Dynamic prediction method and system for service life of insulating material of generator

Abstract

The invention discloses a dynamic prediction method and system for the service life of an insulating material of a generator. The method comprises the steps of obtaining electrical test data of a whole-phase winding of a generator stator; judging the aging stage of the insulating material of the generator according to the result of the electrical test data; and obtaining the residual life of the generator insulating material according to the characteristic parameters of different aging stages. According to the characteristics of different aging stages, a refined calculation model is adopted, and the accuracy of residual life prediction is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular, to a method and system for dynamically predicting the life of generator insulation materials. Background Art

[0002] During the operation of large generators, affected by the operating state and environment, the stator insulation is prone to damage, leading to generator failures. The prediction of the life of stator insulation materials, which has been a research hotspot for many years, is also an important way to improve the operating stability of generators. Many studies on the prediction of the life of generator insulation materials have been carried out at home and abroad. IEC proposes that the life of the stator coil insulation of rotating electrical machines is determined by the percentage reduction of the minimum value of the remaining breakdown voltage compared to the initial value. When the remaining breakdown voltage drops to 50% of the initial value, it is the end of the life.

[0003] The aging process of generator epoxy mica insulation is a complex process affected by various factors, usually including three stages: the initial stage, the middle stage, and the late stage of aging. In the initial stage of aging, under the action of an electric field, the charges inside the insulation material will undergo polarization and migration. At this time, the dielectric properties of the epoxy mica insulation material are relatively good, the charge injection and detrapping currents are small, and partial discharges are not obvious. As the thermal aging time extends, the macromolecules of epoxy resin break chains, forming more small molecules and free polar groups. This will lead to a decrease in the adhesion between epoxy resin and mica, the appearance of more air gaps, and the existing air gaps will gradually merge into sheets. The impurities generated by aging and the larger air gaps will introduce more traps, enhancing the trapping effect of traps on charges, resulting in an increase in the number of trapped charges, an increase in the trap charge density, and an increase in the trap depth. In the late stage of aging, under the continuous action of thermal stress, the degree of deterioration of epoxy resin further deepens, the structural strength of the molecular chain significantly decreases, and the thermal stability decreases. The initial decomposition temperature of the epoxy resin in the insulation gradually decreases, indicating that its thermal stability becomes worse. At this time, the air gap defects inside the insulation significantly increase in number and volume, the partial discharge inception voltage decreases, and the partial discharge phase distribution spectrum shows an increase in discharge quantity, an increase in discharge times, and a wider discharge phase, and the dielectric properties of the insulation significantly decline. Summary of the Invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a method and system for dynamically predicting the life of generator insulation materials to solve the problem that the existing methods cannot accurately reflect the change trend of insulation performance during the entire aging process.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for dynamically predicting the life of a generator insulation material, including:

[0008] Obtaining electrical test data of the entire-phase winding of the generator stator;

[0009] Judging the aging stage of the generator insulation material according to the results of the electrical test data;

[0010] Obtaining the remaining life of the generator insulation material according to the characteristic parameters of different aging stages.

[0011] As a preferred embodiment of the method for dynamically predicting the life of the generator insulation material according to the present invention, wherein:

[0012] The electrical test data of the entire-phase winding of the generator stator includes partial discharge quantity, tangent value of dielectric loss angle, ground capacitance value, and blue light whiteness value.

[0013] As a preferred embodiment of the method for dynamically predicting the life of the generator insulation material according to the present invention, wherein:

[0014] The judging of the aging stage of the generator insulation material includes:

[0015] When the partial discharge quantity under the test voltage satisfies 1500 pC ≤ Q m ≤ 5000 pC, the generator insulation material is in the initial stage of aging;

[0016] When the partial discharge quantity under the test voltage satisfies 5000 pC < Q m ≤ 20000 pC, the generator insulation material is in the middle stage of aging;

[0017] When the partial discharge quantity Q m > 20000 pC, the generator insulation material is in the late stage of aging.

[0018] As a preferred embodiment of the method for dynamically predicting the life of the generator insulation material according to the present invention, wherein:

[0019] The initial stage of aging includes:

[0020] Calculating a first ratio based on the partial discharge quantity and logarithmic function conversion;

[0021] Obtaining the remaining life of the generator insulation material in the initial stage of aging according to the first ratio;

[0022] The first ratio is expressed as:

[0023] K 1 = 12.8335 - 2.4667 × lg Q m

[0024] The remaining life at the initial stage of the aging of the generator insulation material is expressed as:

[0025]

[0026] where N is the operating time of the generator.

