Method for eliminating local working hot spots of high-temperature superconducting rotor magnet

Abstract

The invention discloses a method for eliminating local working hot spots of a high-temperature superconducting rotor magnet, and the method comprises the steps: dividing a cold helium circulation channel into a plurality of heat management units according to the real-time temperature value and temperature gradient of each position of the magnet, and periodically calculating the comprehensive severity index of each unit; and when the temperature of a certain unit exceeds a hot spot temperature threshold value or the temperature gradient exceeds a hot spot gradient threshold value, the unit is judged as a local working hot spot. After the hot spot is judged, valve opening degrees of a shunting branch and a diversion branch which are connected with the hot spot unit are adjusted through cooling capacity priority scheduling, and on the premise that the total flow is basically unchanged, the flow of cold helium flowing through the hot spot unit is increased in a self-adaptive mode, and the flow of a low-load unit is reduced; and meanwhile, high-temperature cold helium subjected to heat exchange with a hot spot is preferentially led out of a circulating system or led to a special heat dissipation branch through a flow guide branch, flow distribution is recovered in combination with overall temperature gradient feedback, and rapid transfer and lead-out of local heat are achieved. According to the invention, local working hot spots can be effectively eliminated.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature superconducting motors and their cryogenic engineering technology, specifically relating to a method for eliminating local hot spots in a high-temperature superconducting rotor magnet. Background Technology

[0002] With the development of large-scale power grids with high proportions of new energy and high-voltage transmission systems, high-temperature superconducting synchronous condensers have become an important technological direction for improving power grid stability and dynamic reactive power support capabilities due to their advantages such as low loss, small size, and strong reactive power regulation capability. The rotor of a high-temperature superconducting synchronous condenser typically uses a high-temperature superconducting rotor magnet, combined with a vacuum insulation structure and a circulating cold helium cooling system, enabling the superconducting windings to operate at low temperatures to achieve a higher critical current and reliable operational stability.

[0003] In actual operation, high-temperature superconducting rotor magnets need to withstand frequent strong excitation, weakened excitation, and transient support during power grid faults. The superconducting wires generate AC losses under the influence of alternating current and superimposed magnetic fields, and the electromagnetic coupling between the stator and rotor also causes drastic changes in the magnetic field in localized areas of the rotor. The combined effect of these factors easily leads to the formation of hot spots in localized areas of the high-temperature superconducting rotor magnets, especially in the inner arc region, end transition region, or complex cold helium flow areas within certain thermal management units, where the local temperature rises significantly faster than in other areas. If these localized hot spots are not suppressed in a timely and effective manner, the temperature of the superconducting strip in that region may approach or even exceed the critical temperature, causing localized quenching failure, which could potentially spread to surrounding areas and, in severe cases, jeopardize the safe and stable operation of the entire system.

[0004] Existing methods for cooling high-temperature superconducting rotor magnets mostly employ circulating cold helium. This involves introducing low-temperature cold helium into the rotor through cooling plates and circulating channels to exchange heat with the superconducting coils. To improve overall operational stability, existing technologies have proposed temperature equalization control methods based on overall rotor temperature feedback. These methods adjust the total flow rate, inlet pressure, or inlet temperature of the circulating cold helium to maintain the average temperature of each superconducting magnet within a predetermined range and control the temperature difference between different magnets to not exceed a certain threshold. While these methods can improve the overall temperature distribution at the system level and reduce temperature unevenness between different magnets, they typically treat each group of magnets as a single unit for control, neglecting the fine-scale temperature distribution within individual rotor magnets and making it difficult to address specific local hot spots independently and promptly.

[0005] On the other hand, existing technologies for controlling cold helium gas primarily focus on adjusting the overall cooling capacity, such as increasing the total flow rate, improving cooling power, or altering the global flow distribution ratio. Under engineering conditions where total cooling capacity is limited and rotor structure constraints are stringent, simply increasing the overall flow rate not only significantly increases the energy consumption and pressure drop burden of the cooling system but may also further lower the temperature in non-hotspot areas, leading to an increase in the internal temperature gradient of the high-temperature superconducting rotor magnet. Furthermore, in existing circulating cold helium systems, cold helium typically flows sequentially through various regions along pre-defined channels. Helium that has increased in temperature after heat exchange with local hotspots often continues to flow downstream cooling units, easily causing a decline in the quality of the cold source in subsequent regions, thus amplifying the impact of local hotspots on the overall temperature field.

[0006] In summary, existing technologies primarily focus on overall temperature uniformity and flow rate regulation for temperature control of high-temperature superconducting rotor magnets. However, they lack a method for eliminating localized hotspots that uses circulating cold helium as the main control object, targets multiple thermal management units within the rotor magnet, adaptively distributes cooling capacity based on real-time temperature and temperature gradient information, and directionally extracts localized high-temperature cold helium. Existing technologies struggle to achieve rapid elimination of localized hotspots and effective protection of non-hotspot areas under conditions of limited total flow rate or total cooling capacity, and also fail to simultaneously suppress the overall temperature gradient during localized hotspot treatment. Therefore, it is necessary to propose a novel method for eliminating localized hotspots in high-temperature superconducting rotor magnets. This method, through dynamic distribution and extraction control of circulating cold helium among different thermal management units, aims to achieve rapid suppression of localized hotspots and long-term stability of the rotor magnet's temperature field without significantly increasing system energy consumption. Summary of the Invention

[0007] To overcome the problems of local hot spots easily generated in high-temperature superconducting rotor magnets under strong excitation and complex operating conditions, and the slow response of traditional control methods based on overall flow regulation to individual hot spot areas, which easily amplify the internal temperature gradient of the rotor and have high cooling energy consumption, this invention proposes a method for eliminating local hot spots in high-temperature superconducting rotor magnets. Using circulating cold helium gas as the main control object, a cooling capacity priority scheduling method based on temperature and temperature gradient classification is constructed for multiple thermal management units inside the rotor magnet, so as to achieve rapid elimination of local hot spots and effective suppression of the overall temperature gradient.

[0008] Specifically, this invention is applicable to high-temperature superconducting rotor magnets cooled by circulating cold helium gas. Based on the real-time temperature values ​​and temperature gradients at different locations of the magnet, the cold helium gas circulation channel is divided into multiple thermal management units. The comprehensive severity index of each unit is calculated periodically. When the temperature and temperature gradient of a certain unit simultaneously exceed a preset threshold, that unit is identified as a local hot spot. After hot spot identification, by adjusting the valve openings of the branch and guide branches connected to the unit, the flow rate of cold helium gas flowing through the hot spot unit is adaptively increased while the flow rate of low-load units is reduced, while the high-temperature cold helium gas that has exchanged heat with the hot spot is preferentially discharged from the circulation system through the guide branch or led to a dedicated heat dissipation branch, achieving rapid transfer and discharge of local heat. This invention uses temperature gradient and heat load as the core criteria to achieve dynamic distribution of cooling capacity among units and directional discharge of local heat. It can effectively eliminate local hot spots and maintain the uniformity and long-term stability of the temperature field of the high-temperature superconducting rotor magnet without relying on complex system-level control models.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for eliminating localized hot spots in a high-temperature superconducting rotor magnet includes the following steps:

[0011] Step 1: Divide the cold helium gas circulation channel inside the high-temperature superconducting rotor magnet into multiple thermal management units, periodically collect temperature data of each thermal management unit, and calculate the temperature deviation of each thermal management unit relative to the target temperature and the temperature gradient between adjacent units.

