Temperature monitoring system and over-temperature protection method suitable for fusion reactor low-clutter system

Abstract

The invention discloses a temperature monitoring system suitable for a fusion reactor low-clutter system and an over-temperature protection method. The temperature monitoring system comprises a high-speed temperature acquisition unit, a thermocouple sensor, an industrial control upper computer and a database server. A microwave excitation signal of the microwave excitation source is amplified by the microwave source klystron and then transmitted to the low-clutter coupled antenna through the microwave transmission line, and a plurality of temperature measuring points are arranged on the waveguide surface of the microwave transmission line and the end face of the low-clutter coupled antenna. Measurement output ends of the thermocouple sensors are uniformly accessed and gathered into the high-speed temperature acquisition unit and are uploaded to the industrial control upper computer, and the industrial control upper computer records and stores acquired multi-channel real-time temperature data, control signal output values and alarm events into the database server. The method has the advantages that early warning and temperature regulation are carried out for potential thermal runaway faults, so that the equipment safety of a high-power microwave transmission device and the normal operation of a low-clutter current driving system are guaranteed.

Description

Technical Field

[0001] This invention relates to the fields of thermal monitoring and high-power microwaves, specifically to a temperature monitoring system and over-temperature protection method applicable to low-hybrid microwave systems in fusion reactors. Background Technology

[0002] In fully superconducting tokamak nuclear fusion experimental devices, the core of physics experiments lies in the optimization and confinement of plasma. Low-hybrid current drive (LHCD) is one of the important methods for plasma-assisted heating. It consists of a klystron used as a microwave source, a microwave transmission line, and a coupling antenna. A single branch can have a maximum power of 500 kW, a frequency of 4.6 GHz, and a maximum operating pulse width >1000 s. High-power microwaves experience energy loss when passing through the microwave transmission line and coupling antenna. This energy is converted into heat, causing a certain temperature to accumulate on the transmission line waveguide. Excessive waveguide temperature leads to increased reflected power and a higher risk of arcing. Furthermore, to improve coupling efficiency, the low-hybrid antenna is generally located close to the plasma. The antenna end face is directly subjected to the thermal radiation impact of the high-temperature plasma, and excessively high temperatures can easily cause the antenna end face to soften, deform, or even melt.

[0003] Temperature measurement can be divided into two methods: contact measurement and non-contact measurement. Non-contact measurement methods can measure the surface temperature of the object without direct contact, such as infrared thermometers and infrared thermal imagers. However, due to limitations imposed by the strong electromagnetic environment and space constraints near low-spurious transmission lines and antenna ports, non-contact sensors that require contact with the object surface are no longer suitable. Contact measurement, on the other hand, measures temperature by direct contact with the object surface. For temperature measurement in high-temperature environments, thermocouple sensors are used. These sensors utilize the thermoelectric potential difference generated by different metals or alloys at different temperatures to measure temperature. They are a common and cost-effective temperature sensor that can provide reliable measurements over a wide temperature range. For example, a thermal protection method for a low-spurious antenna disclosed in Chinese Patent Publication No. CN106684521A uses thermocouples to measure the temperature of the low-spurious antenna.

[0004] Existing temperature measuring instruments are mostly scanning inspection instruments or dedicated PLC modules for temperature measurement, which suffer from slow scanning speeds and poor data storage. During experiments, real-time temperature changes need to be stored in a database server for access by other devices. Furthermore, considering the strong electromagnetic environment near the equipment, temperature measuring instruments require electromagnetic shielding capabilities, which traditional instruments cannot meet. In addition, current methods for high-power microwave systems do not effectively combine waveguide transmission line and antenna end-face temperatures for system-level temperature feedback control. Existing temperature feedback control methods often employ simple fixed threshold control strategies, failing to fully consider the differences in material properties at different temperature measurement points, the dynamic characteristics of temperature changes, and the time lag between microwave power and temperature response, resulting in poor control performance. Simultaneously, high-frequency sampling data storage and thermal accumulation effect assessment under long-pulse operation conditions are also urgent problems to be solved.

[0005] Therefore, it is necessary to establish a high-speed temperature monitoring system and over-temperature protection method suitable for low-hybrid wave systems in fusion reactors. This system should be able to monitor the transmission line waveguide surface temperature and antenna end face temperature in real time and accurately, detect abnormal high temperature conditions and locate over-temperature points, provide early warning and temperature control for potential thermal runaway faults, and ensure the equipment safety of high-power microwave transmission devices and the normal operation of the low-hybrid wave current drive system. Summary of the Invention

[0006] The technical problem to be solved by this invention is that the existing technology lacks a system-level temperature feedback control method that effectively combines the waveguide transmission line and antenna end face temperature for high-power microwave systems. It is impossible to monitor the transmission line waveguide surface temperature and antenna end face temperature in real time and accurately, detect abnormal high temperature conditions, and locate over-temperature points.

[0007] This invention solves the above-mentioned technical problems through the following technical means: a temperature monitoring system applicable to low-hybrid wave systems in fusion reactors, comprising a high-speed temperature acquisition unit, thermocouple sensors, an industrial control host computer, and a database server; the microwave excitation signal from the microwave excitation source is amplified by the microwave source klystron and transmitted to the low-hybrid wave coupling antenna via a microwave transmission line; multiple temperature measuring points are set on the waveguide surface of the microwave transmission line and the end face of the low-hybrid wave coupling antenna; a thermocouple sensor is arranged at each temperature measuring point; the measurement output terminals of the thermocouple sensors are uniformly connected to and aggregated in the high-speed temperature acquisition unit and uploaded to the industrial control host computer; the industrial control host computer outputs control signals according to the received temperature data to adjust the output of the microwave excitation source, controls the temperature in real time, and stores the acquired multi-channel real-time temperature data, control signal output values, and alarm event records in the database server.

