Cascade fused salt electric heater control method and system

Abstract

The invention relates to the technical field of heat energy control and heating, and discloses a cascade fused salt electric heater control method and system, and the method comprises the steps: distributing the initial heating power according to the set fused salt outlet temperature and total power and the rated power of each stage of electric heater; initial fused salt flow is obtained, and the frequency of a variable frequency pump is adjusted according to the deviation between the fused salt flow and a set value so as to adjust the fused salt flow; and in the fused salt flow adjusting process, the power distribution of each stage of electric heater is dynamically adjusted according to the temperature safety margin of each stage of electric heater. Accurate temperature regulation and stable heat energy output are realized through dynamic power distribution and fused salt flow control of the multi-stage electric heater. The system adopts a cascade PID control technology to ensure that the outlet temperature quickly reaches a set value, and meanwhile, the temperature safety margin of each level of heater tends to be consistent, so that the safety and the reliability of the system are enhanced.

Description

Technical Field

[0001] The present invention relates to the field of thermal energy control and heating technology, and in particular to a control method and system for a cascade molten salt electric heater. Background Art

[0002] Molten salt electric heating energy storage technology is an advanced thermal energy storage solution suitable not only for solar thermal power generation but also for a wide range of applications, including industrial process heating, space heating, and power peak load regulation. This technology is closely aligned with the global energy transition, which aims to improve energy efficiency, reduce carbon emissions, and enhance grid flexibility.

[0003] With growing global awareness of environmental protection and the urgent need to reduce greenhouse gas emissions, countries are increasing their investment in renewable energy. Clean energy sources such as solar and wind power have become a priority for development due to their clean and sustainable nature. However, one of the greatest challenges of these energy sources is the intermittent and unpredictable nature of their power generation. This necessitates efficient and reliable energy storage technologies to smooth power output and ensure stable grid operation.

[0004] Molten salt electric heating energy storage technology has been developed to meet this need. It uses molten salt as an energy storage medium, converting electrical energy into heat through electrical heating and storing it in the salt. When needed, the heat is converted back into electricity or other useful energy forms through a heat exchanger. Molten salt, as an energy storage medium, offers advantages such as high specific heat capacity, high thermal stability, and excellent thermal conductivity, making it ideal for large-scale thermal energy storage.

[0005] The core of molten salt electric heating energy storage technology is to use electricity to heat molten salt, allowing it to store a large amount of thermal energy at a certain temperature. Normally, molten salt is solid at room temperature, but it will turn into liquid when heated to a certain temperature. Once the required temperature is reached, the molten salt can be safely stored in an insulated container. When the heat energy needs to be released, the molten salt transfers the heat energy to other media (such as water) through a heat exchanger, generating steam, which in turn drives a turbine to generate electricity or is directly used for heating industrial processes.

[0006] Molten salt electric heating and energy storage technology was initially applied in solar thermal power generation. In recent years, with technological advancements and cost reductions, this technology has begun to expand into a wider range of fields. For example, some industrial users use molten salt energy storage systems to recover waste heat, improving energy efficiency. In the heating sector, molten salt energy storage is also used to provide a stable heat source, particularly in centralized heating systems in cold northern regions.

[0007] Looking ahead, molten salt electric heating energy storage technology holds broad application prospects. With the continued development of the electricity market and technological innovation, molten salt energy storage technology will further reduce costs and improve efficiency. Furthermore, as the intelligence level of the power grid increases, molten salt energy storage technology can be better integrated with other energy technologies to form a more flexible and efficient integrated energy system. Furthermore, policy support and market incentives will promote the widespread application of this technology, contributing to the realization of global energy transition goals.

[0008] In short, molten salt electric heating energy storage technology not only provides an effective means to address the intermittent nature of renewable energy, but also lays a solid foundation for building a cleaner and more efficient energy system. With the continuous advancement of technology and the expansion of application scenarios, molten salt electric heating energy storage technology will play an increasingly important role in the future energy structure. Summary of the Invention

[0009] In view of the above problems, the present invention is proposed.

[0010] Therefore, the technical problems solved by the present invention are: unstable temperature control in a multi-stage electric heater molten salt heating system, unbalanced temperature safety margins of heaters at each stage, and low energy utilization efficiency.

