Device for reducing temperature rise of dry-type hollow high-capacity current-limiting reactor and design method thereof

Abstract

According to the device for reducing the temperature rise of the dry-type hollow high-capacity current-limiting reactor and the design method thereof, a double-layer rainproof device technology and a split type staggered ventilation structure are adopted to realize rainproof and heat dissipation decoupling; according to the invention, heat dissipation is carried out through annular grating ventilation holes in the vertical direction of a top-layer rainproof cap and a middle ventilation net between the top-layer rainproof cap and a bottom-layer rainproof cap, and a coupling simulation technology of a magnetic field-flow field-temperature field of a reactor is utilized to form a correlation between structural parameters of a double-layer rainproof device and a flow rate change rate of fluid in an air passage of an encapsulation chamber; a bidirectional coupling model of a flow field and a temperature field is established, and the synergistic effect of encapsulated radiation and convective heat transfer is solved through a finite element method. Through multi-field coupling simulation and parametric modeling, the problem of collaborative optimization of rainproof device design and electric reactor thermal performance is solved, the equivalent heat dissipation area is increased to 2-3 times that of a single-layer structure, the use amount of wires is reduced by 8-15%, the coil hot-spot temperature rise is reduced to 78K from 88K of a traditional structure, and the reduction amplitude reaches 11.4%.

Description

Technical Field

[0001] The present invention belongs to the technical field of reactors, and more specifically, relates to a device for reducing the temperature rise of dry-type air-core large-capacity current-limiting reactors and a design method thereof. Background Art

[0002] In the technical development of dry-type air-core current-limiting reactors, as outdoor primary electrical equipment, with the increase in capacity and current requirements, the multi-layer encapsulation structure has become the mainstream design. The contradiction between the heat dissipation and rain protection performance of the traditional single-layer rain protection device is mainly reflected in the following aspects: The dry-type air-core reactor uses the air natural cooling (AN) method for heat dissipation. Ventilation channels and rain protection cover holes need to be set between its multi-layers of encapsulations to ensure heat diffusion. As the number of encapsulation layers increases, the heat dissipation area needs to be expanded synchronously. However, the single-layer coverage design of the traditional rain protection device will hinder the airflow through the encapsulation gaps, resulting in the accumulation of internal heat and affecting the stability of the equipment. The existing single-layer rain protection structure usually realizes rainwater diversion through an umbrella-shaped cover at the top. However, such a design will block the ventilation path above the encapsulation, forming an opposition between "rain protection - heat dissipation". Especially in rainy or high-humidity environments, when the rain protection requirement increases, the ventilation efficiency needs to be further sacrificed, exacerbating the temperature rise problem.

[0003] In the prior art, the existing solutions include: (1) Using a vertical annular grille: However, relying solely on the vertical annular grille for ventilation and heat dissipation, the heat dissipation area is small under the condition of ensuring the rain protection effect, and the ventilation and heat dissipation effect for large-capacity dry-type air-core current-limiting reactors is poor.

[0004] (2) Using a combination of an inner sound-absorbing ring and an outer sound-absorbing ring for ventilation and heat dissipation: However, for large-capacity dry-type air-core reactors, the heat dissipation area is still too small, which is not conducive to optimizing the coil temperature rise and causes waste of wires.

[0005] (3) Using multi-stage rain caps: However, similar to relying solely on the vertical annular grille for ventilation and heat dissipation, the multi-stage rain caps only rely on the multi-layer grilles on the side for ventilation and heat dissipation, without considering the rain protection function and being unable to effectively prevent rain. In this way, the ventilation and rain protection functions cannot be effectively balanced, resulting in a limited ventilation area. To meet the coil temperature rise performance, more wires need to be used. If the ventilation area between two layers of rain protection covers is extremely small, a forced cooling device needs to be installed at the bottom to ensure ventilation and heat dissipation. However, installing a forced cooling device at the bottom of the reactor requires connecting an additional power supply, which brings potential safety hazards to the operation of the reactor, and the investment cost and operation cost will also increase significantly. At the same time, due to insulation and heating problems, high-voltage and large-capacity dry-type air-core reactors are not suitable for this device.

