Cascade control method, system, device and medium for closed cooling circulating water system

Abstract

This invention proposes a cascade control method, system, equipment, and medium for a closed-loop cooling water circulation system. The method includes: acquiring pressure and temperature signals from the supply and return water mains to obtain real-time pressure difference and real-time temperature difference; running pressure difference PI control and temperature difference PI control in parallel, calculating the control output quantities of pressure difference and temperature difference respectively; based on the comparison results of and , and the duration of continuous less than , selecting the output quantity of one PI control as the main control quantity, and superimposing it with the historical output quantity of the other PI control as the bias quantity to generate the final control output quantity; applying the final control output quantity to the circulation pump group to drive its operation. This invention relies solely on pressure and temperature sensors of the supply and return water mains, and through constant temperature difference and constant pressure difference cascade control, simultaneously achieves rapid response to heat dissipation requirements and reliable assurance of remote hydraulic balance without additional hardware costs.

Description

Technical Field

[0001] This invention belongs to the field of cooling technology for equipment such as beamline electromagnets and accelerator electromagnets, and specifically relates to a cascade control method, system, equipment and medium for a closed-loop cooling circulating water system. Background Technology

[0002] In proton radiotherapy systems, the beam transmission line is equipped with numerous diode and quadrupole electromagnets for deflecting and focusing the proton beam. These electromagnets are typically made of highly conductive copper coils. During high-energy beam operation, the coils generate significant Joule heating due to resistive losses. If this heat is not removed promptly, the electromagnet temperature will rise rapidly, leading to a further increase in coil resistance and consequently, magnetic field drift, which compromises the stability of proton beam transmission and treatment precision. Therefore, maintaining a constant electromagnet temperature is crucial for ensuring the long-term stable operation of the proton therapy system, and a closed-loop circulating water cooling system is typically used for forced convection heat transfer.

[0003] Existing closed-loop water cooling systems mostly employ two-stage pump sets for centralized pumping. However, in large proton therapy devices, the widespread distribution of electromagnet clusters and the complex piping layout lead to significant resistance differences in the hydraulic system. Particularly for the terminal electromagnets located far from the cold source, hydraulic imbalance often arises. Due to competition for water from the nearby load, the delivery pressure in the distant pipes is lower, resulting in insufficient cooling water flow, low heat dissipation efficiency, and consequently, localized hot spots, affecting magnetic field stability.

[0004] To address the aforementioned hydraulic imbalance and energy-saving requirements, existing technologies have proposed various control strategies. One common method is to determine the differential pressure reference value by acquiring the current water flow rate in the supply and return mains, and then adjust the target frequency of the water pump by comparing the current differential pressure with this reference value. However, this approach relies on real-time, accurate acquisition of the mains water flow rate and requires establishing a historical statistical model of water flow rate and mains pressure difference. In complex actual operating conditions, even with the same mains water flow rate, variations in the resistance characteristics of different load pipelines can cause fluctuations in the mains pressure difference, making it difficult to accurately quantify the correspondence between cooling demand and the pressure difference setpoint, thus limiting control accuracy. Another control method connects multiple terminals via a parallel differential pressure converter in the unit's main water circuit. It acquires the supply and return water temperature difference and pressure difference in the main water circuit, as well as the supply and return water temperature difference at each terminal, to regulate the water pump, and uses differential pressure valves to adaptively adjust the terminal flow rate. While this method can accommodate terminal demand, its technical drawback lies in its complex system architecture, requiring the addition of independent differential pressure valves and data acquisition modules in the terminal branches to centrally process large amounts of terminal cooling data. This not only significantly increases the hardware investment cost of the system, but also makes the subsequent maintenance and calibration work cumbersome. For older or simplified systems that only have basic manifold sensors, implementation is quite difficult.

[0005] In summary, existing technologies for electromagnet cooling in proton therapy systems generally suffer from high hardware costs, complex data acquisition, or poor adaptability of control models. In particular, without adding extra flow sensors and terminal smart valves, how to achieve hydraulic balance for remote loads and energy-saving frequency regulation of pump units using only the baseline pressure and temperature signals from the manifold remains a technical challenge that has not yet been effectively solved by existing technologies. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a cascade control method, system, device and medium for a closed cooling circulating water system, so as to solve the problems of unstable heat dissipation and slow response of electromagnet clusters, and the problems of insufficient cooling circulating water supply pressure and small flow rate of local remote magnets, resulting in low heat dissipation efficiency.

