A method for gas temperature inversion inside a gas-insulated device

Abstract

The present application relates to a kind of gas-insulated equipment gas chamber inside gas temperature inversion technique.For the temperature in the existing gas-insulated equipment gas chamber cannot be directly measured, the precision of indirect measurement is low and the timeliness is insufficient, the temperature, pressure real-time operating parameters collected by the density relay on the existing gas-insulated equipment are used in the present application, the heat transfer process between external environment and internal gas is deconstructed, and a temperature dynamic compensation model considering the two heat transfer time constants of external environment and equipment shell and equipment shell and internal gas is established.The model can automatically complete the identification and calibration of the two heat transfer time constants of different equipment according to the collected temperature and pressure data sequence and the model established in the present application.After fixing the calibrated two time constants in the model, the model can calculate the temperature of internal gas of gas-insulated equipment in real time according to the model.The present application has the advantages of strong anti-environment high-frequency interference ability, zero additional hardware cost, high precision and strong real-time performance.

Description

Technical Field

[0001] This invention relates to the field of power technology, specifically to a method for inverting the internal gas temperature of a gas-insulated device. Background Technology

[0002] Currently, gas-insulated equipment frequently experiences overheating and distorted gas density monitoring values. Overheating occurs when poor contact between components or repeated switching on and off of switches increases contact resistance, leading to significant heat generation. If not identified and addressed promptly, the overheating problem worsens, eventually causing equipment failure, downtime, or even explosion, resulting in substantial direct and indirect economic losses. Distorted gas density monitoring manifests as fluctuating density readings throughout the day, with excessive density volatility. When temperature variations are significant, the monitored density values ​​become inaccurate, causing the system to issue false alarms indicating density exceeding thresholds. This necessitates on-site intervention by maintenance personnel, wasting resources and causing considerable disruption to maintenance work.

[0003] In power systems, gas density is measured by normalizing the pressure at a specific temperature and converting it to a standard pressure at 20°C (P20). P20 is derived from the pressure and temperature measured in real-time on-site by a density relay. The pressure is connected to the gas-insulated equipment, where the gas is stationary and the internal pressure is uniform throughout; the measured pressure represents the actual internal pressure of the insulating gas equipment. Temperature, however, is represented by a temperature sensor installed inside the density relay, indicating the temperature of the gas inside the insulating equipment. Temperatures have gradients, and due to varying degrees of influence from the external environment, there is a significant temperature difference between the measured temperature and the actual temperature of the gas inside the insulation chamber. Therefore, the P20 directly converted by the density relay has a large error, which explains its significant fluctuations with environmental changes. Because the internal temperature of equipment is limited by the application environment and scenario, it is difficult to accurately monitor directly using a temperature sensor. This is one reason why assessing changes in the internal gas temperature of equipment is not currently used for overheat fault diagnosis. Currently, overheat faults are mainly diagnosed using methods such as thermal imaging and analysis of decomposition materials. However, thermal imaging is susceptible to weather conditions and remains limited. As for decomposition methods, the perspective of a thermal fault cannot be known in advance, and the limitation of periodically detecting decomposition products after a thermal fault lies in the significant time required for the products to diffuse. During this process, they may be absorbed by adsorbents or react with each other, making it difficult for maintenance personnel to detect them during regular inspections and accurately diagnose the fault. Solving the problem of accurately assessing the internal gas temperature of equipment would not only enable accurate monitoring of the internal temperature of gas-insulated equipment but also provide new insights into diagnosing overheating faults.

[0004] Therefore, how to provide a method that can significantly reduce the impact of environmental factors and accurately monitor the internal temperature of insulating gas has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for inverting the internal gas temperature of gas-insulated equipment. During the operation of gas-insulated equipment, this method reduces the problem that current external temperature sensors are greatly affected by the environment, resulting in serious errors in the gas temperature difference monitoring. It improves the accuracy of gas monitoring inside the equipment and the ability to identify overheating faults, ensuring the safe operation of the power grid. At the same time, it reduces the ineffective workload of maintenance personnel caused by false alarms and misreports of fault information.