[0012] Step 2: Based on the preset temperature threshold and temperature gradient threshold, classify each thermal management unit into normal zone, warning zone or hot zone, and set hysteresis interval to avoid frequent state switching;

[0013] Step 3: Based on the state classification results, establish a cold helium energy priority scheduling rule, set the cold energy priority of the hot spot area to the highest, the warning area to the second highest, and the normal area to the lowest. Under the premise that the total mass flow rate of circulating cold helium remains basically unchanged, adjust the cold helium flow rate of each thermal management unit by setting a compensation ratio coefficient, so that the cold helium flow rate of the hot spot area increases to exceed its normal operating flow rate, the cold helium flow rate of the warning area is moderately increased, and the cold helium flow rate of the normal area is correspondingly reduced.

[0014] Step 4: Monitor the cold helium temperature at the outlet of each thermal management unit. When the cold helium temperature at the outlet of the hot spot exceeds the export threshold, according to the export ratio coefficient, the high-temperature cold helium of the unit is preferentially exported to the circulation system through the export branch or led to the dedicated heat dissipation branch to reduce the proportion of it flowing into the downstream thermal management unit.

[0015] Step 5: When the temperature and temperature gradient of the hot spot thermal management unit recover to the range of the warning zone or normal zone, the compensation proportional coefficient in step 3 and the derived proportional coefficient in step 4 are smoothly restored based on the overall temperature gradient, so that the system gradually returns from the hot spot suppression mode to the normal equilibrium mode.

[0016] Furthermore, in step 1, the collected temperature data is subjected to first-order smoothing, and the current sampled value is weighted and combined with the historical smoothed value to obtain the smoothed temperature, which is used to calculate the temperature deviation and temperature gradient.

[0017] Furthermore, in step 2, a comprehensive severity index is constructed by performing dimensionless processing on the positive part of the temperature deviation and the absolute value of the spatial gradient, and then weighting and summing them to form a scalar index for state classification.

[0018] Furthermore, in step 3, the total mass flow rate is divided into two parts: basic mass flow rate and compensation mass flow rate. The basic mass flow rate is allocated according to the structural weight coefficient of each thermal management unit, and the compensation mass flow rate is normalized and allocated according to the degree to which the comprehensive severity index exceeds the normal zone exit threshold.

[0019] Furthermore, in step 3, a flow adjustment coefficient is used to smoothly update the target mass flow rate, so that the actual mass flow rate gradually approaches the target value and avoids sudden changes in flow rate.

[0020] Furthermore, in step 4, derived weights are constructed based on the regional status markers of the thermal management unit and the outlet temperature exceeding the limit. The derived priority coefficient of the hot spot area is higher than that of the warning area, and the derived priority coefficient of the normal area is zero.

[0021] Furthermore, in step 4, a maximum export ratio coefficient at the unit level is set to limit the export mass flow rate of a single thermal management unit to no more than half of its total mass flow rate.

[0022] Furthermore, in step 5, the difference between the highest and lowest temperatures in all thermal management units is used as the overall temperature gradient. An upper limit for the overall temperature gradient and two graded thresholds are set to drive the recovery process of the compensation proportional coefficient and the derived proportional coefficient.

[0023] Furthermore, in step 5, a first-order smooth update method is adopted to make the compensation proportional coefficient and the derived proportional coefficient gradually approach the target value determined by the overall temperature gradient, so as to avoid the temperature field disturbance caused by the sudden withdrawal of the control strategy.

[0024] Furthermore, it is suitable for high-temperature superconducting rotor magnets cooled by circulating cold helium.

[0025] Beneficial effects:

[0026] 1. This invention distinguishes between hot spots, warning zones, and normal zones by classifying states based on temperature and temperature gradients, making the allocation of cold helium gas clear and prioritizing the cooling needs of local hot spots without significantly increasing the total mass flow rate.

[0027] 2. This invention enables the cold helium gas to be distributed as needed among multiple thermal management units by setting the priority scheduling and allocation coefficient of cold energy. This not only speeds up the cooling rate of hot spots, but also avoids excessive cooling of non-hot spots, which would amplify the temperature gradient.

[0028] 3. This invention reduces the impact of high-temperature cold helium on the quality of the downstream unit's cold source by prioritizing the export of high-temperature cold helium from the hot spot area, thereby effectively suppressing the negative effects of local hot spots on the overall temperature field.

[0029] 4. By introducing hysteresis and gradual change strategies during state classification and recovery, this invention avoids secondary temperature fluctuations caused by frequent switching and sudden flow changes. This helps to maintain a small temperature gradient inside the high-temperature superconducting rotor magnet in the long term, thereby reducing the risk of local quenching and improving the safety and reliability of the whole machine operation. Attached Figure Description

[0030] Figure 1 This is a flowchart of a method for eliminating local hot spots in a high-temperature superconducting rotor magnet according to the present invention.

[0031] Figure 2 A schematic block diagram of the algorithm for temperature monitoring and state quantity calculation steps;

[0032] Figure 3 This is a schematic diagram of status classification and regional division based on a comprehensive severity index;

[0033] Figure 4 A schematic diagram illustrating the relationship between priority scheduling of cooling capacity and mass flow rate allocation of circulating cold helium.

[0034] Figure 5 Schematic diagram of the control for priority export of high-temperature circulating cold helium gas from the hot spot outlet;

[0035] Figure 6 This is a schematic diagram of the compensation proportional coefficient and the recovery process of the derived proportional coefficient based on the overall temperature gradient. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0037] The present invention provides a method for eliminating local hot spots in a high-temperature superconducting rotor magnet. This method is applied to a high-temperature superconducting rotor magnet cooled by circulating cold helium gas. The rotor magnet is internally divided into several thermal management units along the cold helium gas flow direction. Each thermal management unit corresponds to a specific cold helium gas channel section or superconducting coil region. The cold helium gas mass flow rate can be distributed and adjusted among different thermal management units. Specifically, as shown... Figure 1 As shown, firstly, temperature monitoring points or temperature monitoring intervals are set for each thermal management unit. Real-time temperature data of each thermal management unit is periodically collected, and the temperature difference between adjacent thermal management units is calculated to obtain a temperature gradient index reflecting local spatial changes. The target temperature and allowable temperature deviation range are determined by system operating requirements, and the temperature gradient threshold is set based on the rotor structure and allowable temperature uniformity requirements. Through the aforementioned real-time temperature and temperature gradient data, fine-scale temperature distribution information of the high-temperature superconducting rotor magnet along the cooling path can be obtained. Then, based on the preset temperature threshold and temperature gradient threshold, the status of each thermal management unit is classified into normal zone, warning zone, and hot spot zone. When the real-time temperature and temperature gradient of a thermal management unit are both within the normal range, the thermal management unit is determined to be in the normal zone; when the real-time temperature is close to the upper limit of the target temperature or the temperature gradient increases significantly but has not yet reached the hot spot determination condition, the thermal management unit is determined to be in the warning zone; when the real-time temperature exceeds the hot spot temperature threshold or the temperature gradient exceeds the hot spot gradient threshold, the thermal management unit is determined to be in the hot spot zone. To avoid frequent switching of the thermal management unit between different states, upper and lower limits and hysteresis ranges are set for both the temperature threshold and the temperature gradient threshold, so that the state classification has a certain degree of memory and stability.