[0007] To achieve the above and other related objectives, the present invention provides a cascade control method for a closed-loop cooling water system for heat dissipation and cooling of load equipment, comprising: Obtain the pressure and temperature signals from the supply and return water mains, and obtain the real-time pressure difference. and real-time temperature difference ; Based on real-time pressure difference pressure difference with the preset target deviation Calculate the differential pressure control output. And based on real-time temperature difference The temperature difference with the preset target deviation Calculate the output of temperature difference control ; According to the real-time pressure difference With the target pressure difference The comparison results, the real-time temperature difference The target temperature difference The comparison results, and the real-time temperature difference The temperature difference remains consistently less than the target temperature difference. The time length is determined by selecting the output of one of the PI controls, pressure differential proportional integral PI control and temperature differential proportional integral PI control, as the main control quantity, and superimposing the historical output of the other PI control as the bias quantity to generate the final control output quantity. The final control output is applied to the circulating pump unit to drive its operation.

[0008] In one embodiment of the present invention, the selection of the output of one of the PI controls, pressure difference proportional-integral PI control and temperature difference proportional-integral PI control, as the main control quantity, and the superposition of the historical output of the other PI control as the bias quantity, specifically includes: When the system starts, the output of the differential pressure PI control is used as the main control quantity, and zero is used as the bias quantity to generate the final control output quantity.

[0009] In one embodiment of the present invention, the step of selecting the output of one of the PI controls, differential pressure proportional-integral PI control and temperature difference proportional-integral PI control, as the main control quantity, and superimposing the historical output of the other PI control as the bias quantity, further includes: When the real-time pressure difference Stable and the real-time temperature difference The temperature difference remains consistently less than the target temperature difference. Length of time Greater than the preset threshold At that time, the system switches to the output controlled by the proportional-integral PI of the temperature difference. The main control variable is PI control with the current pressure difference as the proportional integral. These are superimposed as bias values ​​to generate the final control output.

[0010] In one embodiment of the present invention, the final control input is as follows:

[0011] in, The system clock value at the time of switching. The proportional gain is for temperature difference PI control. The integral gain of the temperature difference PI control. The deviation between the real-time temperature difference and the target temperature difference. The sampling period.

[0012] In one embodiment of the present invention, the method further includes: in a mode dominated by temperature difference proportional-integral PI control, when the system heat exchange decreases, the temperature difference proportional-integral PI control automatically reduces its output to maintain the real-time temperature difference. This equals the target temperature difference, thereby achieving automatic reduction of the operating speed of the circulating pump group and energy-saving operation.

[0013] In one embodiment of the present invention, the method of using the output of one of the PI controls, pressure difference proportional-integral PI control and temperature difference proportional-integral PI control, as the main control quantity, and using the historical output of the other PI control as the bias quantity for superposition, further includes: In the mode primarily based on temperature difference proportional-integral PI control, when the system detects real-time pressure difference... Less than the target pressure difference When the pressure difference is controlled by a proportional-integral PI controller, the system immediately switches to using the output quantity controlled by the pressure difference as the main control quantity, and uses the temperature difference as the current temperature difference as the output quantity. These are superimposed as bias values ​​to generate the final control output.

[0014] In one embodiment of the present invention, the final control output is as follows:

[0015] in, The system clock value at the time of switching. The proportional gain is for differential pressure PI control. The integral gain of the differential pressure PI control. The deviation between the real-time differential pressure and the target differential pressure. The sampling period.

[0016] In one embodiment of the present invention, when switching control modes, a seamless switching process is performed, specifically including: Obtain the output of the PI control that was switched off at the moment before the switch, and add it as an bias to the main control quantity after the switch. At the same time, the integral term value of the switched-off PI control is obtained and transferred to the switched-off PI control as its initial value, so as to maintain the mutual transfer of the integral term values ​​of the PI algorithm and realize the smooth transition of the pump group's operating speed.

[0017] In one embodiment of the present invention, the differential pressure control output quantity and temperature difference control output Calculated using the following formulas respectively:

[0018]

[0019] in, , For the proportional gain and integral gain of the differential pressure PI controller, , For the proportional gain and integral gain of the temperature difference PI controller, The sampling period.

[0020] In one embodiment of the present invention, the load device is an electromagnet cluster.

[0021] This invention also proposes a cascade control system for a closed-loop cooling water circulation system, used for heat dissipation and cooling of load equipment, including: Pressure and temperature sensors are installed in the main water supply pipe and the main water return pipe, respectively, to acquire pressure and temperature signals. A circulating pump set is used to drive the circulation of cooling water; The controller is configured to perform the method of the closed-loop cooling water circulation system described in any of the above embodiments.

[0022] The present invention also proposes an electronic device, comprising: at least one processor; a memory communicatively connected to the at least one processor; the memory storing a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform a cascade control method for a closed-loop cooling water circulation system as described in any of the above embodiments.