[0006] In a first aspect, the present invention provides a method for inverting the internal gas temperature of a gas-insulated device, employing the following technical solution:

[0007] A method for inverting the internal gas temperature of a gas-insulated device includes the following steps:

[0008] Step S1: Real-time acquisition of ambient temperature and gas pressure in the gas chamber using temperature and pressure sensors;

[0009] Step S2: Construct a temperature inversion model; the temperature inversion model takes into account the heat transfer time constant between the external environment and the shell, as well as the heat transfer time constant between the inner surface of the shell and the insulating gas;

[0010] Step S3: Based on the historically collected ambient temperature and gas pressure in the gas chamber, identify the coefficient of insulating gas pressure changing with temperature, the heat transfer time constant between the external environment and the shell, and the heat transfer time constant between the inner surface of the shell and the insulating gas in the temperature inversion model.

[0011] Step S4: Convert the real-time collected ambient temperature into a comprehensive ambient temperature, and input it into the temperature inversion model which is solidified in the coefficient of the insulating gas pressure changing with temperature, the heat transfer time constant between the external environment and the shell, and the heat transfer time constant between the inner surface of the shell and the insulating gas. After integrating the temperature inversion model, the average temperature of the gas inside the gas insulation equipment is calculated by intelligent algorithm.

[0012] By adopting the above technical solution, the heat transfer time constant between the external environment and the shell, as well as the heat transfer time constant between the inner surface of the shell and the insulating gas, are taken into account. This reflects the dynamic process of the external environment transferring heat to the internal insulating gas through the equipment shell. Therefore, it achieves the effects of filtering out high-frequency environmental interference, reducing phase lag and amplitude deviation, and improving the accuracy of calculating the average temperature of the gas inside the gas insulation equipment.

[0013] The heat transfer mechanism and calculation steps of this invention are as follows:

[0014] Establish the thermodynamic heat transfer equilibrium equation: During the operation of gas-insulated equipment, heat is transferred between the air and the outer surface of the equipment shell. Heat from the shell is then transferred to the inner surface, bringing the shell temperature to equilibrium. The inner surface then transfers heat with the insulating gas inside the chamber. According to the law of conservation of energy, the rate of change of the internal energy of the shell is equal to the difference between the rate of heat absorption by the shell in the air and the rate of heat dissipation from the shell to the insulating gas. The rate of change of the internal energy of the insulating gas depends on the convective heat transfer rate between it and the inner surface of the shell.

[0015] Solving for the transfer function: The constant-coefficient differential equations for heat transfer from air to the outer surface of the casing and from the inner surface of the casing to the insulating gas are subjected to a Laplace transform. By simultaneously eliminating the intermediate variable of casing temperature, the transfer function between the insulating gas temperature and the overall ambient temperature is derived. The characteristic equation corresponding to this transfer function has two unequal negative real roots. The reciprocals of the absolute values ​​of these two negative real roots correspond to the heat transfer time constants between the external environment and the casing, and between the inner surface of the casing and the insulating gas, respectively.

[0016] Deriving the relationship between impulse response and convolution: Performing an inverse Laplace transform on the transfer function yields the system's unit impulse response function. By the definition of the Laplace transform, the insulating gas temperature equals the convolution of the combined ambient temperature and the system's unit impulse response function over the time span of heat transfer. This transforms the system into a system composed of two standard first-order low-pass filters, where the insulating gas temperature equals the linear superposition of the combined ambient temperature with the heat transfer occurring between the insulating gas and the equipment casing, respectively.

[0017] Integral solution for real-time average temperature: After determining the heat transfer time constant between the external environment and the shell, as well as the heat transfer time constant between the inner surface of the shell and the insulating gas, the real-time collected ambient temperature is converted into a comprehensive ambient temperature and input into the model for integration, thus obtaining the average temperature of the gas inside the gas insulation equipment.

[0018] Preferably, in step S2, the temperature inversion model is constructed based on the law of conservation of heat transfer energy and the transfer function. It is expressed as a second-order constant-coefficient differential equation concerning the average temperature of the gas inside the gas-insulated equipment, the combined ambient temperature, the heat transfer time constant between the external environment and the shell, and the heat transfer time constant between the inner surface of the shell and the insulating gas. By adopting the above technical solution, the second-order constant-coefficient differential equation can characterize the damping attenuation characteristics of a second-order linear steady-state thermodynamic heat transfer system, ensuring that the temperature inversion model conforms to the physical laws of heat transfer.