[0008] This invention provides multiple temperature measurement points on the waveguide surface of the microwave transmission line and the end face of the low-hybridity coupled antenna. The industrial control host computer outputs control signals based on the received temperature data to adjust the output of the microwave excitation source and control the temperature in real time. This effectively combines the waveguide transmission line and antenna end face temperatures for system-level temperature feedback control in high-power microwave systems. It can monitor the waveguide surface temperature and antenna end face temperature in real time and accurately, detect abnormal high temperature conditions and locate over-temperature points, and provide early warning and temperature regulation for potential thermal runaway faults to ensure the equipment safety of high-power microwave transmission devices and the normal operation of the low-hybridity current drive system.

[0009] Furthermore, the high-speed temperature acquisition unit is housed within an electromagnetic shielding enclosure. The enclosure employs an aluminum alloy frame structure. The enclosure panel features multiple K-type thermocouple sockets, a 220V power input socket, an Ethernet communication interface, and a power switch. Inside the enclosure, an NI-9214 thermocouple input module and a cDAQ-9181 sensor measurement slave unit are also installed. These are connected via slots. Signal lines from the 16 K-type thermocouple sockets are connected to the terminals of the thermocouple input module. The thermocouple input module is connected to the slot of the sensor measurement slave unit. The power input of the sensor measurement slave unit is connected to the 220V power input socket on the electromagnetic shielding enclosure. The entire unit is controlled by the power switch. The communication side of the sensor measurement slave unit communicates with an external industrial control host computer via an Ethernet communication interface.

[0010] The present invention also provides an over-temperature protection method for a temperature monitoring system applicable to a fusion reactor low hybrid wave system, comprising: S1. In the discharge experiment of the tokamak device, the high-speed temperature acquisition unit continuously acquires multiple temperature signals from the surface of the microwave transmission line waveguide of the low clutter system and the antenna end face of the low clutter coupling antenna at a set sampling frequency. The acquired raw signals are processed by the multi-level anti-interference signal processing algorithm module in the industrial control host computer for median filtering, anomaly detection and physical constraint verification to obtain the current temperature value T(t) of each temperature measurement point. S2. For the preprocessed current temperature value T(t), the sliding window linear fitting method is used to calculate the real-time temperature rise rate of each temperature measurement point; based on the current temperature value T(t) and the temperature rise rate dT / dt, the temperature value T_predict is predicted after time Δt1. S3. Set the reference warning temperature T1_base and reference alarm temperature T2_base for each temperature measurement point; dynamically correct the reference thresholds according to the plasma parameters and microwave power settings of the current experiment to obtain the first dynamic threshold T1 = T1_base × α and the second dynamic threshold T2 = T2_base × α, where α is the power correction coefficient. S4. Based on the current temperature value T(t), the predicted temperature T_predict, the first dynamic threshold T1, and the second dynamic threshold T2, execute a hierarchical temperature control strategy; S5. The industrial control host computer writes the collected multi-channel real-time temperature data, control signal output values, and alarm event records into the database server in real time; the database server evaluates the thermal accumulation effect of each temperature measurement point based on the stored historical temperature data. When the thermal accumulation factor exceeds the set accumulation threshold, it outputs component thermal fatigue warning information to prompt the operation and maintenance personnel to arrange inspections and maintenance.

[0011] Furthermore, the multi-level anti-interference signal processing algorithm module includes a median filtering layer, a sliding window anomaly detection layer, and a physical constraint verification layer. The median filtering layer processes the original sampling sequence using a median filter with a window length of 5; the sliding window anomaly detection layer takes N sampling points before and after the current sampling point as the center to form a detection window, calculates the mean μ and standard deviation σ of the data within the detection window. If the absolute value of the difference between the current sampling value and the mean exceeds kσ, where k represents the multiple threshold, it is determined as an outlier and replaced with the mean of the detection window; the physical constraint verification layer is used to constrain the temperature change amount between two adjacent valid sampling values not to exceed the product of the preset maximum allowable change rate ΔTmax and the sampling period Δt. If it exceeds, the current sampling value is determined as an interference outlier and corrected with the superposition value of the previous valid value and the maximum allowable change amount.

[0012] Even further, the correction with the superposition value of the previous valid value and the maximum allowable change amount includes: Let the previous valid temperature value be T_valid, the current value be y(i). If |y(i) - T_valid| > ΔTmax × Δt, then let y(i) = T_valid + sign(y(i) - T_valid) × ΔTmax × Δt.

[0013] Furthermore, the S2 includes: Take the temperature values and time values of the M sampling points before the current moment for least squares linear fitting. The slope of the fitted line is the current temperature rise rate dT / dt. Based on the current temperature value T(t) and the temperature rise rate dT / dt, predict the temperature value T_predict = T(t) + (dT / dt) × Δt1 after Δt1 time.

[0014] Furthermore, the S4 includes: The first-level preventive adjustment: When T_predict ≥ T1 and T(t) < T1, it is determined as a temperature rise trend warning state. The system reduces the output power of the microwave excitation source with a power adjustment step size of ΔP1, and the adjustment period is 10s; Second-level adaptive PID regulation: When T(t) ≥ T1 and T(t) < T2, it is determined as the over-temperature warning state, and the adaptive PID controller is started to adjust the output power of the microwave excitation source; the control law of the adaptive PID controller is: u(t) = Kp(t)·e(t) + Ki(t)·∫e(t)dt + Kd(t)·de(t) / dt where e(t) = T(t) - T_target is the temperature deviation, and T_target is the target temperature set value; Kp(t), Ki(t), and Kd(t) are the PID parameters adjusted adaptively; the inputs of the adaptive PID controller are the target temperature set value T_target and the current temperature T(t), and the output u(t) of the adaptive PID controller is converted into the power set value of the microwave excitation source after amplitude limiting and rate limiting; Third-level emergency shutdown protection: When T(t) ≥ T2 or the temperature rise rate dT / dt exceeds the emergency rate threshold, it is determined as the over-temperature alarm state, and the system immediately outputs a shutdown signal to the microwave excitation source to terminate the current discharge experiment process, and at the same time records the over-temperature event information.