[0006] (4)Digital design of rain protection cap: Only considering the rain protection cap, or wrapping the reactor as a whole in a sound insulation device and then designing the rain protection cap to obtain the values of various construction parameters of the rain protection cap, the ventilation and heat dissipation effect area is restricted by the rain protection effect and cannot be larger, which has great limitations. Summary of the Invention

[0007] To solve the deficiencies in the prior art, the present invention provides a device and method for reducing the temperature rise of dry-type air-core large-capacity current-limiting reactors. It adopts a double-layer rain protection device technology, breaks through the use of a split-type misaligned ventilation structure to achieve decoupling of rain protection and heat dissipation. It jointly dissipates heat through the vertical annular grid ventilation holes of the top rain protection cap and the middle ventilation net between the top rain protection cap and the bottom rain protection cap. The equivalent heat dissipation area is increased to 2-3 times that of the single-layer structure, the wire usage is reduced by 8-15%, and the coil hot spot temperature rise is reduced from 88K of the traditional structure to 78K, with a reduction of 11.4%.

[0008] The present invention adopts the following technical solutions.

[0009] The first aspect of the present invention provides a device for reducing the temperature rise of dry-type air-core large-capacity current-limiting reactors, including: a rain protection grille, a top rain protection cap, a middle rain protection baffle net, and a bottom rain protection cap; the bottom rain protection cap and the top rain protection cap form a double-layer split-type rain protection cap structure. Both the bottom rain protection cap and the top rain protection cap are of an integrated annular hemispherical design, with a height difference between the inner diameter and the outer diameter, and the height difference is an annular arc surface structure; the middle rain protection baffle net is a louver structure, connected between the top rain protection cap and the bottom rain protection cap. The height of the middle rain protection baffle net matches the ventilation and heat dissipation area of the device for reducing the temperature rise of dry-type air-core large-capacity current-limiting reactors, and is used to achieve decoupling of rain protection and heat dissipation by increasing the diameter of the ventilation opening of the bottom rain protection cap and increasing the height of the baffle net according to the actual required ventilation and heat dissipation area; the rain protection grille is arranged at the inner diameter of the top rain protection cap; the ventilation and heat dissipation area of the device for reducing the temperature rise of dry-type air-core large-capacity current-limiting reactors is larger than the air duct heat dissipation area of the reactor body.

[0010] Preferably, the outer diameter size of the bottom rain protection cap matches the outer diameter size of the current-limiting reactor, and the outer diameter size of the top rain protection cap matches the inner diameter size of the bottom rain protection cap.

[0011] Preferably, the rain protection grille is spliced by multiple epoxy inserts into a square structure; a circular epoxy net with a set mesh size is laid along the upper edge of the rain protection grille.

[0012] Preferably, the middle rain protection baffle net is a circular ring-shaped louver structure, with air ducts between each circular ring-shaped sheet for increasing the heat dissipation surface; the blades are at a set inclination angle to prevent the invasion of 30° rainwater.

[0013] The second aspect of the present invention provides a design method for a device for reducing the temperature rise of a dry-type air-core large-capacity current-limiting reactor as described in the first aspect, including the following steps: Construct a field-circuit co-simulation model of the current-limiting reactor to obtain the losses of the current-limiting reactor under set conditions; According to the structure of the device for reducing the temperature rise of the dry-type air-core large-capacity current-limiting reactor, establish a fluid flow-temperature field simulation model of the reactor with the device installed; Generate different parameter combinations of the structure parameters of the bottom rain cover, top rain cover, rain grille, and middle rain baffle of the device, substitute them into the fluid flow-temperature field simulation model, and perform batch simulations with the losses as the heat source excitation to obtain the fluid flow field of the heat dissipation channel; Quantify the contribution degrees of the structure parameters of the bottom rain cover, top rain cover, rain grille, and middle rain baffle of the device to the flow rate of the cooling medium; screen the parameters exceeding the threshold as the main control parameters; Establish a design model of the temperature rise with respect to the main control parameters, and solve the optimal parameter combination with the goal of minimizing the temperature rise and in combination with the constraint conditions.