[0019] Preferably, in step S3, the specific steps for identifying the coefficient of change of insulating gas pressure with temperature include: assuming the gas insulation equipment is well-sealed and there is no gas leakage, selecting gas pressure and ambient temperature data from the gas chambers for any two days with unequal average temperatures and converting them into the average temperature of the comprehensive ambient temperature within the corresponding period; based on the assumption that the net heat absorption of the gas insulation equipment is approximately zero over any two consecutive days with similar macroscopic average temperatures, calculating using the difference method, and taking the ratio of the average difference of the gas pressure in the gas chambers for the two consecutive days to the average difference of the comprehensive ambient temperature as the obtained coefficient of change of insulating gas pressure with temperature. By adopting the above technical solution, utilizing the macroscopic thermal balance characteristics of the equipment having approximately zero net heat absorption and the average temperature of the insulating gas being equal to the average temperature of the comprehensive ambient temperature within a continuous period, the coefficient of change of insulating gas pressure with temperature can be calculated without introducing additional hardware.

[0020] Preferably, in step S3, the specific steps for identifying the heat transfer time constant between the external environment and the shell, and the heat transfer time constant between the inner surface of the shell and the insulating gas, include: approximating the change of the overall ambient temperature over time as a sine wave; according to the theory of linear time-invariant systems, the average temperature of the gas inside the gas-insulated device and the pressure of the gas in the gas chamber both correspond to periodic waves with the same frequency as the overall ambient temperature; calculating the amplitude ratio and phase shift using historically collected overall ambient temperature and gas pressure in the gas chamber; and simultaneously solving the transfer function using the amplitude ratio and phase shift to obtain the heat transfer time constant between the external environment and the shell, and the heat transfer time constant between the inner surface of the shell and the insulating gas. By adopting the above technical solution, utilizing the periodic temperature excitation signal caused by the diurnal temperature difference, and combining it with the theory of linear time-invariant systems, the specific heat transfer time constants of different gas-insulated devices can be identified and calibrated, achieving parameter calibration.

[0021] Preferably, in step S4, the specific steps for calculating the average temperature of the gas inside the gas-insulated equipment include: directly outputting real-time comprehensive ambient temperature parameters that change over time from the temperature sensor; integrating the temperature inversion model, and then using an intelligent algorithm built into the intelligent control module or background monitoring system to calculate the continuous average temperature of the gas inside the gas-insulated equipment. By adopting the above technical solution, and through the online or offline operation of discrete integral calculation and intelligent algorithm, the continuity and real-time performance of the calculation process are ensured.

[0022] Preferably, after calculating the average temperature of the gas inside the gas-insulated equipment in step S4, the method further includes step S5: using the calculated average temperature of the gas inside the gas-insulated equipment and the real-time collected pressure of the gas in the gas chamber for conversion, thereby improving the accuracy of gas density monitoring and providing a basis for equipment operation and maintenance decisions. By adopting the above technical solution, the deviation in gas density calculation caused by inaccurate temperature measurement is reduced, and the risk of false alarms and missed alarms in daily operation and maintenance is lowered.

[0023] Preferably, after calculating the average temperature of the gas inside the gas-insulated equipment in step S4, the method further includes step S6: based on the calculated average temperature of the gas inside the gas-insulated equipment, monitoring the deterioration of the overheating fault in the switch chamber of the gas-insulated equipment and predicting its degree of deterioration, thus providing greater safety assurance for the reliable operation of power equipment. By adopting the above technical solution, abnormal heating faults caused by poor contact or switch opening and closing can be detected in a timely manner, deterioration trends can be warned, and operational safety can be improved.

[0024] Preferably, the algorithm corresponding to the temperature inversion model is a second-order filter. In an outdoor environment, after integrating the temperature inversion model, the second-order filter filters out high-frequency interference from gusts and short-term cloud cover, ensuring that the average temperature of the gas inside the gas insulation equipment lags behind the overall ambient temperature in phase and is smaller in amplitude. By adopting the above technical solution, the low-pass characteristic of the second-order filter smooths high-frequency fluctuations in ambient temperature, making the temperature curve of the inverted output conform to the physical reality that the internal pressure of the gas chamber does not change abruptly, thus ensuring the stability of the output signal.

[0025] Preferably, the gas-insulated device specifically includes a gas-insulated metal-enclosed switchgear (GIS) device, and the insulating gas filled in the gas-insulated device specifically includes sulfur hexafluoride (SF6) gas; the density monitoring device specifically includes an external density relay. By adopting the above technical solution, the application of this method to specific power equipment is provided, improving the practicality of the solution in the field operation and maintenance of power systems.