[0015] Furthermore, the power adjustment step size ΔP1 = 0.03×Prated, where Prated represents the rated power, and the value range of the target temperature set value is 0.8×T1 to 0.9×T1.

[0016] Further, the evaluation of the thermal accumulation effect for each temperature measurement point includes: For each temperature measurement point, the system calculates the thermal accumulation increment ΔHF within this period with a period of 1 minute, , where is the reference temperature of the component material corresponding to this temperature measurement point under normal operating conditions, is the measured temperature value at time , t is the calculation period of the thermal accumulation increment, represents the temperature value at the i-th sampling moment, is the sampling period, and n is the total number of sampling points; the thermal accumulation increments of all temperature measurement points are added up to obtain the thermal accumulation factor HF of each temperature measurement point within the set time window. When HF > 0.8×HF_th, the system outputs a thermal fatigue warning message to prompt for inspection; when HF > HF_th, the system outputs a thermal fatigue alarm message to require arranging maintenance and replacement. HF_th represents the set accumulation threshold; the accumulation threshold is determined according to the thermal fatigue characteristics and design life of the component material. The accumulation threshold of the copper waveguide of the microwave transmission line is set to 1×10 7 ℃·s, and the accumulation threshold of the stainless steel material of the antenna end face of the LHCD antenna is set to 5×10 7 ℃·s.

[0017] Furthermore, the sampling frequency of the industrial control host computer is dynamically adjusted according to the temperature change characteristics. The sampling modes are divided into low-frequency sampling mode and high-frequency sampling mode. The sampling frequency of the low-frequency sampling mode is set to 10 S / s, and the sampling frequency of the high-frequency sampling mode is set to 68 S / s. The sampling mode switching criterion is: When the temperature rise rate dT / dt of any channel exceeds the rate switching threshold R_th or the current temperature value exceeds 80% of the first dynamic threshold T1, the system automatically switches from low-frequency sampling mode to high-frequency sampling mode; when the temperature rise rate is continuously lower than the rate switching threshold R_th and the current temperature value is lower than 70% of the first dynamic threshold T1 for a duration exceeding the set stability judgment time T_stable, the system automatically switches back to low-frequency sampling mode.

[0018] The advantages of this invention are: (1) Multiple temperature measurement points are set on the waveguide surface of the microwave transmission line and the end face of the low-hybrid wave coupling antenna of the present invention. The industrial control host computer outputs control signals to adjust the output of the microwave excitation source according to the received temperature data, and controls the temperature in real time. Thus, the system-level temperature feedback control is effectively combined with the waveguide transmission line and antenna end face temperature for high-power microwave systems. The temperature of the waveguide surface of the transmission line and the antenna end face is monitored in real time and accurately. Abnormal high temperature conditions are detected and over-temperature points are located. Early warning and temperature regulation are provided for potential thermal runaway faults to ensure the equipment safety of high-power microwave transmission devices and the normal operation of the low-hybrid wave current drive system.

[0019] (2) The present invention uses NI cDAQ-9181 and NI-9214 thermocouple acquisition modules with high sampling rate and 24-bit ADC precision to realize high-speed synchronous acquisition of multiple temperature signals, which can capture the rapid temperature rise process in the thermal shock environment of low noise system. Compared with traditional scanning inspection instrument, it greatly improves the sampling rate and measurement accuracy.

[0020] (3) This invention proposes a multi-level anti-interference signal processing algorithm at the software level, which includes median filtering, sliding window anomaly detection and physical constraint verification, and realizes reliable acquisition and accurate measurement of thermocouple signals in high-power microwave environment.

[0021] (4) The present invention proposes an adaptive frequency conversion sampling control method, which dynamically adjusts the sampling frequency according to the temperature change characteristics. While ensuring the acquisition accuracy of key temperature change processes, it effectively reduces the system data throughput and storage burden, and is particularly suitable for the large-capacity data management needs of long pulse experiments.

[0022] (5) This invention proposes an adaptive graded temperature control strategy based on the prediction of temperature rise rate. It achieves preventive power regulation by predicting future temperature change trends and uses a PID controller with online adaptive parameter adjustment to achieve precise temperature closed-loop control. Compared with the traditional fixed threshold control method, it has better control effect and higher safety margin.

[0023] (6) This invention proposes a thermal accumulation effect assessment method and a discharge timing collaborative monitoring strategy, which realizes long-term tracking and assessment of the thermal fatigue state of equipment and collaborative cooperation with the tokamak discharge experiment process, providing effective support for equipment operation and maintenance management and experimental safety assurance.

[0024] (7) The present invention uses a small thermocouple plug and a 16-channel quick-change interface design to make the number and position of temperature measurement points flexibly adjustable according to experimental needs, while avoiding the complex wiring of traditional terminals, which facilitates equipment maintenance, test point expansion and long-term operation management. Attached Figure Description