[0014] Preferably, the establishment of the fluid flow-temperature field simulation model of the reactor with the device installed includes: Construct a parametric three-dimensional model of the reactor of the device, including the reactor body and the air channels of the rain covers, and set the parameters of the device for reducing the temperature rise of the dry-type air-core large-capacity current-limiting reactor, including: the ventilation opening area A1 of the top rain cover, the ventilation opening area A2 of the bottom rain cover, the blade width w of the middle rain baffle, the inclination angle θ of the air channel blades, the blade spacing d, and the number of openings n.

[0015] Preferably, the establishment of the fluid flow-temperature field simulation model of the reactor with the device installed includes: Based on the lattice Boltzmann method, set the MRT model to simulate the turbulence in the air channels of the reactor with the device installed, and extract the velocity distribution nephogram and local flow velocity.

[0016] Preferably, the screening of the parameters exceeding the threshold as the main control parameters includes: For the blade spacing d, the blade width w of the middle rain baffle, the ventilation opening area A1 of the top rain cover, the ventilation opening area A2 of the bottom rain cover, and the inclination angle θ of the air channel blades, generate parameter combinations by using orthogonal experiments; Based on ANOVA, calculate the contribution degrees of the parameters to the flow rate, and determine the parameters whose influence on the flow rate exceeds the set threshold as the main control parameters.

[0017] Preferably, the establishment of the design model of the temperature rise with respect to the main control parameters includes: Construct a response surface model of the flow rate change rate and the structure parameters of the device in a data-driven fitting manner; Substitute the response surface model into the convective heat transfer model to obtain a design model of the temperature rise with respect to the main control parameters.

[0018] Preferably, solving for the optimal parameter combination with the goal of minimizing the temperature rise and considering the constraint conditions includes: Use a set proportion of the simulation data in the batch simulation as the validation set to evaluate the design model of the temperature rise with respect to the main control parameters. If the error does not exceed the set threshold, then with the goal of minimizing the temperature rise based on the design model, considering the rainproof performance and / or structural strength constraint conditions, solve for the optimal parameter combination; if the error exceeds the threshold, feedback to modify the design model until the error is less than the threshold.

[0019] Compared with the prior art, the beneficial effects of the present invention at least include: The present invention takes into account both the rainproof and ventilation functions, can ensure the safe and reliable insulation performance of the reactor and the temperature rise performance, and reduces the amount of wire used. The middle baffle of the louver structure between the two rain caps can effectively prevent rain from splashing in at a 30° angle, and its ventilation area is not affected by the rainproof function. It can be achieved by increasing the diameter of the ventilation opening of the bottom rain cap and increasing the height of the baffle according to the actual required ventilation and heat dissipation area, which is simple and reliable.

[0020] Analyze the main factors affecting the coil temperature rise of the rain cap, and redesign the structure of the rain cap. While ensuring the rainproof effect, the ventilation and heat dissipation area of the rain cap is maximally increased, and the influence of adding the rain cap on the coil temperature rise is reduced. It can ensure the safe and reliable insulation performance of the reactor and the temperature rise performance, reduce the amount of wire used, and reduce the cost of the reactor. Brief Description of the Drawings

[0021] Figure 1 is a schematic diagram of the overall structure of the device for reducing the temperature rise of a large-capacity current-limiting reactor according to Embodiment 1 of the present invention; Figure 2 is a schematic diagram of the bottom rain cap according to Embodiment 1 of the present invention; Figure 3 is a schematic diagram of the top rain cap according to Embodiment 1 of the present invention; Figure 4 is a schematic diagram of the rainproof grille according to Embodiment 1 of the present invention; Figure 5 is a schematic diagram of the middle rainproof baffle according to Embodiment 1 of the present invention; Figure 6 is a schematic diagram of the details of the louver structure of the middle rainproof baffle according to Embodiment 1 of the present invention; Figure 7 is a flowchart of the design method of a device for reducing the temperature rise of a dry-type air-core large-capacity current-limiting reactor according to Embodiment 2 of the present invention; Figure 8 It is a schematic diagram of the simulation optimization of the coil temperature rise with a double-layer rainproof structure provided according to Embodiment 2 of the present invention; In the figure: 1 - rainproof grille, 2 - top rainproof cap, 3 - middle rainproof net, 4 - bottom rainproof cap. Specific embodiments