[0026] Secondly, the present invention provides a gas state monitoring system for gas-insulated equipment, which adopts the following technical solution:

[0027] A gas state monitoring system for gas-insulated equipment comprises a basin-type insulator, a shell, a conductor, an insulator, and a density monitoring device;

[0028] The basin-type insulator and the insulator are sealed at both ends of the housing, and the conductor is sealed in the insulator; after the basin-type insulator, the insulator, the housing and the conductor are assembled, a sealed gas chamber filled with insulating gas is formed.

[0029] The gas in the sealed gas chamber is connected to a pressure sensor in the density monitoring device installed outside the gas insulation equipment through a gas passage provided on the housing. The pressure sensor is used to collect the pressure of the gas in the gas chamber in real time.

[0030] The density monitoring device is also equipped with a temperature sensor and an intelligent control module. The temperature sensor is installed inside or outside the density monitoring device to monitor the ambient temperature. The intelligent control module has a built-in temperature inversion model. The intelligent control module is used to calculate the average temperature of the gas inside the gas insulation device by using the ambient temperature and gas pressure data collected by the temperature sensor and the pressure sensor and the gas pressure data in the gas chamber. Alternatively, the intelligent algorithm is set in the background monitoring system.

[0031] By adopting the above technical solution, an airtight foundation is constructed using existing structural components such as basin insulators, shells, conductors, and insulators. The gas path is connected through a pressure sensor in an externally installed density monitoring device. Combined with a temperature sensor and intelligent control module, the average temperature of the gas inside the gas insulation equipment can be obtained in real time through built-in intelligent algorithms and temperature inversion models without adding new hardware or changing the existing hardware layout inside the gas chamber. This reduces the cost of modification and construction and enables online monitoring of the status of the gas insulation equipment.

[0032] This invention provides a method for inverting the internal gas temperature of a gas-insulated device. It has the following beneficial effects:

[0033] 1. This invention uses a software measurement method to automatically establish correlation equations with different compensation coefficients for different environments and devices. It has strong environmental adaptability and is completely unaffected by different external environments and devices. It can be used directly on any device and in any environment. During application, no special labeling or debugging is required based on the environment.

[0034] 2. The present invention significantly reduces the temperature difference between the temperature obtained by inversion and the temperature inside the equipment, greatly improving the accuracy of monitoring the gas temperature inside the equipment.

[0035] 2. This invention can monitor and invert the temperature of SF6 inside electrical equipment in real time, providing more accurate basic data for the diagnosis and prediction of overheating faults in the equipment, and providing accurate information and decision support for equipment fault diagnosis and operation and maintenance. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the internal temperature monitoring system of a gas-insulated device according to an embodiment of the present invention;

[0037] Figure 2This is a schematic diagram of the pressure, temperature, and actual temperature curves collected by the sensor in an internal temperature monitoring system of a gas-insulated device according to an embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram of a performance verification test platform for a gas temperature inversion method inside a gas-insulated device according to an embodiment of the present invention;

[0039] Figure 4 This is a performance comparison curve of a gas temperature inversion method for gas-insulated equipment in an embodiment of the present invention and a traditional method in field application.

[0040] Among them, 1. Basin insulator; 2. Shell; 201. Outer surface of shell; 202. Inner surface of shell; 3. Conductor; 4. Insulator; 5. Density monitoring device. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] See Figure 1 A gas state monitoring system for gas-insulated equipment comprises a basin-type insulator 1, a housing 2, a conductor 3, an insulator 4, and a density monitoring device 5. The basin-type insulator 1 and the insulator 4 are sealed and installed at both ends of the housing 2, and the conductor 3 is sealed and installed inside the insulator 4. After the basin-type insulator 1, the insulator 4, the housing 2, and the conductor 3 are assembled, they form a sealed gas chamber filled with insulating gas.

[0043] The gas in the sealed gas chamber is connected to a pressure sensor in the density monitoring device 5, which is installed outside the gas insulation equipment, via a gas passage on the housing 2. The pressure sensor can collect the pressure of the gas in the gas chamber in real time. The density monitoring device 5 also includes a temperature sensor to monitor the ambient temperature; the temperature sensor can be installed inside or outside the density monitoring device 5. The density monitoring device 5 also includes an intelligent control module, which can have a built-in temperature inversion model. This module can accurately calculate the average temperature of the gas inside the gas insulation equipment using the temperature and pressure data collected by the sensors and its built-in intelligent algorithm. This algorithm can also be set up in a background monitoring system.

