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

Abstract

A device and design method for reducing the temperature rise of dry-type, hollow, large-capacity, current-limiting reactors employs a double-layer rain shield and a split, staggered ventilation structure to decouple rain protection and heat dissipation. Heat is dissipated through vertical annular grille vents on the top rain shield and a central ventilation mesh between the top and bottom rain shields. Using coupled simulation technology for the reactor's magnetic field, flow field, and temperature field, the device's structural parameters are correlated with the rate of change of the fluid flow velocity within the airway between the envelopes. A bidirectional coupling model of the flow and temperature fields is established, and the finite element method is used to account for the synergistic effect of envelope radiation and convective heat transfer. Through multi-field coupled simulation and parametric modeling, the device solves the challenge of collaboratively optimizing the rain shield design and the reactor's thermal performance. The device increases the equivalent heat dissipation area to 2-3 times that of a single-layer structure, reduces wire usage by 8-15%, and reduces the coil hotspot temperature rise from 88K in conventional structures to 78K, a reduction of 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 a dry-type hollow large-capacity current-limiting reactor and a design method thereof. Background Art

[0002] In the technological development of dry-type air-core current-limiting reactors, as outdoor primary electrical equipment, multi-layer enclosure structures have become the mainstream design as capacity and current demands increase. Traditional single-layer rain shields present a major conflict between heat dissipation and rain protection performance: Dry-type air-core reactors utilize air natural cooling (AN) for heat dissipation, requiring ventilation ducts and rain shield vents between the multiple layers of enclosure to ensure heat dissipation. As the number of enclosure layers increases, the heat dissipation area must also be expanded. However, the single-layer design of traditional rain shields can hinder airflow through the enclosure gaps, leading to internal heat accumulation and compromising equipment stability. Existing single-layer rain shields typically utilize an umbrella-shaped top cover to divert rainwater, but this design blocks the ventilation path above the enclosure, creating a "rain protection vs. heat dissipation" conflict. Especially in rainy or high-humidity environments, the increased demand for rain protection requires further compromise in ventilation efficiency, exacerbating temperature rise.

[0003] In the prior art, existing solutions include:

[0004] (1) Use vertical ring grilles: However, ventilation and heat dissipation only rely on vertical ring grilles. While ensuring rain protection, the heat dissipation area is small, and the ventilation and heat dissipation effect is poor for large-capacity dry-type hollow current-limiting reactors.

[0005] (2) Use a combination of inner and outer sound-absorbing coils 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.

[0006] (3) Use of multi-level rainproof cap: However, similar to relying solely on vertical ring grilles for ventilation and heat dissipation, multi-level rainproof caps rely solely on the side multi-layer grilles for ventilation and heat dissipation, without considering the rainproof function, and cannot effectively prevent rain. This cannot effectively take into account both ventilation and rainproof functions, resulting in limited ventilation area. In order to meet the coil temperature rise performance, more wires need to be used. If the ventilation area between the two layers of rainproof covers is particularly small, a forced cooling device at the bottom is required to ensure ventilation and heat dissipation. However, installing a forced cooling device at the bottom of the reactor requires connecting to an additional power supply, which poses a safety hazard to the operation of the reactor, and the investment cost and operating cost will also increase significantly. At the same time, due to insulation and heat generation problems, high voltage and large capacity dry-type air-core reactors are not suitable for this device.

[0007] (4) Digital design of rain cap: However, if only the rain cap is considered, or the reactor is wrapped in a sound insulation device and then the rain cap is designed, the values ​​of various construction parameters of the rain cap are obtained. The ventilation and heat dissipation effect area cannot be larger due to the restriction of rain protection effect, which is very restrictive. Summary of the Invention

[0008] In order to address the deficiencies in the prior art, the present invention provides a device and method for reducing the temperature rise of a dry-type hollow large-capacity current-limiting reactor. The device and method adopt double-layer rainproof device technology, and achieve decoupling of rain protection and heat dissipation by adopting a split-type staggered ventilation structure. The device dissipates heat through the vertical annular grille ventilation holes of the top rainproof cap and the middle ventilation network between the top rainproof cap and the bottom rainproof cap. The equivalent heat dissipation area is increased to 2-3 times that of a single-layer structure, the amount of wire used is reduced by 8-15%, and the coil hot spot temperature rise is reduced from 88K of the traditional structure to 78K, a decrease of 11.4%.