[0038] Based on the state classification results, a priority scheduling rule for cold helium gas is established among the thermal management units. The cold helium priority is set highest for hotspot areas, followed by warning areas, and lowest for normal areas. Under the premise that the total mass flow rate of circulating cold helium remains basically unchanged or is only slightly adjusted (generally controlled within 5% to 10% of the current total mass flow rate), a target mass flow rate is calculated for each thermal management unit according to the priority and allocation coefficient corresponding to each level. This ensures that hotspot areas receive significantly more cold helium gas flow rate than under normal operating conditions in a short period, for example, increasing their target mass flow rate to 1.3 to 2.0 times that of normal operating conditions. Warning areas receive a moderately increased cold helium gas flow rate, while normal areas receive a moderately reduced flow rate while ensuring basic heat dissipation needs. By adjusting the opening degree or equivalent control quantity of the flow regulation units connected to each thermal management unit, the actual flow rate gradually approaches the target mass flow rate, achieving a spatially graded allocation of cold helium gas.

[0039] The reason why minor adjustments are generally controlled within the range of 5% to 10% of the current total mass flow rate is as follows: the flow rate adjustment coefficient is generally taken as 0.1 to 0.3 to control the dynamic rate of change of mass flow rate; the derived proportion coefficient is generally taken as 0.05 to 0.2 to limit the proportion of derived mass flow rate to total mass flow rate. In this context, limiting the adjustment range of total mass flow rate to 5% to 10% is a more conservative range than the upper limit of the derived proportion coefficient, which helps ensure the stable operation of the entire circulating cold helium system under the premise that the total mass flow rate is basically limited.

[0040] Based on this, the present invention also prioritizes the extraction of high-temperature cold helium gas after heat exchange with the hot spot, according to the cold helium gas temperature at the outlet of each thermal management unit and its status. When the cold helium gas temperature at the outlet of the hot spot exceeds a preset extraction threshold, it is marked as a high-temperature outlet unit, and the high-temperature cold helium gas of this unit is preferentially led to the regeneration or dedicated heat dissipation path through the extraction path, reducing the proportion of it directly flowing into the downstream thermal management unit. For thermal management units in the warning zone and whose outlet temperature is close to the extraction threshold, the extraction ratio can be selectively activated or adjusted according to the overall temperature distribution, thereby ensuring rapid cooling of the hot spot while taking into account the overall cooling efficiency and energy consumption level.

[0041] As the real-time temperature and temperature gradient of the thermal management unit in the hotspot area gradually decrease and return to the judgment range of the warning zone or normal zone, the cooling priority and allocation coefficient are further smoothed back. Specifically, as the state transitions from the hotspot area to the warning zone or normal zone, the cooling priority of the thermal management unit is gradually reduced, and its cold helium flow allocation coefficient is slowly transitioned from the bias value in the hotspot state to the equilibrium value in the normal operation state. At the same time, based on the number and spatial distribution of the warning zones, the allocation ratio between the warning zones and the normal zones is appropriately adjusted so that the cold helium flow allocation remains continuously changing during the transition phase after the hotspot is eliminated, avoiding new temperature fluctuations or local overcooling.

[0042] Through the above steps, this invention transforms the complex temperature field changes inside the high-temperature superconducting rotor magnet into a finite-state hierarchical control problem. With temperature and temperature gradient as the core criteria and the distribution and extraction of cold helium gas among different thermal management units as the main control means, it achieves rapid suppression of local hot spots and effective protection of non-hot spot areas under engineering conditions where the total cooling capacity is basically limited.

[0043] This invention can be used in conjunction with high-temperature superconducting rotor magnets and circulating cold helium systems of various specific structural forms, and is not limited to a specific structure.

[0044] Example:

[0045] In this embodiment, a method for eliminating local hot spots in a high-temperature superconducting rotor magnet is specifically as follows: Figure 2 As shown, step 1 includes:

[0046] In this embodiment, the region inside the high-temperature superconducting rotor magnet that is directly thermally coupled to the cold helium gas channel is divided into several thermal management units along the main flow direction of the circulating cold helium gas, for example, denoted as... One, numbered as At least one temperature monitoring point is arranged in each thermal management unit, or a temperature sensor is arranged at a location with strong thermal coupling to the unit, and a rotor temperature measurement system is used to measure the temperature at a fixed sampling period. Collect temperature data. At each sampling time, the thermal management unit The original measured temperature is denoted as ;

[0047] Considering the unavoidable noise, transient disturbances, and sampling jitter in temperature measurement signals under low-temperature environments, this embodiment first performs first-order smoothing on the original temperature data to obtain smoothed temperature data for subsequent calculations, in order to reduce the impact of a single abnormal sampling on subsequent classification decisions. .

[0048] The smoothing process uses a recursive approach. ;

[0049] in, For smoothing coefficients, Used to adjust the weights of the current sampled value and historical smoothed values ​​in the smoothing result. When the temperature is large, the smoothed temperature is more sensitive to changes in the latest measurements; when When the temperature is smaller, the smoothing temperature change is more gradual, which helps to suppress occasional disturbances. In this embodiment, The temperature value can be taken as the first temperature collected after the system has cooled and stabilized, or the preset target temperature can be used.

[0050] The desired target temperature for the high-temperature superconducting rotor magnet is set as follows: Then the first Each thermal management unit at the sampling time Temperature deviation is defined as:

[0051] ;

[0052] Temperature deviation This reflects the degree of deviation of the overall temperature level of the thermal management unit from the target temperature. This indicates that the temperature of the unit is higher than the target value. This indicates that the temperature of the unit is lower than the target value. This indicates that the unit temperature equals the target value. Subsequent steps will use... Whether the temperature exceeds the threshold of different levels is an important basis for classification.

[0053] To characterize the spatial temperature non-uniformity along the direction of cold helium gas flow, this embodiment uses a first-order spatial gradient to describe the local temperature difference between the thermal management unit and its neighboring units. For internal units... Define its spatial gradient for:

[0054] ;

[0055] In this definition, and Thermal management unit Smoothing temperature of adjacent upstream and downstream units, Represents the average temperature of the neighborhood, when When the value is positive and large, it indicates that the temperature of this unit is significantly higher than the average level of the surrounding area, making it more likely to form local hot spots.

[0056] For boundary elements and Since it is only directly adjacent to one side of the adjacent unit, this embodiment adopts a one-sided gradient form, as shown in the following formula:

[0057] ;

[0058] This approach ensures that all thermal management units have spatial gradient indices associated with their neighboring regions, facilitating standardized classification in subsequent steps.

[0059] After obtaining the temperature deviation and spatial gradient, this embodiment combines the two to construct a state vector for subsequent steps. :

[0060] ;

[0061] in, This reflects the overall deviation of the unit from the target temperature. This reflects the degree of local temperature surge of the unit relative to its neighborhood. This is achieved by simultaneously considering... and It can identify areas with generally high temperature levels as well as areas with significant local temperature differences, providing a quantitative basis for subsequently dividing the thermal management unit into normal zones, warning zones, and hotspot zones.