[0044] The principle of a method for inverting the internal gas temperature of a gas-insulated device is as follows:

[0045] When gas-insulated equipment is in operation, its heat transfer environment includes the ambient air, the equipment casing, and the insulating gas inside the equipment. The heat transfer process can be divided into three stages. First, the overall ambient temperature is T. air Heat transfer occurs between the air and the outer surface 201 of the equipment housing; the heat transfer coefficient for this process is h. w Then, the heat from the outer surface 201 of the housing is rapidly transferred to the inner surface 202 of the housing by the gas-insulated equipment, and the temperature of the housing 2 quickly reaches equilibrium at a temperature of T. w Finally, the inner surface 202 of the shell transfers heat to the insulating gas inside the gas chamber, with a heat transfer coefficient of h. g The gas temperature is T g The heat transfer process of the GIS equipment system follows the law of conservation of energy. The rate of change of the internal energy of its shell 2 is equal to the difference between the rate at which the shell 2 absorbs heat in the air and the rate at which the shell 2 dissipates heat to the insulating gas; while the rate of change of the internal energy of the insulating gas depends entirely on the convective heat transfer rate between it and the inner surface 202 of the shell.

[0046] (1)

[0047] (2)

[0048] Among them, M w c is the mass of the equipment housing 2; w Specific heat capacity of GIS equipment housing 2; M g The mass of the insulating gas; c g S is the specific heat capacity of the insulating gas. out S is the area of ​​the outer surface 201 of the equipment housing; in The area of ​​the inner surface 202 of the equipment housing; The rate of change of the temperature of shell 2 over time; This represents the rate of change of the temperature of the insulating gas over time.

[0049] The heat transfer equations from air to the outer surface 201 of the shell and from the inner surface 202 of the shell to the insulating gas are both constant coefficient differential equations. After performing a Laplace transform on equations (1) and (2) and solving them simultaneously, the intermediate variable T is eliminated. w The transfer function between the insulating gas temperature and the overall ambient temperature is G(s).

[0050] (3)

[0051] As shown in equation (3), the thermodynamic heat transfer system consisting of the external environment, the equipment shell 2, and the internal insulating gas is a second-order linear steady system. Heat transfer follows the second law of thermodynamics, moving from a high-temperature region to a low-temperature region. This process does not exhibit inertial oscillation characteristics, but only damped attenuation. The characteristic equation of the system's transfer function G(s) has two unequal negative real roots, and the reciprocals of the absolute values ​​of these two negative real roots correspond to the two characteristic time constants of the system: namely, the heat transfer time constant between the external environment and the shell 2. And the heat transfer time constant between the inner surface 202 of the shell and the insulating gas. Equation (3) can be written as

[0052] (4)

[0053]

[0054] Performing an inverse Laplace transform on equation (4) yields the system's unit impulse response function g(t).

[0055] (5)

[0056] According to Laplace's definition, the temperature of the insulating gas is equal to the convolution of the combined ambient temperature and the system's unit impulse response function over the time span in which heat transfer occurs.

[0057] (6)

[0058] Equation (6) can be written as a system consisting of two standard first-order low-pass filters, i.e., the temperature of the insulating gas is equal to the linear superposition of the heat transfer between the overall ambient temperature and the insulating gas and the equipment housing 2.

[0059] (7)

[0060] As shown in equation (7), the temperature of the insulating gas is dominated by two heat transfer processes: the heat transfer between the air and the outer surface of the GIS housing, and the heat transfer between the inner surface of the GIS housing and the insulating gas. After determining the heat transfer time constants of the two heat transfer processes, the real-time temperature of the insulating gas can be obtained by integration based on the comprehensive ambient temperature collected by the sensor in real time. Furthermore, it can be seen from the formula that when the comprehensive ambient temperature is transferred to the insulating gas, the change in the insulating gas temperature lags behind the comprehensive ambient temperature, and the unit impulse response function also smooths out its fluctuations. Therefore, the actual temperature of the insulating gas in the GIS equipment lags behind the comprehensive ambient temperature in phase and is smaller in amplitude than the comprehensive ambient temperature. This also explains why the current practice of equating the comprehensive ambient temperature with the insulating gas temperature in engineering applications is prone to errors, especially in areas with large diurnal temperature differences.

