Method for obtaining the arrangement of graphene PI heating sheet and heating and heat-retaining device

Abstract

A method for obtaining the arrangement of a graphene PI heating sheet and a heating and insulation device, the method including: establishing a parameterized model of a heating and insulation device for a tank body of an SF6 tank-type circuit breaker; calling the established parameterized model and combining it with set input variables to simulate a transient heating process; analyzing the sensitivity of the input variables to the SF6 gas temperature and flow rate, and selecting key input variables from the input variables according to the sensitivity analysis; constructing a test parameter set according to the set experimental design method and the selected key input variables; combining it with the test parameter set and the set response surface construction method to construct a response surface model; performing iterative optimization on the selected key input variables in combination with a set optimization algorithm through the constructed response surface model, obtaining the optimized input variables, and using the optimized input variables to perform the arrangement of the graphene PI heating sheet.

Description

[Technical Field]

[0001] This application claims priority from a Chinese patent application bearing application number 202211318376.8, filed with the China Patent Office on October 26, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the technical field of high-voltage power supply equipment, for example, to a method for obtaining the arrangement of a graphene polyimide (PI) heating sheet and a heating and heat-retaining device. [Background technology]

[0003] Sulfur hexafluoride (SF6) tank-type circuit breakers have already been widely applied in ultra-high voltage, large-capacity power systems, with advantages such as excellent arc-extinguishing performance, reliable operation, and long-term maintenance-free operation. The gas chamber of an SF6 tank-type circuit breaker is exposed to the atmosphere, and in many SF6 tank-type circuit breakers currently in operation on power grids, when the ambient temperature is lower than -27.5°C, the SF6 gas will liquefy, causing a sudden drop in pressure in the gas chamber of the SF6 tank-type circuit breaker, which will cause the circuit breaker to issue an alarm and even close due to pressure or trip out of sequence, causing serious impacts on the stable operation of the power grid.

[0004] Current SF6 tank-type circuit breaker heating and insulation devices typically use conventional nickel-chromium alloy resistor sheets for heating. The structural schematic of a nickel-chromium alloy resistor sheet is shown in Figure 1. The nickel-chromium alloy resistor sheet 1 must be coated on both sides with silicone rubber film 2, which reduces thermal efficiency. Due to its series connection characteristics, the nickel-chromium alloy resistor sheet 1 may partially melt after a period of use, necessitating the complete replacement of the heating sheet, shortening its lifespan, wasting materials, and potentially posing safety hazards and economic losses. Cutting the nickel-chromium alloy requires chemical etching, which is not environmentally friendly. The cutting design and layout are both limited by its series connection characteristics, further wasting materials. Summary of the Invention

[0005] This application provides a method for arranging graphene-PI heating sheets, which can be used to heat and insulate the tank body of an SF6 tank-type circuit breaker after the graphene-PI heating sheets are arranged rationally.

[0006] In a first aspect, an embodiment of the present application provides a method for obtaining a configuration of a graphene-PI heating sheet, the method comprising: establishing a parameterized model of a heating and insulation device for a tank body of an SF6 tank-type circuit breaker; calling the established parameterized model and combining it with predetermined input variables to simulate a transient heating process; analyzing the sensitivity of the input variables to SF6 gas temperature and flow rate, and selecting key input variables from the input variables according to the sensitivity analysis; constructing a test parameter set according to a predetermined experimental design method and the selected key input variables; constructing a response surface model in combination with the test parameter set and a predetermined response surface construction method; and performing iterative optimization of the selected key input variables using the constructed response surface model in combination with a predetermined optimization algorithm to obtain optimized input variables.

[0007] Preferably, the input variables include the length, width, and spacing between adjacent graphene PI heating sheets. Preferably, when performing the sensitivity analysis, the center point of the graphene PI heating sheet and the center point of the top end of the pole pole of the SF6 tank-type circuit breaker are used as variable reference points, and the SF6 gas temperature and flow velocity at the center point and the SF6 gas temperature and flow velocity at the center point are extracted.

[0008] Preferably, the Spearman rank correlation coefficient method is employed to analyze the sensitivity.

[0009] Preferably, after the graphene PI heating sheet is positioned using the optimized input variables, the method further includes simulating the transient heating process in conjunction with the parameterized model and verifying the positioned graphene PI heating sheet.