[0062] In practical engineering applications, the number and location of temperature sensors can be optimized based on the rotor structure, the distribution of cold helium gas channels, and the requirements for sensitivity to local hot spots. This embodiment does not limit the specific sensor type or installation method; as long as the temperature measurement values ​​of each thermal management unit in the time series can be obtained, the state vector can be obtained through the above smoothing and gradient calculation steps. The update period of the state variables is the same as or an integer multiple of the temperature sampling period, and can be set according to the response requirements of the control system.

[0063] Through the implementation of step 1 above, this embodiment, without changing the total cooling capacity and rotor structure, extracts the complex temperature field information inside the high-temperature superconducting rotor magnet into a set of concise state vectors. This state variable not only has sufficient physical meaning, but also facilitates the classification and determination in subsequent steps according to preset temperature thresholds and temperature gradient thresholds. Based on this, priority scheduling of cold helium and priority export of high-temperature cold helium are implemented, thus laying the data foundation and algorithm entry point for the core method of this invention.

[0064] In step 1 above, the temperature deviation of each thermal management unit along the direction of circulating cold helium gas flow in the high-temperature superconducting rotor magnet has been obtained. and spatial gradient And constructed the state vector. Based on this, the goal of this step is to divide each thermal management unit into a normal zone, a warning zone, and a hotspot zone, providing clear input variables for subsequent priority scheduling of cold helium gas and control of high-temperature cold helium gas extraction.

[0065] Specifically, such as Figure 3 As shown, step 2 includes:

[0066] In this embodiment, a comprehensive severity index is constructed to unify temperature deviation and spatial gradient onto the same scalar. This scalar is then compared with a grading threshold to determine the state of each thermal management unit, thereby avoiding the need to process multiple indices separately in subsequent control and simplifying the control logic.

[0067] First, to highlight the risks associated with temperatures exceeding the target temperature, this embodiment takes the positive portion of the temperature deviation. :

[0068] ;

[0069] Only when the temperature of the thermal management unit is higher than the target temperature Severity is only considered when the temperature is below the target temperature; areas with temperatures below the target temperature are not included in the determination of local hot spots.

[0070] To enable the weighted superposition of physical quantities with different dimensions, a reference temperature deviation is introduced. and reference space gradient These represent the representative temperature exceedance level and spatial temperature difference level in engineering, respectively. Then, the positive temperature deviation and spatial gradient are dimensionless:

[0071] ;

[0072] in, and They represent the first The ratio of the current temperature level and local temperature difference of each thermal management unit to the reference level.

[0073] Based on this, a comprehensive severity index is defined. :

[0074] ;

[0075] in, This is used to adjust the relative importance of temperature deviation and spatial gradient in the overall severity score. Generally, the weights can be selected based on signal reliability and operating conditions: for example, under steady-state operation or weak excitation conditions, the weights can be appropriately increased. To highlight the absolute temperature exceeding the limit; under strong excitation or drastic magnetic field changes, the absolute temperature can be appropriately increased. To emphasize localized temperature differences. Reference temperature deviation. Reference space gradient and weighting coefficients , It can be determined through simulation and experimental calibration during the system debugging phase.

[0076] To map the comprehensive severity index to discrete regional states, a state label quantity is introduced. Defined as:

[0077] ;

[0078] in, This indicates that the thermal management unit is in the normal range. This indicates that the area is in a warning zone. This indicates that you are in a hotspot area.

[0079] Set two thresholds for overall severity and ,satisfy Ideally, the following basic hierarchical relationship can be adopted:

[0080] when At that time, the temperature deviation of the thermal management unit and the temperature difference in the space were considered to be within acceptable ranges, and were thus determined to be in the normal zone, denoted as . ;

[0081] when At that time, it was determined that the unit had shown a clear warming trend or an increase in local temperature difference, but had not yet developed into a typical local hot spot, and was therefore identified as a warning zone, denoted as [missing information]. ;

[0082] when At that time, it was determined that the unit had formed a local working hotspot, and was identified as a hotspot area, denoted as . .

[0083] Considering measurement noise and operating condition fluctuations, and to avoid frequent state switching near the threshold, this embodiment introduces the concepts of entry threshold and exit threshold for the comprehensive severity threshold. For example, a threshold for entering the warning zone is introduced to define the boundary between the normal zone and the warning zone. and the threshold for exiting the warning zone ,satisfy:

[0084] ;

[0085] A threshold for entering the hotspot zone is introduced to define the boundary between the warning zone and the hotspot zone. and the threshold for exiting the hotspot zone ,satisfy:

[0086] ;

[0087] In the control implementation, the state at the previous sampling time is taken into account. Update status according to the following principles :

[0088] When the previous time step was in the normal zone, only when Only when entering the warning zone; while in the warning zone, only when Only after returning to the normal zone, when Only when entering the hotspot zone; while in the hotspot zone, only when Only then is it downgraded to a warning zone. This state transition rule, with its hysteresis characteristics, can effectively suppress [the situation caused by] [the situation]. The high-frequency state transitions caused by small oscillations near the threshold give the state classification a certain degree of memory and stability.

[0089] Comprehensive Severity Index and the corresponding state flags This will serve as a direct input for cold helium mass flow rate allocation and high-temperature cold helium extraction strategies in subsequent steps. For example, in cold energy priority scheduling, hotspot units can be used. Assign the highest priority to cooling capacity, warning zone unit Assign the second highest priority, normal zone unit Assign the lowest priority; alternatively, the cooling capacity allocation coefficient can be designed as a comprehensive severity index. The monotonic function implements the scheduling principle that the higher the severity, the more cooling capacity is obtained.

[0090] Through the implementation of step 2 above, this embodiment, while maintaining the clarity of physical meaning, condenses temperature deviation and spatial gradient into a comprehensive severity index that is easy to process, and constructs a three-state hierarchical rule with hysteresis characteristics. This provides a unified and stable state description for subsequent priority scheduling of cold helium and elimination of local working hotspots, making the core of the whole method more compact and clear.

[0091] In steps 1 and 2 above, the temperature deviation of each thermal management unit along the direction of circulating cold helium gas flow in the high-temperature superconducting rotor magnet has been obtained. Spatial gradient State variables were constructed. And further calculate the comprehensive severity index. Based on this, each thermal management unit is classified into normal zone, warning zone, and hot zone, resulting in a status label quantity. Based on this, this step revolves around one of the core contents of the present invention, namely, under the condition that the total mass flow rate of circulating cold helium is basically limited, priority scheduling of the mass flow rate of circulating cold helium in each thermal management unit is achieved by superimposing the basic mass flow rate and the severity compensation mass flow rate, thereby realizing the concentration of cooling capacity for local hot spots.

[0092] Specifically, such as Figure 4 As shown, step 3 includes:

[0093] In this embodiment, it is assumed that the circulating cold helium gas is at the sampling time. The total mass flow rate is The high-temperature superconducting rotor magnet is divided into sections along the main flow direction of the circulating cold helium gas. One thermal management unit, numbered as . No. Each thermal management unit at the sampling time The target circulating cold helium mass flow rate is denoted as Define the sum of the base mass flow rate and the compensated mass flow rate:

[0094] ;

[0095] in, This is the base mass flow rate, used to ensure the basic cooling requirements of the thermal management unit when there are no obvious hot spots; To be based on the comprehensive severity index Compensated mass flow rate is allocated at an angle to enhance the unit's cooling capacity in the presence of warning or hot spots.

