Transformer temperature intelligent regulation method and system based on phase change immersion liquid cooling technology

Abstract

The present application relates to the technical field of transformer temperature regulation, and particularly relates to a transformer temperature intelligent regulation method and system based on phase change immersion liquid cooling technology, which collects heat power, saturated steam pressure, dewing state and gas phase temperature layered data, calculates overheat degree distribution and identifies low momentum steam stagnation area, dynamically adjusts forced cooling fan to generate directional disturbance airflow to drive steam migration, generates and executes pressure regulation and thermal management instructions, dynamically optimizes overheat degree parameters, realizes intelligent regulation of transformer temperature, effectively prevents local failure of condenser tube group, and improves heat dissipation efficiency.

Description

Technical Field

[0001] This invention relates to the field of transformer temperature control technology, and in particular to a method and system for intelligent control of transformer temperature based on phase change immersion liquid cooling technology. Background Technology

[0002] In the field of transformer cooling using phase change immersion liquid cooling technology, the conventional approach typically involves immersing the entire transformer core in a phase change working fluid within a closed cavity. The vapor generated by the phase change evaporation of the working fluid after absorbing heat rises and carries the heat to a condensation heat exchange component located at the top of the cavity for exothermic condensation. The condensed liquid working fluid then flows back to the bottom of the cavity by gravity, forming a natural circulation cooling loop. To control the cooling process, existing systems often configure several forced-air cooling fans in the condensation area. Based on a single parameter such as the surface temperature of the condensation component or the average temperature of the gas phase space within the cavity, they use a constant speed or simple start-stop logic to drive the airflow through the condenser to enhance heat exchange. Furthermore, some solutions incorporate an expansion tank to maintain system pressure stability; however, pressure regulation is mostly based on fixed threshold triggers, lacking dynamic coupling with the real-time thermal state of the transformer.

[0003] The aforementioned conventional approach has significant drawbacks. On the one hand, during the steam's ascent, momentum decays due to condensation along the way, friction with the wall, and density changes caused by temperature differences at different heights. This is particularly problematic above the transformer's localized high-power-density areas, where insufficient steam ascent velocity can easily create low-momentum steam stagnation zones. This prevents the corresponding condenser tubes above these zones from receiving a sufficient supply of gaseous working fluid, leading to a sharp decline in heat exchange efficiency or even localized failure. Existing control methods relying on average temperature or fixed fan speed cannot identify and address these spatially uneven heat exchange bottlenecks. On the other hand, the condensation state on the heat exchange surfaces of the condenser heat exchange components has long been neglected. Condensation significantly reduces the condensation heat transfer coefficient, but existing control strategies do not incorporate this state as a feedback parameter into the control logic. This results in the fan operation failing to adapt to actual condensation disturbances, leading to energy waste or insufficient cooling capacity. Summary of the Invention

[0004] This invention provides a method and system for intelligent temperature control of transformers based on phase change immersion liquid cooling technology, which can solve the problems in the prior art.

[0005] A first aspect of the present invention provides a method for intelligent temperature control of a transformer based on phase change immersion liquid cooling technology, comprising: Data on the heat generation power of the transformer core, the saturated vapor pressure of the phase change working fluid, the condensation state of the heat exchange surface of the condensation heat exchange component, and the gas phase temperature stratification data in the closed cavity were collected. Based on the saturated steam pressure data and gas phase temperature stratification data, the superheat distribution at different heights is calculated, and the momentum decay law during the steam rise process is predicted by combining the heating power data, thus identifying the low momentum steam stagnation area that leads to local failure of the condenser tube group. Based on the location information of the low momentum steam retention area and the condensation state data of the heat exchange surface, the start-stop combination mode and phase difference control strategy of the forced cooling fan are dynamically adjusted. A directional turbulent airflow is formed in the gas phase space through asynchronous pulse air supply, driving the retained steam to migrate to the condensation area. Based on the low-momentum steam retention area and the distribution state of the retained steam after migration, a pressure regulation strategy for the expansion tank and a thermal management command for the transformer are generated. The pressure regulation strategy and thermal management instructions are executed, and the saturated steam pressure data and gas phase temperature stratification data after execution are collected to dynamically optimize the calculation parameters of the superheat distribution.

[0006] Based on the saturated steam pressure data and gas phase temperature stratification data, the superheat distribution at different heights is calculated, and the momentum decay pattern during the steam rise process is predicted by combining the heat generation power data. Low-momentum steam stagnation regions leading to localized failure of the condenser coil assembly are identified, including: Substituting the saturated vapor pressure data into the Clausius-Clapeyron relation, the theoretical saturated temperature distribution curves corresponding to different height positions within the closed cavity are calculated. These curves are then compared point-by-point with the gas phase temperature stratification data to construct a three-dimensional superheat distribution model. Gradient tensor analysis is performed on the three-dimensional superheat distribution model to identify abnormal regions where the superheat gradient reverses. The spatial coordinates of these abnormal regions and the peak superheat value are output as thermodynamic imbalance characteristic parameters. The evaporation mass transfer rate of the transformer core surface is calculated based on the heat generation power data. A steam density correction model is established in combination with the thermodynamic imbalance characteristic parameters to calculate the actual density distribution of steam at different height positions. Substituting the actual density distribution into the momentum transport equation, the buoyancy reduction caused by density change during the steam's ascent is calculated, and the quantitative relationship curve of the decrease in steam momentum with height is obtained by combining the flow resistance coefficient of the closed cavity. In the quantitative relationship curve, identify the height threshold point where the momentum drops below the critical value for maintaining upward flow, and spatially match the height threshold point with the spatial coordinates of the abnormal region to define the region that simultaneously satisfies insufficient momentum and abnormal superheat as the low momentum steam retention region.

[0007] Based on the heat generation power data, the evaporation mass transfer rate on the transformer core surface is calculated. A steam density correction model is established using the thermodynamic imbalance characteristic parameters to calculate the actual density distribution of steam at different heights, including: The heat generation power data is normalized with the surface area of ​​the transformer core to obtain the heat flux density per unit area, and then divided by the latent heat of vaporization of the phase change working fluid to calculate the evaporation mass transfer rate. Extract the superheat peak value of each abnormal region from the thermodynamic imbalance characteristic parameters, and multiply the superheat peak value by the saturated vapor density at the corresponding spatial location to obtain the density correction coefficient; The amount of steam generated per unit time is obtained by multiplying the evaporation mass transfer rate by the molecular mass of the phase change working fluid, and the initial density of steam at the initial height is calculated based on the amount of steam generated and the bottom cross-sectional area of ​​the closed cavity. The initial density is coupled with the density correction coefficient, and the initial density is recursively corrected layer by layer according to the density correction coefficient corresponding to each height position. The density decrease gradient of steam in the vertical upward path is calculated by the cumulative change of density during the recursive correction process. The density decreasing gradient is mapped to the height coordinates of the enclosed cavity to generate a spatial distribution function in which the steam density changes continuously with height. The values ​​of the spatial distribution function at each discrete height position are taken as the actual density distribution of steam at different height positions.

[0008] Based on the location information of the low-momentum vapor retention area and the condensation state data of the heat exchange surface, the start-stop combination mode and phase difference control strategy of the forced cooling fan are dynamically adjusted. A directional turbulent airflow is formed in the gas phase space through asynchronous pulsed air delivery, driving the retained vapor to migrate towards the condensation area, including: Gradient field reconstruction is performed on the condensation state data of the heat exchange surface to calculate the liquid film thickness gradient at each location, identify weak condensation regions where the gradient value is less than the condensation threshold, perform spatial correlation analysis on the low momentum steam retention region and the weak condensation region, construct a pairing relationship map, and determine the spatial path for establishing a steam transport channel. Calculate the path direction vector based on the starting point and ending point of the spatial path, establish the wind turbine action area coverage matrix, filter out effective wind turbines with non-zero contribution to the path direction, and calculate the projection component of the air delivery vector of each wind turbine in the path direction as the cooperative driving intensity. Based on the cooperative driving intensity, the effective wind turbines are divided into a main driving group and an auxiliary driving group. A timing phase difference is designed so that the main driving group starts before the auxiliary driving group, so that the initial turbulent airflow is continuously driven by the subsequent airflow. The timing phase difference control is executed, and the gas velocity vector field in the stagnation area is collected in real time. When the angle between the dominant velocity direction and the path direction is less than the allowable deviation angle, it is determined that a directional disturbance airflow is formed. The liquid film thickness change rate in the weak condensation area is monitored, and the timing phase difference is adjusted based on the change rate.

[0009] Spatial correlation analysis was performed on the low-momentum steam retention region and the weak condensation region to construct a pairing relationship map and determine the spatial paths for establishing steam transport channels, including: Extract the spatial coordinates of the low-momentum vapor stagnation region and the weak condensation region, calculate the spatial distance and relative height difference between each low-momentum vapor stagnation region and each weak condensation region, and construct a spatial topology matrix; obtain the flow resistance field distribution data in the closed cavity, perform resistance integral calculation along the straight path between the low-momentum vapor stagnation region and the weak condensation region, and fill it into the spatial topology matrix to calculate the comprehensive transport cost coefficient; The spatial topology matrix is ​​scanned to identify multiple weak condensation regions with comprehensive transport cost coefficients below the feasible threshold corresponding to the same low momentum vapor retention region. The remaining heat transfer capacity of the weak condensation region is introduced as a weighting factor and weighted and fused with the comprehensive transport cost coefficient to calculate the pairing priority. According to the pairing priority from high to low, a unique target weak condensation region is assigned to each low momentum steam retention region, and a pairing relationship map is constructed. The pairing relationship map takes the retention region as the source node and the target weak condensation region as the target node, and the straight path connecting the source node and the target node is determined as the spatial path of the steam transport channel.