[0025] Figure 1 This is a block diagram illustrating the working principle of a temperature monitoring system applicable to a low hybrid wave system in a fusion reactor, as disclosed in an embodiment of the present invention. Figure 2 This is an isometric schematic diagram of a high-speed temperature acquisition unit in a temperature monitoring system applicable to a low hybrid wave system of a fusion reactor, as disclosed in an embodiment of the present invention. Figure 3 This is a front view of a high-speed temperature acquisition unit in a temperature monitoring system applicable to a low hybrid wave system of a fusion reactor, as disclosed in an embodiment of the present invention. Figure 4 This is a schematic diagram of the back of a high-speed temperature acquisition unit in a temperature monitoring system applicable to a low hybrid wave system of a fusion reactor, as disclosed in an embodiment of the present invention. Figure 5 This is a flowchart of temperature monitoring and over-temperature protection in a temperature monitoring system applicable to a low hybrid wave system of a fusion reactor, as disclosed in an embodiment of the present invention. Figure 6 This is a flowchart of a multi-level anti-interference signal processing algorithm in a temperature monitoring system applicable to a low hybrid wave system of a fusion reactor, as disclosed in an embodiment of the present invention. Figure 7 This is a state transition diagram of a graded temperature control strategy in a temperature monitoring system applicable to a low hybrid wave system of a fusion reactor, as disclosed in an embodiment of the present invention. Figure 8 This is an adaptive frequency conversion sampling control logic diagram of a temperature monitoring system applicable to a low hybrid wave system of a fusion reactor, as disclosed in an embodiment of the present invention. Detailed Implementation

[0026] 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 in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0027] like Figure 1 As shown, this embodiment of the invention provides a high-speed temperature monitoring system and over-temperature protection method applicable to low-hybrid wave systems in fusion reactors. The high-speed temperature monitoring system mainly includes a high-speed temperature acquisition unit 6, a K-type thermocouple sensor 8, an industrial control host computer 3, and a database server 5. The microwave excitation signal from the microwave excitation source 1 is amplified by the microwave klystron 2 and then transmitted to the low-hybrid wave coupling antenna 7 via the microwave transmission line 4. The K-type thermocouple sensor 8 is arranged on the waveguide surface of the transmission line and the end face of the low-hybrid wave antenna. The measurement output terminals of the K-type thermocouple sensor 8 are uniformly connected to and aggregated in the high-speed temperature acquisition unit 6. The 16 channels of temperature measurement data acquired by the high-speed temperature acquisition unit 6 are uploaded to the industrial control host computer 3. The industrial control host computer 3 is responsible for receiving temperature data, executing multi-level anti-interference signal processing algorithms, and storing the data in the database server 5. When an excessively high temperature is detected, an adaptive graded temperature control strategy based on temperature rise rate prediction adjusts the signal output of the microwave excitation source 1 through feedback control.

[0028] like Figures 2 to 4 As shown, in this embodiment of the invention, the high-speed temperature acquisition unit 6 is placed inside an electromagnetic shielded enclosure 61. The electromagnetic shielded enclosure 61 has a panel equipped with 16 K-type thermocouple sockets 64, a 220V power input socket 66, an Ethernet communication interface 65, and a power switch 67. The electromagnetic shielded enclosure 61 also houses an NI-9214 type thermocouple input module 62 and a cDAQ-9181 type sensor measurement slave unit 63, which are connected via standard slots to form a complete high-speed temperature acquisition hardware platform.

[0029] The electromagnetic shielding enclosure 61 is made of aluminum alloy and has a 1U rack-mount structure. It has good electromagnetic shielding and vibration resistance capabilities and can be easily installed in the equipment field cabinet. The signal lines from the 16-channel K-type thermocouple socket 64 are connected to the terminals of the thermocouple input module 62. The thermocouple input module 62, model NI-9214, is a high-density thermocouple input module with a built-in automatic zeroing channel for offset error compensation. The thermocouple input module 62 is connected to the slot of the sensor measurement slave computer 63, forming a slave computer system for temperature measurement. The sensor measurement slave computer 63, model cDAQ-9181, is an Ethernet chassis designed for small or distributed sensor measurement systems, supporting a total sampling rate of 68 S / s and 24-bit ADC sampling accuracy, enabling it to capture more accurate temperature changes. The power input terminal of the sensor measurement slave computer 63 is connected to the 220V power input socket 66 on the electromagnetic shielding chassis, and the whole system is controlled by the power switch 67 to receive external power. On the communication side, data communication with the external industrial control host computer 3 is achieved by connecting the Ethernet interface on the sensor measurement slave computer 63 to the Ethernet communication interface 65 on the electromagnetic shielding chassis. The K-type thermocouple sensor 8 uses a small connector plug for its measurement output end, which matches the 16-channel K-type thermocouple socket 64 on the high-speed temperature acquisition unit. Its easy plugging and unplugging feature eliminates the cumbersome operation of traditional wiring terminals, and the number and position of channels can be adjusted at any time according to the system's temperature measurement point requirements. The K-type thermocouple sensor 8 has two types of probes: patch probes and armored probes. The patch probes are arranged on the surface of the transmission line waveguide and can perform point monitoring of high-temperature transmission devices such as ceramic windows, power combiners, arc detection windows, and flexible waveguides on microwave transmission lines, and can quickly respond to surface temperature changes. The armored probe is arranged on the antenna end face in the vacuum chamber of the low-clutter antenna by vacuum brazing. Its wires are protected in a stainless steel metal jacket, which provides physical protection for the wires and prevents damage to the wires from the external environment. At the same time, it can also improve the mechanical strength of the thermocouple. This allows it to adapt to the internal structure of the low-clutter antenna to a certain degree of bending and compression. It has excellent mechanical strength and radiation resistance and can adapt to the bending path and limited space inside the antenna. The probe lead of the K-type thermocouple sensor 8 is wrapped with stainless steel shielded mesh wire, which effectively suppresses electromagnetic interference under high-power microwave radiation and provides good electromagnetic shielding performance.

[0030] In this embodiment of the invention, the industrial control host computer 3 uses an NI PXIe-8840 embedded controller. It maintains real-time data communication with the sensor measurement slave computer 63 of the high-speed temperature acquisition unit 6 via Ethernet to receive multiple channels of temperature data. The industrial control host computer 3 is responsible for receiving and parsing 16 channels of temperature data, displaying the temperature curve in real-time on a visual interface, writing the data to the database server 5, and performing over-temperature feedback control based on threshold judgment. Furthermore, the industrial control host computer 3 has a built-in NI-6259 acquisition card, which can output analog voltage signals to control the output power of the microwave excitation source 1, achieving closed-loop temperature regulation.