[0022] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0023] The present invention proposes a device for reducing the temperature rise of dry-type air-core large-capacity current-limiting reactors and its design method. Aiming at the problem of the contradiction between heat dissipation and rain protection in the existing rain protection devices for air-core reactors, the double-layer rain protection device proposed by the present invention forms the correlation between the structural parameters of the double-layer rain protection device and the change rate of the fluid velocity in the air duct between the packages through innovative structural design and by means of the coupled simulation technology of the magnetic field-fluid field-temperature field of the reactor, establishes a two-way coupled model of the fluid field and the temperature field, and solves the synergistic optimization problem of the design of the rain protection device and the thermal performance of the reactor through the finite element method to solve the synergistic effect of the radiation and convective heat transfer of the package.

[0024] As Figure 1 shown, Embodiment 1 of the present invention provides a device for reducing the temperature rise of a large-capacity current-limiting reactor, including: a rainproof grille 1, a top rainproof cap 2, a middle rainproof net 3 and a bottom rainproof cap 4; the middle rainproof net with a louver structure is connected between the top rainproof cap and the bottom rainproof cap in the double-layer split rainproof cap structure, and it can decouple rain protection and heat dissipation by increasing the diameter of the ventilation opening of the bottom rainproof cap and increasing the height of the net according to the actual required ventilation and heat dissipation area, achieving the maximum reduction of the impact of adding the rainproof cap on the temperature rise of the reactor and improving the service life of the reactor.

[0025] As Figure 2 shown, the bottom rainproof cap is made of epoxy fiberglass and is designed as an integral annular hemispherical surface, with a height difference between the inner diameter and the outer diameter, and the height difference is an annular arc surface structure.

[0026] The outer diameter size of the bottom rainproof cap is determined according to the outer diameter size of the current-limiting reactor. Preferably but not limited to, the outer diameter of the bottom rainproof cap is greater than the outer diameter of the current-limiting reactor. Further preferably but not limited to, to ensure the smoothness of heat convection, the outer diameter of the bottom rainproof cap is more than 200 mm larger than the outer diameter of the reactor.

[0027] The inner diameter size of the bottom rainproof cap is determined according to the required ventilation and heat dissipation area. The outer diameter surface and the inner diameter opening surface of the bottom rainproof cap adopt a flanging design for connection with adjacent components.

[0028] As Figure 3 shown, the top rainproof cap is made of epoxy fiberglass and is designed as an integral annular hemispherical surface. There is a height difference between the inner diameter and the outer diameter, and the structure between the height differences is an annular arc surface.

[0029] The outer diameter size of the top rainproof cap is determined according to the inner diameter size of the bottom rainproof cap. Preferably but not limited to, the outer diameter of the top rainproof cap is the same as the inner diameter size of the bottom rainproof cap.

[0030] The inner diameter size of the top rainproof cap is determined according to the inner diameter size of the reactor. Preferably but not limited to, to ensure the rainproof effect, the inner diameter of the top rainproof cap is not greater than the inner diameter of the reactor. The outer diameter surface and the inner diameter opening surface of the top rainproof cap adopt a flanging design for connection with adjacent components.

[0031] As Figure 4 shown, the rainproof grille is made of epoxy fiberglass and is set at the inner diameter of the top rainproof cap to ensure the rainproof effect. It is spliced by multiple epoxy inserts into a square structure.

[0032] A circular epoxy net is laid on the upper edge of the rainproof grille. Preferably but not limited to, the mesh size of the circular epoxy net is 15*15mm, which is used to prevent birds and rain.

[0033] The height and density of the rainproof grille inserts are determined according to the ratio of the difference between the inner diameter of the top rainproof cap and the inner diameter of the coil to the overall height of the rainproof cap, which is used to better prevent rainwater from splashing. There is a flanging design in the middle of the rainproof grille, and it is fixedly connected to the inner diameter flanging of the top rainproof cap by bolts.

[0034] As Figure 5 、 6 shown, the middle rainproof baffle net is made of epoxy fiberglass and is set between the top rainproof cap and the bottom rainproof cap to prevent rainwater from entering the coil encapsulation through the middle ventilation net and thus affecting the coil insulation. Preferably but not restrictively, the middle rainproof baffle net is a circular ring-shaped louver structure. The air ducts between each circular ring-shaped sheet need to increase the heat dissipation surface as much as possible. At the same time, the inclination angle of the blades needs to prevent the invasion of 30° rainwater and also has the function of preventing birds.