[0096] To reflect the long-term average cooling capacity requirements of each thermal management unit in terms of structure and thermal design, this embodiment introduces a structural weighting coefficient. ,satisfy:

[0097] ;

[0098] The total basic mass flow rate of the circulating cold helium gas is denoted as . Then the first Basic mass flow rate of each thermal management unit Defined as:

[0099] ;

[0100] In the simplest case, you can choose To achieve uniform base distribution; when some thermal management units have more coil layers, higher thermal resistance, or higher expected heat load, the corresponding base layer can be appropriately increased. This allows it to obtain relatively more circulating cold helium cooling even in the absence of hot spots.

[0101] The compensated mass flow rate reflects the cold energy redistribution mechanism of this invention for localized hot spots. Therefore, the comprehensive severity index obtained in step 2 is first utilized. Constructing nonnegative compensation weights :

[0102] ;

[0103] in, This is the exit threshold between the normal zone and the warning zone in step 2. When a thermal management unit is in the normal zone and the overall severity... At that time, the compensation weight of the unit It does not participate in the competition for compensated quality flow; when the unit enters the warning zone or hotspot zone, Its compensation weight It increases with the increase of overall severity, representing its relative demand for compensating mass flow rate.

[0104] In order to map the compensation weights to specific allocation ratios, Normalization is performed. When at least one thermal management unit satisfies... When defining normalized weights :

[0105] ;

[0106] Where j is the index value, ranging from j=1 to N, used to iterate and sum the compensation weights of all thermal management units divided along the main flow direction of circulating cold helium, thereby normalizing the compensation weights of thermal management units that currently have compensation needs.

[0107] At this time there is ;

[0108] When the overall severity of all thermal management units does not exceed the normal zone exit threshold, i.e. When this occurs, it indicates that there are currently no warning zones or hot spots requiring additional cooling. In this embodiment, it is preferable to set the total compensated mass flow rate to zero in this case to avoid unnecessary disturbances to the circulating cold helium flow rate, i.e.:

[0109] ;

[0110] in, Indicates at the sampling time Total mass flow rate of circulating cold helium used for severity compensation; Indicates at the sampling time Assigned to the Compensated mass flow rate of each thermal management unit;

[0111] ,in The total number of thermal management units obtained by dividing along the main flow direction of the circulating cold helium gas; is the discrete sequence number of the sampling time.

[0112] To ensure the conservation of the total mass flow rate of the circulating cold helium and limit the compensation intensity, this embodiment divides the total mass flow rate into a basic part and a compensation part, defined as follows:

[0113] ;

[0114] in, The proportionality coefficient is used to characterize the proportion of circulating cold helium mass flow rate that can be used for local hotspot tilting to the total mass flow rate. From this, we can obtain...

[0115] ;

[0116] when When the mass flow rate is small, the proportion of compensation mass flow rate is small, and the cooling load tilt is relatively mild; when When the mass flow rate is large, the proportion of compensation mass flow rate increases, which is more conducive to quickly concentrating cooling capacity into hot spots under conditions such as strong excitation.

[0117] exist and In the case of the first The compensated mass flow rate of each thermal management unit is defined as:

[0118] ;

[0119] At this time, the Each thermal management unit at the sampling time The target circulating cold helium mass flow rate can be written as:

[0120] ;

[0121] Using uniform base distribution In this case, the above formula can be simplified to:

[0122] ;

[0123] When all thermal management units are in the normal range and meet the requirements At that time, due to ,have .

[0124] At this point, each thermal management unit achieves approximately uniform cooling only through the basic mass flow rate. When some thermal management units enter the warning zone or hotspot zone, their overall severity... Exceed ,correspond and By increasing the mass flow rate, a higher proportion can be obtained in the compensation mass flow rate allocation, thereby allowing more circulating cold helium to be preferentially delivered to local working hotspots and their surrounding areas while keeping the total mass flow rate basically unchanged.

[0125] In actual control, to avoid drastic fluctuations in the flow state of circulating cold helium and pipeline pressure caused by sudden changes in mass flow rate, this embodiment performs a smoothing process on the mass flow rate update. Let... The first sampling time The actual circulating cold helium mass flow rate of each thermal management unit at the current sampling time. Based on target quality flow rate Update the actual quality flow rate as follows:

[0126] ;

[0127] in, For a moment The actual circulating cold helium mass flow rate, κ is the flow rate adjustment factor. When κ is small (e.g., 0.1 to 0.3), the mass flow rate changes more gradually, which is beneficial for maintaining the stability of the circulating cold helium system. When κ is large, the mass flow rate approaches the target value more quickly, which is beneficial for providing enhanced cooling in a timely manner when local hot spots form.

[0128] Meanwhile, to ensure that each thermal management unit has safe cooling capacity at all times and to avoid excessive concentration of cold helium gas circulating in a single unit, this embodiment also sets upper and lower limits for the mass flow rate:

[0129] ;

[0130] in, The minimum circulating cold helium mass flow rate required for the thermal management unit to maintain the target temperature during steady-state operation can be determined based on this. This is determined based on the maximum allowable flow rate, pressure drop limit, and mechanical safety margin of the corresponding cold helium gas channel. When the calculated... When the value exceeds the above range, a saturation cutoff process can be applied, i.e., the nearest boundary value is taken to ensure that the circulating cold helium system operates within a safe operating range.

[0131] Through step 3 above, this embodiment comprehensively assesses the severity index. Based on this, a priority scheduling mechanism for circulating cold helium capacity was constructed, which combines basic mass flow rate and severity-compensated mass flow rate control. On one hand, through the basic mass flow rate... To ensure long-term balanced cooling of all thermal management units when there are no obvious hot spots; on the other hand, by compensating for mass flow rate By spatially tilting the limited circulating cold helium towards the warning zone and hot spot zone, the local working hot spot can obtain a higher cooling supply under the condition that the total mass flow rate is basically limited, which provides the necessary cooling basis and adjustment margin for the subsequent hot spot outlet high temperature circulating cold helium priority export control.

[0132] Specifically, such as Figure 5 As shown, step 4 includes:

[0133] In step 3, based on the comprehensive severity index and status marker In the total mass flow rate of circulating cold helium Under fundamentally limited conditions, the actual circulating cold helium mass flow rate of each thermal management unit along the circulation direction has been obtained. At this point, although the unit where the local hot spot is located receives more circulating cold helium, the temperature of the circulating cold helium after exchanging heat with this unit will increase significantly. If it continues to flow through the downstream thermal management unit in the correct order, it will lead to a decrease in the quality of the downstream cold source, weakening the cooling capacity of the subsequent areas and thus amplifying the overall temperature gradient.

[0134] This step revolves around another core aspect of the invention: while maintaining the overall circulation structure, priority control is implemented for the export of high-temperature circulating cold helium gas from local hot spots. By quantitatively identifying the degree of high temperature at the outlet and the severity of the area, the circulating cold helium gas from each thermal management unit is diverted to the export path in a certain proportion, thereby effectively controlling the temperature of the circulating cold helium gas entering the downstream thermal management unit and achieving decoupling between the local working hot spots and the downstream area in terms of cold source quality.

