Wireless control system suitable for feedback regulation of valve body of steam pipeline in petrochemical industry

Abstract

This application relates to the field of industrial automatic control technology, specifically to a wireless control system for feedback regulation of valves in petrochemical steam pipelines. The system comprises: a field wireless terminal module that collects pipeline operating data and calibrates the moment of a sudden event based on the pressure difference between adjacent times at the steam supply end; and a cloud service platform module that constructs a hydrothermal coupling simulation model based on the operating data to obtain the dynamic thermodynamic parameters of each node after the sudden event; furthermore, it constructs steam supply stability characteristic values ​​characterizing pressure recovery capability and steam supply quality characteristic values ​​characterizing thermal degradation, and merges them to determine the comprehensive steam supply characteristic value; with the goal of minimizing the comprehensive steam supply characteristic value, it selects key valves and optimizes their opening, generating valve control commands. This application solves the problems of existing valve regulation lacking prediction, leading to regulation lag, over-regulation, or under-regulation, and improves the dynamic disturbance rejection capability and steam supply reliability of the steam pipeline network.

Description

Technical Field

[0001] This application relates to the field of industrial automatic control technology, specifically to a wireless control system applicable to feedback regulation of valve bodies in petrochemical steam pipelines. Background Technology

[0002] In petrochemical production, steam, as a core high-temperature heat energy carrier, is widely used in reactor heating, process driving, and energy transfer. Steam pipeline systems typically exhibit a vast network characteristic of multiple steam sources, users, and loops, with a complex topology and covering multiple pressure levels. In actual operation, the network is highly susceptible to drastic fluctuations in steam pressure and significant deviations in flow rate due to the combined effects of intermittent changes in user steam consumption, frequent adjustments to production loads, seasonal operating condition switching, and sudden accidents. If such hydraulic and thermal imbalances are not promptly addressed, they can easily induce severe safety accidents such as steam hammer and water surge, causing irreversible damage to pipelines and critical equipment.

[0003] Valve regulation in steam pipelines is the most direct and effective means of dealing with pressure fluctuations and ensuring the safe operation of the pipeline network. Existing valve control methods mostly use simple on / off control or fixed parameter PID, which cannot cope with the nonlinear, large inertia, and large hysteresis characteristics of steam systems. They lack quantitative analysis and prediction of the dynamic response characteristics of the pipeline network, and the problem of inappropriate regulation amplitude is prominent, which can easily lead to over-regulation or under-regulation, reducing the dynamic disturbance rejection capability and steam supply reliability of the steam pipeline network. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a wireless control system suitable for feedback regulation of valve bodies in petrochemical steam pipelines. The specific technical solution adopted is as follows: This application proposes a wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines, the system comprising: The on-site wireless terminal module is used to collect in real time the opening degree of pipeline valves in the steam pipeline network, the pressure and temperature of steam at the steam supply end, and the mass flow rate at the user end; based on the difference in steam pressure at any steam supply end between adjacent moments, it is used to calibrate the moment of sudden change. The cloud service platform module is used to establish a hydrothermal coupling simulation model based on the opening degree of the pipeline valve body, the steam temperature and steam pressure at the steam supply end, and the mass flow rate at the user end, so as to obtain the steam pressure and steam temperature of any node in the topology of the steam pipeline network at preset time steps after the sudden moment. After a sudden event, the average distribution of steam pressure at any node within a preset time step interval and the degree of fluctuation of steam pressure at any node within a preset duration are analyzed to construct the steam supply stability characteristic value of the steam pipeline network. After the sudden event, by analyzing the phase change risk and enthalpy fluctuation of steam temperature at any node within the adjacent time step, the steam supply quality characteristic value of the steam pipeline network is constructed, and combined with the steam supply stability characteristic value, the comprehensive steam supply characteristic value of the steam pipeline network is determined. Based on the comprehensive steam supply characteristic values, key valve bodies are screened and the optimal opening degree is searched to generate steam pipeline valve body control commands, which are used to control the closed-loop feedback of non-point variables such as steam pressure, steam temperature, and steam flow in the steam pipeline network.

[0005] Preferably, the determination of the sudden event includes: The moment when the difference between the steam pressure at any steam supply end at any given moment and the steam pressure at the next adjacent moment exceeds a preset steady-state threshold is designated as a sudden moment.

[0006] Preferably, the step of obtaining the steam pressure and steam temperature of any node in the topology of the steam pipeline network at each preset time step after the sudden event includes: The opening degree of the pipeline valve body, the steam pressure and steam temperature at the steam supply end, and the mass flow rate at the user end at the moment immediately preceding the sudden incident are input into the water-thermal coupling simulation model, and the steam pressure, steam temperature, and mass flow rate at all nodes in the topology of the steam pipeline network at the moment immediately preceding the sudden incident are output. Replace the steam pressure and steam temperature of the corresponding node at the steam supply end in the steam network topology at the time immediately preceding the sudden event with the steam pressure and steam temperature at the time of the sudden event. Keep the other data as the corresponding data at the previous time and use them as input to the hydrothermal coupling simulation model. Output the steam pressure and steam temperature of any node in the topology of the steam network at each preset time step after the sudden event.

[0007] Preferably, the process of constructing the topology of the steam pipeline network includes: The valve body, steam supply end, user end, pipe junction, pipe diameter change point, and pipe end closure point in the steam pipeline network are respectively regarded as nodes in the topology, and the pipes in the steam pipeline network are equivalent to edges in the topology to construct the topology of the steam pipeline network.

[0008] Preferably, the hydrothermal coupling simulation model includes the mass conservation equation, momentum conservation equation, and energy conservation equation for each node in the topology of the steam pipeline network.

[0009] Preferably, the process for constructing the stable steam supply characteristic values ​​of the steam pipeline network is as follows: After the sudden event, calculate the average steam pressure at any node within all time steps in the preset time step interval, and record it as the steady-state response value of any node. The recovery delay ratio of any node is constructed by comparing the steam pressure and steady-state response value at each time step. The steam supply stability characteristic value of the steam pipeline network is positively correlated with the degree of fluctuation of steam pressure at any node within a preset time after the sudden event and the recovery delay ratio.

[0010] Preferably, the process for constructing the recovery latency ratio of any node is as follows: Within a preset time period following the sudden event, for any node, if the deviation between the steam pressure and the steady-state response value under a preset number of consecutive time steps is within a preset threshold range, then the ratio of the order corresponding to the first time step among the preset number of time steps to the number of all time steps within the preset time period is used as the recovery delay ratio of any node; otherwise, the recovery delay ratio of any node is set to 1.

[0011] Preferably, the process of constructing the steam supply quality characteristic values ​​of the steam pipeline network is as follows: After the sudden event, calculate the steam saturation temperature and specific enthalpy of the steam temperature at any node within each adjacent time step. Within a preset time period following the sudden event, the steam temperature phase change risk characteristic value of any node is constructed by analyzing the difference between the steam temperature and the steam saturation temperature at any node within each time step. By analyzing the degree of enthalpy fluctuation within a preset time after a sudden event, the enthalpy fluctuation amplitude at any node is constructed. The steam supply quality characteristic value of the steam pipeline network is positively correlated with the steam temperature phase change risk characteristic value and the enthalpy fluctuation amplitude, respectively.

[0012] Preferably, the comprehensive steam supply characteristic value of the steam pipeline network is the result of a weighted sum of the steam supply stability characteristic value and the steam supply quality characteristic value of the steam pipeline network.

[0013] Preferably, the process of screening key valve bodies and searching for the optimal opening degree includes: In all the pipe valves of the steam network, the opening of any pipe valve is adjusted according to a preset adjustment amount, while keeping the opening of all other pipe valves unchanged. According to the calculation method of the comprehensive steam supply characteristic value, the comprehensive steam supply characteristic value of the steam network after the opening of any pipe valve is adjusted is calculated. Based on the difference between the comprehensive steam supply characteristic values ​​before and after the opening degree adjustment of any pipeline valve, the opening sensitivity of any pipeline valve is calculated in order to screen out the key valve from all pipeline valves. Based on the opening sensitivity of key valve bodies, and using the golden section search algorithm to search within the preset feasible region of valve body openings, the opening of all key valve bodies that minimize the comprehensive characteristic value of the steam pipeline network is taken as their respective optimal opening.