[0023] The present invention also proposes a computer-readable storage medium storing computer instructions, which, when read and executed by a computer, cause the computer to perform a cascade control method for a closed-loop cooling water circulation system as described in any of the above embodiments.

[0024] This invention proposes a cascade control method and system for a closed-loop cooling water circulation system. Compared to the single differential pressure or temperature difference frequency modulation control method used in traditional closed-loop circulating water pump sets, this invention, without adding additional main pipe flow monitoring and terminal temperature and pressure difference data acquisition links, relies solely on the data acquisition conditions of traditional manifold supply and return water pressure sensors and temperature sensors. By cascading switching between main pipe differential pressure control and temperature difference control, it achieves a dynamic balance between local remote load pressure and water flow supply, satisfying both the heat dissipation stability requirements of the electromagnet and ensuring energy-saving operation of the cooling water circulation pump set. Specific beneficial effects are as follows: The disturbance-free switching strategy proposed in this embodiment is the core algorithm mechanism for achieving "cascade switching". This strategy, through the synergistic effect of dual technical means, aims to completely solve the industry problem of sudden changes in pump speed during mode switching, ensuring the stability and reliability of the control system when switching between different operating conditions.

[0025] The bias superposition proposed in this embodiment achieves "memory inheritance" of the control signal by superimposing the PI control output that was switched off at the moment before the switch onto the main control output after the switch. This mechanism retains the historical adjustment information of the abandoned controller, so that the newly enabled control mode is not blindly adjusted from scratch, but is smoothly connected based on the previous actual operating state of the system, avoiding large jumps in the output signal caused by control logic gaps.

[0026] The integral term transfer proposed in this embodiment eliminates the common problems of integral saturation or sudden changes in initial integral values ​​during controller switching by directly assigning the accumulated value of the original PI controller's integral term to the new controller's integral term at the moment of switching. This method ensures the continuity of integral action and prevents system response hysteresis or overshoot caused by resetting the initial integral value. It is a key technical means to ensure that the control output does not undergo a step change at the moment of switching. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a flowchart of a cascade control method for a closed-loop cooling water circulating system in one embodiment of the present invention.

[0029] Figure 2 This is a system block diagram of a cascade control system for a closed-loop cooling water circulation system in one embodiment of the present invention.

[0030] Figure 3 This is a logic diagram of a cascade control method for a closed-loop cooling water circulation system in one embodiment of the present invention. Detailed Implementation

[0031] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0032] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components relevant to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0033] Please see Figure 1 , Figure 2 and Figure 3As shown, this embodiment addresses the heat dissipation requirements of the beam transmission line electromagnet cluster in a proton radiotherapy system by providing a cascade control method and system for a closed-loop cooling circulating water system. This method utilizes conventional sensor data at the manifold and resolves the contradiction between remote hydraulic imbalance and energy-saving system operation through cascade switching controlled by pressure and temperature differences.

[0034] Please see Figure 1 , Figure 2 and Figure 3 As shown, a closed-loop circulating water system is constructed, comprising a two-stage pump set, a manifold, an electromagnet cluster load (two-pole and four-pole electromagnets), and heat exchange equipment. This invention proposes a cascade control method for a closed-loop cooling circulating water system to dissipate heat from the load equipment, addressing the problems of unstable heat dissipation and slow response in the electromagnet cluster, as well as insufficient cooling water supply pressure and low flow rate at the remote magnets, leading to low heat dissipation efficiency. Pressure and temperature detection points are set at the supply and return water manifolds: supply water main monitoring point 1 and return water main monitoring point 2, with pressures P1 and P2 at the two points and temperatures T1 and T2 at the two points, respectively. The specific method includes: S1. Acquire the pressure and temperature signals of the supply and return water mains, and obtain the real-time pressure difference. and real-time temperature difference Specifically, pressure sensors and temperature sensors are installed at the manifolds of the main supply and return water pipes, respectively. The controller acquires the signals in real time and calculates the real-time pressure difference. (Right now ) and real-time temperature difference (Right now ).

[0035] S2, based on real-time pressure difference pressure difference with the preset target deviation Calculate the differential pressure control output. And based on real-time temperature difference The temperature difference with the preset target deviation Calculate the output of temperature difference control Specifically, the controller internally operates a differential pressure proportional-integral (PI) controller and a temperature difference proportional-integral (PI) controller in parallel. Specifically, this includes: The differential pressure PI controller calculates the deviation between the real-time differential pressure and the target differential pressure. Calculate the differential pressure control output. .

[0036] The temperature difference PI controller is based on the deviation between the real-time temperature difference and the target temperature difference. Calculate the temperature difference control output. .

