Long-distance GIL deformation monitoring device and stress three-dimensional inversion method

Abstract

The invention discloses a long-distance GIL deformation monitoring device, which is characterized in that after millimeter waves emitted by a millimeter wave radar are reflected by a GIL shell and a metal corner reflector, received digital signals are transmitted to a data calculation unit for processing through a data transmission unit, so as to analyze deformation data of the GIL; and finally, visual display is carried out through a visual software platform, and the result is clear, visual and accurate. According to the stress three-dimensional inversion method, on the basis of the deformation monitoring device of the long-distance GIL, the mechanical fault hidden danger position of the GIL can be effectively positioned, and the operation state of each part of the long-distance GIL can be accurately and visually reflected. The method is generally suitable for various technical environments, low in light requirement, free of continuous manual observation, high in automation degree, good in reliability and high in stability, can accurately position the mechanical fault hidden danger of the GIL and evaluate the state in real time, and meets the operation requirements of the GIL.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment, and in particular to a deformation monitoring device and a three-dimensional stress inversion method for a long-distance GIL. Background Art

[0002] In the field of GIL fault monitoring, in order to ensure the safe and reliable operation of GIL, there are currently many monitoring methods to monitor latent defects and partial discharges inside GIL. However, deformation monitoring of long-distance GIL after production and commissioning still relies on manual measurement methods.

[0003] Traditional means of GIL deformation monitoring are mainly carried out through leveling, total stations, theodolites and other equipment, but the current technical environment adaptability is poor, has high requirements for light, requires continuous manual observation, and cannot provide real-time GIL status assessment. Due to monitoring frequency limitations, it cannot meet GIL reliability requirements. Currently, there is an urgent need for a deformation monitoring device and stress inversion method to provide real-time monitoring and assessment of GIL, so as to ensure the normal operation of GIL. Summary of the invention

[0004] The object of the present invention is to provide a deformation monitoring device and a three-dimensional stress inversion method for a long-distance GIL to solve the above defects.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A deformation monitoring device for a long-distance GIL comprises a GIL shell, a millimeter-wave radar, a metal corner reflector, a data transmission unit and a data calculation unit, wherein a plurality of millimeter-wave radars are arranged and are evenly distributed at a certain distance outside the GIL shell through a fixed support base, and the metal corner reflector is used as a target and is arranged at each position to be measured on the GIL shell; the millimeter wave emitted by the millimeter-wave radar is reflected by the GIL shell and the metal corner reflector and then received by the millimeter-wave radar, and the received digital signal is then transmitted to the data calculation unit via the data transmission unit for processing, so as to analyze the deformation data of the GIL, and perform three-dimensional rapid and accurate calculation of the stress of the GIL shell and internal insulating parts based on the deformation data.

[0007] Preferably, it also includes a visualization platform, which is connected to the data calculation unit and is used to intuitively display the deformation data of the GIL.

[0008] Preferably, the millimeter wave radar includes a radio frequency front-end circuit, an antenna, a digital signal processing circuit and a wireless communication circuit, wherein the radio frequency front-end circuit is used to modulate the millimeter wave; the antenna is connected to the radio frequency front-end circuit and transmits and receives the millimeter wave; the digital signal processing circuit is connected to the antenna and converts the received reflected millimeter wave into a digital signal; the wireless communication circuit is connected to the digital signal processing circuit and transmits the digital signal.

[0009] Preferably, the millimeter wave radar operates in a continuous wave system, specifically FMCW frequency modulated continuous wave; the millimeter wave radar continuously transmits frequency modulated signals to measure the distance, angle and speed information of multiple targets to achieve continuous tracking of the targets.

[0010] Preferably, the frequency selected for the millimeter wave radar is 60 GHz.

[0011] Preferably, the metal corner reflector is a triangular pyramid structure, and the three inclined surfaces of the metal corner reflector are perpendicular to each other.