[0011] To solve the above technical problems, the present invention provides the following technical solutions: a control method for a cascade molten salt electric heater, comprising:

[0012] Based on the set molten salt outlet temperature and total power, the initial heating power is allocated according to the rated power of each level of electric heater;

[0013] Obtain the initial molten salt flow rate, and adjust the frequency of the variable frequency pump to adjust the molten salt flow rate according to the deviation between the molten salt flow rate and the set value;

[0014] During the molten salt flow rate adjustment process, the power distribution of the electric heaters at each level is dynamically adjusted according to the temperature safety margin of the electric heaters at each level.

[0015] As a preferred solution of the control method of the cascade molten salt electric heater according to the present invention, the initial molten salt flow rate includes obtaining the initial molten salt flow rate by looking up a table according to historical operating data or empirical values;

[0016] The initial power allocation includes setting the molten salt outlet temperature and the total power of the electric heaters, and allocating the initial power to each heater level according to a weighted formula based on the rated maximum power of each heater level. The formula is expressed as:

[0017]

[0018] Among them, P i represents the initial power distribution value of the i-th level electric heater, Pset Indicates the set total heating power, P i.MAX Indicates the rated maximum power of the i-th level electric heater, n represents the total number of electric heater levels, and i refers to the heater level currently being calculated.

[0019] As a preferred embodiment of the control method of the cascade molten salt electric heater described in the present invention, regulating the molten salt flow rate includes adopting a cascade PID control method, wherein the outer loop uses the molten salt flow rate as the control variable and the outlet molten salt temperature as the tracking variable, and the outlet molten salt temperature is adjusted to reach a set value through PID regulation;

[0020] The formula for PID control is:

[0021] L(t)=Kpl*ΔT n +Kil*∫ΔT n dt+Kdl*dΔT n / dt

[0022] ΔT n =T n.实测 -T n.设定

[0023] Where L(t) represents the controlled amount of molten salt flow at time t, Kpl represents the proportional coefficient of the outer loop control, ΔT n Indicates the outlet molten salt temperature T n The deviation between the measured value and the set value, Kil represents the integral coefficient of the outer loop control, and Kdl represents the differential coefficient of the outer loop control.

[0024] As a preferred embodiment of the control method of the cascade molten salt electric heater described in the present invention, regulating the molten salt flow rate further comprises: using the frequency conversion pump frequency as the control variable and the molten salt flow rate as the tracking variable in the inner loop, and using PID control to make the molten salt flow rate reach the set value, the formula is expressed as follows:

[0025] f(t)=Kpf*ΔL+Kif*∫ΔLdt+Kdf*dΔL / dt

[0026] ΔL=L 实测 -L 设定

[0027] Wherein, f(t) represents the frequency of the molten salt variable frequency pump, Kpf represents the proportional gain coefficient, ΔL represents the deviation of the molten salt flow rate, Kif represents the integral gain coefficient, and Kdf represents the differential gain coefficient.

[0028] As a preferred embodiment of the control method of the cascade molten salt electric heater of the present invention, in which: during the dynamic adjustment process of the molten salt heating system, the outlet temperature and the maximum temperature of each heater stage will continuously change;

[0029] By adjusting the power distribution, the temperature safety margin of each stage heater can be made consistent while the total power remains unchanged.

[0030] As a preferred embodiment of the control method of the cascade molten salt electric heater according to the present invention, the power distribution of each stage of the electric heater includes: during the molten salt flow adjustment process, the temperature safety margin of each stage of the heater changes with the power change, and the formula is expressed as follows:

[0031]

[0032] T i.T =T i.MAX -T i.MAX.T

[0033] Where ΔP i represents the power adjustment value of the i-th level heater, k represents the adjustment coefficient, P0 represents the reference adjustment power, T i.T represents the temperature safety margin of the i-th stage heater, T i.MAX Indicates the maximum allowable temperature of the i-th stage heater, T i.MAX.T Indicates the actual temperature value of the i-th level heater at the current moment.

[0034] As a preferred embodiment of the control method of the cascade molten salt electric heater according to the present invention, the power distribution of each electric heater also includes that each power adjustment does not affect the total power of the system; the above power adjustment is repeated at a fixed actual interval until the distribution of the temperature safety margin meets the set acceptable deviation value, which is expressed as follows:

[0035]

[0036] Where ΔP i represents the power adjustment value of the i-th level heater, k represents the adjustment coefficient, P0 represents the reference adjustment power, T i.T represents the temperature safety margin of the i-th stage heater, T j.T Represents the average of all heater temperature safety margins.