[0009] The present invention adopts the following technical solutions.

[0010] The first aspect of the present invention provides a device for reducing the temperature rise of a dry-type hollow large-capacity current-limiting inductor, comprising: a rainproof grille, a top rainproof cap, a middle rainproof net and a bottom rainproof cap; the bottom rainproof cap and the top rainproof cap form a double-layer split rainproof cap structure, and the bottom rainproof cap and the top rainproof cap are both one-piece annular hemispherical designs, with a height difference between the inner diameter and the outer diameter, and an annular arc surface structure between the height difference; the middle rainproof net is a louver structure, connected between the top rainproof cap and the bottom rainproof cap, and the height of the middle rainproof net matches the ventilation and heat dissipation area of ​​the device for reducing the temperature rise of the dry-type hollow large-capacity current-limiting inductor, and is used to achieve rain protection and heat dissipation decoupling by increasing the diameter of the ventilation port of the bottom rainproof cap and increasing the height of the net according to the actual 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 hollow large-capacity current-limiting inductor is greater than the air duct heat dissipation area of ​​the reactor body.

[0011] Preferably, the outer diameter of the bottom rainproof cap matches the outer diameter of the current-limiting reactor, and the outer diameter of the top rainproof cap matches the inner diameter of the bottom rainproof cap.

[0012] Preferably, the rainproof grille is formed by splicing a plurality of epoxy plug-in plates into a U-shaped structure; a circular epoxy net with a set size of mesh is laid on the upper edge of the rainproof grille.

[0013] Preferably, the central rainproof net is a louver structure in the form of circular sheets, with air ducts between each circular sheet to increase the heat dissipation surface; the blades adopt a set inclination angle to prevent the invasion of 30° rain.

[0014] A second aspect of the present invention provides a method for designing a device for reducing the temperature rise of a dry-type hollow large-capacity current-limiting reactor as described in the first aspect, comprising the following steps:

[0015] Construct a field-circuit collaborative simulation model for a current-limiting reactor to obtain the losses of the current-limiting reactor under set conditions;

[0016] According to the structure of the device for reducing the temperature rise of a dry-type hollow large-capacity current-limiting reactor, a flow field-temperature field simulation model of the reactor equipped with the device is established;

[0017] Different parameter combinations are generated for the structural parameters of the bottom rain cap, top rain cap, rain grille, and middle rain screen of the device, and the parameters are substituted into the flow field-temperature field simulation model. Batch simulation is performed using the loss as a heat source excitation to obtain the flow field of the heat dissipation channel;

[0018] Quantify the contribution of the structural parameters of the bottom rain cap, top rain cap, rain grille, and middle rain screen of the device to the flow rate of the cooling medium; select parameters exceeding the threshold value as the main control parameters;

[0019] A design model of temperature rise related to main control parameters is established, with the goal of minimizing temperature rise, and the optimal parameter combination is solved in combination with constraint conditions.

[0020] Preferably, the establishment of a flow field-temperature field simulation model of a reactor equipped with the device includes:

[0021] A parametric three-dimensional model of the reactor of the device is constructed, including the reactor body and the rain cap air duct, and parameters of the device for reducing the temperature rise of the dry hollow large-capacity current-limiting reactor are set, including: the ventilation area A1 of the top rain cap, the ventilation area A2 of the bottom rain cap, the blade width w of the middle rain shield, the inclination angle θ of the air duct blades, the blade spacing d, and the number of openings n.

[0022] Preferably, the establishment of a flow field-temperature field simulation model of a reactor equipped with the device includes:

[0023] Based on the lattice Boltzmann method, an MRT model was set up to simulate the turbulent flow in the air duct of the reactor equipped with the device, and the velocity distribution cloud map and local flow velocity were extracted.

[0024] Preferably, the parameters that are screened to exceed the threshold value include, as main control parameters:

[0025] Orthogonal experiments were used to generate parameter combinations for the blade spacing d, the width w of the middle rain shield blade, the ventilation area A1 of the top rain cap, the ventilation area A2 of the bottom rain cap, and the inclination angle θ of the duct blades.

[0026] The contribution of each parameter to the flow rate was calculated based on ANOVA, and the parameter whose influence on the flow rate exceeded the set threshold was determined as the main control parameter.

