurately described by static conversion methods, resulting in large prediction errors and insufficient dynamic prediction capability. SUMMARY

[0004] In order to solve the problems in the prior art in the evaluation of the moisture state of oil-paper insulation, the application provides a moisture state estimation method and system for oil-paper insulation samples of power equipment.

[0005] In order to achieve the above-mentioned purpose, the application provides the following technical scheme: A moisture state estimation method for oil-paper insulation samples of power equipment, comprising the following steps: Based on the water balance curve of insulating oil and insulating paper, the corresponding relationship between the moisture content of insulating oil and insulating paper in the heating and cooling processes is obtained, and a dynamic equation with heating and cooling asymmetry is fitted based on the corresponding relationship; Temperature change data of oil-paper moisture diffusion are obtained, a temperature-dependent time constant equation is constructed, a rate-dependent equation is constructed based on a rate sensitivity coefficient and the temperature change data, and a dynamic core kinetic equation is constructed based on the dynamic equation with heating and cooling asymmetry, the temperature-dependent time constant equation and the rate-dependent equation; wherein the temperature change data are temperature and temperature diffusion rate; The temperature change data and the water content change data of the insulating oil of the oil-paper insulation sample in the set time period are obtained, the derivative of the dynamic core kinetic equation with respect to time is transformed, the temperature change data and the water content change data of the insulating oil of the oil-paper insulation sample in the set time period are substituted into the transformed dynamic core kinetic equation, and the water content change data of the insulating paper in the set time period is obtained.

[0006] Preferably, the temperature-dependent time constant equation is specifically as follows: represents the water content of the insulating paper; represents the water content of the insulating oil; and T represents the temperature. , , , and are fitting parameters.

[0007] Preferably, the temperature-dependent time constant equation is specifically as follows: wherein τ represents a time constant; represents a time constant calibration parameter; represents a temperature diffusion rate parameter, T represents the temperature of the water diffusion of the oil-paper, and is the aging degree of the insulating material.

[0008] Preferably, the rate-dependent equation is specifically as follows: wherein is a rate-sensitive coefficient of the water migration between the oil and the paper; sign(dT / dt) is a symbol for judging the temperature change rate dT / dt, and linear-saturation , saturation parameter.

[0009] Preferably, the dynamic core kinetic equation is specifically as follows: wherein is the temperature-dependent time constant equation. is the temperature-dependent time constant equation.

[0010] The application further provides an oil-paper insulation sample water content state estimation system of a power equipment, and specifically comprises: ​​​​​The data processing module is used to obtain the relationship between the moisture content of insulating oil and insulating paper during the heating and cooling process based on the water balance curve of insulating oil-insulating paper, and to fit the relationship between the moisture content to obtain the kinetic equation for the asymmetry of heating and cooling.

[0011] The mathematical model module is used to acquire temperature change data of moisture diffusion in oil paper and construct a temperature-dependent time constant equation; construct a rate-dependent equation based on the rate sensitivity coefficient and the temperature change data; and construct a dynamic core dynamic equation based on the kinetic equation of temperature rise and fall asymmetry, the temperature-dependent time constant equation, and the rate-dependent equation; wherein, the temperature change data is temperature and temperature diffusion rate.

[0012] The state estimation module is used to acquire temperature change data and insulating oil moisture content change data of the oil-paper insulation sample to be tested within a set time period. It transforms the time derivative of the dynamic core dynamic equation, and substitutes the temperature change data and insulating oil moisture content change data of the oil-paper insulation sample to be tested within the set time period into the transformed dynamic core dynamic equation to obtain the moisture content change data of the insulation paper within the set time period.

[0013] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps described in the method for estimating the moisture state of oil-paper insulation samples of power equipment.

[0014] The present invention also provides a computer-readable storage medium storing a computer program, which, when loaded by a processor, is capable of executing the steps described in the method for estimating the moisture state of oil-paper insulation samples for power equipment.