[0037] A cascade molten salt electric heater control system, wherein:

[0038] The initial setting module allocates the initial heating power according to the rated power of each level of electric heater based on the set molten salt outlet temperature and total power;

[0039] The adjustment module obtains the initial molten salt flow rate and adjusts the frequency of the variable frequency pump to adjust the molten salt flow rate according to the deviation between the molten salt flow rate and the set value;

[0040] The power distribution module dynamically adjusts the power distribution of each level of electric heaters according to the temperature safety margin of each level of electric heaters during the molten salt flow adjustment process.

[0041] A computer device comprises: a memory and a processor; the memory stores a computer program, wherein the processor implements the steps of any one of the methods of the present invention when executing the computer program.

[0042] A computer-readable storage medium stores a computer program thereon, wherein the computer program, when executed by a processor, implements the steps of any one of the methods of the present invention.

[0043] The present invention provides a beneficial effect: The proposed control method for cascaded molten salt electric heaters achieves precise temperature regulation and stable heat output through dynamic power allocation and molten salt flow control across multiple heater stages. The system employs cascaded PID control technology to ensure that the outlet temperature quickly reaches the set value while maintaining consistent temperature safety margins across each heater stage, enhancing system safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 An overall flow chart of a control method for a cascade molten salt electric heater provided by the first embodiment of the present invention;

[0046] Figure 2 A schematic structural diagram of a cascade molten salt electric heater control method provided in the first embodiment of the present invention. DETAILED DESCRIPTION

[0047] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0048] Example 1, reference Figure 1 and Figure 2 , as one embodiment of the present invention, provides a control method for a cascade molten salt electric heater, comprising:

[0049] S1: Based on the set molten salt outlet temperature and total power, the initial heating power is allocated according to the rated power of each level of electric heater.

[0050] The electric heater is divided into 1, 2...n levels. T0, T1 are the inlet and outlet temperatures of the first-level heater, T1, T2 are the inlet and outlet temperatures of the second-level heater, and T n-1 ,T n is the inlet temperature and outlet temperature of the second stage heater, that is, the outlet temperature of the previous stage is the inlet temperature of the next stage. 1.MAX ,T 2.MAX ,T n.MAX The maximum internal temperature of each heater stage. 1.MAX.T ,T 2.MAX.T ,T n.MAX.T is the maximum temperature that each stage heater can withstand, and this value is determined according to the actual material properties used. L is the measured value of the molten salt flow meter. n is the real-time power of each level of electric heater, P 1.MAX.T ,P 2.MAX.T ,P n.MAX.T is the rated maximum power of each level of electric heater, P set It is the total heating power setting value. Before the system starts running, the operator sets the required temperature T of the molten salt at the total outlet. n And the total power of the electric heater P set The first step is to allocate the initial heating power. The initial power is allocated according to the given total power P set The initial power is allocated based on the weighted value of the rated power of each electric heater. Since the rated power of each electric heater is generally based on the maximum flow rate and the rated power, the heaters of each level operate in a safe temperature range. Therefore, the initial power is allocated based on the weighted value of the rated power, which is closer to the final required steady-state value, helping the control system to quickly reach a stable state.

[0051]

[0052] Among them, P i represents the initial power distribution value of the i-th level electric heater, P set Indicates the set total heating power, P i.MAX Indicates the rated maximum power of the i-th level electric heater, n represents the total number of electric heater levels, and i refers to the heater level currently being calculated.

[0053] Obtain the initial molten salt flow rate from a table. The initial molten salt flow rate is obtained from a table based on historical operating data or empirical values. The table contains information for different temperature differences.

[0054] Table showing the corresponding molten salt flow rates at different total powers. For system safety and reliability, a margin of 1.1-1.5 times is added to the actual value.

[0055] The data table is as follows (the data is for reference only and does not represent the actual situation):

[0056] Table 1 Data sheet

[0057]

[0058] The control system allocates initial heating power and initial molten salt flow rate instead of starting from zero, which helps the system quickly reach the desired steady state.

[0059] By rationally allocating the initial power to each electric heater and determining the initial molten salt flow rate based on the set molten salt outlet temperature and total power, the system quickly enters steady-state operation. By weighting the distribution according to the rated power of each heater, the initial power is closer to the steady-state value, reducing system adjustment time and avoiding unnecessary fluctuations caused by starting from zero. Furthermore, the initial molten salt flow rate obtained through table lookup and appropriate margin design ensures system safety and reliability during startup, improving control accuracy and operational efficiency.