[0035] Furthermore, the height of the middle rainproof baffle net and the number of circular ring-shaped sheets are determined according to the size of the heat dissipation area of the reactor air duct. Preferably but not limited to, the ventilation and heat dissipation area of the device for reducing the temperature rise of the dry-type air-core large-capacity current-limiting reactor is larger than the air duct heat dissipation area of the reactor body, which is used to ensure good ventilation and heat dissipation effects.

[0036] As Figure 7 shown, Embodiment 2 of the present invention provides a design method for a device to reduce the temperature rise of a dry-type air-core large-capacity current-limiting reactor, forming the correlation between the structural parameters of the double-layer rain-proof device and the change rate of the fluid velocity in the air duct between the windings, establishing a bidirectional coupling model of the flow field and the temperature field, and solving the synergistic effect of the radiation and convection heat transfer of the windings by the finite element method. Through multi-field coupling simulation and parametric modeling, through multiple iterations, the problem of the synergistic optimization of the rain-proof device design and the thermal performance of the reactor is solved, and the final design structure scheme of the double-layer rain-proof cap is formed.

[0037] The design method includes: Step 1: Construct a field-circuit collaborative simulation model of the current-limiting reactor to obtain the losses of the current-limiting reactor under set conditions.

[0038] Preferably but not restrictively, Step 1 specifically includes: using finite element software to construct a three-dimensional model of the current-limiting reactor, defining material properties, and applying current excitation conditions; preferably but not limited to, applying the rated current of the current-limiting reactor as the excitation; through a transient magnetic field solver or frequency-domain harmonic analysis, obtaining the current and magnetic field distributions of each winding coil, and under the conditions of the current and magnetic field distributions, respectively extracting the resistance loss component and the eddy current loss component, and further obtaining the loss density distribution of each winding coil under a strong magnetic field as the heat source for temperature field simulation.

[0039] Step 2: Establish a flow field-temperature field simulation model of the reactor with the installed device according to the preliminarily designed device for reducing the temperature rise of the dry-type air-core large-capacity current-limiting reactor, apply the calculated losses as excitation conditions to the model, use the lattice Boltzmann method numerical wind tunnel technology for turbulent simulation, set the multiple relaxation time (MRT) model, simulate the turbulence in the air duct, and calculate the steady-state / transient flow field, as Figure 8 shown.

[0040] Preferably but not restrictively, Step 2 specifically includes: Step 2.1: Construct a parametric three-dimensional model in the simulation software, including the reactor body and the air duct of the rain-proof cap.

[0041] More preferably but not restrictively, set the key parameters of the device for reducing the temperature rise of the dry-type air-core large-capacity current-limiting reactor, including: the ventilation area A1 of the top rain-proof cap, the ventilation area A2 of the bottom rain-proof cap, the width w of the middle rain-proof net blades, the inclination angle θ of the air duct blades, the blade spacing d, the number of openings n, etc., which affect the heat dissipation parameters of the rain-proof cap.

[0042] Step 2.2: Based on the lattice Boltzmann method, simulate the turbulence in the air duct of the reactor with the installed device.

[0043] Further preferably but not limited thereto, the lattice Boltzmann method is adopted, the MRT model is set up, and the turbulence in the air duct is simulated. The boundary conditions are defined as: natural convection inlet / outlet, and the surface of the reactor is a constant heat flux boundary. The steady-state / transient flow field is calculated, and the velocity distribution contour map and the local flow velocity v(x, y, z) are extracted.

[0044] Step 3: Generate different parameter combinations from the structural parameters of the bottom rain cap, top rain cap, rain grille and middle rain baffle of the device, substitute them into the flow field-temperature field simulation model, and perform batch simulations with the loss as the heat source excitation to obtain the flow field of the heat dissipation channel.

[0045] Preferably but not limited thereto, Step 3 specifically includes: Step 3.1: Experimental design of parameter combination.