[0031] Database server 5 is a WR3220 G2 rack server running Ubuntu 22.04.5 LTS and configured with the timescaleDB time-series database, enabling efficient access to multiple temperature data streams. The server is equipped with two 960GB SSDs and six 24TB HDDs, allowing for long-term storage of high-frequency, high-capacity temperature data generated during experiments, providing a data foundation for experimental analysis, equipment operation status evaluation, and historical temperature tracing.

[0032] like Figure 5 As shown, the over-temperature protection method of the present invention is applicable to the low hybrid discharge experimental operation of a tokamak device, and includes the following steps: S1. Real-time temperature data acquisition and preprocessing: In the discharge experiment of the tokamak device, the high-speed temperature acquisition unit 6 continuously acquires multiple temperature signals from the waveguide surface of the microwave transmission line 4 of the low-spurious wave system and the antenna end face of the low-spurious coupling antenna 7 at a set sampling frequency. The acquired raw signals are processed by the multi-level anti-interference signal processing algorithm module in the industrial control host computer 3 for median filtering, anomaly detection and physical constraint verification to obtain reliable temperature values ​​T(t) at each temperature measurement point. like Figure 6As shown, the multi-level anti-interference signal processing algorithm module in this embodiment includes a median filtering layer, a sliding window anomaly detection layer, and a physical constraint verification layer. The median filtering layer uses a median filter with a window length of 5 to process the original sampling sequence, removing isolated impulse noise interference points while maintaining the step change characteristics of the temperature signal. The sliding window anomaly detection layer uses a sliding window detection method based on the improved 3σ criterion, specifically: taking the current sampling point as the center, taking N sampling points before and after to form a detection window, calculating the mean μ and standard deviation σ of the data within the window, if the absolute value of the difference between the current sampling value and the mean exceeds... kσ, where k represents a multiple threshold, is considered an outlier and replaced with a window mean. N ranges from 10 to 50, and k ranges from 2.5 to 3.5, adaptively adjusted according to the actual interference environment. The physical constraint verification layer sets temperature change rate constraints based on the physical characteristics of thermocouple temperature measurement. Specifically, the temperature change between two adjacent valid sample values ​​does not exceed the product of the preset maximum allowable change rate ΔTmax and the sampling period Δt. If it exceeds this limit, the current sample value is determined to be an interference outlier, corrected by the sum of the previous valid value and the maximum allowable change rate. The specific implementation process is as follows: S11: Input the original temperature sampling sequence. Let the current sampling sequence be {x(1), x(2), ..., x(n)}.

[0033] S12: Median filtering. For each sampling point x(i) in the sequence, take the two points before and after it to form a window {x(i-2), x(i-1), x(i), x(i+1), x(i+2)}. Sort the five values ​​in the window and take the median as the filtered output y(i).

[0034] S13: Sliding window anomaly detection. Take parameters N=20 and k=3. For each point y(i) in the filtered sequence, calculate the mean μ and standard deviation σ of the window {y(iN), ..., y(i-1), y(i+1), ..., y(i+N)} in which it is located. If |y(i)-μ|>kσ, then replace y(i) with the mean μ.

[0035] S14: Physical constraint verification. Let the previous valid temperature value be T_valid and the current value be y(i). If |y(i)-T_valid|>ΔTmax×Δt, where Δt is the sampling period and Tmax is the preset maximum allowable rate of change, then let y(i)=T_valid+sign(y(i)-T_valid)×ΔTmax×Δt.

[0036] S2. Calculation of temperature rise rate and temperature prediction: For the preprocessed temperature data, the sliding window linear fitting method is used to calculate the real-time temperature rise rate of each temperature measurement point. Specifically, the temperature values and time values of the M sampling points before the current moment are taken for least squares linear fitting, and the slope of the fitting line is the current temperature rise rate dT / dt, where the value range of M is 5 - 20; Based on the current temperature value T(t) and the temperature rise rate dT / dt, predict the temperature value after Δt1 time: T_predict = T(t) + (dT / dt) × Δt1, and the prediction time Δt1 is set to 10 - 30 s according to the system thermal inertia characteristics; S3. Dynamic threshold calculation: According to the material characteristics, installation positions and historical operation data of the components where each temperature measurement point is located, the reference warning temperature T1_base and the reference alarm temperature T2_base of each temperature measurement point are set respectively; According to the plasma parameters and the set value of microwave power of the current experiment, the reference thresholds are dynamically corrected to obtain the first dynamic threshold T1 = T1_base × α, and the second dynamic threshold T2 = T2_base × α, where α is the power correction coefficient, and the value range is 0.8 - 1.2. When operating at high power, α takes a smaller value to improve the safety margin; S4. Execution of hierarchical temperature control strategy: Based on the current temperature T(t) obtained in step S1, the predicted temperature T_predict obtained in step S2, and the first dynamic threshold T1 and the second dynamic threshold T2 obtained in step S3, execute the following hierarchical temperature control strategy: The first-level preventive adjustment: When the predicted temperature T_predict≥T1 and the current temperature T(t)<T1, it is determined as the temperature rise trend warning state, and the system starts to slowly reduce the output power of the microwave excitation source 1 with a small power adjustment step ΔP1. The adjustment period is 10 s, and the power adjustment step ΔP1 is set to 2% - 5% of the rated power; The second-level adaptive PID adjustment: When the current temperature T(t)≥T1 and T(t)<T2, it is determined as the over-temperature warning state, and the adaptive PID controller is started to adjust the output power of the microwave excitation source 1; The control law of the adaptive PID controller is: u(t) = Kp(t)·e(t) + Ki(t)·∫e(t)dt + Kd(t)·de(t) / dt Among them, e(t) = T(t) - T_target is the temperature deviation, where T_target is the target temperature set value, set to 0.9×T1; Kp(t), Ki(t), Kd(t) are the PID parameters adjusted adaptively, which are adjusted online according to the magnitude and change trend of the temperature deviation: when the temperature deviation is large, Kp is increased to accelerate the response speed, when the temperature deviation is small and stable, Ki is increased to eliminate the steady-state error, and when the temperature changes violently, Kd is increased to suppress overshoot; the input of the PID controller is the target temperature set value T_target and the current temperature T(t), and the output u(t) of the PID controller is converted into the power set value of the microwave excitation source 1 after amplitude limiting and rate limiting. The control period is set to 20s to match the system's thermal response time constant; The third-level emergency shutdown protection: when the current temperature T(t) ≥ T2 or the temperature rise rate dT / dt exceeds the emergency rate threshold Remergency, it is determined as the over-temperature alarm state. The system immediately outputs a shutdown signal to the microwave excitation source 1 to terminate the current discharge experiment process. At the same time, the over-temperature event information including the over-temperature temperature measurement point number, over-temperature time, triggered temperature value, and temperature rise rate value is recorded for post-event analysis and system optimization; As Figure 7 shown, the state transition logic of the hierarchical temperature control strategy in the embodiment of the present invention is as follows: After the system is powered on, it enters the normal monitoring state Sate0. The temperatures of each temperature measurement point are within the safe range, and the microwave excitation source 1 outputs normally according to the set power.