[0027] Preferably, establishing a design model of temperature rise with respect to main control parameters includes:

[0028] constructing a response surface model of the flow rate change rate and the structural parameters of the device in a data-driven fitting manner;

[0029] The response surface model is substituted into the convective heat transfer model to obtain the design model of temperature rise with respect to the main control parameters.

[0030] Preferably, the method of solving the optimal parameter combination with the constraint conditions with the goal of minimizing the temperature rise includes:

[0031] A set proportion of simulation data in the batch simulation is used as a validation set to evaluate the design model of temperature rise with respect to the main control parameters. If the error does not exceed a set threshold, the optimal parameter combination is solved based on the design model with the goal of minimizing temperature rise, combined with rainproof performance and / or structural strength constraints. If the error exceeds the threshold, feedback is provided to modify the design model until the error is less than the threshold.

[0032] Compared with the prior art, the beneficial effects of the present invention include at least:

[0033] This invention combines rain protection with ventilation, ensuring both safe and reliable reactor insulation and temperature-rise performance while reducing wire usage. The central screen between the two rain caps effectively prevents rainwater from entering at a 30° angle. The ventilation area is unaffected by rain protection, and can be adjusted to the desired ventilation and heat dissipation area by increasing the diameter of the vents in the bottom rain cap and the height of the screen. This is simple and reliable.

[0034] The main factors affecting the temperature rise of the coil due to the rain cap were analyzed, and the structure of the rain cap was redesigned. While ensuring the rainproof effect, the ventilation and heat dissipation area of ​​the rain cap was maximized, reducing the impact of the rain cap on the temperature rise of the coil. This can ensure the safety and reliability of the 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

[0035] Figure 1 1 is a schematic diagram of the overall structure of a device for reducing the temperature rise of a large-capacity current-limiting reactor provided in accordance with Example 1 of the present invention;

[0036] Figure 2 is a schematic diagram of a bottom rain cap provided according to Example 1 of the present invention;

[0037] Figure 3 is a schematic diagram of a top rain cap provided according to Example 1 of the present invention;

[0038] Figure 4 is a schematic diagram of a rainproof grille provided according to embodiment 1 of the present invention;

[0039] Figure 5 Schematic diagram of a middle rainproof screen provided in accordance with Example 1 of the present invention;

[0040] Figure 6 Schematic diagram of the louver structure details of the middle rainproof screen provided in accordance with Example 1 of the present invention;

[0041] Figure 7 This is a flow chart of a method for designing a device for reducing the temperature rise of a dry-type hollow large-capacity current-limiting reactor provided in accordance with Example 2 of the present invention;

[0042] Figure 8 This is a schematic diagram of the simulation optimization of coil temperature rise with a double-layer rainproof structure provided in accordance with Example 2 of the present invention;

[0043] In the picture:

[0044] 1-Rainproof grille, 2-Top rain cap, 3-Middle rainproof net, 4-Bottom rain cap. DETAILED DESCRIPTION

[0045] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0046] This invention proposes a device and design method for reducing the temperature rise of dry-type hollow, large-capacity, current-limiting reactors. Addressing the conflict between heat dissipation and rain protection in existing hollow reactor rainproof devices, the double-layer rainproof device proposed in this invention utilizes innovative structural design and leverages coupled simulation technology of the reactor's magnetic field, flow field, and temperature field to establish a correlation between the structural parameters of the double-layer rainproof device and the rate of change of the fluid flow velocity within the airway between the enclosures. This establishes a bidirectional coupling model of the flow field and temperature field, and uses the finite element method to solve the synergistic effect of enclosure radiation and convective heat transfer. Through multi-field coupled simulation and parametric modeling, the challenge of collaborative optimization of rainproof device design and reactor thermal performance is resolved.

[0047] like Figure 1As shown, embodiment 1 of the present invention provides a device for reducing the temperature rise of a large-capacity current-limiting reactor, comprising: a rainproof grille 1, a top-level rainproof cap 2, a middle rainproof net 3 and a bottom-level rainproof cap 4; the middle rainproof net of the louver structure is connected between the top-level rainproof cap and the bottom-level rainproof cap in the double-layer split rainproof cap structure, which can decouple rain protection and heat dissipation by increasing the diameter of the vents of the bottom-level rainproof cap and increasing the height of the net according to the actual required ventilation and heat dissipation area, thereby minimizing the impact of the installation of the rainproof cap on the temperature rise of the reactor and improving the service life of the reactor.