[0010] Preferably, the selected key input variables are iteratively optimized using an optimization method such as screening, multi-objective genetic algorithm (MOGA), non-linear programming by quadratic lagrangian (NLPQL), or mixed-integer sequential quadratic programming (MISQP).

[0011] In a second aspect, an embodiment of the present application provides a heating and insulation device including a tank body insulation housing, an insulation layer, and a heating layer, which are arranged in order from the outside to the inside, wherein the heating layer is formed by connecting multiple graphene-PI heating sheets in parallel, and the multiple graphene-PI heating sheets are arranged using the graphene-PI heating sheet arrangement acquisition method described in the first aspect, and are attached and fixed to the outer surface of the tank body of the SF6 tank-type circuit breaker.

[0012] Preferably, the heat-retaining layer is made of foamed rubber of ethylene propylene diene monomer (EPDM).

[0013] Preferably, the tank body heat-insulating housing is constructed by removably connecting at least two housing parts.

[0014] Preferably, the heating and insulation device further includes a temperature sensor, a temperature controller and a contactor, wherein the temperature sensor is attached to the top end of the pole and connected to the temperature controller, and the contactor is attached to the power supply circuit of the multiple graphene PI heating sheets and connected to the temperature controller. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing the distribution of a nickel-chromium alloy resistance sheet in an SF6 tank-type circuit breaker according to the related art. [Figure 2] FIG. 1 is a flow diagram of the method of Example 1 of the present application. [Figure 3] FIG. 1 is a schematic diagram of the workflow of the method of Example 1 of the present application. [Figure 4] FIG. 1 is a schematic diagram of extraction of input variables in Example 1 of the present application. [Figure 5] FIG. 2 is a schematic diagram of grid division according to the first embodiment of the present invention. [Figure 6] 1 is a schematic diagram 1 in which a response surface model of Example 1 of the present application is constructed. [Figure 7] 2 is a schematic diagram 2 in which a response surface model of Example 1 of the present application is constructed. [Figure 8] FIG. 1 is a schematic diagram of the heating effect before optimization. [Figure 9] FIG. 10 is a heating effect diagram of the layout plan obtained by adopting the method of Example 1 of the present application. [Figure 10] FIG. 1 is a schematic diagram of the overall structure of Example 2 of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0016] The application of graphene PI film heating sheets to the heating of the tank body of an SF6 tank-type circuit breaker can solve the technical drawbacks of using nickel-chromium alloy resistance sheets for heating. In this application, graphene PI film heating sheets, which are connected in parallel to each other and can be arbitrarily cut, are rationally arranged and then used to heat the tank body of an SF6 tank-type circuit breaker.

[0017] Example 1 This example provides a method for obtaining a graphene-PI heating sheet arrangement, including the following steps, as shown in Figures 2-3.

[0018] In step S1, a parameterized model of the heating and insulation device for the tank body of the SF6 tank-type circuit breaker is established.

[0019] In this embodiment, a parameterized model of the heating and insulation device for the tank body of an SF6 tank-type circuit breaker is established by combining SolidWorks and Workbench. The modeling is performed by the parameterized modeling module of Design Modeler. The modeling method can be any method in the related art, and will not be described here.

[0020] In step S2, the sensitivity of the parameters is analyzed.

[0021] In this example, as shown in Figure 4, the widths of three graphene PI heating sheets, designated P1, P2, and P3, are extracted, and the spacing distances between adjacent graphene PI heating sheets, designated P4, P5, and P6, are extracted. After the input variables are extracted, they are stored in the parameter manager.

[0022] In this embodiment, six parameters, P1, P2, P3, P4, P5, and P6, are selected as input variables in the parameter manager of the Workbench platform. Numerical values ​​of several sets of input variables are manually set and then stored in the parameter manager. A transient heating process is simulated according to the set initial experimental design method. The SF gas temperature P7 at the center of the top of the polar column and the SF gas temperature P8 at the center of the arrangement are extracted. The average gas temperature P9 of the SF gas in the middle cross section is extracted. Parameter P10 is set as the difference between the SF gas temperature at the center of the arrangement and the SF gas temperature at the center of the top of the polar column. Equation (2) is as follows:

[0023]

number

[0024] The number of samples required to construct the response surface increases significantly with the number of input parameters, resulting in a significant increase in computational costs. Therefore, the sensitivity of the input variables to the SF6 gas temperature and flow velocity is analyzed, and input variables are selected based on the sensitivity analysis. The parameter correlation sensitivity analysis module uses the Spearman rank correlation coefficient method to analyze the sensitivity of the input variables to the SF6 gas temperature and flow velocity, and then ranks the input variables by correlation degree to select the input variables.