[0135] To describe this step, let the first step be... Each thermal management unit at the sampling time The outlet circulating cold helium temperature is ;

[0136] This is the outlet temperature of the circulating cold helium gas after heat exchange with the corresponding superconducting coil region in this thermal management unit. The outlet temperature threshold is set based on the system's allowable upper limit for temperature recovery. and define the outlet temperature exceeding the limit. :

[0137] ;

[0138] when When the temperature of the circulating cold helium gas at the unit outlet does not exceed the threshold, it indicates that the temperature of the gas does not exceed the threshold. This indicates that there is a significant temperature rise in the outlet circulating cold helium gas in this unit.

[0139] To limit the total amount of circulating cold helium exported from the entire system and prevent excessive disturbance to the refrigeration circuit, this embodiment sets a ratio coefficient between the total exported mass flow rate and the total mass flow rate of the circulating cold helium. At the sampling time The corresponding total exported quality flow rate is:

[0140]

[0141] in, The value can be adjusted according to the system's regenerative capacity, pressure drop margin, and long-term energy consumption optimization requirements. Generally, the value is much less than 1, for example, 0.05~0.2.

[0142] Let the first Each thermal management unit at the sampling time The exported circulating cold helium mass flow rate is The mass flow rate of the circulating cold helium gas continuing to flow to the downstream thermal management unit is ,have:

[0143] ;

[0144] and satisfy

[0145] This embodiment employs a continuous derivation control strategy based on a weighted average of outlet temperature exceeding limits and regional severity, as detailed below:

[0146] Step 4.1: Derive priority coefficients and construct derived weights:

[0147] Considering the varying importance of different state regions in the derived control, this embodiment utilizes the state flag quantity obtained in step 2. (0 represents the normal zone, 1 represents the warning zone, and 2 represents the hotspot zone), and a priority coefficient for export is pre-set for each state type. Definition:

[0148] ;

[0149] in, , , where are the export priority coefficients for the warning zone and the hot spot zone, respectively. Since the normal zone thermal management unit does not have significant working hot spots and its outlet circulating cold helium temperature is generally low, this embodiment sets the export priority coefficient of the normal zone unit to 0, meaning it does not participate in export competition; the warning zone and hot spot zone units are assigned different positive coefficients according to their severity, giving the hot spot zone unit a higher weight in export allocation.

[0150] ;

[0151] in, For the first Each thermal management unit at the sampling time The derived weights; For the thermal management unit at the sampling time The outlet temperature exceeded the limit; For the state flag quantity of this unit The corresponding export priority coefficient is used to characterize the importance of the region (normal zone, warning zone, or hotspot zone) to which the unit belongs in export control. This relationship shows that the export weight increases with the degree of temperature exceedance at the unit's outlet and the level of its region (reflected by the priority coefficient).

[0152] When this unit is a normal area Or the outlet temperature did not exceed the limit When, derive the weights This indicates that the unit does not need to prioritize the export of high-temperature circulating cold helium. When the unit simultaneously meets the two conditions of (1) being in the warning zone or hot spot zone and (2) the outlet temperature exceeds the limit, the export weight increases together with the degree of outlet temperature exceeding the limit and the regional level, reflecting the priority of the unit with both high temperature and high risk in export control.

[0153] In order to distribute the exported mass flow rate among the various thermal management units, for Normalization is performed. When at least one thermal management unit satisfies... At that time, define the exported allocation weights. :

[0154] ;

[0155] Therefore, .

[0156] When all thermal management units meet When this occurs, it indicates that the current system does not have high-temperature circulating cold helium that needs to be prioritized for export. In this embodiment, it is set to... At this point, all circulating cold helium continues to flow downstream along the original path, with no output action.

[0157] Step 4.2 Exporting mass flow rate assignment and constraints:

[0158] There exists at least one derived weight In this case, assign weights based on the exported values. Export total mass flow rate Distribute the allocation. Each thermal management unit at the sampling time The exported mass flow rate is defined as:

[0159] ;

[0160] To avoid an excessively high export ratio from a single thermal management unit, which would result in almost no circulating cold helium downstream, this embodiment sets unit-level constraints on the export mass flow rate:

[0161] ;

[0162] in, This is the maximum derived scaling factor at the unit level. For example, it can be taken as... This indicates that the mass flow rate of circulating cold helium exported by a single thermal management unit at any given time does not exceed half of the total mass flow rate of that unit.

[0163] In actual implementation, when based on Calculated When the above upper limit is exceeded, it can be truncated, and the exported quantities of other units can be renormalized or kept unchanged as needed. In this case, the total exported mass flow rate may be slightly less than the limit. But still satisfied:

[0164] ;

[0165] For most engineering applications, the main purpose of the export ratio is to reduce the impact of high-temperature circulating cold helium gas from the hot spot outlet on the downstream, and it is not required to strictly use all the export capacity. Therefore, the above treatment method is acceptable in engineering.

[0166] After the mass flow rate is determined, the first The mass flow rate of the circulating cold helium gas continuing to flow downstream from each thermal management unit is:

[0167] ;

[0168] Through proper piping design and control valve arrangement, it is possible to The corresponding circulating cold helium is introduced into a reheating, recooling, or dedicated heat dissipation path to reduce its temperature before returning to the system, thereby avoiding crosstalk between downstream thermal management units caused by high-temperature circulating cold helium.

[0169] Step 4.3 ensures consistency between the exported control and the preceding and following steps:

[0170] In this embodiment, the export control is activated only when both the hotspot area and the warning area simultaneously meet the condition of exceeding the export temperature limit, and the export ratio is determined by the amount of the export temperature exceeding the limit. Regional Severity Coefficient This decision is made jointly. This design ensures that step 4 remains consistent with steps 1-3 in both physical meaning and control logic.

[0171] First, steps 1 and 2 are based on temperature deviation. With spatial gradient The combination of these factors constructs a comprehensive severity index reflecting the local thermal state. and status marker This provides a unified state description for subsequent adjustments.

[0172] Second, step 3 utilizes the comprehensive severity index. and threshold Constructing compensation weights The total mass flow rate of circulating cold helium is spatially tilted towards the warning zone and hot spot zone, so as to realize the centralized cooling capacity on demand.

[0173] Third, step 4, based on the mass flow rate allocation determined in step 3, introduces the outlet temperature exceeding the limit. With regional status To construct derived weights and exporting assigned weights Priority is given to exporting the circulating cold helium gas whose temperature rises significantly after exchanging heat with the hot spot, thus cutting off the channel for the high-temperature circulating cold helium gas to propagate downstream from the cold source side.

[0174] By first adjusting the flow rate and then guiding the high temperature, this invention, while keeping the total mass flow rate basically limited, improves the local heat exchange capacity of the hot spot area in step 3, thereby shortening the duration of the local working hot spot. On the other hand, it prioritizes the export of the high-temperature circulating cold helium gas from the hot spot area outlet in step 4, preventing it from raising the downstream inlet temperature, thus achieving the dual goals of eliminating local hot spots and controlling the overall temperature gradient.