[0012] Preferably, a three-dimensional stress inversion method comprises the following steps:

[0013] S1, obtaining deformation data of the GIL shell (1) relative to the tunnel in which it is installed, and obtaining three-dimensional bending data and twisting deformation data of the GIL shell (1) in combination with the settlement data of the tunnel;

[0014] S2, constructing a global geometric model of the GIL including the GIL shell (1), busbar, insulator, and insulating gas, calculating the stress of each measured point on the long-distance GIL shell (1), and evaluating the mechanical stress and damage risk of the long-distance GIL shell (1);

[0015] S3. Construct a refined model of the GIL as a whole and calculate the three-dimensional stress of the insulating parts, and evaluate the mechanical stress and damage risk of the insulating parts.

[0016] Preferably, the step S1 is specifically as follows:

[0017] S11, obtaining axial, radial and tangential deformation data of the GIL shell (1) relative to the tunnel in which it is installed, and obtaining horizontal displacement and vertical settlement data of the tunnel;

[0018] S12. Analyze the settlement data of the tunnel to determine the rate, direction and extent of the settlement;

[0019] S13, comparing and analyzing the deformation data of the GIL shell (1) and the settlement data of the tunnel, calculating the displacement and rotation angle of the GIL shell (1), and then analyzing and obtaining the three-dimensional bending and twisting deformation data of the GIL shell (1) relative to the tunnel.

[0020] Preferably, the step S2 is specifically as follows:

[0021] S21, obtaining detailed design parameters of the GIL housing (1) and data related to the environment in which the GIL housing (1) is located;

[0022] S22, establishing a global geometric model of the GIL as a whole according to the detailed design parameters of the GIL shell (1) and data related to the surrounding environment;

[0023] S23, perform finite element analysis on the global geometric model of the GIL;

[0024] S24, extracting stress data of each measured point on the long-distance GIL shell (1) according to the finite element analysis results;

[0025] S25. Evaluate the mechanical stress and damage risk of the long-distance GIL casing (1) based on the stress data combined with the material properties and design requirements of the long-distance GIL casing (1).

[0026] Preferably, the step S3 is specifically as follows:

[0027] S31, construct a refined model of the GIL's internal insulation, busbars, and contacts;

[0028] S32, calculating the three-dimensional stress of the insulating component using the three-dimensional bending and twisting deformation data of the long-distance GIL shell (1) as boundary constraints;

[0029] S33, evaluating the stress level of each measured point on the long-distance GIL casing (1) according to the three-dimensional stress calculation result of the insulating component;

[0030] S34. Evaluate the damage risk of the long-distance GIL casing (1) based on the overall operating environment and service life of the GIL.

[0031] The beneficial effects of the present invention are:

[0032] (1) The deformation monitoring device for the long-distance GIL of the present invention transmits the millimeter wave emitted by the millimeter wave radar to the GIL shell and the metal corner reflector, and then the received digital signal is transmitted to the data calculation unit for processing through the data transmission unit to analyze the deformation data of the GIL, and finally visualized through the visualization software platform, and the results are clear, intuitive and accurate.

[0033] (2) The three-dimensional stress inversion method of the present invention, based on the deformation monitoring device of the long-distance GIL, can effectively locate the hidden dangers of GIL mechanical failure and can accurately and intuitively reflect the operating status of each component of the long-distance GIL.

[0034] (3) The present invention is generally applicable to various technical environments, has low light requirements, does not require continuous manual observation, has a high degree of automation, can accurately locate potential mechanical failures of the GIL and conduct real-time status assessment, has good reliability and high stability, and meets the operation requirements of the GIL. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 : A schematic structural diagram of a deformation monitoring device for a long-distance GIL according to the present invention;

[0036] Figure 2 : A schematic diagram of the arrangement of the millimeter wave radar, the metal corner reflector and the surface to be monitored of the GIL shell of the present invention;

[0037] Figure 3 : Flow chart of the stress three-dimensional inversion method of the present invention;

[0038] Figure 4 : Flow chart of step S1 in the three-dimensional stress inversion method of the present invention;

[0039] Figure 5 : Flow chart of step S2 in the three-dimensional stress inversion method of the present invention;

[0040] Figure 6 : Flow chart of step S3 in the three-dimensional stress inversion method of the present invention;

[0041] Figure 7 The three-dimensional inversion calculation result diagram of the global deformation-stress distribution of the GIL;

[0042] Figure 8 The local stress result diagram of the three-dimensional inversion calculation of the global deformation-stress distribution of the GIL;

[0043] Fig. 9 The deformation and stress concentration results of the three-dimensional inversion calculation of the global deformation-stress distribution of the GIL under abnormal conditions (earthquake longitudinal wave vibration) DETAILED DESCRIPTION

[0044] The present invention is further described below in conjunction with the embodiments. It should be noted that these are merely examples and illustrations of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should be deemed to fall within the protection scope of the present invention.