[0015] The method for estimating the moisture state of oil-paper insulation samples for power equipment provided by this invention has the following beneficial effects: This invention extends the oil-paper moisture balance curve into two independent sets of kinetic equations for heating and cooling. Under dynamic temperature scenarios, this improves the accuracy of equilibrium value prediction and avoids misjudgments of moisture state due to neglecting asymmetry. Temperature-dependent time constant equations and rate-dependent equations are constructed to dynamically adapt to different parameter change conditions. Based on the kinetic equations, temperature-dependent time constant equations and rate-dependent equations are introduced to obtain the dynamic core kinetic equation, characterizing the non-equilibrium hysteresis effect under rapid temperature changes. The moisture content in the insulating paper at different times is obtained, enabling dynamic prediction of moisture in the paper and providing a more reliable technical tool for the condition assessment of oil-paper insulation equipment. Attached Figure Description

[0016] To more clearly illustrate the embodiments and design schemes of the present invention, the accompanying drawings required for this embodiment will be briefly described below. 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.

[0017] Figure 1 This is the water balance curve of insulating oil and insulating paper in an embodiment of the present invention, namely the Oommen curve.

[0018] Figure 2 This is a flowchart of a method for estimating the moisture state of oil-paper insulation samples for power equipment, as described in an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0020] Example This invention provides a method for estimating the moisture state of oil-paper insulation samples for power equipment, specifically: according to Figure 1 The oil-paper water balance curve shown yields the oil-paper water balance relationship. Fitting the curve in the figure, the asymmetric kinetic equation for the rise / fall is obtained:

[0021] (1); in, Represents the moisture content (%) of the insulating paper. The value represents the moisture content of the insulating oil (ppm), and T represents the temperature (°C). This function represents the static equilibrium value of the paper at a given temperature and oil moisture content (different values ​​for temperature rise and temperature fall). After fitting, the fitting parameters for temperature rise and temperature fall are obtained separately:

[0022] Heating (0-100℃): =3.025918448、 =0.149909805、 =−0.045486424、 =−0.000883233730、 =−0.000619285242.

[0023] Temperature drop (100-0℃): =3.234230071、 =0.153623334、 =−0.048036938、 =−0.000865945084、 =−0.000651814186.

[0024] To address the dynamic changes of the non-equilibrium hysteresis effect under rapid temperature variations, two key modules are added to the traditional aquifer dynamics equations to construct temperature-dependent time constant equations and rate-dependent equations. Specifically: (1) Temperature-dependent time constant equation based on temperature and temperature diffusion rate data: (2); Where τ represents the time constant; Represents the time constant calibration parameter; The temperature diffusion rate parameter is calculated from experimental data. This equation describes the rate of change of oil-paper moisture recovery / diffusion rate with temperature.

[0025] (2) Rate dependence equation: (3); in, This is the rate sensitivity coefficient; sign(dT / dt) is the sign used to determine the rate of temperature change dT / dt. When the temperature rises (dT / dt > 0), sign(dT / dt) = 1; when the temperature falls (dT / dt < 0), sign(dT / dt) = -1. Linear-saturated (This avoids excessively large values ​​at extremely high rates). This equation characterizes the lag or "offset" in oil-paper distribution when the temperature changes rapidly (physical causes: diffusion lag, bubble release, local desorption, etc.), and makes corresponding corrections to the non-equilibrium deviation depending on whether the temperature rises or falls.

[0026] Substituting formulas (1), (2), and (3) into (4), we construct the dynamic core dynamic equation: (4); in, It is an asymmetric kinetic equation for temperature rise / fall, where s represents the direction of heating or cooling (s=1 for heating, s=−1 for cooling); dT / dt is the rate of temperature change. This equation is a complete model of the evolution of paper moisture content over time and can be used to predict short-term non-equilibrium dynamics.

[0027] The derivative of time in formula (4) was transformed, and the moisture content in the insulating paper was obtained by solving for it: (5); Where T represents temperature. W indicates the water content of insulating oil. p(t+Δt) represents the moisture content of the insulating paper at the next moment, τ(T) is the temperature-dependent time constant equation, and Δt represents the time step (the time taken from the initial state to the current state). Ultimately, the outputs are the temperature, the moisture content in the oil, and the rate of temperature change, followed by the moisture content of the insulating paper.

[0028] Substituting the temperature changes and the moisture content changes of the insulating oil at different times into formula (5) yields the process of moisture content change of the insulating paper.