[0046] Further preferably but not limited thereto, key parameters are selected, such as but not limited to, blade spacing d, blade width w of the middle rain baffle, ventilation opening area A1 of the top rain cap, ventilation opening area A2 of the bottom rain cap, and duct blade inclination angle θ, and orthogonal experiments are used to generate parameter combinations.

[0047] Perform batch simulations and record the average flow velocity v0 and the hot spot flow velocity v under each set of parameters max 。

[0048] As one of the prominent substantive features of the present invention, the purpose of batch simulation is to quickly identify the influence law of key design parameters on the flow velocity distribution by systematically testing different parameter combinations, so as to provide data support for optimization. The average flow velocity reflects the overall ventilation efficiency and is used to evaluate the heat dissipation performance, and the hot spot flow velocity marks the local high-speed area. By generating the distribution data of both, batch simulation can construct a complete flow velocity field characteristic map. Batch simulation is the core means to balance design efficiency and accuracy, and the output average flow velocity and hot spot flow velocity data provide a quantitative basis for structural optimization, performance verification and safety assessment.

[0049] Step 3.2: Sensitivity quantification.

[0050] Further preferably but not limited thereto, based on ANOVA (Analysis of Variance), calculate the contribution degree of each parameter to the flow velocity, that is, the influence proportion. Determine the main control parameters as the parameters whose influence on the flow velocity of the bottom rain cap, top rain cap, rain grille and middle rain baffle structure parameters exceeds the set threshold.

[0051] By way of example but not limited thereto, the influence proportions of the blade width w of the middle rain baffle, the duct blade inclination angle θ, and the blade spacing d on the flow velocity exceed 80%. Therefore, the blade width w of the middle rain baffle, the duct blade inclination angle θ, and the blade spacing d are used as the main control parameters.

[0052] Step 4: Flow rate - parameter fitting and temperature rise analysis modeling.

[0053] Preferably but not limitedly, Step 4 specifically includes: Step 4.1: Construct a response surface model of the flow rate change rate Δv / v0 and the structural parameters in a data - driven fitting manner, which is expressed by the following formula:

[0054] In the formula: v0 and Δv are the average flow rate and the difference between the hot - spot flow rate and the average flow rate respectively; w0 and w are the reference blade width and the current blade width respectively; d0 and d are the reference blade spacing and the current blade spacing respectively; θ0 and θ are the reference blade angle and the current blade angle respectively; k1, k2, and k3 are the first, second, and third fitting coefficients respectively. Preferably but not limited to, the first, second, and third fitting coefficients are optimized by multiple - nonlinear regression.

[0055] Step 4.2: Based on the response surface model constructed in Step 4.1, construct a temperature rise model with the following formula:

[0056] In the formula: Q represents the convective heat dissipation; h represents the convective heat transfer coefficient; A represents the heat transfer area; ΔT represents the temperature difference between the solid surface of the encapsulated coil and the fluid; α represents the first calibration parameter, and β represents the second calibration parameter; the first calibration parameter α and the second calibration parameter β are calibrated through simulation data.

[0057] It should be noted that, as another prominent substantial feature of the present invention, Formula (1) fits the relationship between the flow rate and the blade width, spacing, and angle, while Formulas (2), (3), and (4) are all models related to the flow rate. Taking the flow rate change rate in Formula (1) as the input variable of Formulas (2) to (4), the multi - physical - field coupling effect can be predicted.

[0058] The structural parameters still affect the flow rate, and the temperature rise model is related to the flow rate. Therefore, ultimately, the structural parameters such as the blade width, spacing, and angle are adjusted to optimize the temperature rise.

[0059] Step 5: Model verification and optimization.

[0060] Preferably but not limitedly, Step 5 specifically includes: Step 5.1: Cross - validation.

[0061] Use 80% of the simulation data as the training set for model fitting, and the remaining 20% of the data as the validation set to evaluate the generalization performance of the model on the data not involved in training. By comparing the calculated values of the analytical formula with the full-model simulation results, calculate the relative error. If the error exceeds the standard, the model parameters need to be corrected. The main parameters to be corrected are those that have a greater impact on the flow rate change rate, such as blade width, spacing, and angle, etc.

[0062] Reserve 20% of the simulation data to verify the fitting error (target: relative error < 5%).