[0060] S2: Obtain the initial molten salt flow rate, and adjust the frequency of the variable frequency pump to adjust the molten salt flow rate according to the deviation between the molten salt flow rate and the set value.

[0061] The molten salt flow rate is adjusted using a cascade PID control method. The PID outer loop uses the molten salt flow rate as the control variable, and the final outlet molten salt temperature T n is the tracking quantity. After PID automatic adjustment, T n Reach the set value.

[0062] L(t)=Kpl*ΔT n +Kil*∫ΔT n dt+Kdl*dΔT n / dt

[0063] Where L(t) represents the controlled amount of molten salt flow at time t, Kpl represents the proportional coefficient of the outer loop control, ΔT n Indicates the outlet molten salt temperature T n The deviation between the measured value and the set value, Kil represents the integral coefficient of the outer loop control, and Kdl represents the differential coefficient of the outer loop control.

[0064] f(t)=Kpf*ΔL+Kpf*∫ΔLdt+Kdf*dΔL / dt

[0065] Wherein, f(t) represents the frequency of the molten salt variable frequency pump, Kpf represents the proportional gain coefficient, ΔL represents the deviation of the molten salt flow rate, Kpf represents the integral gain coefficient, and Kdf represents the differential gain coefficient.

[0066] Precisely controlling the molten salt flow ensures a stable and efficient heating process. First, by obtaining the initial molten salt flow and calculating its deviation from the setpoint, the gap between the current flow and the target can be effectively identified. Next, a cascaded PID control method is used to adjust the flow. The outer PID loop uses the molten salt flow as the control variable, and ultimately the outlet molten salt temperature as the tracking variable. This allows the system to automatically adjust the frequency of the molten salt variable-frequency pump to minimize flow and temperature deviations.

[0067] Specifically, the PID outer loop regulates the molten salt flow rate to ensure the outlet temperature gradually approaches the setpoint, using proportional, integral, and differential coefficients for precise adjustment to avoid overshoot or undershoot. The inner loop controls the frequency of the variable-frequency pump to ensure the molten salt flow rate remains within the ideal range. This closed-loop control minimizes temperature fluctuations, ensuring the stability and responsiveness of the heating process, improving system efficiency, and ensuring safe operation.

[0068] S3: During the molten salt flow rate adjustment process, the power distribution of each level of electric heaters is dynamically adjusted according to the temperature safety margin of each level of electric heaters.

[0069] During the dynamic adjustment of the molten salt heating system, the outlet temperature of each stage of heater and its maximum temperature will change continuously.

[0070] By adjusting the power distribution, the temperature safety margin of each stage heater can be made consistent while the total power remains unchanged.

[0071] The power distribution of each level of electric heater includes that during the molten salt flow adjustment process, the temperature safety margin of each level of heater changes with the power change, and the formula is expressed as:

[0072]

[0073] T i.T =T i.MAX -T i.MAX.T

[0074] Where ΔP i represents the power adjustment value of the i-th level heater, k represents the adjustment coefficient, P0 represents the reference adjustment power, T i.T represents the temperature safety margin of the i-th stage heater, T i.MAX Indicates the maximum allowable temperature of the i-th stage heater, T i.MAX.T Indicates the actual temperature value of the i-th level heater at the current moment.

[0075] Each power adjustment will not affect the total system power. Repeat the above power adjustment at a fixed actual interval until the distribution of the temperature safety margin meets the set acceptable deviation value. The formula is expressed as:

[0076]

[0077] Where ΔP i represents the power adjustment value of the i-th level heater, k represents the adjustment coefficient, P0 represents the reference adjustment power, T i.T represents the temperature safety margin of the i-th stage heater, T j.T Represents the average of all heater temperature safety margins.

[0078] By dynamically adjusting the power distribution of each electric heater stage, the system maintains consistent temperature safety margins for each heater stage while maintaining a constant total power. By continuously adjusting power, individual heaters are prevented from exceeding their safe temperature ranges, thereby balancing the overall system's thermal energy distribution and ensuring safe operation. This design, through repeated adjustments at fixed intervals, ensures that the distribution of each heater's temperature safety margins meets the specified acceptable deviation, thereby improving system safety, stability, and operational efficiency and preventing local overheating or power waste.

[0079] Example 2, an embodiment of the present invention, provides a cascade molten salt electric heater control system, including:

[0080] The initial setting module allocates the initial heating power according to the rated power of each level of electric heater based on the set molten salt outlet temperature and total power.