[0010] Based on the low-momentum steam retention area and the distribution state of the retained steam after migration, a pressure regulation strategy for the expansion tank and thermal management instructions for the transformer are generated, including: Obtain the boundary profile and steam velocity vector field of the low momentum steam retention region, calculate the average kinetic energy and pressure potential energy of the steam in the region, construct the thermodynamic equation of state and solve it to obtain the disturbance of the pressure of the closed cavity by the retained steam. Collect the distribution status data after migration, identify the steam flow rate transferred from the stagnant area to the active flow area, calculate the cumulative condensation per unit time, and predict the pressure response time constant based on the cumulative condensation and the heat capacity parameter of the closed cavity. Based on the pressure response time constant, a staged pressure regulation strategy for the expansion tank is designed. In the rapid response stage, the instantaneous intake rate of the expansion tank is controlled according to the disturbance amount. In the steady-state maintenance stage, the buffer pressure setpoint is adjusted according to the cumulative condensation amount. Extract the spatial distribution characteristics of the heat exchange surface temperature gradient in the distributed state data, construct a mapping model between the temperature gradient and the heat dissipation efficiency of the transformer winding, calculate the local heat dissipation efficiency improvement coefficient at each winding location, and generate a partitioned load redistribution instruction based on the improvement coefficient as a thermal management instruction.

[0011] Obtain the boundary profile and steam velocity vector field of the low-momentum steam retention region, calculate the average kinetic energy and pressure potential energy of the steam within the region, construct the thermodynamic equation of state, and solve for the disturbance of the retained steam on the pressure of the closed cavity, including: Extract the boundary contour geometric data of the low momentum steam retention region, perform curve fitting to generate a continuous boundary function, calculate the effective volume of the low momentum steam retention region, establish a spatial sampling point matrix within the effective volume and obtain the steam velocity vector of each sampling point to form a steam velocity vector field. The vector in the steam velocity vector field is decomposed into components, the radial velocity component and the tangential velocity component are calculated, and the kinetic energy density distribution function is calculated in combination with the steam density. The kinetic energy density distribution function is spatially integrated within the effective volume to obtain the average kinetic energy of the steam in the region. The pressure field data within the effective volume is collected, the potential energy density is calculated based on the pressure gradient and weighted averaged with the local steam mass to obtain the pressure potential energy of the steam in the region, and the average kinetic energy and the pressure potential energy are substituted into the energy conservation relationship to construct the thermodynamic equation of state. The wall stiffness parameter and volume compressibility coefficient of the closed cavity are modified by introducing the thermodynamic equation of state. The pressure state quantity of the retained steam is obtained by solving the modified thermodynamic equation of state using an iterative numerical method. The disturbance quantity is obtained by performing a differential operation with the steady-state pressure design value of the closed cavity.

[0012] A second aspect of this invention provides a transformer temperature intelligent control system based on phase change immersion liquid cooling technology, comprising: The vaporization heat transfer unit is used to receive the heat generated when the transformer core is working and transfer it to the fluorinated liquid working medium in the liquid immersion area, so that the temperature of the fluorinated liquid working medium rises to the boiling point and absorbs latent heat to undergo a phase change and be converted into gaseous fluorinated vapor. The gaseous fluorinated vapor is driven to rise to the gas phase buffer space and contact the condenser tube group. The condensation and heat dissipation unit is used to transfer the heat of gaseous fluorinated vapor to the radiator through the tube wall of the condenser tube group, and to control the start of the forced fan to discharge the heat on the radiator to the external environment, so that the gaseous fluorinated vapor releases heat on the surface of the condenser tube group, the temperature decreases and a phase change occurs, and it recondenses into liquid fluorinated liquid. The reflux circulation unit is used to use gravity to make the liquid fluorinated liquid drip back into the liquid immersion area at the bottom of the inner cavity of the outer shell, forming a cyclic phase change process from liquid fluorinated liquid to gaseous fluorinated vapor and then back to liquid fluorinated liquid. The anti-condensation treatment unit is used for vacuum evacuation and inert gas replenishment. The vacuum evacuation is used to evacuate the inner cavity of the outer shell before the initial commissioning of the system to remove the internal air. The inert gas replenishment is used to replenish the inner cavity of the outer shell with dry inert gas according to the ambient temperature data. Filling the inner cavity of the outer shell with inert gas reduces condensation caused by temperature difference on the inner wall of the outer shell and the surface of the condenser tube assembly. The pressure balancing unit is used to connect the first expansion tank and the second expansion tank to the gas phase buffer space inside the outer shell through a connecting pipe, so as to accommodate the volume expansion of the fluorinated liquid working fluid due to temperature changes and balance the system pressure.

[0013] A third aspect of the present invention provides an electronic device, comprising: processor; Memory used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the aforementioned method.

[0014] A fourth aspect of the present invention provides a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the aforementioned method.

[0015] In this embodiment of the invention, the accuracy of temperature control of the phase change immersion liquid-cooled transformer is significantly improved. By integrating multi-source data such as heating power, saturated steam pressure, gas phase temperature stratification and condensation state, the momentum decay law during the steam rise process can be analyzed in real time, and the low momentum steam retention area of ​​the condenser tube group in the local failure can be accurately located.

[0016] The asynchronous pulse air supply dynamically adjusts the start-stop combination and phase difference according to the location and condensation state of the area, forming a directional turbulent airflow in the gas phase space, forcing the stagnant vapor to migrate efficiently to the condensation area, eliminating the risk of local overheating, and achieving a qualitative leap in cooling uniformity and heat exchange efficiency.

[0017] The generation strategy of expansion tank pressure and thermal management commands is directly linked to the distribution feedback after the migration of stagnant vapor, enabling a closed-loop linkage between system pressure and temperature control. This avoids the deterioration of condensation efficiency or excessive dissipation of working fluid caused by pressure fluctuations in traditional solutions. The forced cooling fan start-stop combination and phase difference control avoid energy waste and airflow dead zones caused by continuous air supply, significantly improving vapor migration efficiency per unit energy consumption and making the internal temperature gradient of the transformer more gradual. This method does not rely on additional mechanical structures or complex algorithms; it can achieve intelligent upgrades using only existing sensors and fan hardware, simultaneously reducing maintenance costs and the threshold for modification. It is particularly suitable for compact liquid cooling scenarios of high power density transformers, providing reliable temperature adaptive protection for the engineering application of phase change immersion technology. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the intelligent temperature control method for transformers based on phase change immersion liquid cooling technology, as described in an embodiment of the present invention. Figure 2 This is a schematic flowchart of the method for identifying low-momentum vapor retention regions according to an embodiment of the present invention; Figure 3 Right view shows the sensor location. Figure 4 This is a schematic diagram of the sensor location (left view). Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0021] Figure 1 This is a flowchart illustrating the intelligent temperature control method for transformers based on phase change immersion liquid cooling technology according to an embodiment of the present invention. The present invention provides an intelligent temperature control method for transformers based on phase change immersion liquid cooling technology, comprising: Data on the heat generation power of the transformer core, the saturated vapor pressure of the phase change working fluid, the condensation state of the heat exchange surface of the condensation heat exchange component, and the gas phase temperature stratification data in the closed cavity were collected. Based on the saturated steam pressure data and gas phase temperature stratification data, the superheat distribution at different heights is calculated, and the momentum decay law during the steam rise process is predicted by combining the heating power data, thus identifying the low momentum steam stagnation area that leads to local failure of the condenser tube group. Based on the location information of the low momentum steam retention area and the condensation state data of the heat exchange surface, the start-stop combination mode and phase difference control strategy of the forced cooling fan are dynamically adjusted. A directional turbulent airflow is formed in the gas phase space through asynchronous pulse air supply, driving the retained steam to migrate to the condensation area. Based on the low-momentum steam retention area and the distribution state of the retained steam after migration, a pressure regulation strategy for the expansion tank and a thermal management command for the transformer are generated. The pressure regulation strategy and thermal management instructions are executed, and the saturated steam pressure data and gas phase temperature stratification data after execution are collected to dynamically optimize the calculation parameters of the superheat distribution.

[0022] Figure 2 This is a flowchart illustrating the method for identifying low-momentum steam stagnation regions according to an embodiment of the present invention. Based on the saturated steam pressure data and gas phase temperature stratification data, the superheat distribution at different heights is calculated, and the momentum decay pattern during the steam rise is predicted in conjunction with the heating power data. This identifies low-momentum steam stagnation regions that cause localized failure of the condenser coil assembly, including: Substitute the saturated vapor pressure data into the Clausius-Clapeyron relation to calculate the theoretical saturated temperature distribution curves corresponding to different height positions in the closed cavity. Compare the curves with the gas phase temperature stratification data point by point to construct a three-dimensional superheat distribution model. Gradient tensor analysis is performed on the three-dimensional superheat distribution model to identify abnormal regions where the superheat gradient reverses. The spatial coordinates of the abnormal regions and the peak superheat are output as thermodynamic imbalance characteristic parameters. The evaporation mass transfer rate of the transformer core surface is calculated based on the heat generation power data. A steam density correction model is established in combination with the thermodynamic imbalance characteristic parameters to calculate the actual density distribution of steam at different height positions. Substituting the actual density distribution into the momentum transport equation, the buoyancy reduction caused by density change during the steam's ascent is calculated, and the quantitative relationship curve of the decrease in steam momentum with height is obtained by combining the flow resistance coefficient of the closed cavity. In the quantitative relationship curve, identify the height threshold point where the momentum drops below the critical value for maintaining upward flow, and spatially match the height threshold point with the spatial coordinates of the abnormal region to define the region that simultaneously satisfies insufficient momentum and abnormal superheat as the low momentum steam retention region.

[0023] Substituting the collected saturated vapor pressure data into the Clausius-Clapeyron relation, theoretical saturated temperature distribution curves corresponding to different height positions within a closed cavity can be established. The Clausius-Clapeyron relation describes the thermodynamic dependence between the saturated vapor pressure and saturated temperature of the phase change working fluid, and its basic form is: ,in For saturated steam pressure, This represents the theoretical saturation temperature at the corresponding height. The latent heat of vaporization of the phase change working fluid. Let be the gas phase density. Because the static pressure head varies at different heights within the enclosed cavity, the corresponding saturated vapor pressures at different heights are not the same. Therefore, by reading pressure sensor data layer by layer and substituting it into the above relationship, a theoretical saturation temperature curve continuously distributed along the vertical direction can be obtained. ,in This indicates the height coordinates from the bottom of the cavity.