[0014] This application has the following beneficial effects: This application constructs a simulation model of the steam pipeline network topology and hydrothermal coupling, and performs time-domain iterative solution based on the boundary conditions before and after the sudden moment. It achieves accurate prediction of the dynamic response process of steam pressure and temperature at any node in the pipeline network. This method breaks through the limitation of traditional control relying on lagging field feedback. Through simulation, it proactively quantifies the propagation and attenuation characteristics of disturbances along the pipeline network, providing reliable data-driven decision-making basis for subsequent rapid assessment of steam supply stability and thermal quality degradation, accurate selection of key valves, and optimization of control strategies. Furthermore, this application constructs a steam supply stability characteristic value for a steam pipeline network by analyzing the average distribution of steam pressure at any node within a preset time step interval and the degree of fluctuation of steam pressure at any node within a preset duration. The steam supply stability characteristic value characterizes the comprehensive ability of the steam pipeline network to resist pressure shocks and rapidly self-heal, effectively overcoming the one-sidedness of a single fluctuation index or time index, and providing a reliable quantitative basis for accurately assessing the degree of deterioration in steam supply stability and subsequent optimization of valve body control strategies. Furthermore, this application constructs steam supply quality characteristic values ​​of the steam pipeline network by analyzing the phase change risk and enthalpy fluctuation amplitude of steam temperature at any node within adjacent time steps, and combines the steam supply stability characteristic values ​​to determine the comprehensive steam supply characteristic values ​​of the steam pipeline network. The comprehensive steam supply characteristic values ​​characterize the comprehensive anti-disturbance capability of the steam pipeline network under the dual coupling of pressure shock and thermal decay, making up for the shortcomings of single pressure stability assessment, and providing key thermodynamic quantitative basis for optimizing valve body control strategies. Ultimately, this application identifies key valves with global control dominance by quantifying the impact of each valve opening adjustment on the comprehensive characteristic value. Then, it employs the golden section search algorithm to efficiently optimize the valve opening within the safe and feasible region with the goal of minimizing the comprehensive characteristic value, and finally generates valve control commands. This method effectively avoids the computational time consumption and secondary disturbance risks caused by global traversal optimization. Under the premise of ensuring the physical accuracy of the actuator and process safety constraints, it realizes closed-loop feedback regulation of the steam pipeline network with fewer actions, faster response, and higher precision under sudden operating conditions, significantly improving the dynamic anti-disturbance capability and steam supply reliability of the steam pipeline network. Attached Figure Description

[0015] Figure 1 A block diagram of a wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines, provided as an embodiment of this application; Figure 2 This is a schematic diagram of the steam supply comprehensive feature value extraction process provided in one embodiment of this application. Detailed Implementation

[0016] The following description, in conjunction with the accompanying drawings, details the specific scheme of the wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines provided in this application.

[0017] Please see Figure 1 The diagram illustrates a block diagram of a wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines, provided in one embodiment of this application. The system consists of three parts: a field wireless terminal module 101, a cloud service platform module 102, and a monitoring client module 103.

[0018] This embodiment essentially constructs a closed-loop feedback control system based on a digital twin model. The cloud service platform module serves as the core controller of the control system, and its internal "hydrothermal coupling simulation model" acts as a state observer within the control system, used to proactively perceive dynamic changes within the pipeline network. The construction process of the "comprehensive steam supply characteristic value" essentially transforms the multi-variable physical state into a single-dimensional control deviation signal. The process of "screening key valve bodies and optimizing their opening" constitutes the control decision unit. Through the cooperation of the field wireless terminal module (sensor end) and the execution module (execution end), this system achieves automatic adjustment and stable control of the non-electrical variables of steam pipeline network pressure and temperature.

[0019] The on-site wireless terminal module 101 is used to collect in real time the opening degree of the pipeline valve body, the pressure and temperature of the steam at the steam supply end, and the mass flow rate at the user end in the steam pipeline network; and to calibrate the sudden moment based on the difference in steam pressure at any steam supply end between adjacent moments.

[0020] The field wireless terminal module is not only responsible for data acquisition, but also serves as a feedback link in the control system. Its function of "calibrating sudden moments" is equivalent to the trigger signal determination unit of the control system, which is used to identify external disturbances to the system and thus trigger the controller's control actions.

[0021] In petrochemical production scenarios, the use of distributed control systems (DCS) for steam pipeline valve regulation presents problems such as complex changes in field data and the inability to update data in real time, resulting in lag in valve regulation response. For data communication, the use of wired connections or short-range wireless protocols (Zigbee, Lora) has drawbacks such as cumbersome installation, limited communication distance, and high power consumption.

[0022] This embodiment utilizes wireless terminals equipped with low-power NB-IoT modules, which are installed on steam pipeline valve bodies, steam supply instruments, and user instruments to achieve low-power wireless valve control, thereby improving the timeliness, stability, and economy of valve regulation in petrochemical production processes. Based on their installation location, the field wireless terminal modules can be categorized into three types: valve control terminals, steam supply instrument terminals, and user instrument terminals.

[0023] The valve body regulating terminal specifically includes a housing assembly, a sensor acquisition module, a central processing module, and a wireless communication module: Housing assembly: The housing is based on existing explosion-proof certifications, with a gland head model of M8, which can meet the explosion-proof requirements of high-risk scenarios such as petrochemical plants and prevent dust, moisture and other substances from entering the equipment.

[0024] Sensor acquisition module: The valve body adjustment terminal integrates a valve position sensor to measure the valve body opening of the steam pipeline control valve.

[0025] Central Processing Module: The valve body adjustment terminal is set to a fixed-cycle upload mode. Every fixed cycle, the central processing module reads the valve opening from the sensor acquisition module through the ADC interface, transmits it to the wireless communication module, and sends a wireless upload command to the wireless communication module. The fixed cycle can be set to 1 hour. The central processing module reads the valve adjustment command sent by the cloud service platform module from the wireless communication module of the valve body adjustment terminal, pauses the fixed-cycle upload mode, transmits the valve adjustment command to the steam pipeline intelligent control valve, records the timestamp TS when the steam pipeline intelligent control valve completes valve body adjustment, reads the latest valve opening data from the sensor acquisition module through the ADC interface, immediately transmits it to the wireless communication module, sends a wireless upload command to the wireless communication module, and restarts the fixed-cycle upload mode from the timestamp TS.

[0026] Wireless communication module: Utilizing NB-IoT communication, it uploads valve opening data transmitted by the central processing module to the cloud service platform module. The valve adjustment terminal needs to receive valve adjustment commands issued by the cloud service platform module. The NB-IoT communication of the wireless communication module adopts eDRX (Extended DRX). After receiving the paging signal from the cloud service platform module, the valve adjustment terminal temporarily exits the eDRX sleep state and enters continuous listening mode to ensure that the valve adjustment terminal receives and executes the opening adjustment command in a timely manner. After the valve adjustment task is completed, the valve adjustment terminal sends back the adjustment result with a timestamp and resumes the low-power cycle mode, balancing the low-power operation of the field wireless terminal module with the real-time adjustment requirements of sudden working conditions.

[0027] The steam supply instrument terminal specifically includes a housing assembly, a sensor acquisition module, a central processing module, and a wireless communication module: Housing assembly: The housing is based on existing explosion-proof certifications, with a gland head model of M8, which can meet the explosion-proof requirements of high-risk scenarios such as petrochemical plants and prevent dust, moisture and other substances from entering the equipment.

[0028] Sensor acquisition module: The steam supply instrument terminal integrates a temperature sensor and a steam pressure transmitter, which are used to measure the steam pressure and steam temperature at the steam supply end, respectively. Since the steam pipeline valve body adjustment needs to take into account both low power consumption and time delay requirements, the acquisition interval of the steam pressure transmitter and temperature sensor is set to 10s. In actual application, as other implementation methods, implementers can also set it according to specific circumstances. This embodiment does not impose any special restrictions.