[0045] Embodiment 1:

[0046] like Figure 1 , 2As shown, a deformation monitoring device for a long-distance GIL includes a GIL shell 1, a millimeter-wave radar 2, a metal corner reflector 3, a data transmission unit, a data calculation unit and a visualization platform.

[0047] There are multiple millimeter-wave radars 2, which are evenly distributed at a certain distance outside the GIL shell 1 through a fixed support base, to ensure that each millimeter-wave radar 2 can fully monitor the GIL shell 1 and timely obtain the vertical, horizontal and corner deformation information of the GIL shell 1.

[0048] The millimeter wave radar 2 includes a radio frequency front-end circuit, an antenna, a digital signal processing circuit, and a wireless communication circuit. The radio frequency front-end circuit is used to modulate the millimeter wave; the antenna is integrated on the PCB board, the antenna is connected to the radio frequency front-end circuit, and transmits and receives the millimeter wave; the digital signal processing circuit is connected to the antenna, and converts the received reflected millimeter wave into a digital signal; the wireless communication circuit is connected to the digital signal processing circuit, and transmits the digital signal.

[0049] Millimeter wave radar 2 works in a continuous wave system, specifically FMCW frequency modulated continuous wave; millimeter wave radar 2 continuously transmits frequency modulated signals to measure the distance, angle and speed information of multiple targets and achieve continuous tracking of targets. The selected frequency is 60GHz, and its detection performance is stable, the environmental applicability is good, and the ability to penetrate smoke and dust is strong.

[0050] Among them, the fixed support base adopts PEEK to realize rigid support and fixation of the millimeter wave radar 2, ensure its stability, prevent mechanical extrusion damage, and avoid the influence of radar micro-movement on the test results.

[0051] like Figure 2 As shown, the metal corner reflector 3 is used as a target and is arranged at each position to be measured on the GIL shell 1. The metal corner reflector 3 is a radar wave reflector, which uses a metal triangular reflector, specifically a triangular pyramid structure, and the three inclined surfaces of the metal corner reflector 3 are perpendicular to each other. The three mutually perpendicular reflecting surfaces of the metal corner reflector 3 can make the incident wave and the reflected wave in opposite directions as the target of each position to be measured on the GIL shell 1, which is used to generate a stronger echo signal and improve the accuracy and stability of radar monitoring.

[0052] The millimeter wave emitted by the millimeter wave radar 2 is reflected by the GIL shell 1 and the metal corner reflector 3 and then received by the millimeter wave radar 2. The received digital signal is then transmitted to the data calculation unit for processing via the data transmission unit to analyze the deformation data of the GIL and perform three-dimensional rapid and accurate calculation of the stress of the GIL shell and internal insulation parts based on the deformation data. The visualization platform is connected to the data calculation unit to intuitively display the deformation data of the GIL.

[0053] In a deformation monitoring device for a long-distance GIL of the present invention, real-time monitoring of the deformation state of the long-distance GIL and accurate restoration of the stress field are realized. It has the advantages of accurate measurement, safety and reliability, and easy operation. It provides a strong guarantee for the safe operation of the long-distance GIL and solves the problem in the prior art that the deformation monitoring of the long-distance GIL is completely dependent on manual labor and has high requirements on environmental conditions.