[0025] In this embodiment, since the parameters P1, P2, and P3 (the widths of the heating sheets with three different specifications) are not sensitive to changes in the four output variables P7, P8, P9, and P10, a total of three parameters, P4, P5, and P6, are selected as key input variables after selection.

[0026] The method to obtain the gas temperature and flow velocity of SF6 under different input variables through the simulation of the transient heating process is as follows.

[0027] In step a, the Mechanical module is used to perform grid division on the parameterized model constructed in step 1. The model employs a tetrahedral grid division, and the grid type is set to a Computational Fluid Dynamics (CFD) grid. The overall grid size is 30 mm, and a partial grid of 7 mm is used for the PI heating sheet. A schematic diagram of the grid division is shown in Figure 5.

[0028] In step b, the boundary conditions of the thermal fluid analysis model of the heating and heat-retaining device for the tank body of the SF6 tank-type circuit breaker are set, In this example, the Fluent fluid analysis software on the Workbench platform is used to complete the boundary condition setting of the thermal fluid model by combining the input variables. The heat source power of the PI heating sheet is determined using Equation (1), and the sheet resistance R in the equation is c =120Ω.

[0029]

number

[0030] Expand the Enger option for the Energy Equation, select the Realizable k-ε equation for viscosity, and employ the Body Force Weighted pressure equation in the Calculation Method panel to ensure natural convection conditions for SF6.

[0031] In step c, a thermal fluid analysis solver for the heating and heat-retaining device for the tank body of the SF6 tank-type circuit breaker is set, The transient thermal fluid solution method is selected, and the average gas temperature inside the tank body, the SF6 gas temperature at the center of the arrangement, and the SF6 gas temperature at the center of the top of the pole column are monitored. The solution time is set to 1800 s, and the model is solved to obtain the SF6 gas flow rate and temperature distribution inside the tank body of the circuit breaker with different input variables.

[0032] In step S3, the experimental group is designed and the test parameter set for constructing the response model is completed.

[0033] Central Composite Design, Optimal Space-Filling Design, Box-Behnken Design, Sparse Grid Initialization, or Latin Hypercube Sampling Design is selected as the experimental design method to complete the design of the experimental groups.

[0034] In this embodiment, the experimental design was performed using the design exploration module of the Workbench platform. Since the geometric parameters of the PI heating sheet are continuous variables, the Central Composite Design design method was selected and used as the post-optimization test design method. The parameter variation range of the input parameters was set to 30%. According to the size of the tank body, the test parameters corresponding to the 45 sets of selected input variables were manually set and stored in the parameter manager.

[0035] In step S4, the test parameters corresponding to the 45 sets of selected input variables obtained in step S3 are combined with a response surface algorithm to construct a response surface model (RSM). The construction of the response surface model can be completed by selecting a response surface construction method such as Genetic Aggregation, Standard Response Surface, Kriging, Non-Parametric Regression, Neural Network, or Parse Grid. The construction method can be any method in the related art, and the steps involved will not be described here.

[0036] In this embodiment, the Kriging response surface construction method is selected according to the test parameter set constructed in step S3 to complete the construction of the response surface model. Kriging is a multidimensional interpolation technique suitable for the optimization problems of highly nonlinear and complex processes. The function expression is as shown in Equation (3):

[0037]

number

[0038] In step S5, the response surface model constructed in step S4 is used in combination with the input variables selected in step S3 to select an optimization algorithm such as Screening, MOGA, NLPQL, or MISQP, and perform an optimal iterative solution for the input variables to obtain the optimized input variable parameters, and finally obtain the optimal graphene PI heating sheet layout plan.

[0039] In this embodiment, the response surface model constructed in step S4 is used in conjunction with the input variables selected in step S3 to select the MOGA optimization algorithm, and an iterative optimization solution for the input variables is performed to obtain the optimized input variable parameters. The three optimized graphene PI heating sheet layout plans finally obtained are shown in Table 1. The expression for optimizing the objective of the multi-objective optimization in this step is shown in Equation (4). The constructed objective function requires that the difference P10 between the gas temperature at the layout center and the gas temperature at the center of the top of the polar pillar be less than 35K, that the SF6 gas temperature P7 at the center of the top of the polar pillar be greater than 258K, and that the maximum average gas temperature P9 of the SF6 mid-section be less than 273K.