[0024] The theoretical saturation temperature distribution curve Stratified data with gas phase temperature Perform point-by-point comparisons and calculate the local superheat at each height location. ,in To measure the gas phase temperature, This represents the superheat at the corresponding height. Due to the lateral temperature non-uniformity within the closed cavity, a single height coordinate cannot fully characterize the thermodynamic state. Therefore, it is necessary to extend the superheat distribution from one dimension to three dimensions, constructing a three-dimensional superheat distribution model. ,in and These are two orthogonal coordinate components on the horizontal cross-section inside the cavity. This three-dimensional model is generated through joint data interpolation of a multi-point temperature sensor array and a pressure sensor grid, and can reflect the spatial non-uniformity of the thermodynamic state inside the cavity.

[0025] Gradient tensor analysis was performed on the three-dimensional superheat distribution model to calculate the first-order partial derivatives of superheat in three spatial directions, forming a gradient vector field. Under normal operating conditions, superheat should decrease monotonically along the height direction, meaning that steam gradually releases heat and approaches saturation as it rises. If a region exhibits a sign reversal in the superheat gradient, i.e., the local superheat increases with increasing height, it indicates a thermodynamic imbalance in that region, where steam cannot effectively transfer heat to the condenser coils. All regions satisfying the gradient reversal criterion are marked as anomalous regions. Their three-dimensional spatial coordinate sets and corresponding superheat peak values ​​are extracted, and the output is a thermodynamic imbalance characteristic parameter for subsequent steam density correction and momentum analysis.

[0026] Based on heating power data Calculate the evaporation mass transfer rate on the surface of the transformer core. The relationship between the evaporation mass transfer rate and the heating power is as follows: ,in This represents the latent heat of vaporization of the phase change working fluid. In actual operating conditions, the inner core surface does not heat uniformly; therefore, it is necessary to calculate the evaporation mass transfer rate of each local region based on the inner core power density distribution. By incorporating thermodynamic imbalance characteristic parameters, a correction term for the local evaporation mass flux on the gas phase density is introduced into the steam density correction model to establish a steam density correction model and calculate the actual density distribution of steam at different heights. This modified model takes into account the local gas phase component concentration deviations caused by uneven evaporation rates and the effect of temperature stratification on density, making the calculated density distribution closer to the actual physical state.

[0027] Actual density distribution Substituting into the momentum transport equation, we analyze the momentum change during the vertical ascent of steam within the closed cavity. The driving force for the steam's ascent originates from the buoyancy force generated by the density difference between the gas and liquid phases. The magnitude of the buoyancy force is related to the density of the liquid working fluid. Actual density of the gas phase The difference is directly proportional to the amount of buoyancy reduction. ,in It is the acceleration due to gravity. This refers to the characteristic volumetric parameters of a unit volume of steam bubble. As the steam rises higher, the gas phase density changes due to decreasing temperature and pressure variations, causing the buoyancy to decrease accordingly. Simultaneously, the flow resistance coefficient within the closed cavity also increases. This reflects the combined hindering effect of the cavity structure, condenser tube arrangement, and liquid film coverage on steam flow. The steam momentum is obtained by combining the buoyancy reduction with the flow resistance coefficient. The quantitative relationship curve with decreasing altitude comprehensively reflects the dynamic balance between buoyancy drive and drag dissipation.

[0028] The quantitative relationship curve of vapor momentum decreasing with altitude In this process, a critical momentum threshold is set to maintain the upward flow of steam. This critical value is determined by the minimum momentum required for steam to overcome its own weight and flow resistance, and can be calibrated jointly using the geometric parameters of the closed cavity and the physical properties of the phase change working fluid. The curve is scanned height by height to identify... First drop The following height coordinates are denoted as height threshold points. .exist In the aforementioned areas, the steam no longer has sufficient momentum to sustain its upward movement, making it highly susceptible to stagnation and accumulation in localized areas.

[0029] height threshold point Spatial matching was performed with the spatial coordinates of the abnormal regions extracted from the aforementioned thermodynamic imbalance characteristic parameters to screen out regions that simultaneously meet two criteria: first, the vapor momentum is below a critical threshold. Secondly, there is an anomaly in the superheat gradient. Only spatial regions that simultaneously meet both the conditions of insufficient momentum and anomaly in superheat are ultimately identified as low-momentum vapor stagnation regions. This dual-criteria design effectively eliminates misjudgments caused solely by local temperature fluctuations, ensuring that the identification results have clear physical meaning. The spatial coordinate information of the low-momentum vapor stagnation region will serve as the input basis for subsequent forced cooling fan disturbance strategies and expansion tank pressure regulation strategies, driving the closed-loop optimization of the entire intelligent temperature control process.

[0030] Based on the heat generation power data, the evaporation mass transfer rate on the transformer core surface is calculated. A steam density correction model is established using the thermodynamic imbalance characteristic parameters to calculate the actual density distribution of steam at different heights, including: The heat generation power data is normalized with the surface area of ​​the transformer core to obtain the heat flux density per unit area, and then divided by the latent heat of vaporization of the phase change working fluid to calculate the evaporation mass transfer rate. Extract the superheat peak value of each abnormal region from the thermodynamic imbalance characteristic parameters, and multiply the superheat peak value by the saturated vapor density at the corresponding spatial location to obtain the density correction coefficient; The amount of steam generated per unit time is obtained by multiplying the evaporation mass transfer rate by the molecular mass of the phase change working fluid, and the initial density of steam at the initial height is calculated based on the amount of steam generated and the bottom cross-sectional area of ​​the closed cavity. The initial density is coupled with the density correction coefficient, and the initial density is recursively corrected layer by layer according to the density correction coefficient corresponding to each height position. The density decrease gradient of steam in the vertical upward path is calculated by the cumulative change of density during the recursive correction process. The density decreasing gradient is mapped to the height coordinates of the enclosed cavity to generate a spatial distribution function in which the steam density changes continuously with height. The values ​​of the spatial distribution function at each discrete height position are taken as the actual density distribution of steam at different height positions.

[0031] After obtaining the heat generation power data of the transformer core, it needs to be converted into a fundamental physical quantity that can be used for steam density modeling. Divide by the effective heat exchange surface area of ​​the transformer core The heat flux density per unit area is obtained. ,Right now This normalization process eliminates the interference of local heat flux inhomogeneities caused by differences in the core geometry on subsequent calculations, making the calculation of the evaporation mass transfer rate spatially representative. Based on this, the heat flux density per unit area is divided by the latent heat of vaporization of the phase change working fluid. The evaporation mass transfer rate per unit area was obtained. The physical significance of this step lies in the fact that the heat released per unit area per unit time on the inner core surface will drive a phase change in the liquid working fluid corresponding to an equal amount of latent heat, thereby quantitatively describing the mass conversion intensity at the gas-liquid interface.

[0032] After calculating the evaporation mass transfer rate, a vapor density correction model needs to be established to reflect the non-uniform thermodynamic state of the gas phase space within the closed cavity. The superheat peak values ​​of each anomalous region are extracted from the thermodynamic imbalance characteristic parameters. The peak value is compared with the saturated vapor density at the corresponding spatial location. Multiplying them together yields the density correction factor. The introduction of this correction factor is based on the following physical understanding: in regions with high local superheat, steam is in a state of thermodynamic imbalance, and its actual density deviates from the theoretical saturation density. The greater the superheat, the more significant the steam expansion, and the more pronounced the density deviation from the theoretical value. By coupling the peak superheat with the saturation density, the density deviation amplitude in each anomalous region can be quickly quantified without introducing complex iterative state equations, providing a spatially resolved correction basis for subsequent layer-by-layer iterative corrections.

[0033] After determining the density correction factor, calculate the initial density of the steam at the initial height. Then, calculate the evaporation mass transfer rate. Multiply by the molecular weight of the phase change working fluid The molar amount of steam generated per unit area per unit time is obtained, and then converted into the mass generation rate. Based on the bottom cross-sectional area of ​​the closed cavity. The steam mass generation rate is related to the gas phase control volume at the bottom of the chamber. Combined, calculate the initial density of the steam at the initial height. The initial density is the physical reference value of the density when the vapor just leaves the liquid surface and enters the gas phase space, representing the vapor mass concentration at the bottom of the gas phase space. This value is affected by the heating power of the inner core, the physical properties of the working fluid, and the geometry of the bottom of the cavity, and is the starting point for subsequent recursive calculations of the density distribution.

[0034] Obtaining the initial density Density correction factor at each height position Then, the vertical distribution of the actual steam density is established through a layer-by-layer recursive correction process. This is applied to the discretized height nodes within the cavity. ( ,in (where the discrete height is the number of layers), in the... Actual density of the layer From the density of the previous layer With the density correction factor of this layer The density is determined jointly. Specifically, the initial density is coupled with the density correction coefficients of each layer, so that the density value of each layer, while inheriting the density information of the previous layer, is superimposed with the contribution of the local thermodynamic imbalance of that layer to the density correction. During the recursive process, the cumulative change in density... Defined as the total density decay from the initial height to the current height node, it is obtained by progressively accumulating the correction amounts for each layer. Density Decrease Gradient This is calculated by dividing the cumulative density change by the corresponding height span, i.e. ,in This represents the height spacing between adjacent discrete layers.

[0035] Density Decreasing Gradient This reflects the density decay rate of steam during its vertical ascent due to pressure reduction, temperature stratification, and uneven distribution of localized superheat. In a closed cavity, because the pressure at the top of the gas phase space is lower than at the bottom, the steam expands during its ascent, and its density decreases with increasing height. Simultaneously, the presence of localized superheated regions exacerbates the nonlinear density change, causing the density distribution with height to exhibit a piecewise variation rather than a simple linear decrease. The layer-by-layer calculation of the density decrease gradient is precisely to capture this nonlinear characteristic, ensuring that the density distribution model accurately reflects the complex thermodynamic state of the gas phase space within the cavity.

[0036] The density decrease gradient is correlated with the height coordinates of the closed cavity. By mapping, a spatial distribution function in which the steam density continuously varies with altitude is constructed. This function generates a continuous density curve covering the entire atmospheric height range by piecewise interpolation or fitting of the density calculation values ​​at discrete nodes. In practical implementation, piecewise linear interpolation can be used to linearize the density changes between adjacent discrete nodes, or a polynomial fitting method can be used to establish a smooth density distribution function over the global height range. The spatial distribution function is located at each discrete height position. The value at that point represents the actual density of the steam at that altitude. The final calculated result of the steam density distribution is output.