[0175] In summary, the continuous export control method based on the weighting of outlet temperature exceeding the limit and regional severity, as described in step 4, forms a logical closed loop with the aforementioned steps: status monitoring and classification (steps 1 and 2) provide status information, cold energy priority scheduling (step 3) focuses on delivering cold energy to hot spots, and the priority export of high-temperature circulating cold helium gas at the outlet (step 4) focuses on removing heat from hot spots and isolating it from downstream areas. Together, these two methods support the rapid elimination of local working hot spots in the high-temperature superconducting rotor magnet and the long-term stability of the temperature field.

[0176] Step 5: Distribution recovery and temperature field stabilization maintenance after local hotspot elimination:

[0177] In steps 1 to 4, rapid identification and suppression of localized hot spots in the high-temperature superconducting rotor magnet were achieved through temperature state quantity calculation and state classification, basic allocation and severity compensation of circulating cold helium mass flow rate, and priority control of hot spot outlet high-temperature circulating cold helium. As the localized hot spots were weakened, the overall severity index of each thermal management unit increased. Gradually decrease, state flag quantity It also gradually recovers from the hotspot area and the warning area to the normal area. If the compensation ratio coefficient and the derived ratio coefficient are maintained for a long time after the hotspot has been basically eliminated, it will cause the circulating cold helium gas to continue to tilt excessively to the local area. The downstream area may experience local supercooling or new temperature gradients, which is not conducive to the long-term stability of the overall temperature field.

[0178] Therefore, the goal of this step is to smoothly restore the compensation ratio coefficient used in step 3 and the derived ratio coefficient used in step 4 after the local hot spot is effectively suppressed and the overall temperature gradient inside the rotor is restored to the allowable range, so that the system gradually returns from the hot spot suppression mode to the normal equilibrium mode, and maintains the uniformity of the internal temperature field of the high-temperature superconducting rotor magnet over a longer time scale.

[0179] Before providing a detailed description, for ease of expression, the compensation proportional coefficient in step 3 and the derived proportional coefficient in step 4 will be explicitly represented as quantities updated with the control cycle, and denoted as follows: and At each sampling time , and The mass flow rates involved in steps 3 and 4 can be considered constant within a control cycle, and are updated according to the rules of this step between different control cycles.

[0180] like Figure 6 As shown, in this embodiment, the overall temperature gradient constraint is used as the dominant quantity in the recovery process. The difference between the highest and lowest temperatures inside the high-temperature superconducting rotor magnet is used to characterize the smoothness of the overall temperature field, and this is used to drive the recovery process. and It converges smoothly towards the predetermined normal value.

[0181] Step 5.1 Definition and threshold setting of the overall temperature gradient:

[0182] According to the definition in step 1, the first Each thermal management unit at the sampling time The smoothing temperature is: ;

[0183] Based on this, the highest and lowest temperatures at the current moment are defined as follows:

[0184] ;

[0185] ;

[0186] From this, we can obtain the current overall temperature gradient (which can also be understood as the overall temperature difference):

[0187] ;

[0188] Based on the design requirements and engineering operation experience of high-temperature superconducting rotor magnets, an allowable upper limit is set for the overall temperature gradient. Based on this, two graded thresholds are introduced for the recovery process. and ,satisfy: .

[0189] in, This indicates an area where the overall temperature gradient is still relatively large, and at this point, it is necessary to continue to maintain strong compensation and derivation. This indicates that the overall temperature gradient has been restored to a relatively uniform level, and it is advisable to gradually reduce the compensation and derivation effects. When the situation falls between these two extremes, a transitional recovery strategy should be adopted.

[0190] Step 5.2 Setting the target values ​​for the compensation ratio coefficient and the derived ratio coefficient:

[0191] To achieve smooth recovery of the compensation and derived data, this embodiment uses a compensation ratio coefficient. and derived scaling factor Set upper and lower target values. Assume the upper limit of the compensation ratio coefficient used when there are significant local hot spots is [value missing]. The lower limit of the compensation ratio coefficient used during normal operation is ,satisfy:

[0192] ;

[0193] in, The compensation intensity corresponds to that in step 3 when dealing with strong hot spots. The compensation intensity under the normal equilibrium mode after hotspot elimination (can be zero or a small positive value).

[0194] Similarly, let the upper limit of the derived proportional coefficient when hotspots are significant be . The lower limit during normal operation is ,satisfy:

[0195] ;

[0196] in, This corresponds to the maximum export ratio used in step 4 for obvious hotspots. This corresponds to the basic level of cold helium gas extracted from the outlet high-temperature cycle during normal operation (which can be zero or a very small positive value to maintain a slight regenerative cycle).

[0197] Based on the current overall temperature gradient In this embodiment, the target value of the compensation ratio coefficient is constructed. for:

[0198] ;

[0199] That is, when the overall temperature gradient is large, the compensation ratio should be kept close to the average. When the overall temperature gradient has decreased to a low level, the target value of the compensation ratio coefficient is reduced to... In the intermediate region, linear interpolation is used to adjust the compensation intensity accordingly. The changes are continuous.

[0200] Derive the target value of the scaling factor Similar definitions are:

[0201] ;

[0202] It can be seen that, and Both are monotonic functions of the overall temperature gradient: the larger the overall temperature gradient, the higher the target compensation and derivation intensity; the smaller the overall temperature gradient, the lower the target compensation and derivation intensity.

[0203] Step 5.3 Smooth update of compensation scaling factor and derived scaling factor:

[0204] To avoid abrupt changes in the compensation proportional coefficient and the derived proportional coefficient between different control cycles, this embodiment... and A first-order smooth update method is used to gradually approach the corresponding target value. , Let the compensation ratio coefficient actually used in the current control cycle be... The derived scaling factor is Then the update rule for the next control cycle is:

[0205] ;

[0206] ;

[0207] in, , This is a recovery adjustment factor used to control the recovery speed. When... or When smaller, and The relatively slow response to changes in the target value is beneficial for maintaining the stability of the temperature field evolution; when local hotspots have been fully eliminated and a rapid return to normal operation is desired, the [temperature value] can be appropriately increased. and .

[0208] At each sampling time The updated result and This will be used in the calculation of each mass flow rate in steps 3 and 4 during the next control cycle, that is:

[0209] ;

[0210] ;

[0211] ;

[0212] Based on this, the circulating cold helium mass flow rate and the output mass flow rate of each thermal management unit are obtained by using the formulas in steps 3 and 4 above.

[0213] Through the above design, when local hotspots still exist and the overall temperature gradient remains... When it is large, and Approaching the upper limit and It maintains strong cooling compensation and high-temperature circulating cold helium extraction capabilities over several control cycles; as local hotspots are eliminated and the overall temperature gradient decreases, when Gradually falling into Even lower hour, and Gradually towards and Convergence, under the effect of first-order smooth update. and The temperature field gradually decreases smoothly, and the system gradually returns from the hotspot suppression mode to the normal equilibrium mode, avoiding new disturbances to the temperature field caused by the sudden withdrawal of the control strategy.