[0037] When it is detected that the predicted temperature T_predict of any temperature measurement point ≥ T1 and the current temperature T(t) < T1, the system transfers to the preventive adjustment state Sate1. At this time, the output power of the microwave excitation source is reduced by ΔP1 = 0.03×Prated (3% of the rated power) every 10s until the predicted temperature drops below T1 and then returns to the Sate0 state. Prated represents the rated power.

[0038] When it is detected that the current temperature T(t) of any temperature measurement point ≥ T1 and T(t) < T2, the system transfers to the PID adjustment state Sate2, and the adaptive PID controller starts to work. The control target is to stabilize the temperature of the highest temperature measurement point near 0.9×T1. The PID parameter adaptive rule is: the initial parameters Kp0 = 2.0, Ki0 = 0.1, Kd0 = 0.5; when |e(t)| > 10℃, Kp = 1.5×Kp0; when |e(t)| < 2℃ and lasts for 5 control cycles, Ki = 1.5×Ki0; when |de / dt| > 1℃ / s, Kd = 2.0×Kd0. When the temperature drops below 0.9×T1 and lasts for 60s, the system returns to the Sate0 state.

[0039] When the current temperature T(t) of any temperature measuring point is detected to be ≥ T2 or the temperature rise rate dT / dt > 10℃ / s, the system enters the emergency shutdown state Sate3, immediately outputs a shutdown signal to terminate the microwave excitation source output and records the alarm event. It can only return to the Sate0 state after manual confirmation and reset.

[0040] S5. Data Storage and Thermal Accumulation Assessment: The temperature change curves, temperature rise rate curves, and control status information of each temperature measuring point are displayed in real time on the human-machine interface of the industrial control host computer 3. The collected multi-channel real-time temperature data, control signal output values, and alarm event records are written to the database server 5 in real time. Based on the stored historical temperature data, the thermal accumulation effect of each temperature measuring point is assessed. Specifically, the thermal accumulation factor HF = ∫[T(t)-T0]dt is calculated for each temperature measuring point within a set time window, where T0 is the reference temperature, and the thermal accumulation factor characterizes the cumulative heat load borne by the component corresponding to that temperature measuring point. When the thermal accumulation factor exceeds the set accumulation threshold HF_th, a component thermal fatigue warning message is output, prompting maintenance personnel to arrange inspection and maintenance. Specifically, the thermal accumulation effect assessment is implemented as follows: For each temperature measurement point, the system calculates the cumulative heat increment ΔHF within a 1-minute period: Where T0 is the reference temperature of the component material corresponding to the temperature measurement point under normal operating conditions. The T0 of the transmission line waveguide component is set to 40℃, and the T0 of the antenna end face is set to 100℃. For a moment The measured temperature value is given, where t is the calculation period for the heat accumulation increment, which is 1 minute. Since the digital sampling system is discrete, numerical integration is used in the actual calculation. This represents the temperature value at the i-th sampling time. The sampling period corresponds to a sampling frequency of 10 S / s. The sampling interval is 0.1s, and n is the total number of sampling points. At a sampling frequency of 10s / s per minute, 600 sampling points can be obtained.

[0041] The system accumulates the heat accumulation factor HF = ΣΔHFi at each temperature measurement point and compares it with the accumulation threshold HF_th of the component. The accumulation threshold is determined based on the thermal fatigue characteristics and design life of the component material; the HF_th of the transmission line copper waveguide is set to 1 × 10⁻⁶. 7 ℃·s, the HF_th of the stainless steel material on the antenna end face is set to 5×10 7 ℃·s.

[0042] When HF > 0.8 × HF_th, the system outputs a thermal fatigue early warning message prompting an inspection; when HF > HF_th, the system outputs a thermal fatigue alarm message requiring maintenance or replacement. Thermal accumulation factor data is periodically stored in database server 5 for thermal history tracking throughout the equipment's lifespan.

