A method, system, and device for steam generator water level control based on fusion estimation.

Abstract

This invention discloses a steam generator water level control method, system, and device based on fusion estimation, including a nonlinear dynamic model, an online state estimation platform, and a proactive disturbance rejection water level control system. First, a nonlinear dynamic model is established based on the steam generator's operating principle as prior knowledge for the online state estimation platform. Then, the online state estimation platform is built, and state estimation is performed using information measured by multiple sensors and prior knowledge to obtain the online state estimation result. Finally, a proactive disturbance rejection water level control system is designed based on the online state estimation result and the control objective requirements. This invention achieves accurate online estimation of the steam generator's operating state and eliminates unknown disturbances in the steam generator through the proactive disturbance rejection water level control system, enabling the steam generator water level to quickly reach the set value and achieving the goal of rapid load tracking.

Description

Technical Field

[0001] This invention belongs to the field of pressurized water reactor steam generator control technology, and relates to a steam generator water level control method, system and device based on fusion estimation. Background Technology

[0002] The U-Tube Steam Generator (UTSG) is a crucial component of pressurized water reactor power plants, and the steam generator water level is a critical indicator that needs to be controlled during operation. Traditional steam generator water level control systems primarily adjust the feedwater flow rate based on the deviation between the measured water level and its setpoint to maintain the water level at the set level. Two key aspects are the water level measurement and the control system. Firstly, due to the harsh operating environment of steam generators, it is difficult to install water level sensors that require advanced electronic equipment and ample maintenance space. Therefore, in actual industrial production, the water level is calculated using the pressure difference between the upper and lower ends of the steam generator. However, water level calculations require calibration, and deviations from calibration conditions can lead to significant errors in the measurement results. Currently, the errors in the estimation of the steam generator system state are generally quite large. Secondly, the control system not only needs to track changes in the setpoint but also overcome various measurable and unmeasurable disturbances in the system. Because there are numerous disturbance factors, compensating for each disturbance individually would result in a large system size, increased system coupling, system instability, and safety risks. Therefore, the existing steam generator water level control system has large water level measurement errors and is unstable due to too many disturbance factors, which are technical problems that need to be solved. Summary of the Invention

[0003] The purpose of this invention is to solve the technical problems of large measurement error and unstable control system of steam generator in the prior art, and to provide a steam generator water level control method, system and device based on fusion estimation.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] Firstly, a steam generator water level control method based on fusion estimation includes the following steps:

[0006] Establish a nonlinear dynamic model to obtain prior knowledge;

[0007] Based on prior knowledge and information measured by multiple sensors, state estimation is performed using an online state estimation platform to obtain online state estimation results;

[0008] Based on the online state estimation results and control objective requirements, the water level of the steam generator is controlled by combining an active disturbance rejection water level control system.

[0009] A further improvement of the present invention is that:

[0010] The establishment of the nonlinear dynamic model includes:

[0011]

[0012]

[0013]

[0014] Among them, P i To control the inlet working fluid pressure, Pa; W i To control the inlet flow rate of the working medium, kg·s -1 W o To control the flow rate of the working fluid at the outlet, kg·s -1 A represents the flow area of ​​the control volume, in meters. 2 L is the length of the control volume in meters; ρ is the average density of the working fluid in the control volume, in kg·m³. -3 h represents the average enthalpy of the control medium, in J·kg⁻¹. -1 h o To control the outlet enthalpy of the working fluid, J·kg -1 P represents the average pressure of the working fluid in the control volume, in Pa; P i To control the inlet working fluid pressure, Pa; h i To control the inlet enthalpy of the working fluid, J·kg -1 ;ρ o To control the density of the working fluid at the outlet, kg·m -3 g is the acceleration due to gravity, in m·s². -2 θ is the angle between the control volume and the horizontal plane, in rad; C f is the fluid flow resistance coefficient; Dh is the hydraulic diameter.

[0015] The nonlinear dynamic model uses the primary side inlet temperature, feedwater flow rate, feedwater temperature, and steam flow rate as input parameters to calculate the parameters of steam generator water level, steam content, circulation flow rate, steam pressure, and primary side outlet temperature.

[0016] The specific method for building the online state estimation platform is as follows:

[0017] During the operation of the steam generator, the information measured by the multi-source sensors includes parameters such as actual feedwater flow rate, actual steam flow rate, actual primary inlet temperature, actual feedwater temperature, actual water level, actual steam pressure, and actual primary outlet temperature.

[0018] The parameters of actual water flow rate, actual steam flow rate, actual primary inlet temperature, actual water temperature, actual water level, actual steam pressure, and actual primary outlet temperature are used as inputs to the online state estimation platform.