[0054] Embodiment 2:

[0055] like Figure 4-9 As shown, a three-dimensional stress inversion method of the present invention, based on the deformation monitoring device of the long-distance GIL of Example 1, specifically comprises the following steps:

[0056] S1. Obtain deformation data of the GIL shell 1 relative to the tunnel in which it is installed, and obtain three-dimensional bending data and twisting deformation data of the GIL shell 1 in combination with the settlement data of the tunnel, as follows:

[0057] S11. The axial, radial and tangential deformation data of the GIL shell 1 relative to the tunnel in which it is installed are obtained through the high-precision pull-wire displacement sensor installed on the GIL as a whole, and the horizontal displacement and vertical settlement data of the tunnel are obtained. The data include the overall settlement, horizontal displacement, inclination and curvature change of the tunnel; the high-precision pull-wire displacement sensor has a range of 100mm and an accuracy of ±0.25%. The collected GIL shell 1 and tunnel deformation data are then preprocessed, including data cleaning, denoising and calibration, to ensure the accuracy and consistency of the data, providing a reliable basis for subsequent analysis.

[0058] S12. Analyze the settlement data of the tunnel to determine the rate, direction and extent of the settlement.

[0059] S13, comparing and analyzing the deformation data of the GIL shell 1 and the settlement data of the tunnel, calculating the displacement and rotation angle of the GIL shell 1, and then analyzing and obtaining the three-dimensional bending and twisting deformation data of the GIL shell 1 relative to the tunnel.

[0060] During the data processing and analysis process, it is necessary to ensure the accuracy and timeliness of the data, and to promptly discover and handle outliers and errors in the data to avoid adverse effects on the analysis results.

[0061] In summary, in step S1, by combining the deformation data of the GIL shell 1 relative to the installation tunnel and the settlement data of the tunnel, the three-dimensional bending data and twisting deformation data of the long-distance GIL can be obtained, which are of great significance for evaluating the safety and stability of the GIL and formulating maintenance plans and management strategies.

[0062] S2. Construct a global geometric model of the GIL including the GIL shell 1, busbar, insulator, and insulating gas, calculate the stress of each measured point on the long-distance GIL shell 1, and evaluate the mechanical stress and damage risk of the long-distance GIL shell 1, as follows:

[0063] S21. Obtain the detailed design parameters of the GIL as a whole, including size, material, structure, etc.; obtain relevant data on the environment in which the GIL as a whole is located, including the terrain along the line, geological conditions, tunnel structure, etc.

[0064] In the GIL as a whole, the busbar is fixedly mounted on the axis of the GIL shell 1 through a plurality of insulators. The insulators are installed between the busbar and the inner wall of the GIL shell 1 to withstand voltage and mechanical stress; and the insulating gas is filled inside the GIL shell 1.

[0065] S22. Establish a global geometric model of the GIL based on the detailed design parameters of the GIL and the relevant data of the environment in which it is located. The model should include key parts such as the GIL shell 1 and its supporting structure, connecting components, etc.

[0066] First, an initial geometric model of the GIL shell 1 is constructed; then the main deformation type is determined based on the three-dimensional bending data and the twisting deformation data; a mathematical equation or model describing the GIL deformation is established based on the deformation type and deformation data, and the shape of the initial geometric model is adjusted to reflect the actual deformation of the GIL shell 1.

[0067] The accuracy and completeness of the model can be verified by comparing it with actual on-site data, and necessary corrections and optimizations can be made to the model to ensure that it can truly reflect the actual situation of the GIL housing 1.

[0068] S23, setting simulation parameters according to the overall operating conditions and design requirements of the GIL, and then performing finite element analysis on the overall global geometric model of the GIL;

[0069] S24. Extract stress data of each measured point on the long-distance GIL shell 1 according to the finite element analysis results; the data includes the stress magnitude, direction and stress distribution of each point.

[0070] S25. Evaluate the mechanical stress and damage risk of the long-distance GIL casing 1 based on the stress data combined with the material properties and design requirements of the long-distance GIL casing 1.

[0071] In summary, in step S2, by constructing the global geometric model of the GIL as a whole, calculating the stress of each measured point on the GIL shell, and evaluating the mechanical stress and damage risk of the GIL shell 1, the stress distribution characteristics of the GIL can be analyzed, the stress concentration area and potential danger points can be determined, and the damage criteria (such as yield criteria, fracture criteria, etc.) can be used to determine whether the shell is in a safe state, focus on potential danger points, analyze their possible damage modes and consequences, and provide important reference for the overall design, manufacture, installation and operation of the GIL.