[0043] As a further improvement, the over-temperature protection method also includes a discharge timing coordinated monitoring strategy, specifically: The industrial control host computer 3 interacts with the tokamak central control system via a reflected memory network or Ethernet to synchronize clock and discharge timing signals. During the discharge preparation phase, the system enters the preheating monitoring mode and records the initial temperature of each temperature measurement point in a low-frequency sampling mode as the reference temperature for this round of discharge. During the discharge execution phase, the system enters real-time protection mode, using high-frequency sampling mode to monitor temperature and execute graded temperature control strategies. During the cooling phase after the discharge ends, the system enters the attenuation monitoring mode to continuously monitor the temperature decay process at each temperature measurement point and record the cooling curves. This is used to evaluate the heat dissipation performance and thermal inertia parameters, providing a basis for correcting the temperature prediction model for the next round of discharge.

[0044] As a further improvement plan, such as Figure 8 As shown, the industrial control host computer includes an adaptive frequency conversion sampling control module, which dynamically adjusts the sampling frequency of each channel according to temperature change characteristics; the adaptive frequency conversion sampling control module divides the sampling mode into a low-frequency sampling mode and a high-frequency sampling mode: The sampling frequency of the low-frequency sampling mode is set to 10 S / s, which is suitable for the stage of stable temperature change, and is used to reduce system data throughput and storage burden; The sampling frequency of the high-frequency sampling mode is set to 68 S / s, which is suitable for the rapid temperature change stage or the stage close to the threshold, and is used to accurately capture the temperature change process. The sampling mode switching criterion is as follows: when the temperature rise rate dT / dt of any channel exceeds the rate switching threshold R_th or the current temperature value exceeds 80% of the first dynamic threshold T1, the system automatically switches from low-frequency sampling mode to high-frequency sampling mode; when the temperature rise rate is continuously lower than the rate switching threshold R_th and the current temperature value is lower than 70% of the first dynamic threshold T1 for a duration exceeding the set stability judgment time T_stable, the system automatically switches back to low-frequency sampling mode.

[0045] In summary, by monitoring the real-time temperature of key thermal load components in the low-hybrid wave system, this invention achieves system-level temperature monitoring of the microwave transmission line and antenna, stable measurement under strong electromagnetic environments, and intelligent thermal safety protection of the experimental device. In actual tokamak device experimental operation, this invention effectively reduces the probability of arcing in the waveguide of the microwave transmission line 4, and improves the structural safety of the low-hybrid wave antenna 7 and the operational stability of the microwave source klystron 2.

[0046] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A temperature monitoring system applicable to low hybrid wave systems in fusion reactors, characterized in that, It includes a high-speed temperature acquisition unit, thermocouple sensors, an industrial control host computer, and a database server. The microwave excitation signal from the microwave excitation source is amplified by the microwave klystron and then transmitted to a low-hybrid wave coupling antenna via a microwave transmission line. Multiple temperature measurement points are set on the waveguide surface of the microwave transmission line and the end face of the low-hybrid wave coupling antenna. Each temperature measurement point is equipped with a thermocouple sensor. The measurement output terminals of the thermocouple sensors are uniformly connected to and aggregated in the high-speed temperature acquisition unit and uploaded to the industrial control host computer. The industrial control host computer outputs control signals based on the received temperature data to adjust the output of the microwave excitation source, control the temperature in real time, and stores the acquired multi-channel real-time temperature data, control signal output values, and alarm event records in the database server.

2. The temperature monitoring system for a low-harmonic system of a fusion reactor according to claim 1, wherein The high-speed temperature acquisition unit is housed in an electromagnetically shielded enclosure, which is an aluminum alloy frame structure. The enclosure panel features multiple K-type thermocouple sockets, a 220V power input socket, an Ethernet communication interface, and a power switch. Inside the enclosure, an NI-9214 thermocouple input module and a cDAQ-9181 sensor measurement slave unit are also installed, connected via slots. Signal lines from the 16 K-type thermocouple sockets are connected to the terminals of the thermocouple input module, which in turn connects to the slot of the sensor measurement slave unit. The power input of the sensor measurement slave unit is connected to the 220V power input socket on the electromagnetically shielded enclosure. The entire unit is controlled by the power switch. The communication side of the sensor measurement slave unit communicates with an external industrial control host computer via an Ethernet communication interface.

3. The over-temperature protection method for a temperature monitoring system of a low- wave system of a fusion reactor according to any one of claims 1-2, characterized in that, include: S1. In the discharge experiment of the tokamak device, the high-speed temperature acquisition unit continuously acquires multiple temperature signals from the surface of the microwave transmission line waveguide of the low clutter system and the antenna end face of the low clutter coupling antenna at a set sampling frequency. The acquired raw signals are processed by the multi-level anti-interference signal processing algorithm module in the industrial control host computer for median filtering, anomaly detection and physical constraint verification to obtain the current temperature value T(t) of each temperature measurement point. S2. For the preprocessed current temperature value T(t), the sliding window linear fitting method is used to calculate the real-time temperature rise rate of each temperature measurement point; based on the current temperature value T(t) and the temperature rise rate dT / dt, the temperature value T_predict is predicted after time Δt1. S3. Set the reference warning temperature T1_base and reference alarm temperature T2_base for each temperature measurement point; dynamically correct the reference thresholds according to the plasma parameters and microwave power settings of the current experiment to obtain the first dynamic threshold T1 = T1_base ×α and the second dynamic threshold T2 = T2_base ×α, where α is the power correction coefficient. S4. Based on the current temperature value T(t), the predicted temperature T_predict, the first dynamic threshold T1, and the second dynamic threshold T2, execute a graded temperature control strategy; S5, the industrial control host computer will write the collected multi-channel real-time temperature data, control signal output values ​​and alarm event records into the database server in real time; Based on the stored historical temperature data, the database server evaluates the thermal accumulation effect for each temperature measurement point. When the thermal accumulation factor exceeds the set accumulation threshold, the output component issues a thermal fatigue warning message to prompt the operation and maintenance personnel to arrange inspections and maintenance.