[0063] Compare the calculated values of the analytical formula with the full-model simulation results, and correct the parameters in the high-error range.

[0064] Step 5.2: Optimize the rain cap.

[0065] With the goal of minimizing the temperature rise and combining the constraints, preferably but not limited to, rainproof performance and structural strength, solve for the optimal parameter combination.

[0066] Compared with only relying on the vertical annular grille for ventilation and heat dissipation, the present invention takes into account both rainproof and ventilation functions, can not only ensure the safe and reliable insulation performance of the reactor but also ensure the temperature rise performance, and reduces the wire consumption. The middle baffle of the louver structure between the two layers of rain caps can effectively prevent rain from splashing in at a 30° angle, and its ventilation area is not affected by the rainproof function. It can be achieved by increasing the diameter of the ventilation opening of the bottom rain cap and increasing the height of the baffle according to the actual required ventilation and heat dissipation area, which is simple and reliable. It prevents the coil from having insulation problems due to rain splashing in, causing damage to the reactor. At the same time, it does not increase additional operating risks and greatly saves costs, and is applicable to dry-type air-core reactors of various voltage levels and capacities. It can achieve the unity of ventilation and heat dissipation and rainproof functions without adding cooling devices, and has high economic benefits and service functions.

[0067] Compared with other solutions for digital design of rain caps in the prior art, the present invention not only considers the influence of the rain cap on the coil temperature rise, but also analyzes the main factors affecting the coil temperature rise by the rain cap, and redesigns the structure of the rain cap. While ensuring the rain-proof effect, the ventilation and heat dissipation area of the rain cap is maximally increased, and the influence of adding the rain cap on the coil temperature rise is reduced. It can not only ensure the safe and reliable insulation performance of the reactor, but also ensure the temperature rise performance, reduce the amount of wire used, and reduce the cost of the reactor. And it considers the thermal convection and thermal radiation effects of the reactor with a double-layer structure of the middle baffle based on the louver structure, constructs a bidirectional coupling model of magnetic field-fluid field-temperature field, and establishes an analysis framework for structural parameter sensitivity to obtain an analytical calculation formula for the temperature rise of the reactor with a double-layer rain-proof device. While taking into account the ventilation function, it can effectively prevent rain, prevent insulation problems caused by rain splashing into the coil, and cause damage to the reactor. Based on the thermal convection and thermal radiation effects of the reactor with a double-layer structure of the middle baffle based on the louver structure, constructs a bidirectional coupling model of magnetic field-fluid field-temperature field, and establishes an analysis framework for structural parameter sensitivity to obtain an analytical calculation formula for the temperature rise of the reactor with a double-layer rain-proof device.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: still can modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement without departing from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A device for reducing the temperature rise of a dry-type air-core large-capacity current-limiting reactor, characterized in that, Including: A rainproof grille (1), a top rainproof cap (2), a middle rainproof net (3), and a bottom rainproof cap (4); The bottom rainproof cap (4) and the top rainproof cap (2) form a double-layer split rainproof cap structure. Both the bottom rainproof cap (4) and the top rainproof cap (2) are of an integrated annular hemispherical design, with a height difference between the inner diameter and the outer diameter, and an annular arc surface structure between the height differences; The middle rainproof net (3) is of a louver structure and is connected between the top rainproof cap (2) and the bottom rainproof cap (4). The height of the middle rainproof net (3) matches the ventilation and heat dissipation area of the device for reducing the temperature rise of the dry-type air-core large-capacity current-limiting reactor, and is used to decouple rain protection and heat dissipation by increasing the diameter of the ventilation opening of the bottom rainproof cap and increasing the height of the net according to the actually required ventilation and heat dissipation area; The rainproof grille is arranged at the inner diameter of the top rainproof cap; The ventilation and heat dissipation area of the device for reducing the temperature rise of the dry-type air-core large-capacity current-limiting reactor is larger than the air duct heat dissipation area of the reactor body.

2. The device for reducing the temperature rise of a dry-type air-core large-capacity current-limiting reactor according to claim 1, characterized in that: The outer diameter size of the bottom rainproof cap matches the outer diameter size of the current-limiting reactor, and the outer diameter size of the top rainproof cap matches the inner diameter size of the bottom rainproof cap.