[0027] As a preferred solution of the dynamic prediction method for the life of the generator insulation material described in the present invention, wherein:

[0028] The middle aging stage includes:

[0029] Calculating the increment of the tangent value of the dielectric loss angle;

[0030] Calculating the increment of the capacitance to ground;

[0031] Calculating the second ratio based on the partial discharge quantity and logarithmic function conversion;

[0032] Obtaining the remaining life of the generator insulation material in the middle aging stage according to the increment of the tangent value of the dielectric loss angle, the increment of the capacitance to ground and the second ratio;

[0033] The second ratio is expressed as:

[0034] K 2 = 1.1825×(12.8335 - 2.4667×lg Q m )

[0035] The increment of the tangent value of the dielectric loss angle is expressed as:

[0036] Δtanδ = tanδ E -tanδ 0

[0037] where tanδ E is the tangent value of the dielectric loss angle under the rated voltage, and tanδ 0 is the tangent value of the dielectric loss angle under 20% of the rated voltage;

[0038] The increment of the capacitance to ground is expressed as:

[0039] ΔC = C E -C 0

[0040] where C E is the capacitance value to ground under the rated voltage of the generator, and C 0 is the capacitance value under 20% of the rated voltage;

[0041] The remaining life of the generator insulation material in the middle aging stage is expressed as:

[0042]

[0043] As a preferred embodiment of the dynamic prediction method for the life of the generator insulation material described in the present invention, wherein:

[0044] The late aging stage includes:

[0045] Calculating a third ratio based on the partial discharge quantity and logarithmic function conversion;

[0046] Obtaining the remaining life of the generator insulation material in the late aging stage according to the blue light whiteness value and the third ratio;

[0047] The third ratio is expressed as:

[0048] K 3 = 1.3360×(12.8335 - 2.4667×lg Q m )

[0049] The remaining life of the generator insulation material in the late aging stage is expressed as:

[0050]

[0051] As a preferred embodiment of the dynamic prediction method for the life of the generator insulation material described in the present invention, wherein:

[0052] The second ratio includes an adjustment based on the partial discharge quantity through a first correction coefficient;

[0053] The third ratio includes an adjustment based on the partial discharge quantity through a second correction coefficient.

[0054] In a second aspect, the present invention provides a dynamic prediction system for the life of a generator insulation material, including:

[0055] An electrical test data acquisition module for acquiring electrical test data of the entire phase winding of the generator stator;

[0056] An aging state evaluation module for judging the aging stage of the generator insulation material according to the result of the electrical test data;

[0057] A remaining life prediction module for obtaining the remaining life of the generator insulation material according to the characteristic parameters of different aging stages.

[0058] In a third aspect, the present invention provides a computing device, including:

[0059] A memory for storing programs;

[0060] A processor for executing the computer-executable instructions, and when the computer-executable instructions are executed by the processor, the steps of the dynamic prediction method for the life of the generator insulation material are implemented.

[0061] In a fourth aspect, the present invention provides a computer-readable storage medium, including: when the program is executed by a processor, the steps of implementing the method for dynamically predicting the life of the generator insulation material are realized.

[0062] Advantages of the present invention: By collecting a variety of electrical test data, the present invention comprehensively reflects the aging condition of the insulation material, avoids misjudgment caused by single-parameter evaluation, adopts a refined calculation model according to the characteristics of different aging stages, significantly improves the accuracy of predicting the remaining life, identifies potential problems in advance, takes measures in a timely manner, ensures the equipment operates in the best state, and improves the overall operation safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0064] Figure 1 is a schematic diagram of the basic process for a method for dynamically predicting the life of a generator insulation material provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0065] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the drawings of the specification. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0066] Embodiment 1

[0067] Referring to Figure 1 , an embodiment of the present invention provides a method for dynamically predicting the life of a generator insulation material, including:

[0068] S1: Obtain electrical test data of the entire-phase winding of the generator stator;

[0069] In the embodiment of the present application, the prediction of the life of the generator insulation material is carried out during the A-class overhaul of the generator. During the A-class overhaul of the generator, an off-line partial discharge test, a dielectric loss angle and capacitance measurement test, and a blue light whiteness measurement test are carried out on the entire-phase winding of the generator stator. The interval years for the A-class overhaul of the generator are usually 4 to 6 years. Each time an A-class overhaul is carried out, the life of the generator insulation material is predicted once.