[0029] Central Processing Module: The central processing module reads the steam temperature and steam pressure at the steam supply end from the sensor acquisition module via the ADC interface. Furthermore, based on the difference in steam pressure at any steam supply end between adjacent time points, it calibrates the moment of sudden change. Specifically, in this embodiment, the difference in steam pressure at any steam supply end between each time point and its adjacent previous time point is calculated. In this embodiment, the absolute difference in steam pressure at any steam supply end between each time point and its adjacent previous time point is divided by the steam pressure at the previous time point, and this result is taken as the difference in steam pressure at any steam supply end between each time point and its adjacent previous time point. For ease of description, this difference is recorded as the steam pressure deviation ratio at any steam supply end at each time point. If the steam pressure deviation ratio is higher than the steady-state threshold, it indicates that the steam supply conditions of the steam pipeline network have fluctuated drastically, and pipeline condition information should be uploaded promptly, and the steam pressure at any steam supply end should be recorded. When the deviation ratio exceeds the preset steady-state threshold, it is designated as a sudden event. The central processing module reads all unuploaded steam temperature and steam pressure data from the register, transmits them to the wireless communication module, and issues a wireless upload command to the wireless communication module. The steam supply instrument terminal then re-enters the fixed-cycle upload mode. Conversely, if the steam pressure deviation ratio does not exceed the steady-state threshold, the steam supply condition of the steam pipeline network is stable, and the steam supply instrument terminal is in the fixed-cycle upload mode. The central processing module collects steam temperature and steam pressure data from all acquisition moments within the fixed cycle, transmits them to the wireless communication module, and issues a wireless upload command to the wireless communication module. In this embodiment, the fixed cycle is set to 1 hour, and the preset steady-state threshold is specifically set to 0.2. In actual applications, as other implementation methods, implementers can also set it according to specific circumstances. This embodiment does not impose any special restrictions.

[0030] Wireless communication module: It adopts NB-IoT communication to upload the steam temperature and steam pressure data transmitted by the central processing module to the cloud service platform module. The NB-IoT communication of the wireless communication module adopts eDRX (Extended DRX) to reduce the replacement cycle of the power supply battery and reduce communication power consumption.

[0031] The user instrument terminal specifically includes a housing assembly, a sensor acquisition module, a central processing module, and a wireless communication module: Housing assembly: The housing is based on existing explosion-proof certifications, with a gland head model of M8, which can meet the explosion-proof requirements of high-risk scenarios such as petrochemical plants and prevent dust, moisture and other substances from entering the equipment.

[0032] Sensor acquisition module: The user instrument terminal integrates a mass flow meter to measure the mass flow rate of steam at the user end. Since the steam pipeline valve adjustment needs to take into account both low power consumption and time delay requirements, the acquisition interval of the mass flow meter is set to 10s in this embodiment. In actual application, the implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0033] Central Processing Module: The central processing module reads the mass flow rate of the sensor acquisition module through the ADC interface, sets the user instrument terminal to a fixed-period upload mode, and reads the mass flow rate value of the sensor acquisition module through the ADC interface every fixed period, transmits it to the wireless communication module, and issues a wireless upload command to the wireless communication module. The fixed period can be set to 1 hour.

[0034] Wireless communication module: It adopts NB-IoT communication to upload the mass flow data transmitted by the central processing module to the cloud service platform module. The NB-IoT communication of the wireless communication module adopts eDRX (Extended DRX) to reduce the replacement cycle of the power supply battery and reduce communication power consumption.

[0035] The cloud service platform module 102 is used to establish a hydrothermal coupling simulation model based on the opening degree of the pipeline valve, the steam temperature and steam pressure at the steam supply end, and the mass flow rate at the user end. This model obtains the steam pressure and steam temperature of any node in the topology of the steam pipeline network at preset time steps after the sudden event. After the sudden event, the model analyzes the average distribution of steam pressure at any node within the preset time step interval and the degree of fluctuation of steam pressure at any node within the preset duration to construct the steam supply stability characteristic value of the steam pipeline network. After the sudden event, the model analyzes the phase change risk and enthalpy fluctuation amplitude of steam temperature at any node within adjacent time steps to construct the steam supply quality characteristic value of the steam pipeline network. Combined with the steam supply stability characteristic value, the model determines the comprehensive steam supply characteristic value of the steam pipeline network. Based on the comprehensive steam supply characteristic value, the model filters key valves and searches for the optimal opening degree to generate steam pipeline valve control commands.

[0036] The cloud service platform module, serving as the central hub for feedback regulation of steam pipeline valves, is deployed on an enterprise private cloud or industrial internet platform, providing data aggregation, storage, analysis, and command issuance services. Core functions include: Data access and storage: The system receives pipeline operating data reported by all field wireless terminal modules via NB-IoT communication. Specifically, the pipeline operating data includes valve opening data of pipeline control valves, steam pressure and steam temperature data of steam supply instruments, and mass flow data of user instruments, and persistently stores them in a time-series database.

[0037] Data Analysis: The steam supply system of petrochemical enterprises relies on boiler groups and waste heat utilization devices to form a layered steam supply structure. Steam is transported to the petrochemical production area through steam pipelines and their accessories. If the cloud service platform module receives the upload information from the steam supply instrument terminal in event-triggered upload mode, it will simultaneously send sampling instructions to all nodes in the steam pipeline network, collect the pipeline condition data of the steam pipeline network at the moment before the sudden event, obtain the topology diagram of the steam pipeline network according to the topology construction module, and obtain the steam pipeline valve control instructions through the simulation digital model construction module and the pipeline valve feedback module.

[0038] Command issuance: After the cloud service platform module obtains the steam pipeline valve body control command through data analysis, it immediately sends a paging command to the selected key valve bodies and issues the valve body control command to the corresponding field wireless terminal module through the NB-IoT network.

[0039] To realize the data analysis and closed-loop feedback regulation functions of the aforementioned cloud service platform module, and to overcome the problems of over- or under-regulation caused by the nonlinearity and large lag of the steam system, this embodiment constructs a pipeline network simulation and deduction system based on digital twins within the cloud service platform module. A hydrothermal coupling simulation model is established based on the opening degree of pipeline valves, the steam temperature and pressure at the steam supply end, and the mass flow rate at the user end. This model obtains the steam pressure and steam temperature of any node in the topology of the steam pipeline network at preset time steps after the sudden event. After the sudden event, the average distribution of steam pressure at any node within the preset time step interval and the degree of fluctuation of steam pressure at any node within the preset duration are analyzed to construct the steam supply stability characteristic value of the steam pipeline network. After the sudden event, the phase change risk and enthalpy fluctuation amplitude of steam temperature at any node within adjacent time steps are analyzed to construct the steam supply quality characteristic value of the steam pipeline network. Combined with the steam supply stability characteristic value, the comprehensive steam supply characteristic value of the steam pipeline network is determined. Based on the comprehensive steam supply characteristic value, key valves are screened and the optimal opening degree is searched to generate steam pipeline valve control commands. The specific process is as follows: S1: Establish a hydrothermal coupling simulation model based on the opening degree of the pipeline valve body, the steam temperature and steam pressure at the steam supply end, and the mass flow rate at the user end, so as to obtain the steam pressure and steam temperature of any node in the topology of the steam pipeline network at each preset time step after the sudden moment.

[0040] Given the complex structure of steam pipeline networks with multiple steam sources, users, loops, and pressure levels, a network topology diagram is needed to characterize the actual connection relationships between pipe segments and nodes in order to calculate the hydraulic and thermal parameters of steam. Therefore, in this embodiment, firstly, based on the geographic information system data of the steam pipeline network, a simplified model of the actual network is performed according to the principle of hydraulic and thermal equivalence: key components of the steam pipeline network are abstracted as topological nodes, and pipe elements connecting adjacent nodes are abstracted as edges between nodes; specifically, the topological nodes include valve body nodes, steam source nodes, user nodes, junction nodes, diameter change nodes, and closed nodes, which are abstracted from valve bodies, steam supply ends, user ends, pipe junctions, pipe diameter change points, and pipe end closure points, respectively; an association matrix is ​​used to describe the topological connection relationships between nodes and edges, and the matrix elements... The definition is: if the steam flow direction of pipe i is from node j, then =1; if the steam flow direction of pipe j is inflow into node i, then =-1; if pipe j is not connected to node i, then =0.

[0041] Furthermore, in this embodiment, a water-thermal coupling simulation model is established based on the opening degree of the pipeline valve body, the steam temperature and steam pressure at the steam supply end, and the mass flow rate at the user end. The water-thermal coupling simulation model includes the mass conservation equation, momentum conservation equation, and energy conservation equation for each node in the topology of the steam pipeline network. The specific establishment process is as follows: (1) Mass conservation equation: For any node i in the steam pipeline network topology, its mass conservation equation is: ; In the formula, This represents the volume (m³) of node i in the topology of the steam pipeline network. This represents the steam density at node i in the topology of the steam pipeline network (unit: kg / m³). These are the elements corresponding to node i and node j in the correlation matrix of the steam pipeline network topology. The mass flow rate (in kg / s) between node i and node j in the topology of the steam pipeline network represents the total number of nodes in the topology of the steam pipeline network.