[0037] The establishment of the spatial distribution function transforms the steam density distribution from discrete node data into a spatially continuous physical quantity description, facilitating the extraction of density values ​​at arbitrary heights. This provides high-precision density input for calculating buoyancy attenuation and identifying low-momentum steam stagnation zones, through the actual density distribution... With the density of the liquid working fluid Substituting the difference into the buoyancy calculation allows for a quantitative assessment of the changing trend of the buoyancy force on the vapor bubble at different heights, which can then be combined with the flow resistance coefficient. Determining the momentum of steam Has it fallen to the critical momentum threshold? The following section details the precise location of the height threshold point. This provides a reliable spatial positioning basis for the subsequent disturbance control strategy of the forced cooling fan. The entire steam density correction model organically integrates the heating power, phase change working fluid properties, thermodynamic imbalance characteristics, and cavity geometric parameters, realizing a refined modeling of the gas phase spatial density distribution and overcoming the applicability limitations of the traditional uniform density assumption in complex thermodynamic environments.

[0038] Based on the location information of the low-momentum vapor retention area and the condensation state data of the heat exchange surface, the start-stop combination mode and phase difference control strategy of the forced cooling fan are dynamically adjusted. A directional turbulent airflow is formed in the gas phase space through asynchronous pulsed air delivery, driving the retained vapor to migrate towards the condensation area, including: Gradient field reconstruction is performed on the condensation state data of the heat exchange surface to calculate the liquid film thickness gradient at each location, identify weak condensation regions where the gradient value is less than the condensation threshold, perform spatial correlation analysis on the low momentum steam retention region and the weak condensation region, construct a pairing relationship map, and determine the spatial path for establishing a steam transport channel. Calculate the path direction vector based on the starting point and ending point of the spatial path, establish the wind turbine action area coverage matrix, filter out effective wind turbines with non-zero contribution to the path direction, and calculate the projection component of the air delivery vector of each wind turbine in the path direction as the cooperative driving intensity. Based on the cooperative driving intensity, the effective wind turbines are divided into a main driving group and an auxiliary driving group. A timing phase difference is designed so that the main driving group starts before the auxiliary driving group, so that the initial turbulent airflow is continuously driven by the subsequent airflow. The timing phase difference control is executed, and the gas velocity vector field in the stagnation area is collected in real time. When the angle between the dominant velocity direction and the path direction is less than the allowable deviation angle, it is determined that a directional disturbance airflow is formed. The liquid film thickness change rate in the weak condensation area is monitored, and the timing phase difference is adjusted based on the change rate.

[0039] Data on condensation status on the heat exchange surface is obtained from a distributed sensor array arranged on the surface of the condensing heat exchange components. The raw data describes the liquid film coverage at each location in the form of discrete points. When reconstructing the gradient field from these discrete data, a two-dimensional gradient estimation method based on finite difference is used. In the unfolded coordinate system of the condenser tube assembly, the difference quotient of the liquid film thickness between adjacent nodes is calculated for each sampling node to obtain the rate of change of the liquid film thickness in each direction of space. The magnitude of the gradient vector of each node is compared with a preset condensation threshold. Regions with gradient values ​​less than the threshold indicate that the liquid film growth rate at that location is lower than the normal condensation level, i.e., weak condensation regions. The physical meaning of weak condensation regions is that the amount of steam arriving at that location is insufficient or the local temperature is too high, resulting in insufficient condensation driving force and the inability of the liquid film to thicken normally.

[0040] After identifying the weak condensation regions, their coordinate sets are spatially correlated with those of the low-momentum steam retention regions. The core of this correlation analysis is determining the spatial proximity and thermodynamic coupling between the two types of regions: if a retention region has a spatially connected path to a weak condensation region, and the steam concentration gradient along this path points towards the weak condensation region, then they are considered a valid pair. All pairs of regions satisfying the pairing conditions are summarized to construct a pairing relationship map. Each edge in the map represents a spatial path for which a steam transport channel needs to be established, with the two endpoints of the edge being the centroid coordinates of the retention region and the weak condensation region, respectively. The path determination comprehensively considers the geometric obstacles within the closed cavity, employing the shortest connected path principle to plan the transport channel direction in three-dimensional space.

[0041] Let the coordinates of the starting point of the transport channel be... The endpoint coordinates are Then the path direction unit vector Defined as: in The three-dimensional coordinate components starting from the origin. The three-dimensional coordinate components with the endpoint as the endpoint.

[0042] When establishing the fan domain coverage matrix, each forced cooling fan in the cavity is numbered, and denoted as the [number]. The unit vector of the typhoon's air delivery direction is The spatial coverage area of ​​the fan is described as a cone-shaped region centered on its installation location and with a radius equal to its rated air delivery range. If the starting point or a middle segment of a transport path enters the... If the typhoon's coverage cone is within the wind turbine's area, then the turbine is considered to have a potential contribution to the path. Further calculations... and The inner product, i.e., the collaborative driving strength : . This indicates that the air delivery component of the fan has a positive propulsion effect in the path direction, making it an effective fan; Fans that do not contribute to the migration of steam along the target path or even cause adverse interference are excluded. After screening all effective fans, based on... Sort them by size. The larger wind turbines were designated as the main drive units. Smaller but still positive fans are designated as auxiliary drive units. The main drive unit fans have the same air delivery direction as the path direction, which can directly drive the trapped steam to move along the target channel; although the air delivery component of the auxiliary drive unit fans is smaller, it can constrain and supplement the airflow laterally, preventing the steam from deviating from the path due to diffusion during transportation.

[0043] The design principle of the timing phase difference is: the main drive group starts before the auxiliary drive group, allowing the main drive airflow to establish initial momentum in the transport channel first. Subsequently, the auxiliary drive group's airflow continuously supplements from the side or rear, pushing the initial disturbed airflow forward and preventing the airflow from stagnating due to momentum loss midway. Let the start-up time of the main drive group be the reference zero point, and the start-up delay time of the auxiliary drive group relative to the main drive group be denoted as... Its initial value is based on the length of the transport channel. Average propulsion speed of the main driving airflow Estimate: in The spatial length of the transport channel. The average propulsion velocity of the main driving airflow along the path direction. This is the phase delay adjustment coefficient, with a value ranging from 0.3 to 0.8. The specific value is pre-calibrated based on the cavity geometry and working fluid characteristics.

[0044] After performing timing phase difference control, the gas velocity vector at each measuring point in the stagnation area is collected in real time by an ultrasonic velocity sensor array or a hot-wire anemometer array arranged in the gas phase space. subscript Number the measuring points, and perform a weighted average of the velocity vectors at all measuring points to obtain the dominant velocity direction within the stagnation area. ,calculate unit vector of path direction The angle between : when Less than the preset allowable deviation angle At this point, it is determined that the directional disturbance airflow has been successfully formed, and the steam transport channel has been effectively established. Allowable deviation angle. The angle is typically set between 15° and 25°, with the specific value determined based on the cavity size and fan layout. If This indicates that the current airflow direction has deviated from the target path, requiring a reassessment of the coordinated drive strength of each fan and adjustment or correction of the main and auxiliary drive groups. .

[0045] After the directional turbulent airflow is formed, the rate of change of liquid film thickness at each node in the weak condensation region is continuously monitored. It is defined as the increment of the liquid film thickness per unit time. When When the lower threshold of the normal condensation rate is exceeded, it indicates that the steam has successfully migrated to the weak condensation region and undergone effective condensation, thus verifying the transport effect. If If the value remains below the threshold, the feedback signal is passed to the phase difference adjustment logic: appropriately reduce... To enhance the synergistic effect of the main and auxiliary drive groups, or to introduce a secondary phase difference within the auxiliary drive group, multiple auxiliary fans can be started sequentially according to a finer-grained timing sequence, forming a continuous pulse propulsion effect.

[0046] The duty cycle of the pulsed air supply is also incorporated as an adjustable parameter into the control strategy. The ratio of the single start-up duration to the shutdown interval of each fan determines the pulse frequency of the airflow. For paths with long transport channels and high flow resistance, the duty cycle is appropriately increased to maintain sufficient airflow; for shorter paths with sensitive vapor migration response, the duty cycle can be reduced to decrease fan power consumption. The entire control process operates continuously in a closed-loop manner. The rate of change of liquid film thickness and the gas phase velocity vector field serve as dual feedback signals, jointly driving the online iterative optimization of the timing phase difference and duty cycle until all weak condensation regions in the pairing relationship graphs recover to normal condensation levels.

[0047] Spatial correlation analysis was performed on the low-momentum steam retention region and the weak condensation region to construct a pairing relationship map and determine the spatial paths for establishing steam transport channels, including: Extract the spatial coordinates of the low-momentum vapor retention area and the weak condensation area, calculate the spatial distance and relative height difference between each low-momentum vapor retention area and each weak condensation area, and construct a spatial topology matrix; Obtain the flow resistance field distribution data within the closed cavity, perform resistance integral calculation along the straight path between the low momentum vapor retention region and the weak condensation region, and fill the spatial topology matrix to calculate the comprehensive transport cost coefficient. The spatial topology matrix is ​​scanned to identify multiple weak condensation regions with comprehensive transport cost coefficients below the feasible threshold corresponding to the same low momentum vapor retention region. The remaining heat transfer capacity of the weak condensation region is introduced as a weighting factor and weighted and fused with the comprehensive transport cost coefficient to calculate the pairing priority. According to the pairing priority from high to low, a unique target weak condensation region is assigned to each low momentum steam retention region, and a pairing relationship map is constructed. The pairing relationship map takes the retention region as the source node and the target weak condensation region as the target node, and the straight path connecting the source node and the target node is determined as the spatial path of the steam transport channel.

[0048] After identifying the low-momentum steam stagnation region and the weak condensation region, a systematic spatial correlation analysis of these two types of regions is needed to determine the specific spatial path of the steam transport channel. The geometric center coordinates of each low-momentum steam stagnation region are then extracted. ( Number the areas where people are stranded. (and the geometric center coordinates of each weak condensation region) ( Number the weak condensation areas. All the above coordinates are represented in the three-dimensional Cartesian coordinate system of the closed cavity, with the horizontal direction aligned with the bottom section of the cavity and the vertical direction extending upwards from the bottom of the cavity as the zero point.