[0037] In this embodiment, the pressure difference controls the output quantity. and temperature difference control output Calculated using the following standard PI formulas: Differential pressure calculation formula:

[0038] Formula for calculating temperature difference:

[0039] in, , For the proportional gain and integral gain of the differential pressure PI controller, , For the proportional gain and integral gain of the temperature difference PI controller, The sampling period is specified. This embodiment employs the standard PI algorithm, which is simple to calculate, responds quickly, and can meet the high-precision control requirements of the electromagnet cooling system for temperature and pressure stability.

[0040] S4. Based on real-time pressure difference Pressure difference with target Comparison results, real-time temperature difference Temperature difference from target The comparison results, and the real-time temperature difference The temperature difference remains consistently below the target temperature. Based on the time duration, logical judgment is used to select the output of one of the PI controls, pressure difference proportional-integral PI control and temperature difference proportional-integral PI control, as the main control quantity. The historical output of the other PI control is then added as an bias quantity to generate the final control output. .

[0041] S5, final control output quantity The signal is converted into a frequency signal and applied to the circulating pump unit to drive its operation.

[0042] This solution utilizes only the main pipe sensor at the manifold, eliminating the need for expensive flow / pressure acquisition equipment in the remote pipe network or at the end electromagnet, thus reducing hardware investment costs. Through cascaded logic of the main control variable and historical bias, it retains the historical adjustment memory of unselected controllers while simultaneously enabling the switching of the current optimal control strategy, ensuring the continuity of system regulation.

[0043] Please see Figure 1 and Figure 3 As shown, in this embodiment, when the system is powered on and started, the water flow in the pipe network is static, and the real-time pressure difference is... =0 or much smaller than the target pressure difference At this point, the selection of using the output of one of the PI controls as the main control quantity and the historical output of the other PI control as the bias quantity for superposition includes: The system forcibly selects the differential pressure control output VPx_output(t) of the differential pressure PI control as the main control quantity, and sets the output of the temperature difference PI control to zero, i.e., uses zero as the bias quantity. Therefore, the final control output quantity at this time is: .

[0044] It solves the problem of hydraulic balance not being established at the moment of system startup. Prioritizing differential pressure control can quickly establish pipeline pressure, overcome pipeline resistance, and ensure that cooling water is delivered to the farthest electromagnet as soon as possible, preventing local overheating caused by startup impact or lack of water, and ensuring the stability of the magnetic field.

[0045] Please see Figure 1 and Figure 3 As shown, in this embodiment, when the system is running stably ( Furthermore, the load heat load is low, resulting in a real-time temperature difference. The temperature difference remains consistently below the target temperature. At this point, the selection of the output of one of the PI controls, differential pressure proportional-integral PI control and temperature difference proportional-integral PI control, as the main control quantity, and the superposition of the historical output of the other PI control as the bias quantity, includes: When the real-time temperature difference The temperature difference remains consistently below the target temperature. Length of time Greater than the preset threshold When the system is deemed to have excessive traffic and potential for energy saving, a preset threshold is used. It can be set according to the system's thermal inertia and response speed requirements.

[0046] The system switches to temperature difference control output using proportional-integral (PI) temperature difference control. As the main control variable.

[0047] Locking the switching time Differential pressure proportional-integral PI control output These are then used as bias values ​​and superimposed to generate the final control output value; specifically, the final control output value is generated as follows:

[0048] in, The system clock value at the time of switching. The proportional gain is for temperature difference PI control. The integral gain of the temperature difference PI control. The deviation between the real-time temperature difference and the target temperature difference. The sampling period.

[0049] Understandably, this process achieves an automatic transition from "maintaining pressure" to "maintaining energy efficiency." While meeting heat dissipation requirements, the pump speed is reduced using temperature difference control. The retained historical pressure difference offset ensures that during low-frequency operation, the pipeline base pressure does not fall below the minimum threshold required to maintain hydraulic balance, avoiding insufficient flow at the far end due to a mere pursuit of energy conservation. In this embodiment, a combination of a dynamic adjustment term for the temperature difference deviation and a static superposition term for the historical pressure difference value is used. The dynamic adjustment term fine-tunes the pump speed based on the current heat load, while the static superposition term maintains the base flow rate. This combination achieves stable maintenance of the system's hydraulic conditions while reducing speed for energy conservation.

[0050] Please see Figure 1 and Figure 3 As shown, in this embodiment, under the mode primarily based on temperature difference proportional-integral PI control: When the system heat exchange rate decreases (i.e., the load heat generation decreases), the real-time temperature difference... It will increase; The temperature difference proportional-integral (PI) controller detected the deviation. Reduce, automatically decrease its output (i.e., the main control quantity) to maintain the real-time temperature difference. Equal to target temperature difference This also causes the operating speed of the circulating pump set to automatically decrease.