[0019] The parameters of actual water flow rate, actual steam flow rate, actual primary inlet temperature, and actual water temperature are used as inputs to the nonlinear dynamic model.

[0020] The parameters for calculating water level, steam pressure, primary side outlet temperature, steam content, and circulation flow rate are obtained through a nonlinear dynamic model and used as inputs for the online state estimation platform.

[0021] An online state estimation platform for a steam generator was designed by using the unscented Kalman filter algorithm to fuse and estimate the input parameters, and to perform online state estimation of the steam generator's water level, steam content, and circulation flow rate.

[0022] The specific method for fusion estimation is as follows:

[0023] The calculated water level, steam pressure, and primary side outlet temperature are fused with the actual water level, steam pressure, and primary side outlet temperature using the unscented Kalman filter algorithm to obtain the estimated water level, steam pressure, primary side outlet temperature, steam content, and circulation flow rate after fusion estimation.

[0024] The design method of the unscented Kalman filter algorithm is as follows:

[0025] Determine the measurement accuracy of multi-source sensors;

[0026] Determine the accuracy of the nonlinear dynamic model;

[0027] An unscented Kalman filter algorithm is designed by deriving parameters for calculating water level, steam pressure, primary side outlet temperature, actual water level, actual steam pressure, actual primary side outlet temperature, estimated water level, estimated steam pressure, estimated primary side outlet temperature, estimated steam content, and estimated circulation flow rate.

[0028] The design method of the self-disruption-resistant water level control system is as follows:

[0029] Based on the control objectives of water level overshoot and settling time of the steam generator, an active disturbance rejection controller is designed, and a nonlinear tracking differentiator is used to arrange the transient process.

[0030] System errors are eliminated by employing a nonlinear error feedback rate.

[0031] Design an extended observer to eliminate unknown disturbances in the steam generator.

[0032] The input parameters of the self-disruption level control system include the estimated water level, estimated steam pressure, estimated primary side outlet temperature, estimated steam content, and estimated circulation flow rate.

[0033] Secondly, a steam generator water level control system based on fusion estimation includes:

[0034] Nonlinear dynamic models are established to obtain prior knowledge.

[0035] The online state estimation platform performs state estimation based on information measured by multi-source sensors and prior knowledge, and obtains the online state estimation result.

[0036] The active disturbance rejection water level control system controls the water level of the steam generator based on online state estimation results and control target requirements.

[0037] Thirdly, an apparatus for implementing the above method includes a steam generator; the steam generator is equipped with multi-source sensors for measuring the feedwater flow rate, feedwater temperature, steam flow rate, steam pressure, primary side inlet temperature, and primary side outlet temperature during operation of the steam generator; the steam generator is connected to a main feedwater pump, and a main feedwater regulating valve and a bypass feedwater regulating valve are connected in parallel on its connecting pipeline; the main feedwater pump is used to connect to a water source and provide pressure to it.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] This invention discloses a steam generator water level control method, system, and apparatus based on fusion estimation. On one hand, the control system uses fusion estimation to determine the steam generator water level, reducing uncertainty, increasing estimation accuracy, and improving system measurement errors. On the other hand, it employs an active disturbance rejection control (ADRC) method based on disturbance information to compensate for internal and external disturbances in the steam generator feedwater control, improving the system's control characteristics. Estimation and control are dual problems; estimation clarifies the system's true state, while control alters the system to the desired state. Combining these two approaches enhances the control effect of the steam generator. This method improves control performance from the perspective of enhancing measurement and estimation accuracy, laying a foundation for intelligent control of future nuclear reactor systems. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart of the control method of the present invention;

[0042] Figure 2 This is a schematic diagram of the online state estimation platform for the steam generator of the present invention;

[0043] Figure 3 This is a schematic diagram of the control system of the present invention;

[0044] Figure 4 This is a schematic diagram of the steam generator of the present invention.

[0045] Figure 5 This is a schematic diagram of the steam generator and its control system of the present invention;

[0046] Figure 6 This is a diagram showing the online state estimation results of the steam generator under feedwater flow disturbance according to the present invention. Figure 6 (a) is a diagram showing the boundary conditions and unmeasurable variables. Figure 6 (b) is a graph showing the water level estimation results;

[0047] Figure 7 This is a diagram showing the online state estimation results of the steam generator under outlet steam flow disturbance according to the present invention. Figure 7 (a) is a diagram showing the boundary conditions and unmeasurable variables. Figure 7 (b) is a graph showing the water level estimation results;

[0048] Figure 8 This is a dynamic response diagram of the system after the set value changes under the designed control system of the present invention, wherein, Figure 8 (a) is a water level diagram of the steam generator. Figure 8 (b) is a water supply flow diagram. Figure 8 (c) The opening degree of the main water supply regulating valve. Figure 8 (d) is a bypass water supply regulating valve.