[0042] (2) Momentum conservation equation: For any pipe segment ij in the topology of the steam pipeline network, its momentum conservation equation is: ; In the formula, This represents the inertia coefficient of the pipe between node i and node j in the topology of the steam pipeline network. , These represent the steam pressures (in Pa) at nodes i and j in the topology of the steam pipeline network. The height potential energy difference (in Pa) between node i and node j in the topology of the steam pipeline network. This represents the resistance coefficient of the pipe between node i and node j in the topology of the steam pipeline network.

[0043] (3) Energy conservation equation: For any node i in the topology of the steam pipeline network, its energy conservation equation is: ; In the formula, This represents the specific internal energy (in kJ / kg) of node i in the topology of the steam pipeline network. , These represent the values ​​of the corresponding elements in the correlation matrix for the steam inflow and outflow nodes of nodes i and j in the topology of the steam pipeline network, respectively. This represents the specific enthalpy (in kJ / kg) at node i in the topology of the steam pipeline network. This represents the heat dissipation flow rate (in kJ / s) of the pipe between node i and node j in the topology of the steam pipe network. The calculation formula is: , This represents the absolute difference (in °C) between the steam temperature inside the pipe between node i and node j in the topology of the steam pipeline network and the ambient temperature. This represents the length (in meters) of the pipe between node i and node j in the topology of the steam pipe network. This represents the heat transfer coefficient per unit length of the pipe between node i and node j in the topology of the steam pipe network (unit: W / (m·K)).

[0044] It should be noted that in the above-mentioned dynamic water-thermal coupling simulation mathematical model of the steam pipeline network, all parameters were calculated using known techniques or obtained through on-site data acquisition: where the node volume is... Pipeline inertia coefficient drag coefficient Potential energy difference at height Pipe section length and heat transfer coefficient per unit length These are all inherent physical properties of the pipeline network, determined by calculations based on the topology of the steam pipeline network and pipe design parameters (such as pipe diameter, roughness, elevation difference, insulation thickness, etc.) using well-known empirical formulas in fluid mechanics and heat transfer; steam pressure , The absolute temperature difference between the inside and outside of the pipeline is collected in real time by instruments at the steam supply end and instrument terminals at the user end. The steam density is calculated from the collected steam temperature and the ambient temperature. Internal energy enthalpy Thermodynamic state parameters of steam are obtained by substituting pressure and temperature obtained through real-time acquisition or simulation iteration into the internationally recognized thermodynamic property formulas for water and steam (IAPWS-IF97) for table lookup and interpolation calculations; mass flow rates between nodes. It serves as an intermediate iterative variable in the dynamic simulation process, and is calculated in real time by simultaneously solving the above mass, momentum, and energy conservation equations.

[0045] Furthermore, in this embodiment, the opening degree of the pipeline valve body, the steam pressure and steam temperature at the steam supply end, and the mass flow rate at the user end at the moment immediately preceding the sudden event are input into the water-thermal coupling simulation model. The fourth-order Runge-Kutta method is used to perform iterative solution in the time domain, and the steam pressure, steam temperature, and mass flow rate at all nodes in the topology of the steam pipeline network at the moment immediately preceding the sudden event are output. The steam pressure and temperature of the corresponding node at the steam supply end in the steam network topology at the moment immediately preceding the sudden event are replaced with the steam pressure and temperature at the moment of the sudden event. The remaining data are kept as the corresponding data at the previous moment and used as input to the hydrothermal coupling simulation model. The fourth-order Runge-Kutta method is used for iterative solution in the time domain, and the obtained differential equation is integrated to output the steam pressure and steam temperature of any node in the steam network topology at each preset time step after the sudden event. In this embodiment, the integration interval is set to 5 seconds, and the integration calculation is performed every 5 seconds. The time when every 5 seconds ends is recorded as a time step. The integration operation is a well-known technique and will not be described in detail.

[0046] The process of using the fourth-order Runge-Kutta method for iterative solution in the time domain is a well-known technique and will not be elaborated further.

[0047] Thus, this embodiment, by constructing a steam pipeline network topology and a hydrothermal coupling simulation model, and by performing time-domain iterative solutions based on the boundary conditions before and after the sudden event, achieves accurate prediction of the dynamic response process of steam pressure and temperature at any node in the pipeline network. This method breaks through the limitations of traditional control relying on lagging field feedback, and proactively quantifies the propagation and attenuation characteristics of disturbances along the pipeline network through simulation deduction. It provides reliable data-driven and decision-making basis for subsequent rapid assessment of steam supply stability and thermal quality degradation, accurate selection of key valves, and optimization of control strategies.

[0048] S2: After the sudden event, the average distribution of steam pressure at any node within a preset time step interval and the degree of fluctuation of steam pressure at any node within a preset duration are analyzed to construct the steam supply stability characteristic value of the steam pipeline network.

[0049] During the control strategy generation process, the control system needs to obtain the dynamic response of the controlled object. The hydrothermal coupling simulation model in step S1 acts as a "state observer" in the control system. Traditional PID control relies on the lag signal fed back by the sensor. However, in this embodiment, the dynamic process of the pipeline network after being disturbed is reconstructed in advance inside the controller through the simulation model, which solves the control problem of large lag system. The steam pressure and steam temperature of any node in the topology of the steam pipeline network at each preset time step after the sudden moment are obtained, which is the predicted state value of the controlled variable obtained by the controller.

[0050] Petrochemical production processes heavily rely on high-quality steam as the core power medium, playing a crucial role in heating, distillation, heat exchange, and equipment operation. Petrochemical plants have stringent requirements for the stability of steam supply at the end of the steam network. For example, the reboiler in the distillation tower needs to maintain stable steam pressure and temperature, while actual steam consumption fluctuates with changes in the plant's heat load. Therefore, to ensure the long-term stable operation of petrochemical plants, the user nodes of the steam network (i.e., the end nodes of the network) must have the ability to suppress drastic fluctuations in steam pressure and minimize the impact of disturbances at the steam supply end on the terminal operating conditions.

[0051] Specifically, steam supply stability depends not only on the severity of pressure fluctuations but also on the speed at which the steam network recovers to a new steady state. Therefore, this embodiment constructs steam supply stability characteristic values ​​for the steam network by analyzing the average distribution of steam pressure at any node within a preset time step interval and the degree of steam pressure fluctuation at any node within a preset time duration. The specific process is as follows: After the sudden event, calculate the average steam pressure at any node within all time steps in the preset time step interval, and record it as the steady-state response value of any node. It should be noted that, after the sudden incident, the time step setting based on the hydrothermal coupling simulation model, which outputs calculation results every 5 seconds (i.e., the 5th second, the 10th second, etc., correspond to discrete time steps k=1, 2, ... respectively), refers to a specific time step range from the sudden incident when the dynamic response of the steam pipeline network has basically decayed to a stable state. In this embodiment, the preset time step range is set to [6, 12], which corresponds to the physical time range of [30 seconds, 60 seconds]. The reason for this is that after a sudden disturbance in the steam supply source, the dynamic response process of the pressure fluctuation of the steam pipeline network usually takes less than 1 minute (60 seconds). After the violent oscillations are completed and a new equilibrium is reached, there may be slight residual vibrations due to the inertia of the pipeline network. Taking the average steam pressure of the last minute interval as the steady-state response value can effectively eliminate the error caused by residual random fluctuations. Setting the starting point of the interval to step 6 (30 seconds) avoids the transient period with the most violent fluctuations in the first 30 seconds and ensures that there are enough sampling steps (7 time steps) at the end to calculate the average, thereby accurately quantifying the new steady-state steam pressure level reached by the user node after the disturbance. In practical applications, as other implementation methods, implementers can also set their own according to specific circumstances. This embodiment does not impose any special restrictions.

[0052] Furthermore, this embodiment constructs the recovery delay ratio of any node by comparing the steam pressure at any time step with the steady-state response value. Specifically: Within a preset time period following the sudden event, for any node, if the deviation between the steam pressure and the steady-state response value under a preset number of consecutive time steps is within a preset threshold range, then the ratio of the order corresponding to the first time step among the preset number of time steps to the number of all time steps within the preset time period is used as the recovery delay ratio of any node; otherwise, the recovery delay ratio of any node is set to 1.