[0070] In the embodiments of the present application, the off-line partial discharge test includes measuring the partial discharge quantity (pC) under the test voltage The dielectric loss angle and capacitance measurement test includes measuring the tangent value of the dielectric loss angle tanδ E at the rated voltage and the tangent value of the dielectric loss angle tanδ 0 at 20% of the rated voltage, as well as the corresponding capacitance values C E and C 0 (unit: pF). The blue light whiteness measurement test includes measuring the blue light whiteness value L of the generator insulating material.

[0071] S2: According to the results of the electrical test data, determine the aging stage of the generator insulating material;

[0072] In the embodiments of the present application, in the off-line partial discharge test of the stator integral phase winding during the Class A overhaul of the generator, when the partial discharge quantity of the generator is greater than or equal to 1500 pC and less than or equal to 5000 pC under the test voltage , it is determined that the generator insulation is in the initial stage of aging. U n is the rated voltage value, with the unit of kV.

[0073] In the embodiments of the present application, when the generator insulating material is in the initial stage of aging, calculate the first ratio expressed as:

[0074] K 1 = 12.8335 - 2.4667×lgQ m

[0075] where K 1 represents the first ratio, which is used for subsequent calculation of the remaining life of the generator insulating material. Specifically, it is a coefficient that comprehensively reflects the influence of the partial discharge quantity on the insulation state; 12.8335 represents the first constant term, which is used to adjust the calculation result to match the insulation state evaluation in the actual situation, and this constant value is obtained based on historical experience; 2.4667 represents the second constant term, which is multiplied by the logarithm (base 10) of the partial discharge quantity to adjust the influence degree of the partial discharge quantity on the insulation state, and this coefficient is also determined through historical experience; lg represents the logarithm function with base 10, and the use of the logarithm function here is to better describe the non-linear relationship between the partial discharge quantity and the insulation state; Q m is the partial discharge quantity of the generator under the test voltage , pC. The partial discharge quantity reflects the number and severity of the micro-defects inside the insulating material. A higher partial discharge quantity usually means that there are more or larger defects in the insulating material, which may lead to faster aging and failure. The above constant terms are used to adjust and calibrate the calculation results.

[0076] The calculated remaining life at the initial stage of the generator insulation material aging is expressed as:

[0077]

[0078] Where N is the operating time of the generator in years.

[0079] In the embodiment of the present application, the initial stage of the generator insulation material aging includes calculating the first ratio K based on the partial discharge quantity 1 , and estimating the remaining life accordingly.

[0080] In the embodiment of the present application, the first ratio K 1 is used for the initial stage of the generator insulation material aging, and is directly calculated based on the partial discharge quantity Q m , without additional correction terms.

[0081] In the embodiment of the present application, in the off-line partial discharge test of the stator integral phase winding during the Class A overhaul of the generator, when the partial discharge quantity of the generator is greater than 5000 pC and less than or equal to 20000 pC under the test voltage , it is determined that the generator insulation is in the middle stage of aging.

[0082] In the embodiment of the present application, when the generator insulation material is in the middle stage of aging, the calculated increment value of the tangent of the dielectric loss angle is expressed as:

[0083] Δtanδ = tanδ E -tanδ 0

[0084] Where tanδ E is the tangent of the dielectric loss angle at the rated voltage, and tanδ 0 is the tangent of the dielectric loss angle at 20% of the rated voltage.

[0085] In the embodiment of the present application, when the generator insulation material is in the middle stage of aging, the calculated increment of the generator-to-earth capacitance is expressed as:

[0086] ΔC = C E -C 0

[0087] Where C E is the generator-to-earth capacitance value at the rated voltage of the generator, and C 0 is the capacitance value at 20% of the rated voltage, in pF.

[0088] In the embodiment of the present application, when the generator insulation material is in the middle stage of aging, the calculated second ratio is expressed as:

[0089] K 2= 1.1825×(12.8335 - 2.4667×lg Q m )

[0090] Then, the remaining life in the middle stage of the generator insulation material aging can be further calculated and expressed as:

[0091]

[0092] Wherein, N is the operating time of the generator, in years.

[0093] In the embodiment of the present application, the middle stage of the generator insulation material aging includes evaluating the insulation state by using the changes in the dielectric loss angle and the capacitance to ground, and calculating the second ratio K in combination with these changes 2 , for estimating the remaining life.

[0094] In the embodiment of the present application, the second ratio K 2 is used for the middle stage of the generator insulation material aging, based on the partial discharge quantity Q m and multiplied by the first correction factor (1.1825), and corrected by combining the changes in the dielectric loss angle and the capacitance to ground.

[0095] In the embodiment of the present application, in the off-line partial discharge test of the stator integral phase winding during the Class A overhaul of the generator, when the partial discharge quantity of the generator is greater than 20000 pC under the test voltage , it is determined that the generator insulation is in the late stage of aging.