[0051] This automatic speed reduction mechanism enables on-demand cooling: when the heat load of the equipment decreases, the system automatically reduces the circulating water volume to avoid energy waste caused by oversupply, thereby achieving automatic reduction of the operating speed of the circulating pump group and energy-saving operation. For example, when some treatment chambers in a proton therapy system stop emitting beams, the heat load of the corresponding electromagnets decreases, and the system automatically reduces the pump speed, achieving energy-saving operation while maintaining a constant temperature difference.

[0052] In this embodiment, during the operation of the temperature difference energy-saving mode, that is, in the mode mainly based on temperature difference proportional integral PI control, if the electromagnet beam current suddenly increases, the load heat generation will increase dramatically.

[0053] Understandably, this embodiment achieves "on-demand operation" of the variable frequency pump set. When the electromagnet load decreases and the heat generation decreases, the PI regulator automatically reduces the operating speed output of the secondary pump set, which maintains a constant system temperature difference and achieves energy-saving operation of the circulating pump set, avoiding energy waste in traditional fixed-speed pumps or single differential pressure control modes.

[0054] Please see Figure 1 and Figure 3 As shown, in this embodiment, when the system detects the real-time pressure difference... Less than the target pressure difference (This means that the current flow rate is insufficient to overcome the resistance, and the hydraulic balance is disrupted.) The system immediately switches back to the output of the differential pressure proportional-integral (PI) control as the main control variable; Locking the switching time Temperature difference proportional-integral PI control output These are then used as bias values ​​and superimposed to generate the final control output value; specifically, the final control output value is generated as follows:

[0055] in, The system clock value at the time of switching. The proportional gain is for differential pressure PI control. The integral gain of the differential pressure PI control. The deviation between the real-time differential pressure and the target differential pressure. The sampling period.

[0056] Understandably, this embodiment achieves rapid fault protection and response. When the system faces a sudden high heat load requiring a larger flow rate, it can immediately abandon the energy-saving mode and prioritize restoring the pipeline pressure to ensure a rapid increase in the cooling flow rate of the electromagnet, preventing equipment overheating damage caused by pursuing energy conservation. This embodiment ensures that when switching back from energy-saving mode to powerful cooling mode, the system can instantly inherit the previous temperature difference control operating state (as a bias) while simultaneously adding the current pressure difference adjustment. This guarantees the smoothness and speed of the pump unit speed recovery process, avoiding a secondary drop in flow rate.

[0057] Please see Figure 1 and Figure 3 As shown, in this embodiment, to prevent sudden changes in pump speed caused by instantaneous mode switching, a non-disruptive switching strategy is adopted: As described in the previous embodiments, when switching between two modes, namely the temperature difference control output and the pressure difference control output, the output of the PI control that was switched off at the moment before the switch is obtained and superimposed on the main control output after the switch as an bias. For example, when switching from the pressure difference mode to the temperature difference mode, VPx_output(ta) is superimposed as the bias; when switching back from the temperature difference mode to the pressure difference mode, VTx_output(tb) is superimposed as the bias.

[0058] Simultaneously, the accumulated value of the integral term in the switched-out PI controller is obtained and transferred to the integral term of the switched-out PI controller as its initial value. For example, when switching from differential pressure mode to differential temperature mode, the current integral term value of the differential pressure PI controller is used as the initial value of the integral term of the differential temperature PI controller; when switching back from differential temperature mode to differential pressure mode, the current integral term value of the differential temperature PI controller is used as the initial value of the integral term of the differential pressure PI controller.

[0059] Understandably, the shift in the integral term eliminates integral saturation or sudden changes in the initial integral value during controller switching, thus ensuring the output signal... The continuity during switching ensures a smooth transition in pump operating speed, avoiding mechanical impact and water hammer damage to the pipeline system. Specifically, through the mutual transfer and offset superposition of integral terms, the system achieves disturbance-free switching during dual PI regulation, avoiding output jumps caused by abrupt changes in the integral term. This ensures a smooth transition in pump operating speed, preventing water hammer and pressure oscillations, and guaranteeing the stability and reliability of system operation.

[0060] Please see Figure 1 , Figure 2 and Figure 3 As shown, in this embodiment, the load device is an electromagnet cluster. Specifically, the electromagnet cluster includes diode and quadrupole electromagnets used in proton or heavy ion radiotherapy systems. These electromagnets are mainly used in beam transmission lines to precisely control the shape and transmission position of the proton beam.