[0061] See Figure 2Due to the Earth's rotation, both solar radiation and ambient temperature exhibit diurnal variation, resulting in a periodic change in the combined ambient temperature. According to the Fourier transform principle, any periodic signal can be divided into a superposition of countless sine and cosine waves. Ignoring high-frequency harmonic interference such as cloud cover and sudden changes in wind speed, the change in combined ambient temperature over time can be approximated as a sine wave, with an average temperature of... The period is 24 hours and the angular frequency is Amplitude A air .

[0062] (8)

[0063] Gas-insulated equipment is excited by the combined ambient temperature. According to the Linear Time-Invariant System Theory (LTI), the temperature T of the insulating gas... g Both (t) and the ambient temperature are periodic waves with the same frequency, but their amplitudes and phases are different. The temperature change of (t) lags behind that of the ambient temperature by a time lag of (t - t). The phase angle is Its amplitude is A g , with A air The ratio is M; its average temperature is .

[0064] (9)

[0065]

[0066]

[0067] Gas-insulated equipment cannot change its volume after manufacturing; it is a constant-volume device. The gas chamber volume does not change with the external environment, therefore its internal gas pressure P g (t) and temperature both exhibit the same phase and period of sine waves.

[0068] (10)

[0069] in, A is the average pressure of the insulating gas. P It represents the amplitude of the insulating gas pressure.

[0070] Under conditions of good sealing and no gas leakage, the insulating gas pressure P of the GIS equipment is... g (t) and its temperature T g (t) exhibits a highly linear correlation, with the pressure varying with temperature by a coefficient k. Therefore, the pressure of the insulating gas can be expressed as a function of temperature.

[0071] (11)

[0072] Equations (9) and (10) are both expressions for the pressure of insulating gas, and they are completely equivalent. By comparison, the relationship between the temperature amplitude and the pressure amplitude of insulating gas can be obtained.

[0073] (12)

[0074] Although the heat absorption and dissipation efficiencies of the equipment differ microscopically between day and night, macroscopically, over two consecutive days with similar average temperatures, the net heat absorption of the GIS equipment after one cycle of heat transfer is approximately zero. Within one cycle, it can be assumed that no heat exchange occurs between the GIS equipment and the environment, and there is no temperature difference between them. Therefore, the average temperature of the insulating gas within this cycle... It must be related to the average temperature of the overall environment within the corresponding period. Since they are equal, equation (10) can be written as

[0075] (13)

[0076] If no leakage occurs in the equipment, select the pressure and temperature data of any two days with different average temperatures, and obtain the coefficient k of the change of insulating gas pressure with temperature by equation (12).

[0077] (14)

[0078] in, The average pressure on the first day; The average temperature of the first day; The average pressure for the second day; This is the average temperature for the second day.

[0079] Complex variables Substituting the transfer function G(s), we can obtain

[0080] (15)

[0081] Complex function G( The modulus and argument are the amplitude ratio M of the insulating gas temperature to the combined ambient temperature and the phase shift. .

[0082] (16)

[0083] (17)

[0084] M, , Substituting into equations (12) and (13), we get... ,

[0085]

[0086] (18)

[0087] When the equipment is running, all its physical properties are already determined, and its heat transfer time constant is also determined accordingly. Under normal circumstances, it will not change with changes in the external environment and is a constant. air (t) represents the real-time integrated ambient temperature parameter collected by the sensor, which changes over time and is directly output by the temperature sensor. It can also be considered a time-independent quantity. Therefore, after integrating equation (7), it can be written as:

[0088] (19)

[0089] See Figure 3 An outdoor test platform was constructed to verify the model's performance. The test platform included a GIS device, a density relay, and a data acquisition and control system. The GIS device was filled with 0.6 MPa of SF6 gas. The density relay contained temperature and pressure sensors. The pressure sensor collected real-time data on the gas pressure within the GIS chamber, while the temperature sensor collected data on the temperature inside the density relay. The intelligent control module within the density relay transmitted the collected data to the data acquisition and control platform. This test platform was used to test the data and verify the model's performance.