[0096] In the embodiment of the present application, when the generator insulation material is in the late stage of aging, the blue light whiteness measurement test obtains the blue light whiteness value L, and the third ratio is calculated and expressed as:

[0097] K 3 = 1.3360×(12.8335 - 2.4667×lg Q m )

[0098] Then, the remaining life in the late stage of the generator insulation material aging can be further calculated and expressed as:

[0099]

[0100] Wherein, N is the operating time of the generator, in years.

[0101] In the embodiment of the present application, the late stage of the generator insulation material aging includes evaluating the insulation state by blue light whiteness measurement and calculating the third ratio K based on the blue light whiteness value 3 , for estimating the remaining life.

[0102] In the embodiment of the present application, the third ratio K 3For the late stage of generator insulation material aging, based on the partial discharge quantity Q m And multiply by the second correction factor (1.3360), and at the same time, correct it in combination with the blue light whiteness value L.

[0103] S3: Obtain the remaining life of the generator insulation material according to the characteristic parameters of different aging stages.

[0104] It should be noted that different correction factors (1, 1.1825, 1.3360 respectively) are used in each stage, and these factors reflect the different degrees of influence of the partial discharge quantity on the insulation state in different aging stages. Other parameters (such as dielectric loss angle, capacitance to ground, blue light whiteness value) are also introduced in the middle and late stages of aging to more comprehensively reflect the state of the insulation material. The calculation method of each stage is designed to capture the insulation characteristics unique to that stage, so as to improve the accuracy of prediction.

[0105] It should be noted that the insulation material in the present invention refers to Epoxy Mica. Epoxy Mica is a high-performance insulation material composed of mica flakes and epoxy resin. Due to its excellent electrical insulation performance, mechanical strength and heat resistance, it has been widely used in the insulation system of the whole-phase winding of the generator stator.

[0106] This embodiment also provides a dynamic prediction system for the life of generator insulation materials, including:

[0107] An electrical test data acquisition module, which is used to acquire the electrical test data of the whole-phase winding of the generator stator;

[0108] An aging state evaluation module, which is used to judge the aging stage of the generator insulation material according to the results of the electrical test data;

[0109] A remaining life prediction module, which is used to obtain the remaining life of the generator insulation material according to the characteristic parameters of different aging stages.

[0110] Furthermore, it also includes:

[0111] A memory, which is used to store programs;

[0112] A processor, which is used to load the program to execute the dynamic prediction method for the life of the generator insulation material.

[0113] This embodiment also provides a computer-readable storage medium, which stores a program, and when the program is executed by a processor, it implements the dynamic prediction method for the life of the generator insulation material.

[0114] The storage medium proposed in this embodiment and the method for dynamically predicting the life of the generator insulation material proposed in the above embodiment belong to the same inventive concept. Technical details not described in detail in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0115] From the above description of the embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software and necessary general hardware. Of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a floppy disk, read-only memory (ROM), random access memory (RAM), flash memory (FLASH), hard disk or optical disc of a computer, etc., including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods of various embodiments of the present invention.

[0116] Embodiment 2

[0117] This is an embodiment of the present invention, which provides a method for dynamically predicting the life of the generator insulation material. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through specific implementation methods and implementation effects.

[0118] The specific content of this embodiment is as follows:

[0119] Experiment 1:

[0120] When the life prediction of the generator insulation material is carried out along with the A-class overhaul of the generator, an off-line partial discharge test of the entire-phase stator winding of the generator is carried out. At the test voltage the partial discharge amount of the generator is 3000 pC. At this time, the generator has been running for 15 years, then K = 4.2565, and the remaining life of the generator insulation is 35.4 years.

[0121] Experiment 2:

[0122] When the life prediction of the generator insulation material is carried out along with the A-class overhaul of the generator, an off-line partial discharge test of the entire-phase stator winding of the generator is carried out. At the test voltage the partial discharge amount of the generator is 12000 pC. At this time, the generator has been running for 30 years, then K = 3.277. At the same time, C 0 = 0.239 μF, ΔC = 2.6 nF, tanδ E = 2.92%, tanδ 0= 1.19%, the remaining life of the generator insulation is 10.2 years.

[0123] Experiment 3:

[0124] When the life prediction of the generator insulation material is carried out along with the Class A overhaul of the generator, the off-line partial discharge test of the entire-phase stator winding of the generator is carried out at the test voltage The partial discharge amount of the generator is 25000 pC. At this time, the generator has been in operation for 35 years. Then K = 2.65. At the same time, the measured blue light whiteness value is 0.14, and the remaining life of the motor insulation is 6.0 years.