[0048] like Figure 2 As shown, the bottom rain cap is made of epoxy fiberglass and has an integrated annular hemispherical design. There is a height difference between the inner diameter and the outer diameter, and the height difference is an annular arc structure.

[0049] The outer diameter of the bottom rain cap is determined according to the outer diameter of the current limiting reactor. Preferably, but not limited to, the outer diameter of the bottom rain cap is larger than the outer diameter of the current limiting reactor. Further preferably, but not limited to, to ensure smooth heat convection, the outer diameter of the bottom rain cap is more than 200mm larger than the outer diameter of the reactor.

[0050] The inner diameter of the bottom rain 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 rain cap are designed with flanges for connection with adjacent components.

[0051] like Figure 3 As shown, the top rain cap is made of epoxy fiberglass and has an integrated annular hemispherical design. There is a height difference between the inner diameter and the outer diameter, and the height difference is an annular arc structure.

[0052] The outer diameter of the top rain cap is determined according to the inner diameter of the bottom rain cap. Preferably, but not limited to, the outer diameter of the top rain cap is the same as the inner diameter of the bottom rain cap.

[0053] The inner diameter of the top rain cap is determined based on the inner diameter of the reactor. Preferably, but not limited to, to ensure rain protection, the inner diameter of the top rain cap is no larger than the inner diameter of the reactor. The outer diameter surface and the inner diameter opening surface of the top rain cap are flanged for connection with adjacent components.

[0054] like Figure 4 As shown, the rainproof grille is made of epoxy fiberglass and is arranged at the inner diameter of the top rainproof cap to ensure the rainproof effect. It is made of multiple epoxy plug-in plates spliced ​​into a U-shaped structure.

[0055] 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.

[0056] The height and density of the rain grille plates are determined by the ratio of the difference between the inner diameter of the top rain cap and the inner diameter of the coil to the overall height of the rain cap, to better prevent rainwater from pouring. The rain grille has a flange design in the middle, which is fixed to the inner diameter flange of the top rain cap with bolts.

[0057] like Figure 5 、 6 As shown, the central rain screen is made of epoxy fiberglass and is positioned between the top and bottom rain caps to prevent rainwater from entering the coil enclosure through the central ventilation net and affecting coil insulation. Preferably, but not limitingly, the central rain screen is a circular, blade-shaped louver structure. The air ducts between each circular blade should maximize the heat dissipation surface. The blades should be tilted at an angle that can prevent 30° rain intrusion and also provide bird protection.

[0058] Furthermore, the height of the central rainproof net and the number of circular 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 hollow large-capacity current-limiting reactor is larger than the heat dissipation area of ​​the air duct of the reactor body, so as to ensure good ventilation and heat dissipation effects.

[0059] like Figure 7 As shown, Example 2 of the present invention provides a design method for a device that reduces the temperature rise of a dry-type, hollow, large-capacity, current-limiting reactor. This method establishes a correlation between the structural parameters of a double-layer rain shield and the rate of change of the fluid velocity within the airway between the enclosures. A bidirectional coupling model of the flow and temperature fields is established, and the finite element method is used to solve the synergistic effect of enclosure radiation and convective heat transfer. Through multi-field coupling simulation and parametric modeling, and through multiple iterations, the challenge of collaboratively optimizing the rain shield design and the reactor's thermal performance is resolved, resulting in a final design scheme for the double-layer rain cap.

[0060] The design method includes:

[0061] Step 1: Construct a field-circuit collaborative simulation model of the current-limiting reactor to obtain the loss of the current-limiting reactor under set conditions.

[0062] Preferably, but not limitatively, step 1 specifically includes: using finite element software to construct a three-dimensional model of a current limiting inductor, defining material properties, and applying current excitation conditions; preferably, but not limited to, applying the rated current of the current limiting inductor as excitation; obtaining the current and magnetic field distribution of each encapsulated coil through a transient magnetic field solver or frequency domain harmonic analysis, and under the current and magnetic field distribution conditions, extracting the resistance loss component and the eddy current loss component respectively, and then obtaining the loss density distribution of each encapsulated coil under a strong magnetic field as a heat source for temperature field simulation.