[0081] The adjustment module obtains the initial molten salt flow rate and adjusts the frequency of the variable frequency pump according to the deviation between the molten salt flow rate and the set value to adjust the molten salt flow rate.

[0082] The power distribution module dynamically adjusts the power distribution of each level of electric heaters according to the temperature safety margin of each level of electric heaters during the molten salt flow adjustment process.

[0083] Example 3, an embodiment of the present invention, is different from the previous two embodiments in that:

[0084] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0085] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0086] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0087] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0088] In Example 4, three electric heaters were used: Electric Heater 1, Electric Heater 2, and Electric Heater 3. Their rated powers were 30 kW, 50 kW, and 70 kW, respectively, for a total power of 120 kW. The experimental objectives were to set the molten salt outlet temperature to 650°C and maintain a molten salt flow rate of 200 liters per minute.

[0089] The initial power distribution is performed based on the rated power of the electric heater. According to the ratio of the rated power of each heater to the total power, the initial power allocated to the electric heater 1 is The initial power allocated to electric heater 2 is The initial power allocated to the electric heater 3 is After the initial power distribution is completed, all three electric heaters start heating the molten salt.

[0090] Based on the preset molten salt flow rate (200 L / min), the variable frequency pump frequency was initially set to 50 Hz. At this point, the flowmeter measured the actual molten salt flow rate at 195 L / min, with a deviation of 5 L / min. Therefore, the PID control system adjusted the variable frequency pump frequency to 52 Hz, correcting the molten salt flow rate to the set value. During this adjustment process, the temperature and flow rate of each heater were monitored in real time.

[0091] As the molten salt flow rate stabilizes, the temperature safety margin of each heater begins to change in real time. Assume that the temperature safety margin of electric heater 1 is 30°C, that of electric heater 2 is 35°C, and that of electric heater 3 is 25°C. In this case, the system dynamically adjusts the power of each heater based on the differences in the temperature safety margin. To ensure that the safety margin of each heater is consistent, the system adjusts the power of each heater using the following formula:

[0092] After dynamic adjustment, the power of electric heater 1 is increased by 2kW, the power of electric heater 2 is reduced by 1kW, and the power of electric heater 3 is reduced by 1kW, so that the temperature safety margins of all heaters tend to be consistent.

[0093] In actual operation, the system automatically repeats this adjustment every 30 seconds, gradually reducing the temperature safety margin differences between the heaters until a steady state is reached. At this point, the safety margin differences between the heaters are controlled within 5°C, and the system operates stably, meeting the preset temperature and flow requirements. The experimental data is shown in Table 2.

[0094] Table 2 Experimental data table

[0095]

[0096] The experimental data above clearly demonstrates the innovative advantages of this invention in power distribution and molten salt flow control. The initial power distribution method allows the system to quickly reach a near-steady state, ensuring that each heater stage operates within a safe range. Initial deviations are quickly corrected through molten salt flow adjustment, bringing the molten salt flow rate to the target value of 200 L / min. Compared to traditional single-stage heating systems, the hierarchical power distribution of this multi-stage electric heater system significantly improves heating efficiency.

[0097] During dynamic power allocation, the temperature safety margins of the heaters vary. The innovation of this invention lies in dynamically adjusting the power to bring the temperature safety margins of each heater into alignment, thus preventing overheating or underheating of individual heaters. Experimental data shows that after dynamic adjustment, the temperature safety margin differences among the three electric heaters were reduced from an initial 10°C to less than 5°C, resulting in safer and more stable system operation. Traditional fixed power allocation methods cannot achieve this precise safety margin control, which can easily lead to localized overheating or power waste in the system.

[0098] In addition, the molten salt flow rate is adjusted by PID control of the frequency of the variable frequency pump, so that the molten salt flow rate can quickly return to the set value of 200L / min, indicating that the present invention has precise flow control capabilities. In practical applications, this control method can improve the response speed of the system, reduce power and resource waste, and have a significant energy-saving effect. Especially in large-scale industrial applications, the multi-stage electric heater system of the present invention can better adapt to complex working conditions, ensure that the system operates efficiently within a safety margin, and overcome the problems of imprecise control and energy waste in traditional technologies.

[0099] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A control method for a cascade molten salt electric heater, characterized in that: include: Based on the set molten salt outlet temperature and total power, the initial heating power is allocated according to the rated power of each level of electric heater; Obtain the initial molten salt flow rate, and adjust the frequency of the variable frequency pump to adjust the molten salt flow rate according to the deviation between the molten salt flow rate and the set value; During the molten salt flow rate adjustment process, the power distribution of the electric heaters at each level is dynamically adjusted according to the temperature safety margin of the electric heaters at each level.