[0049] For the The low-momentum vapor retention zone and the first Spatial distance between weak condensation zones Calculated according to Euclidean distance: Relative height difference Defined as the vertical coordinate of the center of the weak condensation region minus the vertical coordinate of the center of the stagnation region, i.e. ,in and These are the vertical coordinate components corresponding to the center of the region. When When this occurs, it indicates that the weak condensation region is located above the stagnation region, and the steam transport direction is consistent with the buoyancy direction, which is conducive to natural drive; when At that time, stronger forced perturbations are needed to achieve steam migration. (The sentence appears to be incomplete and requires further context.) Fill the spatial topology matrix with the combined spatial distance and relative height difference values. The row index of the matrix corresponds to the number of the detained area. The column index corresponds to the weak condensation region number. This forms the basic topological structure describing the geometric relationship between the two types of regions.

[0050] After obtaining the flow resistance field distribution data within the closed cavity, resistance integration calculations are performed along the straight path between each pair of stagnant and weakly condensing regions, discretizing the straight path into... At each of the three equally spaced sampling points, the interpolation result of the local drag coefficient field is read. ( The local drag coefficients at all sampling points along the path are summed by line integrals to obtain the total drag integral value of the path. The calculation method is as follows This integral value reflects the total flow resistance that steam must overcome to migrate from the stagnation region to the weak condensation region along this path. Fill to matrix The corresponding position completes the supplementation of resistance information.

[0051] Comprehensive transportation cost coefficient Taking into account the three factors of spatial distance, relative height difference, and path resistance integral, the calculation is performed using a weighted combination method: ,in , , These are the dimensionless values ​​of each indicator after normalization. , , These are the corresponding weight coefficients, and the sum of the three is 1. Normalization is performed using global maximum normalization, that is, each indicator is divided by the value of the global maximum value among all indicators. For the maximum value in the combination, take the absolute value of the height difference term and then normalize it to uniformly measure the degree of height mismatch. The smaller the value, the lower the difficulty of steam transport between the stagnant region and the weak condensation region, and the higher the feasibility of the path.

[0052] For matrix The integrated transport cost coefficients stored in the database are scanned line by line, targeting each low-momentum steam stagnation region. Extract all that satisfy A collection of weak condensation regions, among which The feasible threshold is determined by practical engineering experience or offline calibration. When a certain stagnant area corresponds to multiple weakly condensing areas with a comprehensive transport cost coefficient lower than the feasible threshold, the remaining heat transfer capacity of each weakly condensing area is introduced. As a weighting factor, the remaining heat transfer capacity is defined as the difference between the currently available heat transfer capacity and the rated heat transfer capacity of the weak condensation region, calculated using condensation state data of the heat transfer surface and the design parameters of the condensation heat exchange components. Pairing priority. Calculate as follows: ,in To prevent extremely small positive numbers with a denominator of zero. The larger the value, the more abundant the remaining heat transfer capacity and the lower the transportation cost of the weak condensation region. It should be preferentially paired with the corresponding stagnation region.

[0053] Following a descending order of pairing priority, each low-momentum steam retention region is assigned a unique target weak condensation region. The allocation process employs a greedy strategy: in the highest-priority unpaired combination, the weak condensation region is marked as the target node for the corresponding retention region, and then removed from the subsequent candidate set to avoid duplicate occupation of the same weak condensation region by multiple retention regions. If a weak condensation region is already occupied by a higher-priority retention region, the current retention region is reassigned according to the second-highest priority in the remaining candidate set, until all retention regions have obtained a unique target weak condensation region or the candidate set is exhausted. For retention regions with exhausted candidate sets, they are marked as pending processing, triggering subsequent expansion or time-sharing reuse strategies.

[0054] After pairing and assignment are completed, a pairing relationship graph is constructed, with the geometric center of each low-momentum steam retention region as the source node and the geometric center of the corresponding target weak condensation region as the target node. Each directed edge in the graph represents a steam transport channel, with the edge pointing from the source node to the target node. The straight path connecting the two nodes is the spatial path of the steam transport channel. The endpoint coordinates of this straight path are directly inherited from the source node coordinates determined during the pairing process. Coordinates of the target node The path direction unit vector is obtained by normalizing the coordinate difference between two points, providing geometric input for the subsequent planning of the forced cooling fan's airflow direction. The pairing relationship graph is stored in structured data form, containing the source node number, target node number, path space length, path direction unit vector, and comprehensive transport cost coefficient for each transport channel, which can be called by the subsequent asynchronous pulsed airflow control strategy.

[0055] In actual operation, the pairing relationship map is not statically fixed, but dynamically updated as stagnant regions are eliminated and new stagnant regions appear. Whenever a new round of gas phase temperature stratification data and saturated steam pressure data is collected, the above spatial correlation analysis process is re-executed to update the spatial topology matrix and pairing priority, ensuring that the spatial path of the steam transport channel always remains consistent with the current steam distribution state within the cavity, thereby supporting the continuous optimization of global thermal management commands.

[0056] Based on the low-momentum steam retention area and the distribution state of the retained steam after migration, a pressure regulation strategy for the expansion tank and thermal management instructions for the transformer are generated, including: Obtain the boundary profile and steam velocity vector field of the low momentum steam retention region, calculate the average kinetic energy and pressure potential energy of the steam in the region, construct the thermodynamic equation of state and solve it to obtain the disturbance of the pressure of the closed cavity by the retained steam. Collect the distribution status data after migration, identify the steam flow rate transferred from the stagnant area to the active flow area, calculate the cumulative condensation per unit time, and predict the pressure response time constant based on the cumulative condensation and the heat capacity parameter of the closed cavity. Based on the pressure response time constant, a staged pressure regulation strategy for the expansion tank is designed. In the rapid response stage, the instantaneous intake rate of the expansion tank is controlled according to the disturbance amount. In the steady-state maintenance stage, the buffer pressure setpoint is adjusted according to the cumulative condensation amount. Extract the spatial distribution characteristics of the heat exchange surface temperature gradient in the distributed state data, construct a mapping model between the temperature gradient and the heat dissipation efficiency of the transformer winding, calculate the local heat dissipation efficiency improvement coefficient at each winding location, and generate a partitioned load redistribution instruction based on the improvement coefficient as a thermal management instruction.

[0057] To obtain the boundary profile of the low-momentum steam stagnation region, a multi-point velocity sensor array and pressure distribution acquisition network deployed inside the closed cavity are used to fit and reconstruct the three-dimensional boundary of the stagnation region. After determining the boundary profile, the steam velocity vector field at each measuring point within the region is extracted. The velocity vector at each measuring point is moduloed and spatially integrated to obtain the average kinetic energy of the steam within the region. The calculation method involves taking a volume-weighted average of the kinetic energy values ​​at all discrete measuring points within the region. Simultaneously, based on the local saturated steam pressure distribution data within the region and the thermodynamic state parameters of the phase change working fluid at the corresponding temperature, the pressure potential energy of the steam is calculated. .Will and Substituting the thermodynamic equation of state established for the gas phase space of the closed cavity, which is constrained by the conservation of the total internal energy of the closed cavity, and introducing the conservation relationship of steam mass, the disturbance of the overall pressure of the closed cavity by the stagnant steam can be obtained by solving the equation. . It reflects the degree to which the cavity pressure deviates from the steady-state operating point due to the accumulation of steam in local areas, and is a key input parameter for the subsequent design of expansion tank regulation strategies.

[0058] During the collection of post-migration distribution data, the steam flow rate transferred from the original stagnant area to the active flow area is identified by comparing the steam mass density distribution in each spatial region before and after steam migration. The active flow region refers to the area where steam can effectively reach the heat exchange surface of the condenser tube assembly and undergo phase change liquefaction. According to... Integrating over time, calculate the cumulative condensation occurring within the sealed cavity per unit time. Its dimension is the heat released by condensation per unit time, when obtaining Then, the heat capacity parameters of the sealed cavity are considered. (i.e., the equivalent heat capacity of the cavity's gas phase space, including both the working fluid's gas phase heat capacity and the structural heat capacity), predicting the cavity pressure's response time constant to external regulation actions. . The physical meaning is: when the expansion tank applies a unit adjustment, the cavity pressure recovers from the initial deviation to the steady-state deviation. The time required. The smaller the value, the more sensitive the cavity pressure is to the adjustment action, and the higher the required control bandwidth. The larger the value, the stronger the predictive feedforward capability of the adjustment strategy is required to avoid control lag leading to stress overshoot.

[0059] based on The expansion tank is designed with a staged pressure regulation strategy, dividing the regulation process into two sub-stages: a rapid response stage and a steady-state maintenance stage. In the rapid response stage, the regulation objective is to rapidly eliminate the pressure caused by… This causes a pressure deviation in the cavity. The instantaneous intake rate of the expansion tank during this stage. according to The size is controlled proportionally: when When the pressure deviation exceeds the set upper limit, the expansion tank rapidly extracts excess gaseous working fluid from the chamber at a high suction rate, causing the chamber pressure to quickly drop back to the target range; when When within the permissible range, the instantaneous inhalation rate decreases accordingly to avoid over-adjustment leading to negative pressure conditions. The duration of the rapid response phase is related to... Positive correlation, usually set as to This time window ensures that the chamber pressure completes the main dynamic adjustment process.

[0060] During the steady-state maintenance phase, the regulation objective shifts to maintaining stable cavity pressure over a long timescale. As vapor continues to migrate and liquefy in the condensation region, the total amount of gas in the cavity slowly decreases over time; without compensation, the cavity pressure will continue to decline. Therefore, the steady-state maintenance phase is based on... Calculate the corresponding gas phase mass consumption rate and adjust the buffer pressure setpoint of the expansion tank accordingly. . The adjustment direction is: when When the value is large, adjust upwards appropriately. The gaseous working fluid is slowly replenished into the cavity through the expansion tank to maintain the dynamic balance of the total gas volume within the cavity; when When smaller, It remains near the baseline setting, with only minor adjustments made. The adjustment step size and adjustment frequency are both based on the premise of not causing cavity pressure oscillation. This is achieved by introducing a first-order low-pass filter. The calculated values ​​are smoothed to eliminate the interference of short-term fluctuations on steady-state regulation.