[0063] Step 2: Based on the preliminary design of the device for reducing the temperature rise of the dry-type hollow large-capacity current-limiting reactor, a flow field-temperature field simulation model of the reactor equipped with the device is established. The calculated loss is applied to the model as an excitation condition. The lattice Boltzmann method numerical wind tunnel technology is used to perform turbulence simulation. The Multiple Relaxation Time (MRT) model is set to simulate the turbulence in the airway and calculate the steady-state / transient flow field, such as Figure 8 shown.

[0064] Preferably but not limitatively, step 2 specifically includes:

[0065] Step 2.1: Construct a parametric 3D model in the simulation software, including the reactor body and the rain cap air duct.

[0066] It is further preferred but not restrictive that the key parameters of the device for reducing the temperature rise of the dry hollow large-capacity current-limiting reactor are set, including: the ventilation area A1 of the top rain cap, the ventilation area A2 of the bottom rain cap, the blade width w of the middle rain shield, the inclination angle θ of the air duct blades, the blade spacing d, the number of openings n and other parameters affecting the heat dissipation of the rain cap.

[0067] Step 2.2: Based on the lattice Boltzmann method, simulate the turbulent flow in the air duct of the reactor equipped with the device.

[0068] Further preferably, but not limitingly, a lattice Boltzmann method is employed to set up an MRT model and simulate turbulent flow within the airway. Boundary conditions are defined: natural convection inlet / outlet, and a constant heat flux boundary on the reactor surface. Steady-state and transient flow fields are calculated, and velocity distribution contours and local flow velocities v(x, y, z) are extracted.

[0069] Step 3: Generate different parameter combinations for the structural parameters of the bottom rain cap, top rain cap, rain grille and middle rain shield of the device, substitute them into the flow field-temperature field simulation model, and perform batch simulation with the loss as the heat source excitation to obtain the flow field of the heat dissipation channel.

[0070] Preferably but not limiting, step 3 specifically includes:

[0071] Step 3.1: Parameter combination experimental design.

[0072] Further preferably but not restrictively, key parameters are selected, such as but not limited to the blade spacing d, the middle rain shield blade width w, the top rain cap ventilation area A1, the bottom rain cap ventilation area A2 and the duct blade inclination angle θ, and an orthogonal experiment is used to generate a parameter combination.

[0073] Perform batch simulation and record the average flow velocity v0 and hotspot flow velocity v under each set of parameters max .

[0074] As one of the outstanding substantive features of this invention, the purpose of batch simulation is to quickly identify the influence of key design parameters on flow velocity distribution through systematic testing of different parameter combinations, providing data support for optimization. The average flow velocity reflects the overall ventilation efficiency and is used to evaluate heat dissipation performance, while the hotspot flow velocity marks the local high-speed area. Batch simulation can construct a complete flow velocity field characteristic map by generating distribution data of both. Batch simulation is the core means to balance design efficiency and accuracy. The average flow velocity and hotspot flow velocity data it outputs provide a quantitative basis for structural optimization, performance verification and safety assessment.

[0075] Step 3.2: Sensitivity quantification.

[0076] Further preferably, but not limiting, the contribution of each parameter to the flow velocity, i.e., the influence ratio, is calculated based on ANOVA (Analysis of Variance). The parameters of the bottom rain cap, top rain cap, rain grille, and middle rain screen whose influence on the flow velocity exceeds a set threshold are determined as the main control parameters.

[0077] By way of example but not limitation, the influence of the blade width w of the middle rain shield net, the inclination angle θ of the air duct blades, and the blade spacing d on the flow rate accounts for more than 80%. Therefore, the blade width w of the middle rain shield net, the inclination angle θ of the air duct blades, and the blade spacing d are used as the main control parameters.

[0078] Step 4: Flow rate-parameter fitting and temperature rise analytical modeling.

[0079] Preferably but not limitatively, step 4 specifically includes:

[0080] Step 4.1: Construct a response surface model of the flow rate change rate Δv / v0 and structural parameters using a data-driven fitting method, which is expressed as the following formula:

[0081]

[0082] Where:

[0083] v0 and Δv are the differences between the average velocity and the hot spot velocity and the average velocity, respectively;

[0084] w0 and w are the reference blade width and the current blade width respectively;

[0085] d0 and d are the reference blade spacing and the current blade spacing, respectively;

[0086] θ0 and θ are the reference blade angle and the current blade angle respectively;

[0087] 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 using multivariate nonlinear regression.