[0072] S3. Construct a refined model of the GIL as a whole and calculate the three-dimensional stress of the insulation parts, and evaluate the mechanical stress and damage risk of the insulation parts, as follows:

[0073] S31. Collect detailed information data such as the overall design drawings, material properties, and operating environment of the GIL, and perform pre-processing such as data cleaning, denoising, and format conversion on the collected data. Pre-processing can ensure the accuracy and consistency of the data and build a refined model of the internal insulation parts, busbars, and contacts of the GIL.

[0074] S32. The three-dimensional bending and twisting deformation data of the long-distance GIL shell 1 are used as boundary constraints to calculate the three-dimensional stress of the insulating component. The boundary conditions should be set according to the actual operation of the GIL as a whole, such as fixed constraints, load application, etc.

[0075] S33. Evaluate the stress level of each measured point on the GIL shell 1 according to the three-dimensional stress calculation results of the insulating component. Perform three-dimensional stress inversion calculation according to the geometric model to achieve a mapping relationship between a typical deformation and internal stress. Based on this, a database is established to quickly determine the concentration or excess of internal stress according to different deformation types, and achieve rapid inversion of the three-dimensional deformation and stress of the GIL as a whole. Based on this, a rapid assessment of the rapid concentration of the GIL as a whole and whether the stress exceeds the standard is performed.

[0076] S34. Evaluate the damage risk of the long-distance GIL casing 1 in combination with the overall operating environment and service life of the GIL.

[0077] Figure 7 This is the three-dimensional inversion calculation result diagram of the global deformation-stress distribution of the GIL. Figure 8 The local stress result diagram of the three-dimensional inversion calculation of the global deformation-stress distribution of the GIL. Fig. 9 The deformation and stress concentration results of the three-dimensional inversion calculation of the global deformation-stress distribution of the GIL under abnormal conditions (earthquake longitudinal wave vibration) are shown in Figure 1. Figure 7-9 The stress results of different components in the GIL can be obtained.

[0078] When the present invention is implemented, the deformation monitoring device of the long-distance GIL of Example 1 is first used to obtain the deformation data of the GIL shell 1 at different positions and time points; then the collected deformation data is sorted, abnormal data is identified and eliminated, and classified according to dimensions such as position and time; then the deformation trend of the GIL shell 1 in different time periods and the correlation between deformations at different positions are analyzed; finally, the overall geometric model of the GIL is constructed and combined with the material properties, stress analysis is performed to evaluate the impact of deformation on the overall structural safety of the GIL. In summary, by constructing a refined model of the GIL as a whole and calculating the three-dimensional stress of the insulating parts, and then evaluating the mechanical stress and damage risk of the insulating parts, by analyzing the stress distribution characteristics, the stress concentration area and potential danger points can be determined, and by using the damage criterion, it can be determined whether the insulating parts are in a safe state, and then the potential danger points are focused on and their possible damage modes and consequences are analyzed.

[0079] The present invention proposes a deformation monitoring device and a three-dimensional stress inversion method for a long-distance GIL, which realizes real-time monitoring of the overall deformation state of the GIL and accurately restores the stress distribution inside the entire GIL through the three-dimensional stress inversion method. It has the advantages of accurate measurement, safety and reliability, and simple operation, providing reliable guarantee for the safe operation of the equipment and solving the problem in the prior art that the overall deformation monitoring of the GIL is completely dependent on manual labor and has high requirements on environmental conditions.

[0080] The above is an exemplary description of the invention in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as such non-substantial improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A deformation monitoring device for a long-distance GIL, characterized in that: The invention comprises a GIL shell (1), a millimeter wave radar (2), a metal corner reflector (3), a data transmission unit and a data calculation unit. The millimeter wave radar (2) is provided with a plurality of them and are evenly distributed at a certain distance outside the GIL shell (1) through a fixed support base. The metal corner reflector (3) is used as a target and is arranged at each position to be measured on the GIL shell (1). The millimeter wave emitted by the millimeter wave radar (2) is reflected by the GIL shell (1) and the metal corner reflector (3) and then received by the millimeter wave radar (2). The received digital signal is then transmitted to the data calculation unit for processing via the data transmission unit, so as to analyze the deformation data of the GIL and perform three-dimensional rapid and accurate calculation of the stress of the GIL shell and internal insulating parts based on the deformation data.