[0061] In proton radiotherapy systems, there are typically multiple treatment rooms (e.g., three treatment rooms) and an accelerator, requiring the cooling of more than four electromagnet units. These electromagnets are mainly composed of copper coils. During operation, the temperature rise of the electromagnets increases their resistance, thus affecting the stability of the magnetic field. Using the control method of this invention, effective cooling control of the entire electromagnet cluster can be achieved simply by installing pressure and temperature sensors on the supply and return water mains of the manifold.

[0062] This method is specifically designed to address the heat dissipation requirements of electromagnet clusters. It can effectively solve the problems of increased resistance and magnetic field drift caused by temperature rise in electromagnets, ensuring the stable operation of the beam transmission line in the proton therapy system and improving treatment accuracy.

[0063] Please see Figure 1 , Figure 2 and Figure 3 As shown, this embodiment provides a cascade control system for a closed-loop cooling water circulation system, used for heat dissipation and cooling of load equipment. Specifically, the system includes: a pressure sensor, a temperature sensor, a circulation pump set, and a controller.

[0064] Pressure and temperature sensors are installed on the supply and return water mains, respectively, to acquire pressure and temperature signals. Specifically, pressure and temperature sensors are installed at the supply end and the return end of the manifold, respectively. These sensors are only used to acquire the pressure and temperature of the supply and return water mains; no additional mains flow meters or end sensors are installed.

[0065] The circulating pump set is used to drive the cooling water circulation. In this embodiment, the circulating pump set is a two-stage circulating pump set, driven by a frequency converter, and its operating speed is controlled by a controller.

[0066] The controller is configured to execute the cascade control method for the closed-loop cooling water circulation system as described in the above embodiments. The controller receives signals from pressure and temperature sensors, executes the cascade control method of the present invention, outputs control quantities to the frequency converter of the circulating pump group, adjusts the pump group operating speed, and realizes closed-loop control of the cooling water circulation.

[0067] This control system boasts a simple structure and low hardware cost, achieving high-performance cascade control solely through traditional manifold supply and return water pressure and temperature sensors. Compared to existing technologies, it eliminates the need for additional main pipe flow monitoring and terminal temperature and pressure difference data acquisition, significantly reducing initial hardware investment and maintenance costs. Furthermore, the controller's cascade control strategy balances remote hydraulic balancing with dynamic response to heat dissipation demands, ensuring stable operation of the electromagnet cluster.

[0068] This embodiment provides an electronic device for executing the above-described cascade control method.

[0069] The electronic device includes: at least one processor, and a memory communicatively connected to the at least one processor.

[0070] The memory stores a computer program executable by the at least one processor. The computer program contains executable instructions that implement the methods described in any of the above embodiments. When the computer program is executed by the at least one processor, the at least one processor is able to perform the cascade control method for the closed-loop cooling water system described above.

[0071] Specifically, the electronic device can be an industrial controller, an embedded control system, a programmable logic controller (PLC), a distributed control system (DCS), or a general-purpose computer. In practical applications, the electronic device is deployed in the cooling circulating water control system of a proton therapy system and communicates with pressure sensors, temperature sensors, and frequency converters of the circulating pump group located in the supply and return water mains.

[0072] When a processor executes a computer program, it performs the following operations: Obtain the pressure and temperature signals from the supply and return water mains, and obtain the real-time pressure difference. and real-time temperature difference ; Based on real-time pressure difference pressure difference with the preset target deviation Calculate the differential pressure control output. And based on real-time temperature difference The temperature difference with the preset target deviation Calculate the output of temperature difference control ; According to the real-time pressure difference With the target pressure difference The comparison results, the real-time temperature difference The target temperature difference The comparison results, and the real-time temperature difference The temperature difference remains consistently less than the target temperature difference. The time length is determined by selecting the output of one of the PI controls, pressure differential proportional integral PI control and temperature differential proportional integral PI control, as the main control quantity, and superimposing the historical output of the other PI control as the bias quantity to generate the final control output quantity. The final control output is applied to the circulating pump unit to drive its operation.

[0073] By deploying the aforementioned cascade control method as a computer program within an electronic device, automated intelligent control of the cooling water circulation system is achieved. This electronic device only needs to connect to existing pressure and temperature sensors in the main supply and return water pipes; no additional flow meters or end-point acquisition devices are required. It can automatically perform cascade switching control between constant temperature difference and constant pressure difference. Compared to existing technologies, this electronic device has low hardware cost, is easy to deploy, can respond in real-time to changes in heat dissipation demand, and ensures remote hydraulic balance, effectively improving the heat dissipation stability of the electromagnet cluster and the system's operating efficiency.