[0090] See test results Figure 4 Because the equipment is exposed to multiple nonlinear stresses—intense solar radiation, gusts of wind, and diurnal temperature variations—in an outdoor environment, the temperature curve collected by the sensor experiences significant temperature fluctuations throughout the day. The temperature sensor can readily detect high-frequency interference signals from the external environment. However, the temperature inversion model described in this invention exhibits significantly less fluctuation compared to the actual temperature, resulting in a more stable output temperature signal. This is because the dynamic compensation model uses a second-order filter, which filters out high-frequency interference such as gusts and short-term cloud cover. The actual temperature is the average temperature of the gas inside the GIS equipment, which has a strong correlation with gas pressure. Since the pressure does not change abruptly, the temperature also does not change abruptly. Figure 4 The figure (a) shows a comparison of temperature time-series monitoring, prediction, and actual temperature.

[0091] Furthermore, the phase relationship of the model-predicted temperature curves in the figure is consistent with the theoretical derivation. The phase of both the model output temperature curve and the actual temperature curve lags behind the ambient temperature curve by approximately 1.9 hours. Comparing the sensor-acquired temperature and the model-predicted temperature with the actual temperature yields the acquired temperature residual and the model-predicted temperature residual. The sensor-acquired temperature residual is ±9.54℃, while the model output temperature residual is ±2.6℃. The model output temperature residual of this invention exhibits a 72.7% higher suppression rate than the sensor-acquired temperature residual. Figure 4 The time series characteristics of the temperature estimation residuals for different algorithms are shown in (b) of the figure.

[0092] This algorithm significantly improves the accuracy of GIS internal temperature monitoring. This improved accuracy has two main benefits: first, it enables faster and earlier detection of overheating faults in GIS switchgear chambers and predicts the extent of degradation, providing greater safety assurance for the reliable operation of power equipment; second, accurate internal temperature prediction improves the accuracy of gas density monitoring, providing a basis for equipment operation and maintenance decisions. Furthermore, this method is extremely simple to apply, working directly on the density relays of existing equipment. It uses a software-based measurement method that automatically establishes correlation equations with different compensation coefficients for different environments and equipment, exhibiting strong environmental adaptability. It is completely unaffected by external environmental and equipment variations and can be used directly on any equipment in any environment. During application, no special labeling or debugging is required, making it simple to operate and virtually cost-free to implement.

[0093] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for inverting the internal gas temperature of a gas-insulated device, characterized in that, Includes the following steps: Step S1: Real-time acquisition of ambient temperature and pressure of insulating gas in the gas chamber using temperature and pressure sensors; Step S2: Construct a temperature inversion model; the temperature inversion model takes into account the heat transfer time constant between the external environment and the shell, as well as the heat transfer time constant between the inner surface of the shell and the insulating gas; Step S3: Based on the historically collected ambient temperature and the pressure of the insulating gas in the gas chamber, identify the coefficient of the insulating gas pressure changing with temperature, the heat transfer time constant between the external environment and the shell, and the heat transfer time constant between the inner surface of the shell and the insulating gas in the temperature inversion model. Step S4: Convert the real-time collected ambient temperature into a comprehensive ambient temperature and input it into the temperature inversion model, which is based on the coefficient of the insulating gas pressure changing with temperature, the heat transfer time constant between the external environment and the shell, and the heat transfer time constant between the inner surface of the shell and the insulating gas. After integrating the temperature inversion model, the average temperature of the gas inside the gas insulation equipment is accurately calculated by the intelligent algorithm.

2. The method for inverting the internal gas temperature of a gas-insulated device according to claim 1, characterized in that, In step S2, the temperature inversion model is constructed based on the law of conservation of heat transfer energy and the transfer function. It is expressed as a second-order constant coefficient differential equation concerning the average temperature of the gas inside the gas-insulated equipment, the comprehensive ambient temperature, the heat transfer time constant between the external environment and the shell, and the heat transfer time constant between the inner surface of the shell and the insulating gas.

3. The method for inverting the internal gas temperature of a gas-insulated device according to claim 1, characterized in that, In step S3, the specific steps for identifying the coefficient of change of insulating gas pressure with temperature include: under the condition that the gas insulation equipment is well sealed and there is no gas leakage, selecting the gas pressure and ambient temperature data of the gas chamber on any two days with different average temperatures and converting them into the average temperature of the comprehensive ambient temperature within the corresponding period; based on the assumption that the net heat absorption of the gas insulation equipment is approximately zero within two consecutive days with similar macroscopic average temperatures, the difference method is used to calculate the coefficient of change of insulating gas pressure with temperature, and the ratio of the average difference of the gas pressure in the gas chamber on the two days to the average difference of the comprehensive ambient temperature is used as the coefficient obtained by solving.