2. The control method of the cascade molten salt electric heater according to claim 1, characterized in that: The initial molten salt flow rate includes obtaining the initial molten salt flow rate by looking up a table according to historical operating data or empirical values; The initial power allocation includes setting the molten salt outlet temperature and the total power of the electric heaters, and allocating the initial power to each heater level according to a weighted formula based on the rated maximum power of each heater level. The formula is expressed as: Among them, P i represents the initial power distribution value of the i-th level electric heater, P set Indicates the set total heating power, P i.MAX Indicates the rated maximum power of the i-th level electric heater, n represents the total number of electric heater levels, and i refers to the heater level currently being calculated.

3. The control method of the cascade molten salt electric heater according to claim 2, characterized in that: Adjusting the molten salt flow rate includes adopting a cascade PID control method, with the outer loop taking the molten salt flow rate as the control variable and the outlet molten salt temperature as the tracking variable, and adjusting the outlet molten salt temperature to reach the set value through PID adjustment; The formula for PID control is: L(t)=Kpl*ΔT n +Kil*∫ΔT n dt+Kdl*dΔT n / dt ΔT n =T n.实测 -T n.设定 Where L(t) represents the controlled amount of molten salt flow at time t, Kpl represents the proportional coefficient of the outer loop control, ΔT n Indicates the outlet molten salt temperature T n The deviation between the measured value and the set value, Kil represents the integral coefficient of the outer loop control, and Kdl represents the differential coefficient of the outer loop control.

4. The control method of the cascade molten salt electric heater according to claim 3, characterized in that: Adjusting the molten salt flow also includes the inner loop using the variable frequency pump frequency as the control variable and the molten salt flow as the tracking variable, and using PID control to make the molten salt flow reach the set value. The formula is expressed as: f(t)=Kpf*ΔL+Kif*∫ΔLdt+Kdf*dΔL / dt ΔL=L 实测 -L 设定 Wherein, f(t) represents the frequency of the molten salt variable frequency pump, Kpf represents the proportional gain coefficient, ΔL represents the deviation of the molten salt flow rate, Kif represents the integral gain coefficient, and Kdf represents the differential gain coefficient.

5. The control method of the cascade molten salt electric heater according to claim 4, characterized in that: During the dynamic adjustment of the molten salt heating system, the outlet temperature of each heater and its maximum temperature will change continuously; By adjusting the power distribution, the temperature safety margin of each stage heater can be made consistent while the total power remains unchanged.

6. The control method of the cascade molten salt electric heater according to claim 5, characterized in that: The power distribution of each level of electric heater includes that during the molten salt flow adjustment process, the temperature safety margin of each level of heater changes with the power change, and the formula is expressed as: T i.T =T i.MAX -T i.MAX.T Where ΔP i represents the power adjustment value of the i-th level heater, k represents the adjustment coefficient, P0 represents the reference adjustment power, T i.T represents the temperature safety margin of the i-th stage heater, T i.MAX Indicates the maximum allowable temperature of the i-th stage heater, T i.MAX.T Indicates the actual temperature value of the i-th level heater at the current moment.

7. The control method of the cascade molten salt electric heater according to claim 6, characterized in that: The power distribution of each level of electric heaters also includes that each power adjustment will not affect the total power of the system; the above power adjustment is repeated at fixed actual intervals until the distribution of the temperature safety margin meets the set acceptable deviation value, which is expressed as follows: Where ΔP i represents the power adjustment value of the i-th level heater, k represents the adjustment coefficient, P0 represents the reference adjustment power, T i.T represents the temperature safety margin of the i-th stage heater, T j.T Represents the average of all heater temperature safety margins.

8. A cascade molten salt electric heater control system using the method according to any one of claims 1 to 7, characterized in that: The initial setting module allocates the initial heating power according to the rated power of each level of electric heater based on the set molten salt outlet temperature and total power; The adjustment module obtains the initial molten salt flow rate and adjusts the frequency of the variable frequency pump to adjust the molten salt flow rate according to the deviation between the molten salt flow rate and the set value; The power distribution module dynamically adjusts the power distribution of each level of electric heaters according to the temperature safety margin of each level of electric heaters during the molten salt flow adjustment process.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the cascade molten salt electric heater control method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the cascade molten salt electric heater control method according to any one of claims 1 to 7 are implemented.

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