[0074] This embodiment provides a computer-readable storage medium for storing computer instructions for executing the above-described cascade control method.

[0075] The computer-readable storage medium stores computer instructions. When a computer (or processor, controller) reads and executes the computer instructions, the computer performs a cascade control method for a closed-loop cooling water circulation system as described in any of the above embodiments.

[0076] The computer-readable storage medium can be any medium capable of storing data, including but not limited to: read-only memory (ROM), random access memory (RAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, hard disk, solid-state drive (SSD), optical disk (CD-ROM, DVD), floppy disk, magnetic tape, magneto-optical disk, USB flash drive, portable hard drive, or any other medium capable of storing program code. The storage medium can be non-transitory or can temporarily store program instructions.

[0077] Obtain the pressure and temperature signals from the supply and return water mains, and obtain the real-time pressure difference. and real-time temperature difference ; Based on real-time pressure difference pressure difference with the preset target deviation Calculate the differential pressure control output. And based on real-time temperature difference The temperature difference with the preset target deviation Calculate the output of temperature difference control ; According to the real-time pressure difference With the target pressure difference The comparison results, the real-time temperature difference The target temperature difference The comparison results, and the real-time temperature difference The temperature difference remains consistently less than the target temperature difference. The time length is determined by selecting the output of one of the PI controls, pressure differential proportional integral PI control and temperature differential proportional integral PI control, as the main control quantity, and superimposing the historical output of the other PI control as the bias quantity to generate the final control output quantity. The final control output is applied to the circulating pump unit to drive its operation.

[0078] In practical applications, this computer-readable storage medium can be installed in the cooling water controller of a proton therapy system. Technicians can download the program containing the aforementioned computer instructions onto the controller via a USB flash drive, optical disc, or network, thereby enabling the controller to execute the cascade control method of this invention.

[0079] By storing the aforementioned cascade control method as computer instructions in a computer-readable storage medium, the method achieves portability and reusability across different hardware platforms. Users only need to load the computer instructions from this storage medium into any device with basic computing capabilities to enable that device to execute the cascade control method of this invention. This significantly lowers the technical implementation threshold and facilitates the intelligent upgrading and transformation of existing cooling water circulation systems. Furthermore, the storage medium can be easily copied, distributed, and backed up, which is beneficial for the promotion and application of this invention.

[0080] This invention proposes a cascade control method and system for a closed-loop cooling water circulation system, which has the following beneficial effects: The disturbance-free switching strategy proposed in this embodiment is the core algorithm mechanism for achieving "cascade switching". This strategy, through the synergistic effect of dual technical means, aims to completely solve the industry problem of sudden changes in pump speed during mode switching, ensuring the stability and reliability of the control system when switching between different operating conditions.

[0081] The bias superposition proposed in this embodiment achieves "memory inheritance" of the control signal by superimposing the PI control output that was switched off at the moment before the switch onto the main control output after the switch. This mechanism retains the historical adjustment information of the abandoned controller, so that the newly enabled control mode is not blindly adjusted from scratch, but is smoothly connected based on the previous actual operating state of the system, avoiding large jumps in the output signal caused by control logic gaps.

[0082] The integral term transfer proposed in this embodiment eliminates the common problems of integral saturation or sudden changes in initial integral values ​​during controller switching by directly assigning the accumulated value of the original PI controller's integral term to the new controller's integral term at the moment of switching. This method ensures the continuity of integral action and prevents system response hysteresis or overshoot caused by resetting the initial integral value. It is a key technical means to ensure that the control output does not undergo a step change at the moment of switching.

[0083] The combined application of these two strategies ensures the continuity of the final output signal during mode switching, achieving a smooth transition in pump operating speed. This smooth transition effectively avoids mechanical shock and water hammer damage to the pipeline system, not only improving the system's operational stability but also significantly extending the service life of pumps, pipeline valves, and other mechanical equipment, reducing maintenance costs, and providing a reliable guarantee for the continuous and safe operation of industrial production.

[0084] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A cascade control method for a closed-loop cooling water system, used for heat dissipation and cooling of load equipment, characterized in that, include: Obtain the pressure and temperature signals from the supply and return water mains, and obtain the real-time pressure difference. and real-time temperature difference ; Based on real-time pressure difference pressure difference with the preset target deviation Calculate the differential pressure control output. And based on real-time temperature difference The temperature difference with the preset target deviation Calculate the output of temperature difference control ; According to the real-time pressure difference With the target pressure difference The comparison results, the real-time temperature difference The target temperature difference The comparison results, and the real-time temperature difference The temperature difference remains consistently less than the target temperature difference. The time length is determined by selecting the output of one of the PI controls, pressure differential proportional integral PI control and temperature differential proportional integral PI control, as the main control quantity, and superimposing the historical output of the other PI control as the bias quantity to generate the final control output quantity. The final control output is applied to the circulating pump unit to drive its operation.