[0040]

number

[0041] [Table 1]

[0042] In step S6, after obtaining the optimal graphene PI heating sheet layout plan, the established parameterized model is called again according to the obtained optimal layout plan, and then a simulation analysis of the transient heating process is performed to verify the effectiveness of the layout plan, of which the effect of the plan before optimization is as shown in Figure 8, and the effect of adopting the method of this embodiment is as shown in Figure 9. In the plan before optimization, two graphene PI heating sheets are wrapped around the tank body, covering the entire outer surface of the tank body.

[0043] As shown in Figures 8 and 9, when the tank body of the SF6 tank-type circuit breaker is heated using the layout method of the pre-optimization plan, the temperature distribution of the tank body becomes uneven and the heat retention performance of the tank body is poor. However, when the tank body of the SF6 tank-type circuit breaker is heated using the layout method of the graphene PI heating sheet of this embodiment, the generated heating effect is better, the maximum temperature difference is reduced from 39K to 15K, the temperature distribution of the entire tank body is more uniform, the overall power consumption is reduced, and the heat retention effect is good.

[0044] By adopting the method of this embodiment, a response surface model is constructed and combined with the selected input variables, and an optimal graphene PI heating sheet placement plan is obtained through an optimization algorithm, thereby achieving a good heating effect while minimizing the amount of material used, improving the utilization rate of energy and materials, and solving the problem of how to place the graphene PI heating sheet in the tank body heating and insulation device of an SF6 tank-type circuit breaker. At the same time, by analyzing the sensitivity, highly sensitive input variables are selected as input parameters to construct a response surface model, thereby reducing the amount of calculation and significantly reducing the calculation cost.

[0045] Example 2 As shown in FIG. 10, this embodiment provides a heating and insulation device comprising a heating layer 3, a heat-insulating layer 4 and a tank body heat-insulating housing 5, which are arranged in this order from the inside to the outside, wherein the heating layer 3 is attached and fixed to the tank body of the SF6 tank type circuit breaker, the heat-insulating layer 4 covers the tank body of the SF6 tank type circuit breaker to which the heating layer 3 is attached, and the tank body heat-insulating housing 5 is fitted onto the outer periphery of the tank body of the SF6 tank type circuit breaker.

[0046] The heating layer 3 is composed of multiple graphene PI heating sheets 13, and the copper electrodes 12 are connected to the graphene PI heating sheets 13 by pressing. The connection method between the graphene PI heating sheets 13 and the copper electrodes 12 can be that of the related art. The arrangement of the multiple graphene PI heating sheets 13 is obtained by the method of Example 1, and the multiple graphene PI heating sheets 13 are arranged to be connected in parallel in a circuit. The power cable passes through the tank body insulation housing 5 and then connects to the power source through the contactor 10 provided in the heating and insulation device.

[0047] The heat-retaining layer 4 is made of EPDM foam rubber.

[0048] The tank body heat-insulating housing 5 is constructed by removably connecting at least two housing parts 51, and in this embodiment, the tank body heat-insulating housing 5 is constructed by fastening at least two housing parts 51 with bolts.

[0049] By adopting this type of structure, structural limitations such as the small spacing between switchgear in Gas Insulated Substations (GIS) and insufficient installation space can be resolved.

[0050] The heating and keeping device further comprises a temperature sensor 11, a temperature controller 9 and a contactor 10. The temperature sensor 11 is attached to the top end of the pole 6 of the SF6 tank-type circuit breaker, and the temperature sensor 11 is connected to the temperature controller 9, and the temperature controller 9 is connected to a control system attached inside the control box 8.

[0051] The temperature sensor 11 can collect temperature information and transmit it to the temperature controller 9, and the temperature controller 9 is connected to the contactor 10, and the contactor 10 can control the activation and deactivation of the graphene PI heating sheet according to the collected temperature information.

[0052] The temperature controller 9 controls automatic shutdown and turning off on-site, and also realizes centralized control of the device management, making it convenient for users to monitor and operate.

[0053] The contactor 10 is activated to automatically cut off and turn off the power supply to the heating layer 3 of the tank body, and the main function of activating the contactor 10 is to activate the heater and send a signal to command the heater to operate. This device can realize centralized monitoring of the heat retention of the tank body.