2. A deformation monitoring device for a long-distance GIL according to claim 1, characterized in that: It also includes a visualization platform, which is connected to the data calculation unit and is used to intuitively display the deformation data of the GIL.

3. The deformation monitoring device for a long-distance GIL according to claim 1, characterized in that: The millimeter wave radar (2) comprises a radio frequency front-end circuit, an antenna, a digital signal processing circuit and a wireless communication circuit, wherein the radio frequency front-end circuit is used to modulate the millimeter wave; the antenna is connected to the radio frequency front-end circuit and transmits and receives the millimeter wave; the digital signal processing circuit is connected to the antenna and converts the received reflected millimeter wave into a digital signal; and the wireless communication circuit is connected to the digital signal processing circuit and transmits the digital signal.

4. The deformation monitoring device for a long-distance GIL according to claim 1, characterized in that: The millimeter wave radar (2) operates in a continuous wave system, specifically adopting FMCW frequency modulated continuous waves; the millimeter wave radar (2) continuously transmits frequency modulated signals to measure the distance, angle and speed information of multiple targets, thereby achieving continuous tracking of the targets.

5. A deformation monitoring device for a long-distance GIL according to any one of claim 1, characterized in that: The millimeter wave radar (2) uses a frequency of 60 GHz.

6. A deformation monitoring device for a long-distance GIL according to claim 1, characterized in that: The metal corner reflector (3) is a triangular pyramid structure, and the three inclined surfaces of the metal corner reflector (3) are perpendicular to each other.

7. A three-dimensional stress inversion method, based on the long-distance GIL deformation monitoring device according to any one of claims 1 to 5, characterized in that: The steps include: S1, obtaining deformation data of the GIL shell (1) relative to the tunnel in which it is installed, and obtaining three-dimensional bending data and twisting deformation data of the GIL shell (1) in combination with the settlement data of the tunnel; S2, constructing a global geometric model of the GIL including the GIL shell (1), busbar, insulator, and insulating gas, calculating the stress of each measured point on the long-distance GIL shell (1), and evaluating the mechanical stress and damage risk of the long-distance GIL shell (1); S3. Construct a refined model of the GIL as a whole and calculate the three-dimensional stress of the insulating parts, and evaluate the mechanical stress and damage risk of the insulating parts.

8. A three-dimensional stress inversion method according to claim 7, characterized in that: The S1 step is specifically as follows: S11, obtaining axial, radial and tangential deformation data of the GIL shell (1) relative to the tunnel in which it is installed, and obtaining horizontal displacement and vertical settlement data of the tunnel; S12. Analyze the settlement data of the tunnel to determine the rate, direction and extent of the settlement; S13, comparing and analyzing the deformation data of the GIL shell (1) and the settlement data of the tunnel, calculating the displacement and rotation angle of the GIL shell (1), and then analyzing and obtaining the three-dimensional bending and twisting deformation data of the GIL shell (1) relative to the tunnel.

9. A three-dimensional stress inversion method according to claim 8, characterized in that: The S2 step is specifically as follows: S21, obtaining detailed design parameters of the GIL housing (1) and data related to the environment in which the GIL housing (1) is located; S22, establishing a global geometric model of the GIL as a whole according to the detailed design parameters of the GIL shell (1) and data related to the surrounding environment; S23, perform finite element analysis on the global geometric model of the GIL; S24, extracting stress data of each measured point on the long-distance GIL shell (1) according to the finite element analysis results; S25. Evaluate the mechanical stress and damage risk of the long-distance GIL casing (1) based on the stress data combined with the material properties and design requirements of the long-distance GIL casing (1).

10. A three-dimensional stress inversion method according to claim 9, characterized in that: The S3 step is specifically as follows: S31, construct a refined model of the GIL's internal insulation, busbars, and contacts; S32, calculating the three-dimensional stress of the insulating component using the three-dimensional bending and twisting deformation data of the long-distance GIL shell (1) as boundary constraints; S33, evaluating the stress level of each measured point on the long-distance GIL casing (1) according to the three-dimensional stress calculation result of the insulating component; S34. Evaluate the damage risk of the long-distance GIL casing (1) based on the overall operating environment and service life of the GIL.

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