2. The cascade control method for a closed-loop cooling water system according to claim 1, characterized in that, The selection process uses the output of one of the PI controls, differential pressure proportional-integral PI control and temperature difference proportional-integral PI control, as the main control variable, and superimposes it with the historical output of the other PI control as the bias variable. Specifically, this includes: When the system starts, the output of the differential pressure PI control is used as the main control quantity, and zero is used as the bias quantity to generate the final control output quantity.

3. The cascade control method for a closed-loop cooling water circulating system according to claim 1, characterized in that, The selection process, which uses the output of one of the PI controls—pressure differential proportional-integral PI control and temperature differential proportional-integral PI control—as the primary control variable and superimposes it with the historical output of the other PI control as the bias, also includes: When the real-time pressure difference Stable and the real-time temperature difference The temperature difference remains consistently less than the target temperature difference. Length of time Greater than the preset threshold At that time, the system switches to the output controlled by the proportional-integral PI of the temperature difference. The main control variable is PI control with the current pressure difference as the proportional integral. These are superimposed as bias values ​​to generate the final control output.

4. The cascade control method for a closed-loop cooling water circulating system according to claim 3, characterized in that, The final control inputs are as follows: in, The system clock value at the time of switching. The proportional gain is for temperature difference PI control. The integral gain of the temperature difference PI control. The deviation between the real-time temperature difference and the target temperature difference. The sampling period.

5. The cascade control method for a closed-loop cooling water circulating system according to claim 3, characterized in that, The method further includes: in a mode primarily based on temperature difference proportional-integral PI control, when the system heat exchange decreases, the temperature difference proportional-integral PI control automatically reduces its output to maintain the real-time temperature difference. This equals the target temperature difference, thereby achieving automatic reduction of the operating speed of the circulating pump group and energy-saving operation.

6. The cascade control method for a closed-loop cooling water circulating system according to claim 2, characterized in that, The selection process, which uses the output of one of the PI controls—pressure differential proportional-integral PI control and temperature differential proportional-integral PI control—as the primary control variable and superimposes it with the historical output of the other PI control as the bias, also includes: In the mode primarily based on temperature difference proportional-integral PI control, when the system detects real-time pressure difference... Less than the target pressure difference When the pressure difference is controlled by a proportional-integral PI controller, the system immediately switches to using the output quantity controlled by the pressure difference as the main control quantity, and uses the temperature difference as the current temperature difference as the output quantity. These are superimposed as bias values ​​to generate the final control output.

7. The cascade control method for a closed-loop cooling water circulating system according to claim 6, characterized in that, The final control output is as follows: in, The system clock value at the time of switching. The proportional gain is for differential pressure PI control. The integral gain for differential pressure PI control. The deviation between the real-time differential pressure and the target differential pressure. The sampling period.

8. The cascade control method for a closed-loop cooling water circulating system according to any one of claims 1 to 7, characterized in that, When switching control modes, a seamless switching process is performed, specifically including: Obtain the output of the PI control that was switched off at the moment before the switch, and add it as an bias to the main control quantity after the switch. At the same time, the integral term value of the switched-off PI control is obtained and transferred to the switched-off PI control as its initial value, so as to maintain the mutual transfer of the integral term values ​​of the PI algorithm and realize the smooth transition of the pump group's operating speed.

9. The cascade control method for a closed-loop cooling water circulating system according to claim 2, characterized in that, The differential pressure control output and temperature difference control output Calculated using the following formulas respectively: in, , For the proportional gain and integral gain of the differential pressure PI controller, , For the proportional gain and integral gain of the temperature difference PI controller, The sampling period.

10. The cascade control method according to claim 2, characterized in that, The load device is an electromagnet cluster.

11. A cascade control system for a closed-loop cooling water circulation system, used for heat dissipation and cooling of load equipment, characterized in that, include: Pressure and temperature sensors are installed in the main water supply pipe and the main water return pipe, respectively, to acquire pressure and temperature signals. A circulating pump set is used to drive the circulation of cooling water; The controller is configured to perform the cascade control method for a closed-loop cooling water system as described in any one of claims 1 to 10.

12. An electronic device, characterized in that, include: At least one processor; A memory that is communicatively connected to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the cascade control method for a closed cooling circulating water system as described in any one of claims 1 to 10.

13. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when read and executed by a computer, cause the computer to perform the cascade control method for a closed-loop cooling water system as described in any one of claims 1 to 10.

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