[0053] It should be noted that the preset duration in this embodiment is 1 minute. The reason is that after a sudden pressure disturbance occurs in the steam supply source of the petrochemical steam pipeline network, due to the propagation of sound speed in the pipeline and the inertia of the pipeline network, the dynamic response process of the pressure fluctuation can usually complete the violent oscillation and establish a new mass and energy balance within 1 minute (60 seconds) to reach a new steady state. If the value is too short (such as less than 30 seconds), it will not be able to fully cover the dynamic propagation and attenuation process of the disturbance, resulting in the omission of key recovery period characteristics. If the value is too long, the simulation calculation will contain a large amount of invalid steady-state data, reducing the timeliness of valve feedback regulation. This value can be other values. The implementer can adjust it within the range of 30 seconds to 3 minutes according to the specific size of the steam pipeline network, the length of the pipeline, and the physical characteristics such as the specific enthalpy of the medium. The larger the scale of the pipeline network and the longer the pipeline, the longer the dynamic response transition time. The preset duration should be increased accordingly to ensure the complete extraction of response characteristics.

[0054] To further clarify, when constructing the recovery delay ratio of any node, the deviation is specifically the percentage of the absolute value of the difference between the steam pressure of any node and its steady-state response value at each time step relative to the steady-state response value. The preset threshold range is specifically set to [-5%, +5%]. This value is based on the conventional engineering margin setting for the stability of steam pressure in petrochemical processes. In practical applications, it can be adjusted within the range of ±2% to ±10% according to the severity of pressure fluctuations for specific devices. In addition, the preset number is specifically set to 3 consecutive time steps. The purpose is to eliminate the "pseudo-steady-state" phenomenon caused by short-term pressure oscillations crossing the steady-state zone in the dynamic response of the pipeline network, and to ensure that the node pressure truly enters and remains in the stable range. This value can be adjusted within the range of 2 to 5 according to the simulation time step and the magnitude of pipeline inertia. When the step length is short or the pipeline inertia is large, the value can be appropriately increased, and vice versa.

[0055] Furthermore, this embodiment constructs a steam supply stability characteristic value for the steam pipeline network based on the fluctuation degree of steam pressure at any node within a preset time period after the sudden event, and the recovery delay ratio. Specifically: In this embodiment, the steam supply stability characteristic value of the steam pipeline network is positively correlated with the degree of fluctuation of steam pressure at any node within a preset time after the sudden event and the recovery delay ratio.

[0056] It should be understood that a positive correlation means that the dependent variable increases as the independent variable increases, and the dependent variable decreases as the independent variable decreases. The specific relationship can be additive or multiplicative, etc., and is determined by the actual application. This application does not impose any special restrictions.

[0057] Preferably, as one implementation method, the expression for the steam supply stability characteristic value of the steam pipeline network in this embodiment is... for: ; In the formula, This indicates the degree of fluctuation in steam pressure at node x in the topology of the steam pipeline network within a preset time period after the sudden event. This represents the recovery delay ratio of node x in the topology of the steam pipeline network; , These represent the preset first allocation weight and the preset second allocation weight, respectively. X represents the number of all nodes in the topology of the steam pipeline network.

[0058] It should be further explained that in this embodiment, the ratio of the steam pressure range at any node within a preset time period after the sudden event to the steady-state value of the response is used as the degree of steam pressure fluctuation at any node within the preset time period after the sudden event. In order to prevent the denominator from being zero before calculating the ratio, a preset constant greater than 0 is added to the steady-state value of the response. In this embodiment, 0.01 is added to the steady-state value of the response to prevent the denominator from being zero. Under the premise of ensuring that the denominator is not zero and does not excessively affect the calculation result, the implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0059] It should be noted that in this embodiment, the preset first allocation weight and the preset second allocation weight are 0.5 and 0.5 respectively. In actual application, as other implementation methods, implementers can also set them according to specific circumstances. This embodiment does not impose any special restrictions.

[0060] Based on the steam supply stability characteristic value, it can be understood that the steam supply stability characteristic value is used to characterize the comprehensive ability of the end-user node of the steam pipeline network to recover stable pressure after a sudden disturbance of the steam source. It is a dimensionless index. The calculation of the steam supply stability characteristic value is affected by two factors: the degree of fluctuation of the node steam pressure within a preset time after the sudden event and the recovery delay ratio. The degree of fluctuation of the node steam pressure within a preset time after the sudden event reflects the relative severity of the node steam pressure oscillation caused by the disturbance, and the recovery delay ratio reflects the relative speed at which the node recovers from the fluctuating state to the new steady state. The larger the degree of fluctuation of the node steam pressure and the recovery delay ratio within a preset time after the sudden event, the larger the steam supply stability characteristic value, reflecting that the steam pressure fluctuation of the steam pipeline network is more severe and the recovery is slower, that is, the steam pipeline network has a worse resistance to disturbance. Conversely, the smaller the degree of fluctuation of the node steam pressure and the recovery delay ratio within a preset time after the sudden event, the smaller the steam supply stability characteristic value, reflecting that the steam pressure of the steam pipeline network is less affected by the disturbance and can recover quickly to a stable state, that is, the better the steam supply stability of the steam pipeline network, which has a positive effect on ensuring the long-term safe operation of downstream units. Thus, this embodiment constructs the steam supply stability characteristic value of the steam pipeline network by analyzing the average distribution of steam pressure at any node within a preset time step interval and the degree of fluctuation of steam pressure at any node within a preset time period. The steam supply stability characteristic value characterizes the comprehensive ability of the steam pipeline network to resist pressure shocks and rapidly self-heal, effectively overcoming the one-sidedness of a single fluctuation index or time index, and providing a reliable quantitative basis for accurately assessing the degree of deterioration of steam supply stability and subsequent optimization of valve body control strategies.

[0061] S3: After the sudden event, by analyzing the phase change risk and enthalpy fluctuation amplitude of the steam temperature at any node within the adjacent time step, the steam supply quality characteristic value of the steam pipeline network is constructed, and combined with the steam supply stability characteristic value, the comprehensive steam supply characteristic value of the steam pipeline network is determined.

[0062] In petrochemical steam pipeline networks, the core objective of valve feedback regulation is to maintain the safety and reliability of steam supply to end-user nodes. Petrochemical plants have stringent process requirements regarding the thermodynamic state of steam. Low-superheated steam is highly susceptible to approaching saturation or liquid carryover, leading to two-phase flow within the pipeline, which in turn induces water hammer, vibration, and corrosion, potentially damaging valves, elbows, and heat exchange equipment. Wet steam can also impact turbine blades, causing erosion and breakage. Simultaneously, significant fluctuations in steam enthalpy directly cause process temperature oscillations, resulting in deviations in product purity and yield, or failure of safety controls. Therefore, in valve feedback regulation strategies, focusing solely on pressure stability is insufficient to guarantee long-term plant operation; a comprehensive assessment of the steam thermal quality at end-user nodes must be incorporated.

[0063] Specifically, sudden disturbances at the steam supply end not only cause dynamic fluctuations in pipeline pressure but also lead to drastic changes in the thermodynamic parameters of the steam along the pipeline. The drop in steam pressure and the delayed decay of steam temperature can easily cause the steam to approach or even cross the gas-liquid phase transition boundary, resulting in a sharp deterioration in steam quality. Simultaneously, the coupled fluctuations in steam pressure and temperature directly translate into large oscillations in steam specific enthalpy, affecting the actual heat gain capacity of the terminal equipment. Therefore, based on quantifying the characteristic values ​​of steam supply stability, it is also necessary to extract the risk level of steam approaching phase transition through superheat analysis and extract the degree of decay in steam's work-making capacity by combining enthalpy fluctuation analysis, in order to comprehensively characterize the impact of the disturbance propagation along the pipeline on the terminal thermodynamic state. Based on this, this embodiment, after the sudden disturbance, constructs the characteristic values ​​of steam supply quality of the steam pipeline network by analyzing the phase transition risk and enthalpy fluctuation amplitude of steam temperature at any node within adjacent time steps, and combines these with the aforementioned characteristic values ​​of steam supply stability to determine the comprehensive characteristic values ​​of steam supply of the steam pipeline network. The specific process is as follows: In this embodiment, firstly, by analyzing the phase change risk and enthalpy fluctuation amplitude of the steam temperature at any node within adjacent time steps, the steam supply quality characteristic values ​​of the steam pipeline network are constructed. Specifically: After the sudden event, the steam saturation temperature and specific enthalpy of the steam at any node within each adjacent time step are calculated. The calculation of steam saturation temperature and specific enthalpy are well-known techniques and will not be described in detail here.