4. The over-temperature protection method for a temperature monitoring system of a low-hybrid system of a fusion reactor according to claim 3, characterized in that, The multi-level anti-interference signal processing algorithm module includes a median filtering layer, a sliding window anomaly detection layer, and a physical constraint verification layer. The median filtering layer processes the original sampling sequence using a median filter with a window length of 5; the sliding window anomaly detection layer takes N sampling points before and after the current sampling point as the center to form a detection window, calculates the mean μ and standard deviation σ of the data within the detection window. If the absolute value of the difference between the current sampling value and the mean exceeds kσ, where k represents the multiple threshold, it is determined as an outlier and replaced with the mean of the detection window; the physical constraint verification layer is used to constrain the temperature change between two adjacent valid sampling values not to exceed the product of the preset maximum allowable change rate ΔTmax and the sampling period Δt. If it exceeds, the current sampling value is determined as an interference outlier and corrected with the superposition value of the previous valid value and the maximum allowable change amount.

5. The over-temperature protection method for a temperature monitoring system of a low-hybrid system of a fusion reactor according to claim 4, wherein The correction with the superposition value of the previous valid value and the maximum allowable change amount includes: Let the previous valid temperature value be T_valid and the current value be y(i). If |y(i) - T_valid| > ΔTmax × Δt, then let y(i) = T_valid + sign(y(i) - T_valid) × ΔTmax × Δt.

6. The over-temperature protection method for a temperature monitoring system of a low-hybrid system of a fusion reactor according to claim 3, wherein The S2 includes: Take the temperature values and time values of the M sampling points before the current moment for least squares linear fitting. The slope of the fitted line is the current temperature rise rate dT / dt. Based on the current temperature value T(t) and the temperature rise rate dT / dt, predict the temperature value T_predict = T(t) + (dT / dt) × Δt1 after Δt1 time.

7. The over-temperature protection method for a temperature monitoring system applicable to a fusion reactor low-hybrid system according to claim 3, characterized in that, The S4 includes: The first-level preventive adjustment: When T_predict ≥ T1 and T(t) < T1, it is determined as a temperature rise trend warning state, and the system reduces the output power of the microwave excitation source with a power adjustment step size of ΔP1, and the adjustment period is 10s; The second-level adaptive PID adjustment: When T(t) ≥ T1 and T(t) < T2, it is determined as an over-temperature warning state, and the adaptive PID controller is started to adjust the output power of the microwave excitation source; the control law of the adaptive PID controller is: u(t) = Kp(t)·e(t) + Ki(t)·∫e(t)dt + Kd(t)·de(t) / dt where e(t) = T(t) - T_target is the temperature deviation, and T_target is the target temperature setting value; Kp(t), Ki(t), Kd(t) are the adaptive adjustment PID parameters; the input of the adaptive PID controller is the target temperature setting value T_target and the current temperature T(t), and the output u(t) of the adaptive PID controller is converted into the power setting value of the microwave excitation source after amplitude limiting and rate limiting. Level 3 Emergency Shutdown Protection: When T(t)≥T2 or the temperature rise rate dT / dt exceeds the emergency rate threshold, it is determined to be an over-temperature alarm state. The system immediately outputs a shutdown signal to the microwave excitation source to terminate the current discharge experiment process, and records the over-temperature event information at the same time.

8. The over-temperature protection method for a temperature monitoring system of a low-hybrid system of a fusion reactor according to claim 7, wherein, The power adjustment step size ΔP1 = 0.03 × Prated, where Prated represents the rated power, and the target temperature set value ranges from 0.8 × T1 to 0.9 × T1.

9. The over-temperature protection method for a temperature monitoring system of a low- wave system of a fusion reactor according to claim 3, characterized in that, The assessment of the heat accumulation effect at each temperature measurement point includes: For each temperature measurement point, the system calculates the cumulative heat increment ΔHF within a 1-minute period. ,in This is the reference temperature of the component material corresponding to this temperature measurement point under normal operating conditions. For a moment The measured temperature value, where t is the calculation period for the heat accumulation increment. This represents the temperature value at the i-th sampling time. The sampling period is n, and the total number of sampling points is n. The heat accumulation increments of all temperature measurement points are summed to obtain the heat accumulation factor HF for each temperature measurement point within the set time window. When HF > 0.8 × HF_th, the system outputs a thermal fatigue warning message to prompt inspection. When HF > HF_th, the system outputs a thermal fatigue alarm message requiring maintenance or replacement. HF_th represents the set accumulation threshold. The accumulation threshold is determined based on the thermal fatigue characteristics and design life of the component material. The accumulation threshold for the copper waveguide of the microwave transmission line is set to 1 × 10. 7 The cumulative threshold of the stainless steel material at the antenna end face of the low-clutter coupled antenna is set to 5 × 10 °C·s. 7 ℃·s.

10. The over-temperature protection method for a temperature monitoring system of a low- wave system of a fusion reactor according to claim 3, wherein The sampling frequency of the industrial control host computer is dynamically adjusted according to the temperature change characteristics. The sampling modes are divided into low-frequency sampling mode and high-frequency sampling mode. The sampling frequency of the low-frequency sampling mode is set to 10 S / s, and the sampling frequency of the high-frequency sampling mode is set to 68 S / s. The sampling mode switching criterion is: When the temperature rise rate dT / dt of any channel exceeds the rate switching threshold R_th or the current temperature value exceeds 80% of the first dynamic threshold T1, the system automatically switches from low-frequency sampling mode to high-frequency sampling mode; when the temperature rise rate is continuously lower than the rate switching threshold R_th and the current temperature value is lower than 70% of the first dynamic threshold T1 for a duration exceeding the set stability judgment time T_stable, the system automatically switches back to low-frequency sampling mode.

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