[0054] The heating and insulation device of this embodiment is used in an SF6 tank-type circuit breaker, and multiple graphene-PI heating sheets 13 are attached and fixed to the outer surface of the tank body of the SF6 tank-type circuit breaker. A tank body insulation housing 5 is fitted into the tank body of the SF6 tank-type circuit breaker, and the tank body of the SF6 tank-type circuit breaker is fixed by a stand 7. A temperature sensor 11 is attached to the top end of the pole 6 of the SF6 tank-type circuit breaker. A current transformer and a gas-filled bushing are attached to the SF6 tank-type circuit breaker. The terminal box of the heating and insulation device is connected to a control box 8 of the SF6 tank-type circuit breaker, and a control system in the control box 8 is configured to control the heating temperature of the heating layer 3. The relevant electrical control elements of the heating and insulation device are secondary connected to the control box via electric cables.

[0055] The heating and insulation device of this embodiment uses graphene PI heating sheet for heating and is arranged according to the best layout plan, which has better thermal conductivity efficiency and stability, is more energy-saving and environmentally friendly, makes the operation of the switching equipment more reliable, effectively reduces potential safety hazards for the equipment, and at the same time increases the economic efficiency of the equipment operation. [Explanation of symbols]

[0056] 1 Nickel-chromium alloy resistance sheet, 2 Silicone rubber film, 3 Heating layer, 4 Heat insulation layer, 5 Tank body heat insulation housing, 51 Housing part, 6 Electrode, 7 Stand, 8 Control box, 9 Temperature controller, 10 Contactor, 11 Temperature sensor, 12 Copper electrode, 13 Graphene PI heating sheet.

Claims

1. Establishing a parameterized model of a heating and insulation device for a sulfur hexafluoride (SF6) tank-type circuit breaker tank; calling the established parameterized model and combining it with the set input variables to simulate a transient heating process; SF of the input variables ６ analyzing the sensitivity of the input variables to the gas temperature and flow velocity, and selecting key input variables from the input variables according to the sensitivity analysis; constructing a test parameter set according to the established experimental design method and the selected key input variables; constructing a response surface model in combination with the test parameter set and the established response surface construction method; Using the constructed response surface model, iteratively optimize the selected key input variables in combination with a set optimization algorithm to obtain optimized input variables, and then use the optimized input variables to configure the graphene PI heating sheet. Method for obtaining the arrangement of graphene PI heating sheets.

2. The input variables include the length, width, and spacing between adjacent graphene PI heating sheets. The method of claim 1 .

3. When analyzing the sensitivity, the center point of the graphene PI heating sheet and SF ６ The center point of the pole pole top of the tank-type circuit breaker is set as the variable reference point, and the SF of the arrangement center point ６ The gas temperature and flow velocity of the SF at the center point of the top of the pole ６ and extracting the gas temperature and flow velocity of the The method of claim 1 .

4. The sensitivity analysis is performed using the Spearman rank correlation coefficient. The method of claim 1 .

5. After placing the graphene PI heating sheet using the optimized input variables, Further included is simulating the transient heating process in conjunction with the parameterized model and verifying the graphene PI heating sheet after placement. The method of claim 1 .

6. Performing iterative optimization of the selected key input variables by employing a selection or multi-objective genetic algorithm, a Lagrangian nonlinear quadratic programming, or a mixed integer sequential quadratic programming optimization method. The method of claim 1 .

7. science fiction ６ The tank body of the tank-type circuit breaker is provided with a heating layer, a heat-insulating layer and a tank body heat-insulating housing, which are sequentially provided from the inside to the outside of the tank body, and the heating layer is formed by connecting a plurality of graphene PI heating sheets in parallel, and the plurality of graphene PI heating sheets are arranged by adopting the method for acquiring the arrangement of the graphene PI heating sheets according to any one of claims 1 to 6, and the SF ６ It is attached and fixed to the outer surface of the tank body of the tank-type circuit breaker. Heating and insulation device.

8. The heat-retaining layer is made of foamed rubber of ethylene propylene diene monomer rubber. The heating and keeping warm device according to claim 7.

9. The tank body heat-insulating housing is configured by removably connecting at least two housing parts. The heating and keeping warm device according to claim 7.

10. Further comprising a temperature sensor, a temperature controller and a contactor, wherein the temperature sensor is attached to the top end of the pole and connected to the temperature controller, and the contactor is attached to a power supply circuit of the plurality of graphene PI heating sheets and connected to the temperature controller. The heating and keeping warm device according to claim 7.

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