[0064] Furthermore, within a preset timeframe following the sudden event, by analyzing the difference between the steam temperature and the steam saturation temperature at any node within each time step, a characteristic value of the steam temperature phase change risk at any node is constructed. Specifically: In this embodiment, the steam temperature phase change risk characteristic value of node x in the topology of the steam pipeline network is... The expression is: ; In the formula, , Let represent the steam saturation temperature and steam temperature of node x in the topology of the steam pipeline network at time step k, respectively; exp() represents an exponential function with the natural constant as the base; K represents the number of time steps within the preset duration after the sudden event.

[0065] Based on the characteristic value of steam temperature phase change risk, it can be understood that this characteristic value characterizes the degree of risk of steam approaching the gas-liquid phase change boundary and condensing into water during the dynamic response process. It is a dimensionless index because its core calculation formula is an exponential function, and the independent variable is the ratio of temperature difference to saturation temperature, which is a dimensionless value. The calculation of the characteristic value of steam temperature phase change risk is affected by the difference between the steam temperature and the steam saturation temperature at the corresponding pressure. This temperature difference reflects the superheat safety margin of the steam deviating from the phase change boundary. The lower the actual steam temperature is than the steam saturation temperature (i.e., the more negative the temperature difference), the larger the calculated value of the exponential term, and the larger the characteristic value of steam temperature phase change risk. This reflects that the steam at the corresponding node is close to or has entered the wet steam zone, and is very likely to condense into water, causing serious destructive consequences such as water hammer, pipeline vibration, and turbine blade erosion. Conversely, the higher the actual steam temperature is than the steam saturation temperature, the larger the positive value of the temperature difference, the closer the calculated value of the exponential term is to zero, and the smaller the characteristic value of steam temperature phase change risk. This reflects that the steam at the corresponding node has sufficient superheat margin, is in a safe dry steam state, and has a low risk of phase change causing equipment damage.

[0066] Furthermore, this embodiment constructs the enthalpy fluctuation amplitude at any node by analyzing the fluctuation degree of specific enthalpy within a preset time period after the sudden event. Specifically: In this embodiment, the ratio of the specific enthalpy range to the specific enthalpy mean of steam at all time steps within a preset time period after the sudden disturbance is calculated and denoted as the enthalpy fluctuation amplitude at any node. This is used to characterize the relative dispersion of the steam's work capacity and heat power carried after the sudden disturbance. The larger the enthalpy fluctuation amplitude, the larger the specific enthalpy range of the steam relative to the mean, reflecting a significant drop or violent fluctuation in the steam's thermal energy during the dynamic process. This will directly lead to an imbalance in the heat transfer rate of downstream heat exchange equipment and uncontrolled oscillation of process temperature, seriously affecting product purity and yield. Conversely, the smaller the enthalpy fluctuation amplitude, the more gradual the change in the specific enthalpy of the steam before and after the disturbance, which can ensure a smooth transition of the heat load of the petrochemical production unit and the consistency of product quality.

[0067] Furthermore, this embodiment constructs steam supply quality characteristic values ​​for the steam pipeline network based on the steam temperature phase change risk characteristic value and the enthalpy fluctuation amplitude, specifically: In this embodiment, the steam supply quality characteristic value of the steam pipeline network is positively correlated with the steam temperature phase change risk characteristic value and the enthalpy fluctuation amplitude, respectively.

[0068] Preferably, as one implementation method, the steam supply quality characteristic value of the steam pipeline network in this embodiment is... The expression is: ; In the formula, , Let X represent the characteristic value of steam temperature phase change risk and the amplitude of enthalpy fluctuation of node x in the topology of the steam pipeline network, respectively. , These represent the preset third allocation weight and the preset fourth allocation weight, respectively. .

[0069] It should be noted that in this embodiment, the preset values ​​of the third allocation weight and the preset fourth allocation weight are 0.5 and 0.5, respectively. In actual application, as other implementation methods, implementers can also set their values ​​according to specific circumstances. This embodiment does not impose any special restrictions.

[0070] Based on the steam supply quality characteristic value, it can be understood that the steam supply quality characteristic value is used to characterize the degree of deterioration of the steam thermodynamic quality at the end user node of the steam pipeline network after a sudden disturbance. It is a dimensionless index because it is composed of a weighted sum of the dimensionless steam temperature phase change risk characteristic value and the enthalpy fluctuation amplitude. The calculation of the steam supply quality characteristic value is affected by the steam temperature phase change risk characteristic value and the enthalpy fluctuation amplitude. The steam temperature phase change risk characteristic value reflects the degree of loss of the latent heat safety margin of the steam, and the enthalpy fluctuation amplitude reflects the severity of the fluctuation of the sensible heat energy of the steam. The larger the steam temperature phase change risk characteristic value and the enthalpy fluctuation amplitude, the larger the steam supply quality characteristic value, reflecting a serious deterioration of the steam thermal quality. This not only easily induces destructive safety accidents such as water hammer, but also leads to serious imbalances in process heat exchange. Conversely, the smaller the steam temperature phase change risk characteristic value and the enthalpy fluctuation amplitude, the smaller the steam supply quality characteristic value, reflecting that the steam is always maintained in a high-quality superheated dry steam state and the thermodynamic parameters are stable, which can provide a safe, efficient and stable heat source driving force for petrochemical plants.

[0071] The process of constructing the steam supply stability characteristic value and steam supply quality characteristic value described above is essentially the "performance index evaluation link" in the control system. In a multivariable coupled control system, simple pressure deviation can no longer serve as the sole control objective. This embodiment constructs a multi-dimensional comprehensive control objective function (i.e., comprehensive steam supply characteristic value) by integrating pressure recovery capability and the degree of thermal quality deterioration. This function is used as the input deviation signal of the controller to guide the subsequent optimization adjustment direction.

[0072] Furthermore, this embodiment determines the comprehensive steam supply characteristic value of the steam pipeline network based on the steam supply stability characteristic value and the steam supply quality characteristic value, specifically: In this embodiment, the comprehensive steam supply characteristic value of the steam pipeline network is the weighted sum of the steam supply stability characteristic value and the steam supply quality characteristic value of the steam pipeline network, and the specific expression is as follows: In the formula, This represents the comprehensive steam supply characteristic value of the steam pipeline network; , These represent the characteristic values ​​of steam supply stability and steam supply quality of the steam pipeline network, respectively. , These represent the preset first weighting coefficient and the preset second weighting coefficient, respectively. In this embodiment , The values ​​are 0.5 and 0.5 respectively. In practical applications, as other implementation methods, implementers can also set them according to specific circumstances. This embodiment does not impose any special restrictions.

[0073] Preferably, the schematic diagram of the steam supply comprehensive feature value extraction process provided in this embodiment is as follows: Figure 2 As shown.

[0074] Based on the comprehensive characteristic value of steam supply, it can be understood that the comprehensive characteristic value of steam supply reflects the comprehensive disturbance resistance capability of the steam pipeline network under the dual coupling effect of pressure shock and thermal decay. It is a dimensionless index because it is derived from the weighted sum of the dimensionless characteristic values ​​of steam supply stability and steam supply quality. The calculation of the comprehensive characteristic value of steam supply is affected by the characteristic values ​​of steam supply stability and steam supply quality. The characteristic value of steam supply stability reflects the ability of the steam pipeline network to smoothly recover from hydraulic conditions, while the characteristic value of steam supply quality reflects the safety and quality maintenance capability of the steam pipeline network's thermal conditions. The larger the characteristic values ​​of steam supply stability and steam supply quality, the larger the comprehensive characteristic value of steam supply, reflecting the deterioration of the steam pipeline network's operating conditions after disturbance. It faces the risk of pressure runaway and is accompanied by a sharp decline in thermal quality, affecting the safety and continuous operation of the entire petrochemical production chain. Conversely, the smaller the characteristic values ​​of steam supply stability and steam supply quality, the smaller the comprehensive characteristic value of steam supply, reflecting that the steam pipeline network has excellent dynamic disturbance resistance characteristics, can quickly self-heal under steam source disturbance, and maintain high-quality steam supply, ensuring the safe, stable, full-capacity, and high-quality operation of petrochemical plants.