[0061] When extracting the spatial distribution characteristics of the temperature gradient on the heat exchange surface from the distributed state data, spatial difference processing is performed on the temperature sensor data of the condenser tube assembly and the outer wall of the transformer winding to obtain the temperature gradient amplitude of each heat exchange surface. The three-dimensional distribution map shows that regions with large temperature gradients indicate strong heat transfer driving force and high steam condensation efficiency, while regions with small temperature gradients indicate insufficient temperature difference between the heat transfer surface and the gaseous working fluid, resulting in lower heat transfer efficiency. Based on the above temperature gradient distribution, a mapping model between temperature gradient and transformer winding heat dissipation efficiency is constructed. This mapping model uses the amplitude of the temperature gradient of the heat transfer surface corresponding to each winding location as input and the local heat dissipation efficiency of the winding as input. As output, the mapping relationship is obtained by fitting historical running data and is continuously updated during the running process.

[0062] After obtaining the position of each winding After distribution, calculate the heat dissipation efficiency of each winding position relative to the reference. Local heat dissipation efficiency improvement coefficient It is defined as the ratio of the current heat dissipation efficiency to the baseline heat dissipation efficiency, i.e. . The average heat dissipation efficiency of each winding of the transformer under rated operating conditions is taken as a reference benchmark for evaluating the relative merits of heat dissipation capacity in each region. A value greater than 1 indicates that the heat dissipation capacity of this winding area is better than average, and it can withstand higher electrical loads; A value less than 1 indicates that the heat dissipation capacity of the area is insufficient, and the load should be appropriately reduced to avoid local overheating.

[0063] Based on the position of each winding The distribution generates zoned load redistribution instructions as thermal management instructions. The principle of load redistribution is: while maintaining the total output power of the transformer, the load is redistributed from... Lower winding area towards Higher winding areas are transferred. The specific transfer amount depends on each area. The relative difference is determined together with the rated capacity constraint of the winding to ensure that the current density of each winding does not exceed its rated upper limit after redistribution. The thermal management command is issued to the transformer control unit in a structured data format. The control unit adjusts the tap position of each winding or the position of the on-load tap changer according to the command content to realize the physical redistribution of the load. The entire thermal management command generation process is executed in parallel with the expansion tank pressure regulation strategy. Together, they form a closed-loop control mechanism for the transformer's thermodynamic state, ensuring that the temperature distribution of each winding of the transformer tends to be uniform after steam migration is completed, avoiding local hot spots that may cause accelerated insulation aging or false tripping of protection actions.

[0064] Obtain the boundary profile and steam velocity vector field of the low-momentum steam retention region, calculate the average kinetic energy and pressure potential energy of the steam within the region, construct the thermodynamic equation of state, and solve for the disturbance of the retained steam on the pressure of the closed cavity, including: Extract the boundary contour geometric data of the low momentum steam retention region, perform curve fitting to generate a continuous boundary function, calculate the effective volume of the low momentum steam retention region, establish a spatial sampling point matrix within the effective volume and obtain the steam velocity vector of each sampling point to form a steam velocity vector field. The vector in the steam velocity vector field is decomposed into components, the radial velocity component and the tangential velocity component are calculated, and the kinetic energy density distribution function is calculated in combination with the steam density. The kinetic energy density distribution function is spatially integrated within the effective volume to obtain the average kinetic energy of the steam in the region. The pressure field data within the effective volume is collected, the potential energy density is calculated based on the pressure gradient and weighted averaged with the local steam mass to obtain the pressure potential energy of the steam in the region, and the average kinetic energy and the pressure potential energy are substituted into the energy conservation relationship to construct the thermodynamic equation of state. The wall stiffness parameter and volume compressibility coefficient of the closed cavity are modified by introducing the thermodynamic equation of state. The pressure state quantity of the retained steam is obtained by solving the modified thermodynamic equation of state using an iterative numerical method. The disturbance quantity is obtained by performing a differential operation with the steady-state pressure design value of the closed cavity.

[0065] Obtaining the boundary profile of the low-momentum vapor stagnation region requires relying on the spatial location information of the stagnation region identified in the previous steps. Inside the closed cavity, the boundary of the low-momentum vapor stagnation region is not a regular geometric shape, but rather an irregular curved surface enclosed by isosurfaces in the gas phase velocity field where the momentum is below a critical threshold. When extracting the geometric data of this boundary profile, the measurements from a distributed sensor array arranged within the gas phase space are used as a basis. The vapor momentum values ​​at each measuring point are compared with the critical momentum threshold to extract a set of spatial points that satisfy the condition of momentum below the threshold. Then, a three-dimensional surface reconstruction is performed on the outer envelope of this point set to obtain the discrete point cloud data of the boundary profile.

[0066] When performing curve fitting on discrete point cloud data, the least squares method is used to project the boundary profile onto three orthogonal cross-sectional directions. A continuous boundary curve is generated by fitting discrete boundary points on each projected cross-section. Then, surface interpolation is used to extend the continuous boundary curves of multiple cross-sections into a three-dimensional continuous boundary function. During this process, the fitting accuracy is controlled by the root mean square of the residuals. When the root mean square of the residuals is lower than a preset tolerance, the boundary function is considered convergent and usable for subsequent volume calculation. The effective volume is calculated using a three-dimensional numerical integration method. The spatial region enclosed by the continuous boundary function is divided into a uniform grid, and the volumes of each grid cell are summed to obtain the effective volume of the low-momentum vapor retention region. .

[0067] In effective volume When establishing a spatial sampling point array, sampling intervals are set in three coordinate directions according to a uniform grid method to ensure that the sampling points are evenly distributed in space. The steam velocity vector at each sampling point is obtained from the sensor measurement data through interpolation. The interpolation adopts a trilinear interpolation scheme to ensure the spatial continuity of the velocity vector field. The steam velocity vector field thus formed covers the entire effective volume, providing basic data for subsequent kinetic energy density calculation.

[0068] When performing component decomposition on the velocity vector at each sampling point in the steam velocity vector field, the velocity vector is decomposed into axial components along the axis, with the geometric center axis of the cavity as a reference. The radial component perpendicular to the axis and pointing outwards and the tangential component of rotation about the axis The three components satisfy... ,in This is the velocity vector magnitude at this sampling point. Combined with the steam density at this sampling point... kinetic energy density at that point Defined as For the kinetic energy density distribution function in the effective volume Spatial integration is performed within the region, that is, the kinetic energy density values ​​of all sampling points are multiplied by the corresponding grid cell volume and then summed to obtain the average kinetic energy of the steam in the region. Its dimension is joule.

[0069] When collecting pressure field data within the effective volume, distributed pressure sensors within the cavity are used to obtain the local pressure values ​​at each sampling point. To reference pressure (Taking the average pressure during steady-state operation of the closed cavity) as a benchmark, the pressure potential energy density at each sampling point is defined as... This characterizes the pressure potential energy per unit mass of steam relative to a reference state. The pressure potential energy density at each sampling point is compared with the local steam mass at that point. ( The pressure potential energy of steam within the region is obtained by weighting the average of the grid cell volumes. The average kinetic energy With pressure potential energy Substituting the energy conservation equations, a set of equations describing the thermodynamic state of the stagnant steam is constructed. This set of equations is constrained by the conservation of the total energy of the steam within the stagnant region, and includes the steam pressure state variables. As the variable to be solved.

[0070] When introducing correction parameters into the thermodynamic equation of state, it is necessary to consider that the walls of the closed cavity are not absolutely rigid, but have a certain elastic deformation capacity, and thus introduce wall stiffness parameters. (Unit: Pa / m, representing the pressure change corresponding to a unit wall deformation) and volumetric compressibility coefficient The original thermodynamic equation of state is modified by using the term (representing the relative change in volume caused by a unit change in pressure). The modified equation requires consideration of both the compressibility of the steam itself and the effect of elastic deformation of the cavity walls on the pressure distribution within the cavity during the solution process. The introduction of the modification term transforms the equation from linear to nonlinear; therefore, an iterative numerical method is used for solving it.

[0071] The iterative solution process uses the initial guess value As a starting point, the initial guess value is taken as the design value of the steady-state pressure of the closed cavity. In each iteration, the current pressure estimate is substituted into the corrected thermodynamic equation of state to calculate the residual. When the absolute value of the residual is lower than the convergence criterion When the iteration terminates, the pressure estimate at this point is the pressure state variable of the retained steam. .in The value is set according to the actual engineering accuracy requirements, and is usually on the order of 0.1% of the steady-state pressure design value. The iterative method adopts the Newton-Raphson scheme, and the Jacobian matrix is ​​estimated by numerical differentiation in each iteration to ensure the convergence speed.

[0072] Obtain the pressure state quantity of the retained steam Then, compare it with the steady-state pressure design value of the closed cavity. By performing differential calculations, the disturbance of the pressure in the closed cavity caused by the retained steam is obtained. ,Right now .when When the value is positive, it indicates that the steam in the retention area is causing a positive disturbance to the overall pressure of the cavity, and the pressure inside the cavity is higher than the design steady-state value; when A negative value indicates insufficient steam momentum in the stagnant region, leading to local pressure below the steady-state value, which may cause localized recirculation of the working fluid in the condenser coil or a decrease in heat exchange efficiency. This disturbance... This will serve as a key input parameter for generating subsequent expansion tank pressure regulation strategies, used to determine the rapid response intake rate and buffer pressure setpoint of the expansion tank, thereby achieving precise control of the pressure field within the closed cavity and ensuring the safe and stable operation of the transformer under phase change immersion liquid cooling conditions.

[0073] This invention also provides a specific implementation method, such as... Figure 3 , Figure 4As shown, after the transformer is energized, the core and windings continuously heat up under electromagnetic influence. This heat is transferred to the fluorinated liquid, which is in close contact with the heating components. The fluorinated liquid absorbs heat and its temperature gradually rises. When the liquid temperature reaches its boiling point of 47°C, the liquid molecules gain enough energy to overcome intermolecular forces, resulting in a violent vaporization phase transition. During vaporization, the fluorinated liquid absorbs a large amount of latent heat without heating up. This characteristic keeps the surface temperature of the heating components firmly locked near the boiling point, preventing localized overheating. A large number of bubbles are generated on the heating surface and quickly detach, carrying heat upwards.