4. The method for inverting the internal gas temperature of a gas-insulated device according to claim 1, characterized in that, In step S3, the specific steps for identifying the heat transfer time constant between the external environment and the shell, and the heat transfer time constant between the inner surface of the shell and the insulating gas, include: approximating the change of the overall ambient temperature over time as a sine wave; according to the theory of linear time-invariant systems, the average temperature of the gas inside the gas insulation equipment and the pressure of the gas in the gas chamber both correspond to periodic waves with the same frequency as the overall ambient temperature; calculating the amplitude ratio and phase shift using historically collected overall ambient temperature and gas pressure in the gas chamber; and substituting the amplitude ratio and phase shift into the transfer function to solve simultaneously for the heat transfer time constant between the external environment and the shell, and the heat transfer time constant between the inner surface of the shell and the insulating gas.

5. The method for inverting the internal gas temperature of a gas-insulated device according to claim 1, characterized in that, In step S4, the specific steps for accurately calculating the average temperature of the gas inside the gas-insulated equipment include: directly outputting the real-time comprehensive ambient temperature parameters that change over time from the temperature sensor; integrating the temperature inversion model, and then accurately calculating the continuous average temperature of the gas inside the gas-insulated equipment using an intelligent algorithm built into the intelligent control module or the background monitoring system.

6. The method for inverting the internal gas temperature of a gas-insulated device according to claim 1, characterized in that, After accurately calculating the average temperature of the gas inside the gas insulation equipment in step S4, step S5 is also included: using the accurately calculated average temperature of the gas inside the gas insulation equipment and the real-time collected pressure of the gas in the gas chamber for conversion, so as to improve the accuracy of gas density monitoring and provide a basis for decision-making for equipment operation and maintenance.

7. The method for inverting the internal gas temperature of a gas-insulated device according to claim 1, characterized in that, After accurately calculating the average temperature of the gas inside the gas insulation equipment in step S4, step S6 is also included: based on the accurately calculated average temperature of the gas inside the gas insulation equipment, monitoring the deterioration of the overheating fault in the switch chamber of the gas insulation equipment and predicting its degree of deterioration, so as to bring more safety assurance for the reliable operation of power equipment.

8. The method for inverting the internal gas temperature of a gas-insulated device according to claim 1, characterized in that, The algorithm corresponding to the temperature inversion model is a second-order filter. In an outdoor environment, after integrating the temperature inversion model, the second-order filter filters out high-frequency interference from gusts and short-term cloud cover, so that the average temperature of the gas inside the gas insulation equipment is phase-lagging behind the overall ambient temperature and amplitude-smaller than the overall ambient temperature.

9. The method for inverting the internal gas temperature of a gas-insulated device according to claim 1, characterized in that, The gas-insulated equipment specifically includes gas-insulated metal-enclosed switchgear (GIS) equipment, and the insulating gas filled in the gas-insulated equipment specifically includes sulfur hexafluoride (SF6) gas.

10. A gas state monitoring system for gas-insulated equipment, used to implement the gas temperature inversion method for the internal gas of gas-insulated equipment as described in any one of claims 1-9, characterized in that, It consists of a basin-type insulator (1), a shell (2), a conductor (3), an insulator (4), and a density monitoring device (5); The basin-type insulator (1) and the insulator (4) are sealed at both ends of the housing (2), and the conductor (3) is sealed in the insulator (4); after the basin-type insulator (1), the insulator (4), the housing (2) and the conductor (3) are assembled, a sealed gas chamber filled with insulating gas is formed. The density monitoring device (5) specifically includes an external density relay; The gas in the sealed gas chamber is connected to the pressure sensor in the density monitoring device (5) installed outside the gas insulation equipment through the gas passage provided on the housing (2). The pressure sensor is used to collect the pressure of the gas in the gas chamber in real time. The density monitoring device (5) is also equipped with a temperature sensor and an intelligent control module. The temperature sensor is installed inside or outside the density monitoring device to monitor the ambient temperature. The intelligent control module has a built-in temperature inversion model. The intelligent control module is used to accurately calculate the average temperature of the gas inside the gas insulation device by using the ambient temperature and gas pressure data collected by the temperature sensor and the pressure sensor and the gas pressure data in the gas chamber through the intelligent algorithm built into the intelligent control module. Alternatively, the intelligent algorithm is set in the background monitoring system.

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