[0075] Thus, this embodiment constructs the steam supply quality characteristic value of the steam pipeline network by analyzing the phase change risk and enthalpy fluctuation amplitude of the steam temperature at any node within adjacent time steps, and combines the steam supply stability characteristic value to determine the comprehensive steam supply characteristic value of the steam pipeline network. The comprehensive steam supply characteristic value characterizes the comprehensive anti-disturbance capability of the steam pipeline network under the dual coupling of pressure shock and thermal decay, making up for the shortcomings of single pressure stability assessment, and providing key thermodynamic quantitative basis for optimizing valve body control strategy.

[0076] S4: Based on the comprehensive steam supply characteristic value, key valve bodies are screened and the optimal opening degree is searched to generate steam pipeline valve body control commands, which are used to control the closed-loop feedback of non-point variables such as steam pressure, steam temperature and steam flow in the steam pipeline network.

[0077] Screening key valves and searching for optimal opening degrees is a core decision-making step in the control system. In a vast steam pipeline network, directly optimizing all valves using multiple variables leads to the "curse of dimensionality," with computational time insufficient for real-time control requirements. This embodiment reduces the dimensionality of control variables through sensitivity screening, performing a golden ratio search only on key control variables (key valves). This is an improved optimal control strategy, aiming to maximize the optimization of the control objective function (comprehensive steam supply characteristic value) with minimal control action cost (valve opening change), thereby achieving efficient automatic adjustment of non-electrical variables.

[0078] After a sudden disturbance to the steam supply source in a steam pipeline network, the constructed comprehensive characteristic value S of the terminal steam supply fully quantifies the comprehensive impact of the disturbance on the terminal user nodes of the pipeline network in terms of both steam supply stability and thermal quality. In the operation and control of the steam pipeline network, the core objective to improve the overall steam supply reliability of the network is to minimize this comprehensive characteristic value S. However, petrochemical steam pipeline networks typically contain a large number of regulating valves. If the opening degree of all valves is optimized, not only is the computational complexity high and time-consuming, making it difficult to meet the real-time response requirements under sudden operating conditions, but also the different topological positions and flow capacities of each valve in the pipeline network result in vastly different regulation effects on terminal operating conditions. Blindly adjusting the global settings can easily lead to secondary disturbances caused by the redistribution of flow within the pipeline network. Therefore, it is necessary to perform sensitivity screening based on the degree of influence of each valve on the comprehensive characteristic value S of the steam supply, select the key valves that play a decisive role in suppressing terminal disturbances, and then, with the goal of minimizing the comprehensive characteristic value S of the steam supply, perform efficient optimization within the feasible region of the opening degree of the key valves, thereby achieving precise and rapid valve feedback regulation. Based on the comprehensive steam supply characteristic values, key valve bodies are screened and the optimal opening degree is searched to generate steam pipeline valve body control commands. The specific process is as follows: (1) Calculate the opening sensitivity of each valve body and screen the key valve bodies: In all the pipe valves of the steam network, the opening of any pipe valve v is adjusted according to a preset adjustment amount Δθ, while keeping the openings of all other pipe valves unchanged. Following the calculation method for the comprehensive steam supply characteristic value, a hydrothermal coupling simulation is performed again to obtain the comprehensive steam supply characteristic value of the steam network after adjusting the opening of pipe valve v. The absolute difference between the comprehensive steam supply characteristic values ​​before and after adjustment is calculated as the opening sensitivity of pipe valve v. Wherein, if the opening of pipe valve v after adjustment... If the preset adjustment amount Δθ exceeds 100% of the maximum opening limit, then select... The opening adjustment strategy is calculated by subtracting Δθ.

[0079] It should be noted that the preset adjustment amount Δθ is specifically set to 5% in this embodiment. The reason for this value is as follows: if Δθ is too small (e.g., 1%), the simulation calculation results are easily affected by numerical iteration errors and cannot truly reflect the impact of valve body adjustment on the overall operating conditions of the pipeline network; if Δθ is too large (e.g., above 15%), it may significantly change the original flow distribution pattern of the pipeline network, introduce nonlinear secondary disturbances, and lead to distortion of sensitivity calculation; the 5% adjustment amount can both stimulate the response characteristics of the pipeline network and is within a reasonable neighborhood of the linearization assumption. In practical applications, implementers can set it themselves within the range of 2% to 8% according to the scale of the pipeline network and the diameter of the pipeline valve body. This embodiment does not impose any special restrictions.

[0080] Furthermore, the opening sensitivity of all valves in the steam pipeline network is sorted from highest to lowest, and the top M valves are selected as key valves. In this embodiment, M is taken as 10% of the total number of valve nodes in the pipeline network. The reason for this value is that petrochemical steam pipeline networks usually have a "few trunks and many branches" structure. A small number of valves (about 10%) at the main trunk and key hubs determine the global flow and pressure distribution, while the adjustment of valves at the end of the small branches has a weak impact on the global characteristic value. Selecting the top 10% of valves not only eliminates the interference of inefficient adjustment objects and reduces the subsequent optimization dimensions to a range that can be calculated in real time, but also ensures that the selected valves have sufficient control power. The implementer can adjust it within the range of 5% to 20% according to the pipeline network redundancy. This embodiment does not impose any special restrictions.

[0081] (2) Search for the optimal opening degree of the key valve body and generate instructions: Based on the selected key valve bodies, the valve opening is optimized sequentially according to their opening sensitivity from largest to smallest. For the current key valve body to be optimized, the golden section search algorithm is used within its preset feasible region of valve body opening. , The opening degree at which the comprehensive steam supply characteristic value of the steam pipeline network is minimized is taken as the optimal opening degree of the key valve body.

[0082] It should be noted that the preset feasible range of the valve body opening degree [ , [20%, 100%] represents the minimum and maximum opening degrees allowed by the valve body's physical structure and process safety. In this embodiment, these values ​​are specifically set to [20%, 100%]. The reason for these values ​​is that when the valve opening degree is less than 20%, the throttling effect of the valve body is extremely severe. This not only generates an excessive pressure drop leading to flashing and cavitation, severely damaging the valve core and seat, but also causes high-frequency noise and pipeline vibration. Therefore, a lower limit anti-surge constraint of 20% is usually set in the automatic control design. The maximum opening degree is set to 100%, i.e., the fully open state, to retain the maximum flow capacity of the valve body.

[0083] The specific well-known execution process of the golden section search algorithm is as follows: Let the search interval be [a, b], where a = , b = . Take two golden section points x1 = b - 0.618×(b - a) and x2 = a + 0.618×(b - a) within the interval; use the simulation model to calculate the steam supply comprehensive characteristic values S(x1) and S(x2) when the opening degree of the pipeline valve body is x1 and x2 respectively; if S(x1) < S(x2), it means that the minimum value point is within the interval [a, x2], then let b = x2; if S(x1) ≥ S(x2), it means that the minimum value point is within the interval [x1, b], then let a = x1; iteratively shrink the search interval until the interval length |b - a| is less than the preset search step size, then stop the iteration, and take the midpoint of the current interval as the optimal opening degree. In this embodiment, the search step size is set to 2%. The reason for this value is that the mechanical resolution of the actuator of the steam pipe network valve body (such as a pneumatic positioner) is usually about 1% - 2%. A step size of 2% can not only match the physical accuracy of the actuator, avoid meaningless ultra-precision calculations, but also quickly converge to the global optimum within the feasible domain with fewer simulation iterations (usually 6 - 8 times can reduce the domain to within 2%). In practical applications, the search step size can be set within the range of 0.5% - 5%. This embodiment does not make special restrictions

[0084] Furthermore, by sequentially completing the above optimization process for all key valve bodies, the optimal opening degrees of each key valve body are obtained, and then a steam pipeline valve body control instruction is generated by packing. Each control instruction contains a target valve body identifier and a target valve position opening value, which is used to be sent to the on-site wireless terminal module for execution and adjustment

[0085] So far, in this embodiment, the key valve bodies with global regulation dominance are screened out by quantifying the influence degree of the opening degree adjustment of each valve body on the comprehensive characteristic value, and then the golden section search algorithm is used to efficiently optimize its optimal opening degree with the goal of minimizing the comprehensive characteristic value within the safe feasible domain. Finally, a valve body control instruction is generated. This method effectively avoids the calculation time consumption and secondary disturbance risk brought by global traversal optimization, and realizes the closed-loop feedback regulation with few actions, fast response and high precision of the steam pipe network under sudden working conditions on the premise of ensuring the physical accuracy of the actuator and the process safety constraints, significantly improving the dynamic disturbance resistance ability and steam supply reliability of the steam pipe network

[0086] The monitoring client module 103 is used to provide a human-computer interaction interface to realize the visual monitoring of the steam pipe network working conditions, the traceability analysis of historical data, and the remote closed-loop valve position regulation

[0087] The monitoring client module is a Web or mobile App, which provides a human-computer interaction interface. The functions of the monitoring client module include: Real-time operational condition visualization monitoring: Using the steam pipeline network topology map as the core carrier, it intuitively displays the distribution characteristics and real-time operating status of all steam pipeline valves, clearly presents the overall pipeline network architecture, the connection relationship of each pipe section, and the complete flow direction from the steam supply end to the pipe section to the user end. The real-time valve opening of each valve node is displayed synchronously.