[0074] The density of the gaseous fluorinated liquid is much lower than that of the liquid. Driven by buoyancy, it accelerates upward to the gas phase space at the top of the inner cavity. At this point, the high-temperature steam temperature is slightly above 47°C, carrying all the heat absorbed from the transformer. The steam makes full contact with the outer wall of the condenser tube in the top gas phase region. Inside the condenser tube flows a low-temperature medium cooled by the radiator, and the tube wall temperature is significantly lower than the steam temperature. When steam molecules collide with the surface of the condenser tube, heat is transferred through the tube wall to the medium inside the tube by thermal conduction, and then released to the atmosphere by the radiator. The steam molecules, having lost heat, have reduced kinetic energy and re-condense into droplets, adhering to the tube wall.

[0075] Under the influence of gravity, the droplets slide down the tube wall, collect, and drip back into the liquid fluoride in the lower part of the inner cavity. The temperature of the refluxed liquid is slightly lower than that of the liquid surface. After mixing with the high-temperature liquid at the bottom, it is heated to the boiling point again, forming a new round of vaporization cycle. The whole process does not require external power drive and relies entirely on the latent heat of phase change and density difference to achieve natural convection, repeatedly transferring heat from the transformer core to the external environment.

[0076] The dual fans mounted on the top of the radiator generate forced airflow during operation, accelerating airflow over the radiator surface and improving the convective heat transfer coefficient. When both fans operate simultaneously, they share the heat dissipation load. If one fan fails, the other automatically increases its speed to its rated power. At this time, the system simultaneously activates the natural convection enhancement mode, using passive measures such as increasing the radiator fin spacing and optimizing airflow channels to ensure that the heat dissipation capacity still meets the continuous operation requirements of the transformer, even under single-fan operation.

[0077] Before initial system commissioning, the internal cavity must be evacuated to a pressure below 100 Pa to remove residual air and moisture. After evacuation, an appropriate amount of dry nitrogen or argon or other inert gas is introduced according to the ambient temperature to restore the internal cavity pressure to slightly above atmospheric pressure. This operation eliminates the interference of oxygen and water vapor in the air on the phase change process, prevents condensation on the surface of the condenser tubes due to temperature differences, and inhibits the oxidative degradation of the fluorinated liquid. The expansion tank is connected to the gas phase space at the top of the main internal cavity via a connecting pipe. When the transformer load increases, causing the overall temperature of the fluorinated liquid to rise, the liquid volume expands, pushing the liquid level up. Excess gaseous fluorinated liquid is squeezed into the expansion tank, increasing the volume of the gas phase space inside the tank to absorb the expansion. When the load decreases, the temperature drops, the liquid contracts, and the internal cavity pressure decreases. The gas in the expansion tank flows back to the main cavity to maintain pressure balance. The gas phase volume of each expansion tank is designed to be 1.2 times the maximum thermal expansion volume of the system, with 20% as a safety margin to cope with transient impact conditions.

[0078] The pressure sensor continuously collects the pressure value at the top of the inner cavity and transmits it to the control unit. When the pressure exceeds the preset upper limit threshold, the control unit determines that the capacity of the currently used expansion tank is about to be saturated and automatically opens the connecting valve of the backup expansion tank, connecting the two tanks in parallel to expand the buffer volume. If the pressure continues to rise and exceeds the limit value, the safety valve core overcomes the spring preload under pressure and opens the pressure relief channel, releasing the high-temperature gaseous fluorinated liquid. When the temperature sensor at the pressure relief port detects that the temperature of the jet gas exceeds the set value, it immediately triggers the power-off protection, cutting off the transformer power supply to stop heating. After the pressure drops, the safety valve automatically closes under the spring reset force, restoring the sealed state.

[0079] The liquid level sensor uses a float structure. The float rises and falls with the liquid level, causing the connecting rod to rotate. The rotation angle corresponds to the liquid level height. The sensor output signal is converted and displayed as a specific liquid level value. During normal operation, the liquid level is approximately 50mm above the top of the inner core, maintaining a 100mm gas phase space with the top of the inner cavity. When the liquid level is 10mm below the top of the inner core, a low liquid level warning is triggered, prompting the injection of fluorinated liquid through the replenishment port. The replenishment operation is performed with the system stopped. Open the replenishment port valve and slowly inject preheated fluorinated liquid to ambient temperature using a dedicated pump until the liquid level sensor displays the normal value, then close the valve.

[0080] Temperature sensors are positioned at four locations: the bottom of the inner cavity, the liquid surface, the top gas phase zone, and the middle of the sidewall. These sensors monitor the temperature of the bottom liquid phase, the liquid-gas interface, the vapor temperature, and the liquid phase temperature on the sidewall, respectively. These four temperature signals are input to a data acquisition module to calculate the temperature field distribution in real time. The bottom temperature reflects the intensity of the heat source, the liquid surface temperature indicates whether the phase change is proceeding normally, the top temperature characterizes heat dissipation efficiency, and the sidewall temperature is used to detect the uniformity of liquid convection. When the temperature difference between two points on the sidewall exceeds 5°C, it indicates poor liquid convection and a risk of localized overheating, requiring inspection of the inner core installation location or the amount of fluorinated liquid charged.

[0081] Temperature sensing elements embedded in the transformer windings output the winding hot spot temperature signal, which, along with the internal cavity temperature signal, is sent to the main control monitoring system. The monitoring system compares the difference between the winding temperature and the liquid surface temperature to evaluate the phase change heat dissipation effect. Ideally, the temperature difference between the winding hot spot and the liquid surface should be less than 10℃, indicating efficient phase change heat transfer. If the temperature difference continues to increase beyond 15℃, it suggests obstructed fluorinated liquid circulation or insufficient radiator cooling capacity, requiring investigation of the fan operation status, whether the condenser tubes are scaled, and whether the fluorinated liquid has deteriorated.

[0082] The recovery tank is put into use during maintenance or replacement of the fluorinated liquid. Before maintenance, the transformer power is turned off and the internal temperature is allowed to drop to ambient temperature. The outlet valve is then opened, and the fluorinated liquid is completely pumped into the recovery tank using gravity or a vacuum pump. The recovery tank is made of 316 stainless steel, which is resistant to the chemical corrosion of the fluorinated liquid. The tank is equipped with a liquid level observation window and a sampling port for easy confirmation of the recovery volume and liquid quality testing. The recovered fluorinated liquid can be reused after filtration, impurity removal, and degassing, achieving medium recycling. A standby recovery tank is switched on when the main tank is under maintenance or its capacity is insufficient, ensuring continuous maintenance operations.

[0083] A second aspect of this invention provides a transformer temperature intelligent control system based on phase change immersion liquid cooling technology, comprising: The vaporization heat transfer unit is used to receive the heat generated when the transformer core is working and transfer it to the fluorinated liquid working medium in the liquid immersion area, so that the temperature of the fluorinated liquid working medium rises to the boiling point and absorbs latent heat to undergo a phase change and be converted into gaseous fluorinated vapor. The gaseous fluorinated vapor is driven to rise to the gas phase buffer space and contact the condenser tube group. The condensation and heat dissipation unit is used to transfer the heat of gaseous fluorinated vapor to the radiator through the tube wall of the condenser tube group, and to control the start of the forced fan to discharge the heat on the radiator to the external environment, so that the gaseous fluorinated vapor releases heat on the surface of the condenser tube group, the temperature decreases and a phase change occurs, and it recondenses into liquid fluorinated liquid. The reflux circulation unit is used to use gravity to make the liquid fluorinated liquid drip back into the liquid immersion area at the bottom of the inner cavity of the outer shell, forming a cyclic phase change process from liquid fluorinated liquid to gaseous fluorinated vapor and then back to liquid fluorinated liquid. The anti-condensation treatment unit is used for vacuum evacuation and inert gas replenishment. The vacuum evacuation is used to evacuate the inner cavity of the outer shell before the initial commissioning of the system to remove the internal air. The inert gas replenishment is used to replenish the inner cavity of the outer shell with dry inert gas according to the ambient temperature data. Filling the inner cavity of the outer shell with inert gas reduces condensation caused by temperature difference on the inner wall of the outer shell and the surface of the condenser tube assembly. The pressure balancing unit is used to connect the first expansion tank and the second expansion tank to the gas phase buffer space inside the outer shell through a connecting pipe, so as to accommodate the volume expansion of the fluorinated liquid working fluid due to temperature changes and balance the system pressure.

[0084] A third aspect of the present invention provides an electronic device, comprising: processor; Memory used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the aforementioned method.

[0085] A fourth aspect of the present invention provides a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the aforementioned method.

[0086] This invention can be a method, apparatus, system, and / or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for performing various aspects of the invention.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for intelligent temperature control of transformers based on phase change immersion liquid cooling technology, characterized in that, include: Data on the heat generation power of the transformer core, the saturated vapor pressure of the phase change working fluid, the condensation state of the heat exchange surface of the condensation heat exchange component, and the gas phase temperature stratification data in the closed cavity were collected. Based on the saturated steam pressure data and gas phase temperature stratification data, the superheat distribution at different heights is calculated, and the momentum decay law during the steam rise process is predicted by combining the heating power data, thus identifying the low momentum steam stagnation area that leads to local failure of the condenser tube group. Based on the location information of the low momentum steam retention area and the condensation state data of the heat exchange surface, the start-stop combination mode and phase difference control strategy of the forced cooling fan are dynamically adjusted. A directional turbulent airflow is formed in the gas phase space through asynchronous pulse air supply, driving the retained steam to migrate to the condensation area. Based on the low-momentum steam retention area and the distribution state of the retained steam after migration, a pressure regulation strategy for the expansion tank and a thermal management command for the transformer are generated. The pressure regulation strategy and thermal management instructions are executed, and the saturated steam pressure data and gas phase temperature stratification data after execution are collected to dynamically optimize the calculation parameters of the superheat distribution.