[0029] The above scheme will be further illustrated with two specific examples.

[0030] Implementation Case 1: Using a micro-moisture sensor and an oil temperature sensor to continuously monitor the temperature and insulating oil moisture content of an oil-immersed transformer, the temperature T gradually increased from 61.2℃ to 80.1℃, and the insulating oil moisture content increased from 42.5ppm to 57.8ppm. Substituting these values ​​into the following formula, the moisture content in the insulating paper can be calculated: ; =3.025918448、 =0.149909805、 =−0.045486424、 =−0.000883233730、 =−0.000619285242、 =5.904817 min; =0.0188361(1 / °C); γ↑=0.151205; γ↓=6.251542*10^(-7); =88.29786.

[0031] The final calculation yields the process of moisture content change in the insulating paper, i.e., the predicted value of moisture content change. This is not determined by instrument detection, as it is difficult to measure the moisture content of insulating paper that has been soaked in oil using instruments alone. As shown in Table 1:

[0032] Table 1. Changes in moisture content of insulating paper in Implementation Case 1 Implementation Case 2: Using a micro-moisture sensor and an oil temperature sensor to continuously monitor the temperature and insulating oil moisture content of an oil-immersed transformer, the temperature T gradually decreased from 87℃ to 41℃, and the insulating oil moisture content decreased from 51.5ppm to 33.7ppm. Substituting these values ​​into the following formula, the moisture content in the insulating paper can be calculated: ; =3.025918448、 =0.149909805、 =−0.045486424、 =−0.000883233730、 =−0.000619285242、 =5.904817 min; =0.0188361(1 / °C); γ↑=0.151205; γ↓= 6.251542*10^(-7); =88.29786. The final calculation yields the change process of the moisture content of the insulating paper, as shown in Table 2: Table 2. Changes in moisture content of insulating paper in Implementation Case 2 This invention also provides a system for estimating the moisture state of oil-paper insulation samples for power equipment, comprising: The data processing module is used to obtain the relationship between the moisture content of insulating oil and insulating paper during the heating and cooling process based on the water balance curve of insulating oil-insulating paper, and to obtain the dynamic equation of the asymmetry between heating and cooling by fitting the relationship between moisture content.

[0033] The mathematical model module is used to acquire temperature change data of moisture diffusion in oil paper and construct a temperature-dependent time constant equation; a rate-dependent equation is constructed based on the rate sensitivity coefficient and temperature change data; and a dynamic core kinetic equation is constructed based on the kinetic equations of temperature rise and fall asymmetry, the temperature-dependent time constant equation, and the rate-dependent equation; wherein, the temperature change data are temperature and temperature diffusion rate.

[0034] The state estimation module is used to acquire temperature change data and insulating oil moisture content change data of the oil-paper insulation sample to be tested within a set time period. It transforms the dynamic core dynamic equation by calculating the time derivative, and substitutes the temperature change data and insulating oil moisture content change data of the oil-paper insulation sample to be tested within the set time period into the transformed dynamic core dynamic equation to obtain the moisture content change data of the insulating paper within the set time period.

[0035] The modules in the aforementioned system for estimating the moisture state of oil-paper insulation samples for power equipment can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, so that the processor can call and execute the corresponding operations of each module.

[0036] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to implement the steps in an embodiment of a method for estimating the moisture state of oil-paper insulation samples for power equipment. Specific implementation methods can be found in the method embodiments, and will not be repeated here.

[0037] Furthermore, the present invention also provides a non-transitory computer-readable storage medium containing instructions, on which a computer program is stored. For example, a memory containing instructions that can be executed by a processor of a computer device to perform the above-described method. For example, the non-transitory computer-readable storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device, etc. When the computer program is executed by the processor, it can implement the steps in an embodiment of a method for estimating the moisture state of oil-paper insulation samples for power equipment. Specific implementation methods can be found in the method embodiments, which will not be repeated here.

[0038] Those skilled in the art will understand that embodiments of the present invention can provide 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.

[0039] 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, as well as 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... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0040] 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.

[0041] 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.