[0214] Through the overall temperature gradient constraint recovery control described in step 5, this invention ensures that local hot spots are effectively eliminated while closely linking the recovery process of the compensation proportional coefficient and the derived proportional coefficient with the temperature uniformity of the whole machine. This achieves unified adjustment from local control to the overall temperature field, enabling the high-temperature superconducting rotor magnet to maintain a small temperature gradient during long-term operation, reducing the risk of quenching and improving the safety and stability of operation.

[0215] This invention revolves around the core objective of prioritizing the elimination of local hot spots in high-temperature superconducting rotor magnets while taking into account overall temperature gradient control, under the condition that the total cooling capacity of circulating cold helium is basically limited. This results in a complete method chain from state perception to cold distribution, and then to heat removal and operating condition recovery.

[0216] Specifically, step 1 smooths the temperature of each thermal management unit, calculates the temperature deviation and spatial gradient, and constructs a state quantity that can reflect the local temperature level and spatial non-uniformity.

[0217] Step 2 introduces a comprehensive severity index to divide each thermal management unit into normal zone, early warning zone, and hot zone, providing a unified quantitative basis and status label for subsequent cooling capacity scheduling.

[0218] Step 3 uses the comprehensive severity index as the core control quantity. Under the premise of limited total mass flow rate of circulating cold helium, a distribution strategy of superimposed control of basic mass flow rate and severity compensation mass flow rate is adopted to achieve on-demand tilting of circulating cold helium in space: ensuring that all thermal management units have basic cooling capacity, and enabling the warning zone and hot spot zone to obtain more cooling capacity without increasing the total flow rate, thereby accelerating the cooling process of local working hot spots.

[0219] Step 4 further targets the high-temperature circulating cold helium gas after heat exchange with the hot spot. Combining the outlet temperature exceeding the limit and the severity of the area, through export weight allocation and unit export ratio constraints, some of the high-temperature circulating cold helium gas is preferentially exported to the regeneration or dedicated heat dissipation path, which significantly reduces the negative impact of the high temperature at the hot spot outlet on the quality of the downstream cold source and achieves effective decoupling between the local hot spot and the subsequent cooling section.

[0220] Building upon this, step 5 introduces the overall temperature gradient as a constraint on the recovery process, constructing a global temperature difference index based on the difference between the highest and lowest temperatures. Based on this, the compensation and derived proportional coefficients are target-set and smoothly updated. This allows the system to automatically and gradually return from a hotspot suppression mode (enhanced compensation and strong derivation) to a normal operating mode (basic equilibrium) after the local hotspots are eliminated and the overall temperature gradient returns to the allowable range. Through the synergistic effect of these five steps, this invention achieves rapid elimination of local hotspots in high-temperature superconducting rotor magnets and effective control of the internal temperature gradient without significantly increasing cooling power or structural complexity. This improves the safety and long-term stability of the high-temperature superconducting synchronous condenser rotor magnet.

Claims

1. A method of eliminating hot spots in a high temperature superconducting rotor magnet, comprising: The method comprises the following steps: Step 1: divide the cold helium circulation channel inside the high-temperature superconducting rotor magnet into multiple thermal management units, periodically collect temperature data of each thermal management unit, calculate temperature deviation of each thermal management unit relative to a target temperature and temperature gradient between adjacent units; Step 2: according to preset temperature threshold and temperature gradient threshold, classify each thermal management unit into a normal zone, a warning zone or a hot spot zone, and set a hysteresis interval to avoid frequent state switching; Step 3: based on the state classification result, establish a cold helium coldness priority scheduling rule, set the coldness priority of the hot spot zone as the highest, the coldness priority of the warning zone as the second, and the coldness priority of the normal zone as the lowest, under the premise that the total mass flow of the circulating cold helium remains basically unchanged, adjust the cold helium flow of each thermal management unit by setting a compensation proportion coefficient, so that the cold helium flow of the hot spot zone is increased to exceed the flow in the normal operating state, the cold helium flow of the warning zone is moderately increased, and the cold helium flow of the normal zone is correspondingly reduced; Step 4: monitor the cold helium temperature at the outlet of each thermal management unit, when the outlet cold helium temperature of the hot spot zone or the warning zone exceeds the export threshold, according to the export proportion coefficient, the high-temperature cold helium of the unit is preferentially exported to the circulation system or introduced into a special heat dissipation branch through an export branch, so as to reduce the proportion of the cold helium flowing into the downstream thermal management unit; Step 5: when the temperature and temperature gradient of the thermal management unit of the hot spot zone recover to the range of the warning zone or the normal zone, based on the overall temperature gradient, the compensation proportion coefficient in step 3 and the export proportion coefficient in step 4 are smoothly recovered, so that the system gradually returns to the normal balanced mode from the hot spot suppression mode.

2. A method of eliminating local hot spots in a high temperature superconducting rotor magnet according to claim 1, wherein, In step 1, the collected temperature data is first-order smoothed, and the current sampling value and the historical smoothed value are combined to obtain a smoothed temperature, which is used to calculate the temperature deviation and the temperature gradient.

3. A method of eliminating hot spots in a high temperature superconducting rotor magnet according to claim 1, wherein In step 2, a comprehensive severity index is constructed, the positive part of the temperature deviation and the absolute value of the spatial gradient are respectively dimensionless processed and then weighted and summed to form a scalar index for state classification.

4. A method of eliminating hot spots in a high temperature superconducting rotor magnet according to claim 1, wherein In step 3, the total mass flow is divided into a basic mass flow and a compensation mass flow, the basic mass flow is distributed according to the structure weight coefficient of each thermal management unit, and the compensation mass flow is normalized distributed according to the degree that the comprehensive severity index exceeds the normal zone exit threshold.

5. A method of eliminating local hot spots in a high temperature superconducting rotor magnet according to claim 4, wherein, In step 3, a flow adjustment coefficient is used to smoothly update the target mass flow, so that the actual mass flow gradually approaches the target value, avoiding flow mutation.

6. A method of eliminating local hot spots in a high temperature superconducting rotor magnet according to claim 1, wherein In step 4, according to the region state marker quantity and the outlet temperature overrun quantity of the thermal management unit, an export weight is constructed, the export priority coefficient of the hot spot zone is higher than that of the warning zone, and the export priority coefficient of the normal zone is zero.

7. A method of eliminating local hot spots in a high temperature superconducting rotor magnet according to claim 6, wherein In step 4, a maximum export proportion coefficient is set at the unit level, so that the export mass flow of a single thermal management unit does not exceed half of the total mass flow.

8. A method of eliminating local hot spots in a high temperature superconducting rotor magnet according to claim 1, wherein In step 5, the difference between the highest temperature and the lowest temperature in all thermal management units is taken as the overall temperature gradient, and an allowed upper limit of the overall temperature gradient and two classification thresholds are set, which are used to drive the recovery process of the compensation proportion coefficient and the export proportion coefficient.

9. A method of eliminating local hot spots in a high temperature superconducting rotor magnet according to claim 1, wherein In step 5, the first-order smoothing update method is used to make the compensation proportional coefficient and the derived proportional coefficient gradually approach the target value determined by the overall temperature gradient, so as to avoid temperature field disturbance caused by sudden withdrawal of the control strategy.

10. A method of eliminating local hot spots in a high temperature superconducting rotor magnet according to claim 1, wherein The application is suitable for high-temperature superconducting rotor magnets cooled by circulating cold helium.

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