[0088] Historical data query and analysis: It connects to the time-series database of the cloud service platform module, providing historical operating data that can be retrieved by pipe section, time range, and other conditions. This includes records of valve opening, inlet steam temperature, inlet steam pressure, and steam pressure deviation ratio, meeting the needs of production record archiving, accident tracing, and data analysis.

[0089] Remote valve position control: Authorized operators can manually set the target valve position by selecting the corresponding valve body through the monitoring client module and upload it to the cloud service platform module. The cloud service platform module then sends the valve adjustment command to the field wireless terminal module through the NB-IoT network to realize remote feedback adjustment. After the command is executed, the field wireless terminal module sends the actual valve opening back to the cloud service platform module and updates the display, forming a closed-loop steam pipeline valve body feedback adjustment.

[0090] In summary, this embodiment uses a field wireless terminal module to collect real-time pipeline network operating data as feedback input signals for the control system; the cloud service platform module performs state observation and performance index evaluation based on a digital twin model to generate control decisions; and the finally generated steam pipeline valve body control commands drive the actuators of key valve bodies to change the flow resistance characteristics inside the steam pipeline network.

[0091] It is important to emphasize that the control commands adjusting the valve opening are fundamentally aimed at automatically regulating and stabilizing non-electrical variables such as steam pressure, steam temperature, and steam flow rate in the steam pipeline network. This embodiment constructs a complete closed-loop feedback control circuit from non-electrical variable data acquisition to control strategy generation and non-electrical variable adjustment execution, significantly improving the dynamic disturbance rejection capability of the steam pipeline network as the controlled object, and is a typical non-electrical variable control system.

Claims

1. A wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines, characterized in that, The system has the following characteristics: The on-site wireless terminal module is used to collect in real time the opening degree of pipeline valves in the steam pipeline network, the pressure and temperature of steam at the steam supply end, and the mass flow rate at the user end; based on the difference in steam pressure at any steam supply end between adjacent moments, it is used to calibrate the moment of sudden change. The cloud service platform module is used to establish a hydrothermal coupling simulation model based on the opening degree of the pipeline valve body, the steam temperature and steam pressure at the steam supply end, and the mass flow rate at the user end, so as to obtain the steam pressure and steam temperature of any node in the topology of the steam pipeline network at each preset time step after the sudden moment. After a sudden event, the average distribution of steam pressure at any node within a preset time step interval and the degree of fluctuation of steam pressure at any node within a preset duration are analyzed to construct the steam supply stability characteristic value of the steam pipeline network. After the sudden event, by analyzing the phase change risk and enthalpy fluctuation of steam temperature at any node within adjacent time steps, the steam supply quality characteristic value of the steam pipeline network is constructed, and combined with the steam supply stability characteristic value, the comprehensive steam supply characteristic value of the steam pipeline network is determined. Based on the comprehensive steam supply characteristic values, key valve bodies are screened and the optimal opening degree is searched to generate steam pipeline valve body control commands, which are used to control the closed-loop feedback of non-point variables such as steam pressure, steam temperature, and steam flow in the steam pipeline network.

2. The wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines according to claim 1, characterized in that, The specified instantaneous moment includes: The moment when the difference between the steam pressure at any steam supply end at any given moment and the steam pressure at the next adjacent moment exceeds a preset steady-state threshold is designated as a sudden moment.

3. The wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines according to claim 1, characterized in that, The process of obtaining the steam pressure and steam temperature of any node in the topology of the steam pipeline network at each preset time step after the sudden event includes: The opening degree of the pipeline valve body, the steam pressure and steam temperature at the steam supply end, and the mass flow rate at the user end at the moment immediately preceding the sudden event are input into the water-thermal coupling simulation model, and the steam pressure, steam temperature, and mass flow rate at all nodes in the topology of the steam pipeline network at the moment immediately preceding the sudden event are output. Replace the steam pressure and steam temperature of the corresponding node at the steam supply end in the steam network topology at the time immediately preceding the sudden event with the steam pressure and steam temperature at the time of the sudden event. Keep the other data as the corresponding data at the previous time and use them as input to the hydrothermal coupling simulation model. Output the steam pressure and steam temperature of any node in the steam network topology at each preset time step after the sudden event.

4. The wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines according to claim 3, characterized in that, The process of constructing the topology of a steam pipeline network includes: The valve body, steam supply end, user end, pipe junction, pipe diameter change point, and pipe end closure point in the steam pipeline network are respectively regarded as nodes in the topology, and the pipes in the steam pipeline network are equivalent to edges in the topology to construct the topology of the steam pipeline network.

5. The wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines according to claim 3, characterized in that, The hydrothermal coupling simulation model includes the mass conservation equation, momentum conservation equation, and energy conservation equation for each node in the topology of the steam pipeline network.

6. The wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines according to claim 1, characterized in that, The process of constructing the steam supply stability characteristic values ​​of the steam pipeline network is as follows: After the sudden event, calculate the average steam pressure at any node within all time steps in the preset time step interval, and record it as the steady-state response value of any node. The recovery delay ratio of any node is constructed by comparing the steam pressure and steady-state response value at each time step. The steam supply stability characteristic value of the steam pipeline network is positively correlated with the degree of fluctuation of steam pressure at any node within a preset time after the sudden event and the recovery delay ratio.

7. The wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines according to claim 6, characterized in that, The process for constructing the recovery latency ratio of any node is as follows: Within a preset time period following the sudden event, for any node, if the deviation between the steam pressure and the steady-state response value under a preset number of consecutive time steps is within a preset threshold range, then the ratio of the order corresponding to the first time step among the preset number of time steps to the number of all time steps within the preset time period is used as the recovery delay ratio of any node; otherwise, the recovery delay ratio of any node is set to 1.

8. The wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines according to claim 1, characterized in that, The process of constructing the steam supply quality characteristic values ​​of the steam pipeline network is as follows: After the sudden event, calculate the steam saturation temperature and specific enthalpy of the steam temperature at any node within each adjacent time step. Within a preset time period following the sudden event, the steam temperature phase change risk characteristic value of any node is constructed by analyzing the difference between the steam temperature and the steam saturation temperature at any node within each time step. By analyzing the degree of enthalpy fluctuation within a preset time after a sudden event, the enthalpy fluctuation amplitude at any node is constructed. The steam supply quality characteristic value of the steam pipeline network is positively correlated with the steam temperature phase change risk characteristic value and the enthalpy fluctuation amplitude, respectively.

9. The wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines according to claim 1, characterized in that, The comprehensive steam supply characteristic value of the steam pipeline network is the result of the weighted sum of the steam supply stability characteristic value and the steam supply quality characteristic value of the steam pipeline network.

10. The wireless control system for feedback regulation of valve bodies in petrochemical steam pipelines according to claim 1, characterized in that, The process of screening key valve bodies and searching for the optimal opening includes: In all the pipe valves of the steam network, the opening of any pipe valve is adjusted according to a preset adjustment amount, while keeping the opening of all other pipe valves unchanged. According to the calculation method of the comprehensive steam supply characteristic value, the comprehensive steam supply characteristic value of the steam network after the opening of any pipe valve is adjusted is calculated. Based on the difference between the comprehensive steam supply characteristic values ​​before and after the opening degree adjustment of any pipeline valve, the opening sensitivity of any pipeline valve is calculated in order to screen out the key valve from all pipeline valves. Based on the opening sensitivity of key valve bodies, and using the golden section search algorithm to search within the preset feasible region of valve body openings, the opening of all key valve bodies that minimize the comprehensive characteristic value of the steam pipeline network is taken as their respective optimal opening.

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