[0088] Step 4.2: Based on the response surface model constructed in step 4.1, construct a temperature rise model using the following formula:

[0089]

[0090] Where:

[0091] Q represents the amount of heat dissipated by convection;

[0092] h represents the convective heat transfer coefficient;

[0093] A represents the heat exchange area;

[0094] ΔT represents the temperature difference between the solid surface of the encapsulated coil and the fluid;

[0095] 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.

[0096] It is worth noting that, as another outstanding substantial feature of the present invention, formula (1) fits the relationship between flow velocity and blade width, spacing and angle, while formulas (2), (3) and (4) are all models about flow velocity. By using the flow velocity change rate in formula (1) as the input variable of formulas (2) to (4), the multi-physics field coupling effect can be predicted.

[0097] The structural parameters still affect the flow rate, and the temperature rise model is related to the flow rate, so in the end the structural parameters such as blade width, spacing and angle are adjusted to optimize the temperature rise.

[0098] Step 5: Model validation and optimization.

[0099] Preferably but not limitatively, step 5 specifically includes:

[0100] Step 5.1: Cross-validation.

[0101] 80% of the simulation data was used as the training set for model fitting, and the remaining 20% ​​was used as the validation set to evaluate the model's generalization performance on data not used in training. The relative error was calculated by comparing the analytically calculated value with the full model simulation results. If the error exceeded the standard, the model parameters needed to be corrected. This was primarily focused on factors that had a significant impact on the rate of change of flow velocity, such as blade width, pitch, and angle.

[0102] 20% of the simulation data was reserved to verify the fitting error (target: relative error < 5%).

[0103] Compare the analytical calculation values ​​with the full model simulation results and correct the parameters in the high error range.

[0104] Step 5.2: Rain cap optimization.

[0105] With the goal of minimizing temperature rise, combined with constraints, preferably but not limited to, rainproof performance and structural strength, the optimal parameter combination is solved.

[0106] Compared with ventilation and heat dissipation relying solely on vertical annular grilles, the present invention takes into account both rainproof and ventilation functions, which can ensure the safety and reliability of the insulation performance of the reactor and the temperature rise performance, and reduces the amount of wire used. The middle barrier net of the louver structure between the two layers of rainproof caps can effectively prevent rainwater from seeping 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 vents of the bottom rainproof cap and increasing the height of the barrier net 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 rainwater seepage, 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 hollow reactors of various voltage levels and capacities. The unification of ventilation and heat dissipation and rainproof functions can be achieved without adding a cooling device, which has high economic benefits and usage functions.

[0107] Compared with other digitally designed rain cap solutions in the prior art, the present invention not only considers the impact of the rain cap on the coil temperature rise, but also analyzes the main factors affecting the coil temperature rise, and redesigns the rain cap structure. While ensuring the rainproof effect, it maximizes the ventilation and heat dissipation area of ​​the rain cap, reduces the impact of the rain cap on the coil temperature rise, and can ensure both the safety and reliability of the reactor insulation performance and the temperature rise performance, reduces the amount of wire used, and reduces the cost of the reactor. In addition, the thermal convection and thermal radiation effects of the reactor with a double-layer structure based on the middle barrier of the louver structure are taken into account, and a magnetic field-flow field-temperature field bidirectional coupling model is constructed. A structural parameter sensitivity analysis framework is established to obtain an analytical calculation formula for the temperature rise of the reactor with a double-layer rainproof device. While taking into account the ventilation function, it can effectively prevent rain and prevent the coil from causing insulation problems due to rainwater intrusion, causing damage to the reactor. Based on the thermal convection and thermal radiation effects of the double-layer reactor with a central baffle of a louver structure, a bidirectional coupling model of magnetic field, flow field and temperature field is constructed, and a structural parameter sensitivity analysis framework is established to obtain the analytical calculation formula for the temperature rise of the reactor with a double-layer rainproof device.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A device for reducing the temperature rise of a dry-type hollow large-capacity current-limiting reactor, characterized in that: include: Bottom rain cap, top rain cap, rain grille and middle rain screen; The bottom rain cap and the top rain cap are both 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 difference. The outer diameter of the top rain cap is the same as the inner diameter of the bottom rain cap, and the outer diameter of the bottom rain cap matches the outer diameter of the current limiting reactor. The middle rain shield is a louver structure, connected between the top rain shield and the bottom rain shield in the double-layer split rain shield structure, and its height matches the ventilation and heat dissipation area of ​​the device for reducing the temperature rise of the dry-type hollow large-capacity current-limiting reactor, and is used to achieve decoupling of rain protection and heat dissipation by increasing the diameter of the ventilation opening of the bottom rain shield and increasing the height of the shield according to the actual 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 a dry-type hollow 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 hollow large-capacity current-limiting reactor according to claim 1, characterized in that: The rainproof grille is formed by splicing a plurality of epoxy plug-in boards into a U-shaped structure; a circular epoxy net with a set size of mesh is laid on the upper edge of the rainproof grille.