[0042] It should be noted that the specific embodiments described above enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. Therefore, although the present invention has been described in detail in this specification and embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention; and all technical solutions and improvements that do not depart from the spirit and scope of the present invention are covered within the protection scope of the present invention patent. No reference numerals in the claims should be construed as limiting the scope of the claims. Any simple variations or equivalent substitutions of technical solutions that can be readily obtained by those skilled in the art within the scope of the technology disclosed in the present invention are within the protection scope of the present invention.

Claims

1. A method for estimating the moisture state of oil-paper insulation samples for power equipment, characterized in that, Includes the following steps: The relationship between the water content of insulating oil and insulating paper during the heating and cooling processes is obtained based on the water balance curve of insulating oil-insulating paper. The dynamic equation of the asymmetry between heating and cooling is obtained by fitting the relationship between the water content. Acquire temperature change data of moisture diffusion in oiled paper and construct a temperature-dependent time constant equation; construct a rate-dependent equation based on the rate sensitivity coefficient and the temperature change data; construct a dynamic core kinetic equation based on the kinetic equation of temperature rise and fall asymmetry, the temperature-dependent time constant equation, and the rate-dependent equation; wherein, the temperature change data is temperature and temperature diffusion rate. The temperature change data and the moisture content change data of the oil-paper insulation sample to be tested within a set time period are obtained. The time derivative of the dynamic core kinetic equation is transformed. The temperature change data and the moisture content change data of the oil-paper insulation sample to be tested within the set time period are substituted into the transformed dynamic core kinetic equation to obtain the moisture content change data of the insulation paper within the set time period.

2. The method for estimating the moisture state of oil-paper insulation samples for power equipment according to claim 1, characterized in that, The kinetic equations for the asymmetric heating and cooling are as follows: ； in, This represents the moisture content of the insulating paper; The value represents the water content of the insulating oil; T represents the temperature. , , , and All of these are fitting parameters.

3. The method for estimating the moisture state of oil-paper insulation samples for power equipment according to claim 2, characterized in that, The temperature-dependent time constant equation is as follows: ； Where τ represents the time constant; Represents the time constant calibration parameter; The parameter representing the temperature diffusion rate, where T represents the temperature at which moisture diffuses through the oiled paper. This indicates the degree of aging of the insulation material.

4. The method for estimating the moisture state of oil-paper insulation samples for power equipment according to claim 3, characterized in that, The rate dependence equation is as follows: ； in, It is the rate sensitivity coefficient for moisture migration between oil and paper; sign(dT / dt) is the sign used to determine the rate of temperature change dT / dt, linear-saturated. , Saturation parameter.

5. The method for estimating the moisture state of oil-paper insulation samples for power equipment according to claim 4, characterized in that, The dynamic core dynamic equations are as follows: ； in, It is the kinetic equation for asymmetric heating and cooling, where s=1 represents the direction of heating and s=−1 represents the direction of cooling; dT / dt is the rate of temperature change, and sign() is a function to determine the rate of temperature change. This is a temperature-dependent time constant equation.

6. A system for estimating the moisture state of oil-paper insulation samples for power equipment, characterized in that, include: The data processing module is used to obtain the relationship between the moisture content of insulating oil and insulating paper during the heating and cooling process based on the water balance curve of insulating oil-insulating paper, and to fit the relationship between the moisture content to obtain the dynamic equation of the asymmetry between heating and cooling. The mathematical model module is used to acquire temperature change data of moisture diffusion in oiled paper and construct a temperature-dependent time constant equation; construct a rate-dependent equation based on the rate sensitivity coefficient and the temperature change data; and construct a dynamic core dynamic equation based on the kinetic equation of temperature rise and fall asymmetry, the temperature-dependent time constant equation, and the rate-dependent equation; wherein, the temperature change data is temperature and temperature diffusion rate. The state estimation module is used to acquire temperature change data and insulating oil moisture content change data of the oil-paper insulation sample to be tested within a set time period. It transforms the time derivative of the dynamic core dynamic equation, and substitutes the temperature change data and insulating oil moisture content change data of the oil-paper insulation sample to be tested within the set time period into the transformed dynamic core dynamic equation to obtain the moisture content change data of the insulation paper within the set time period.

7. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is loaded by the processor, it is able to perform the steps of the method according to any one of claims 1 to 5.

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