2. The method according to claim 1, characterized in that, Based on the saturated steam pressure data and gas phase temperature stratification data, the superheat distribution at different heights is calculated, and the momentum decay pattern during the steam rise process is predicted by combining the heat generation power data. Low-momentum steam stagnation regions leading to localized failure of the condenser coil assembly are identified, including: Substituting the saturated vapor pressure data into the Clausius-Clapeyron relation, the theoretical saturated temperature distribution curves corresponding to different height positions within the closed cavity are calculated. These curves are then compared point-by-point with the gas phase temperature stratification data to construct a three-dimensional superheat distribution model. Gradient tensor analysis is performed on the three-dimensional superheat distribution model to identify abnormal regions where the superheat gradient reverses. The spatial coordinates of these abnormal regions and the peak superheat value are output as thermodynamic imbalance characteristic parameters. The evaporation mass transfer rate of the transformer core surface is calculated based on the heat generation power data. A steam density correction model is established in combination with the thermodynamic imbalance characteristic parameters to calculate the actual density distribution of steam at different height positions. Substituting the actual density distribution into the momentum transport equation, the buoyancy reduction caused by density change during the steam's ascent is calculated, and the quantitative relationship curve of the decrease in steam momentum with height is obtained by combining the flow resistance coefficient of the closed cavity. In the quantitative relationship curve, identify the height threshold point where the momentum drops below the critical value for maintaining upward flow, and spatially match the height threshold point with the spatial coordinates of the abnormal region to define the region that simultaneously satisfies insufficient momentum and abnormal superheat as the low momentum steam retention region.

3. The method according to claim 2, characterized in that, Based on the heat generation power data, the evaporation mass transfer rate on the transformer core surface is calculated. A steam density correction model is established using the thermodynamic imbalance characteristic parameters to calculate the actual density distribution of steam at different heights, including: The heat generation power data is normalized with the surface area of ​​the transformer core to obtain the heat flux density per unit area, and then divided by the latent heat of vaporization of the phase change working fluid to calculate the evaporation mass transfer rate. Extract the superheat peak value of each abnormal region from the thermodynamic imbalance characteristic parameters, and multiply the superheat peak value by the saturated vapor density at the corresponding spatial location to obtain the density correction coefficient; The amount of steam generated per unit time is obtained by multiplying the evaporation mass transfer rate by the molecular mass of the phase change working fluid, and the initial density of steam at the initial height is calculated based on the amount of steam generated and the bottom cross-sectional area of ​​the closed cavity. The initial density is coupled with the density correction coefficient, and the initial density is recursively corrected layer by layer according to the density correction coefficient corresponding to each height position. The density decrease gradient of steam in the vertical upward path is calculated by the cumulative change of density during the recursive correction process. The density decreasing gradient is mapped to the height coordinates of the enclosed cavity to generate a spatial distribution function in which the steam density changes continuously with height. The values ​​of the spatial distribution function at each discrete height position are taken as the actual density distribution of steam at different height positions.

4. The method according to claim 1, characterized in that, Based on the location information of the low-momentum vapor retention area and the condensation state data of the heat exchange surface, the start-stop combination mode and phase difference control strategy of the forced cooling fan are dynamically adjusted. A directional turbulent airflow is formed in the gas phase space through asynchronous pulsed air delivery, driving the retained vapor to migrate towards the condensation area, including: Gradient field reconstruction is performed on the condensation state data of the heat exchange surface to calculate the liquid film thickness gradient at each location, identify weak condensation regions where the gradient value is less than the condensation threshold, perform spatial correlation analysis on the low momentum steam retention region and the weak condensation region, construct a pairing relationship map, and determine the spatial path for establishing a steam transport channel. Calculate the path direction vector based on the starting point and ending point of the spatial path, establish the wind turbine action area coverage matrix, filter out effective wind turbines with non-zero contribution to the path direction, and calculate the projection component of the air delivery vector of each wind turbine in the path direction as the cooperative driving intensity. Based on the cooperative driving intensity, the effective wind turbines are divided into a main driving group and an auxiliary driving group. A timing phase difference is designed so that the main driving group starts before the auxiliary driving group, so that the initial turbulent airflow is continuously driven by the subsequent airflow. The timing phase difference control is executed, and the gas velocity vector field in the stagnation area is collected in real time. When the angle between the dominant velocity direction and the path direction is less than the allowable deviation angle, it is determined that a directional disturbance airflow is formed. The liquid film thickness change rate in the weak condensation area is monitored, and the timing phase difference is adjusted based on the change rate.

5. The method according to claim 1, characterized in that, Spatial correlation analysis was performed on the low-momentum steam retention region and the weak condensation region to construct a pairing relationship map and determine the spatial paths for establishing steam transport channels, including: Extract the spatial coordinates of the low-momentum vapor stagnation region and the weak condensation region, calculate the spatial distance and relative height difference between each low-momentum vapor stagnation region and each weak condensation region, and construct a spatial topology matrix; obtain the flow resistance field distribution data in the closed cavity, perform resistance integral calculation along the straight path between the low-momentum vapor stagnation region and the weak condensation region, and fill it into the spatial topology matrix to calculate the comprehensive transport cost coefficient; The spatial topology matrix is ​​scanned to identify multiple weak condensation regions with comprehensive transport cost coefficients below the feasible threshold corresponding to the same low momentum vapor retention region. The remaining heat transfer capacity of the weak condensation region is introduced as a weighting factor and weighted and fused with the comprehensive transport cost coefficient to calculate the pairing priority. According to the pairing priority from high to low, a unique target weak condensation region is assigned to each low momentum steam retention region, and a pairing relationship map is constructed. The pairing relationship map takes the retention region as the source node and the target weak condensation region as the target node, and the straight path connecting the source node and the target node is determined as the spatial path of the steam transport channel.

6. The method according to claim 1, characterized in that, Based on the low-momentum steam retention area and the distribution state of the retained steam after migration, a pressure regulation strategy for the expansion tank and thermal management instructions for the transformer are generated, including: Obtain the boundary profile and steam velocity vector field of the low momentum steam retention region, calculate the average kinetic energy and pressure potential energy of the steam in the region, construct the thermodynamic equation of state and solve it to obtain the disturbance of the pressure of the closed cavity by the retained steam. Collect the distribution status data after migration, identify the steam flow rate transferred from the stagnant area to the active flow area, calculate the cumulative condensation per unit time, and predict the pressure response time constant based on the cumulative condensation and the heat capacity parameter of the closed cavity. Based on the pressure response time constant, a staged pressure regulation strategy for the expansion tank is designed. In the rapid response stage, the instantaneous intake rate of the expansion tank is controlled according to the disturbance amount. In the steady-state maintenance stage, the buffer pressure setpoint is adjusted according to the cumulative condensation amount. Extract the spatial distribution characteristics of the heat exchange surface temperature gradient in the distributed state data, construct a mapping model between the temperature gradient and the heat dissipation efficiency of the transformer winding, calculate the local heat dissipation efficiency improvement coefficient at each winding location, and generate a partitioned load redistribution instruction based on the improvement coefficient as a thermal management instruction.

7. The method according to claim 6, characterized in that, Obtain the boundary profile and steam velocity vector field of the low-momentum steam retention region, calculate the average kinetic energy and pressure potential energy of the steam within the region, construct the thermodynamic equation of state, and solve for the disturbance of the retained steam on the pressure of the closed cavity, including: Extract the boundary contour geometric data of the low momentum steam retention region, perform curve fitting to generate a continuous boundary function, calculate the effective volume of the low momentum steam retention region, establish a spatial sampling point matrix within the effective volume and obtain the steam velocity vector of each sampling point to form a steam velocity vector field. The vector in the steam velocity vector field is decomposed into components, the radial velocity component and the tangential velocity component are calculated, and the kinetic energy density distribution function is calculated in combination with the steam density. The kinetic energy density distribution function is spatially integrated within the effective volume to obtain the average kinetic energy of the steam in the region. The pressure field data within the effective volume is collected, the potential energy density is calculated based on the pressure gradient and weighted averaged with the local steam mass to obtain the pressure potential energy of the steam in the region, and the average kinetic energy and the pressure potential energy are substituted into the energy conservation relationship to construct the thermodynamic equation of state. The wall stiffness parameter and volume compressibility coefficient of the closed cavity are modified by introducing the thermodynamic equation of state. The pressure state quantity of the retained steam is obtained by solving the modified thermodynamic equation of state using an iterative numerical method. The disturbance quantity is obtained by performing a differential operation with the steady-state pressure design value of the closed cavity.

8. A transformer temperature intelligent control system based on phase change immersion liquid cooling technology, used to implement the method as described in any one of claims 1-7, characterized in that, include: The vaporization heat transfer unit is used to receive the heat generated when the transformer core is working and transfer it to the fluorinated liquid working medium in the liquid immersion area, so that the temperature of the fluorinated liquid working medium rises to the boiling point and absorbs latent heat to undergo a phase change and be converted into gaseous fluorinated vapor. The gaseous fluorinated vapor is driven to rise to the gas phase buffer space and contact the condenser tube group. The condensation and heat dissipation unit is used to transfer the heat of gaseous fluorinated vapor to the radiator through the tube wall of the condenser tube group, and to control the start of the forced fan to discharge the heat on the radiator to the external environment, so that the gaseous fluorinated vapor releases heat on the surface of the condenser tube group, the temperature decreases and a phase change occurs, and it recondenses into liquid fluorinated liquid. The reflux circulation unit is used to use gravity to make the liquid fluorinated liquid drip back into the liquid immersion area at the bottom of the inner cavity of the outer shell, forming a cyclic phase change process from liquid fluorinated liquid to gaseous fluorinated vapor and then back to liquid fluorinated liquid. The anti-condensation treatment unit is used for vacuum evacuation and inert gas replenishment. The vacuum evacuation is used to evacuate the inner cavity of the outer shell before the initial commissioning of the system to remove the internal air. The inert gas replenishment is used to replenish the inner cavity of the outer shell with dry inert gas according to the ambient temperature data. Filling the inner cavity of the outer shell with inert gas reduces condensation caused by temperature difference on the inner wall of the outer shell and the surface of the condenser tube assembly. The pressure balancing unit is used to connect the first expansion tank and the second expansion tank to the gas phase buffer space inside the outer shell through a connecting pipe, so as to accommodate the volume expansion of the fluorinated liquid working fluid due to temperature changes and balance the system pressure.

9. An electronic device, characterized in that, include: processor; Memory used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having computer program instructions stored thereon, characterized in that, When the computer program instructions are executed by the processor, they implement the method described in any one of claims 1 to 7.

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