3. A device for reducing the temperature rise of a dry-type hollow large-capacity current-limiting reactor according to claim 1 or 2, characterized in that: The central rainproof net is a louver structure in the shape of circular sheets, with air ducts between each circular sheet to increase the heat dissipation surface; the blades adopt a set inclination angle to prevent the invasion of 30° rain.

4. A design method for a device for reducing the temperature rise of a dry-type hollow large-capacity current-limiting reactor according to any one of claims 1 to 3, characterized in that: The following steps are involved: Construct a field-circuit collaborative simulation model for a 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 a dry-type hollow large-capacity current-limiting reactor, a flow field-temperature field simulation model of the reactor equipped with the device is established; Different parameter combinations are generated for the structural parameters of the bottom rain cap, top rain cap, rain grille, and middle rain screen of the device, and the parameters are substituted into the flow field-temperature field simulation model. Batch simulation is performed using the loss as a heat source excitation to obtain the flow field of the heat dissipation channel; Quantify the contribution of the structural parameters of the bottom rain cap, top rain cap, rain grille, and middle rain screen of the device to the flow rate of the cooling medium; select parameters exceeding the threshold value as the main control parameters; A design model of temperature rise related to main control parameters is established, with the goal of minimizing temperature rise, and the optimal parameter combination is solved in combination with constraint conditions.

5. The design method according to claim 4, characterized in that: The establishment of a flow field-temperature field simulation model of a reactor equipped with the device includes: A parametric three-dimensional model of the reactor of the device is constructed, including the reactor body and the rain cover air duct, and the parameters of the device for reducing the temperature rise of the dry hollow large-capacity current-limiting reactor are set, including: the ventilation area A1 of the top rain cover, the ventilation area A2 of the bottom rain cover, the blade width w of the middle rain shield, the inclination angle θ of the air duct blades, the blade spacing d, and the number of openings n.

6. The design method according to claim 5, characterized in that: The establishment of a flow field-temperature field simulation model of a reactor equipped with the device includes: Based on the lattice Boltzmann method, an MRT model was set up to simulate the turbulent flow in the air duct of the reactor equipped with the device, and the velocity distribution cloud map and local flow velocity were extracted.

7. The design method according to any one of claims 4 to 6, characterized in that: The parameters that are screened to exceed the threshold value include, as main control parameters: Orthogonal experiments were used to generate parameter combinations for the blade spacing d, the width w of the middle rain shield blade, the ventilation area A1 of the top rain shield, the ventilation area A2 of the bottom rain shield, and the inclination angle θ of the duct blades. The contribution of each parameter to the flow rate was calculated based on ANOVA, and the parameter whose influence on the flow rate exceeded the set threshold was determined as the main control parameter.

8. The design method according to claim 7, characterized in that: The design model of establishing temperature rise with respect to main control parameters includes: constructing a response surface model of the flow rate change rate and the structural parameters of the device in a data-driven fitting manner; The response surface model is substituted into the convective heat transfer model to obtain the design model of temperature rise with respect to the main control parameters.

9. The design method according to claim 8, characterized in that: The objective of minimizing temperature rise and solving the optimal parameter combination in combination with the constraint conditions include: A set proportion of simulation data in the batch simulation is used as a validation set to evaluate the design model of temperature rise with respect to the main control parameters. If the error does not exceed a set threshold, the optimal parameter combination is solved based on the design model with the goal of minimizing temperature rise, combined with rainproof performance and / or structural strength constraints. If the error exceeds the threshold, feedback is provided to modify the design model until the error is less than the threshold.

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