[0125] It can be seen from this that the present invention can accurately judge the aging stage of the insulation material according to a variety of electrical test data and accurately predict its remaining life. Through the comprehensive evaluation of multiple parameters, the scientificity and reliability of the prediction results are ensured, providing a solid foundation for formulating a reasonable maintenance plan. By means of preventive maintenance and optimizing the maintenance strategy, the service life of the equipment can be significantly extended, and the operation safety and economy can be improved.

[0126] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A dynamic prediction method for the life of generator insulation materials, characterized in that: include: Obtain electrical test data of the generator stator phase winding; Based on the results of the electrical test data, determine the aging stage of the generator insulation material; According to the characteristic parameters of different aging stages, the remaining life of the generator insulation material is obtained.

2. The method for dynamically predicting the life of the generator insulation material according to claim 1, characterized in that: The electrical test data of the generator stator phase winding include partial discharge amount, dielectric loss angle tangent value, ground capacitance value and blue light brightness value.

3. The method for dynamically predicting the life of a generator insulation material according to claim 1 or 2, characterized in that: The step of determining the aging stage of the generator insulation material comprises: When the partial discharge under the test voltage meets 1500pC≤Q m ≤5000pC, the generator insulation material is in the early stage of aging; When the partial discharge under the test voltage meets 5000pC m ≤20000pC, the generator insulation material is in the middle stage of aging;​ When the partial discharge quantity Q m >20000pC, the generator insulation material is in the late stage of aging.

4. The method for dynamically predicting the life of the generator insulation material according to claim 3, characterized in that: The initial stage of aging includes: Calculating a first ratio based on the partial discharge amount and the logarithmic function conversion; The remaining life of the generator insulation material at the initial aging stage is obtained according to the first ratio; The first ratio is expressed as: K1=12.8335-2.4667×lg Q m The remaining life of the generator insulation material at the initial stage of aging is expressed as: Where N is the time the generator has been running.

5. The method for dynamically predicting the life of the generator insulation material according to claim 4, characterized in that: The mid-aging period includes: Calculate the increment of the tangent value of the medium loss angle; Calculate the capacitance increment to ground; Calculating a second ratio based on the partial discharge amount and the logarithmic function conversion; According to the increment of the dielectric loss angle tangent value, the increment of the ground capacitance and the second ratio, the remaining life of the generator insulation material in the middle stage of aging is obtained; The second ratio is expressed as: K2=1.1825×(12.8335-2.4667×lg Q m ) The dielectric loss tangent value increment is expressed as: Δtanδ=tanδ E -tanδ0 Among them, tanδ E is the dielectric loss tangent at rated voltage, and tanδ0 is the dielectric loss tangent at 20% rated voltage; The capacitance increment to ground is expressed as: ΔC=C E -C0 Among them, C E is the capacitance to ground at rated voltage of the generator, C0 is the capacitance at 20% rated voltage; The remaining life of the generator insulation material in the mid-term aging period is expressed as:

6. The method for dynamically predicting the life of the generator insulation material according to claim 5, characterized in that: The late aging stage includes: Calculating a third ratio based on the partial discharge amount and the logarithmic function conversion; According to the blue light whiteness value and the third ratio, the remaining life of the generator insulation material in the late aging stage is obtained; The third ratio is expressed as: K3=1.3360×(12.8335-2.4667×lg Q m ) The remaining life of the generator insulation material in the late stage of aging is expressed as:

7. The method for dynamically predicting the life of the generator insulation material according to claim 6, characterized in that: The second ratio includes adjustment by a first correction factor based on the partial discharge amount; The third ratio is adjusted by a second correction coefficient based on the partial discharge amount.

8. A system based on the method for dynamically predicting the life of the generator insulation material according to claim 1, characterized in that: An electrical test data acquisition module is used to obtain electrical test data of the generator stator phase winding; An aging status assessment module is used to determine the aging stage of the generator insulation material based on the results of the electrical test data; The remaining life prediction module is used to obtain the remaining life of the generator insulation material according to the characteristic parameters of different aging stages.

9. A computing device, characterized in that include: Memory, used to store programs; A processor, used for loading the program to execute the steps of the method for dynamically predicting the life of the generator insulation material as described in any one of claims 1-7.

10. A computer-readable storage medium storing a program, characterized in that: When the program is executed by a processor, the steps of the method for dynamically predicting the life of the generator insulation material as described in any one of claims 1 to 7 are implemented.

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