3. The device for reducing the temperature rise of a dry-type air-core large-capacity current-limiting reactor according to claim 1, characterized in that: The rainproof grille is spliced by multiple epoxy inserts into a square structure; a circular epoxy net with set-sized mesh holes is laid along the upper edge of the rainproof grille.

4. The device for reducing the temperature rise of a dry-type air-core large-capacity current-limiting reactor according to any one of claims 1 to 3, characterized in that: The middle rainproof net is a circular ring-shaped louver structure, with air ducts between each circular ring-shaped sheet for increasing the heat dissipation surface; the blades are at a set inclination angle to prevent the invasion of 30° rainwater.

5. A design method for a device for reducing the temperature rise of a dry-type air-core large-capacity current-limiting reactor as described in any one of claims 1 to 4, characterized in that, Including the following steps: Construct a field-circuit co-simulation model of the current-limiting reactor to obtain the losses of the current-limiting reactor under set conditions; According to the structure of the device for reducing the temperature rise of the dry-type air-core large-capacity current-limiting reactor, establish a fluid flow-temperature field simulation model of the reactor with the device installed; Generate different parameter combinations of the structure parameters of the bottom rainproof cap, top rainproof cap, rainproof grille, and middle rainproof net of the device, substitute them into the fluid flow-temperature field simulation model, and perform batch simulations with the losses as the heat source excitation to obtain the fluid flow field of the heat dissipation channel; Quantify the contribution degrees of the structure parameters of the bottom rainproof cap, top rainproof cap, rainproof grille, and middle rainproof net of the device to the flow velocity of the cooling medium; screen the parameters exceeding the threshold as the main control parameters; Establish a design model of the temperature rise with respect to the main control parameters, and solve the optimal parameter combination with the goal of minimizing the temperature rise and combining the constraint conditions.

6. According to the design method of claim 5, characterized in that: The establishment of the fluid flow-temperature field simulation model of the reactor with the device installed includes: Construct a parametric 3D model of the reactor of the device, including the reactor body and the rainproof cap air duct, and set the parameters of the device for reducing the temperature rise of the dry-type air-core large-capacity current-limiting reactor, including: the area A1 of the ventilation opening of the top rainproof cap, the area A2 of the ventilation opening of the bottom rainproof cap, the width w of the middle rainproof net blade, the inclination angle θ of the air duct blade, the blade spacing d, and the number of openings n.

7. The design method according to claim 6, characterized in that: The establishment of the flow field-temperature field simulation model of the reactor with the device installed includes: Based on the lattice Boltzmann method, set the MRT model to simulate the turbulence in the air duct of the reactor with the device installed, and extract the velocity distribution cloud map and local flow velocity.

8. The design method according to any one of claims 5 to 7, characterized in that: The screening of the parameters exceeding the threshold as the main control parameters includes: For the blade spacing d, the width w of the middle rainproof net blade, the area A1 of the ventilation opening of the top rainproof cap, the area A2 of the ventilation opening of the bottom rainproof cap, and the inclination angle θ of the air duct blade, use the orthogonal experiment to generate parameter combinations; Based on ANOVA, calculate the contribution degree of each parameter to the flow velocity, and determine the parameters whose influence on the flow velocity exceeds the set threshold as the main control parameters.

9. The design method according to claim 8, characterized in that: The establishment of the design model of the temperature rise with respect to the main control parameters includes: Construct a response surface model of the flow velocity change rate and the structural parameters of the device in a data-driven fitting manner; Substitute the response surface model into the convective heat transfer model to obtain the design model of the temperature rise with respect to the main control parameters.

10. The design method according to claim 9, characterized in that: The minimization of the temperature rise as the goal, combined with the constraint conditions to solve the optimal parameter combination includes: Use a set proportion of the simulation data in the batch simulation as the verification set to evaluate the design model of the temperature rise with respect to the main control parameters. If the error does not exceed the set threshold, then based on the design model, with the minimization of the temperature rise as the goal, combined with the rainproof performance and / or structural strength constraint conditions, solve the optimal parameter combination; if the error exceeds the threshold, feedback and modify the design model until the error is less than the threshold.

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