[0049] Wherein: 1-Cylinder; 2-Steam-water separator; 3-U-tube; 4-Wide range water level differential pressure transmitter; 5-Primary side inlet; 6-Primary side outlet; 7-Narrow range water level differential pressure transmitter; 8-Secondary side water supply inlet. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0051] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0052] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0053] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0054] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0055] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0056] The present invention will now be described in further detail with reference to the accompanying drawings:

[0057] See Figure 1 This invention discloses a steam generator water level control method based on fusion estimation, comprising the following steps:

[0058] S1, Establish a nonlinear dynamic model to obtain prior knowledge;

[0059] S2, based on the information measured by multi-source sensors and prior knowledge, state estimation is performed on the online state estimation platform to obtain the online state estimation result;

[0060] S3 controls the water level of the steam generator based on online state estimation results and control target requirements, combined with an active disturbance rejection water level control system.

[0061] See Figure 2 This invention discloses a method and system for controlling the water level of a steam generator based on fusion estimation, comprising the following steps:

[0062] Step one: Based on the operating mechanism of the steam generator, a nonlinear dynamic model is established, as follows:

[0063] Using the equations of conservation of mass, energy, and momentum:

[0064]

[0065]

[0066]

[0067] Among them, P i To control the inlet working fluid pressure, Pa; W i To control the inlet flow rate of the working medium, kg·s -1 W o To control the flow rate of the working fluid at the outlet, kg·s -1 A represents the flow area of ​​the control volume, in meters. 2 L is the length of the control volume in meters; ρ is the average density of the working fluid in the control volume, in kg·m³. -3 h represents the average enthalpy of the control medium, in J·kg⁻¹. -1 h o To control the outlet enthalpy of the working fluid, J·kg -1 P represents the average pressure of the working fluid in the control volume, in Pa; P i To control the inlet working fluid pressure, Pa; h i To control the inlet enthalpy of the working fluid, J·kg -1 ;ρ o To control the density of the working fluid at the outlet, kg·m -3 g is the acceleration due to gravity, in m·s². -2 θ is the angle between the control volume and the horizontal plane, in rad; C f is the fluid flow resistance coefficient; Dh is the hydraulic diameter.

[0068] The nonlinear dynamic model uses the primary side inlet temperature, feedwater flow rate, feedwater temperature and steam flow rate as input parameters. The parameters such as steam generator water level, steam content, circulation flow rate, steam pressure and primary side outlet temperature can be calculated by formulas (1), (2) and (3).

[0069] Step two: Based on the information measured by the multi-source sensors and prior knowledge, state estimation is performed using an online state estimation platform to obtain the online state estimation result. The specific method is as follows:

[0070] Signals measured by multi-source sensors are transmitted to an online state estimation platform. During the operation of the steam generator, the multi-source sensors measure the following information: feedwater flow rate, steam flow rate, primary inlet temperature, feedwater temperature, water level, steam pressure, and primary outlet temperature. The feedwater flow rate, steam flow rate, primary inlet temperature, and feedwater temperature serve as inputs to a nonlinear dynamic model, which calculates the water level, steam pressure, primary outlet temperature, steam holdup, and circulation flow rate. An unscented Kalman filter algorithm is used to fuse the calculated water level, steam pressure, and primary outlet temperature with those measured by the sensors, yielding fused estimates of the steam generator's water level, steam pressure, primary outlet temperature, steam holdup, and circulation flow rate. This allows for online state estimation of the steam generator's water level, steam holdup, and circulation flow rate. The accuracy of the sensor measurement and the accuracy of the nonlinear dynamic model of the steam generator are determined. Based on the measurable information such as the steam generator water level, steam pressure, primary side outlet temperature, feedwater temperature, feedwater flow rate, feedwater pressure, primary side inlet coolant temperature, primary side inlet coolant flow rate, primary side inlet coolant pressure, and steam generator outlet steam flow rate, an unscented Kalman filter is designed.

[0071] Step 3: Based on the online state estimation results and control objective requirements, the water level of the steam generator is controlled using an active disturbance rejection water level control system. The specific method is as follows:

[0072] The deviation between the water level setpoint and the water level obtained through state estimation, as well as the deviations in steam flow rate and feedwater flow rate, are fused together as inputs to the active disturbance rejection (ADRR) water level control system. Based on control objectives such as water level overshoot and settling time, the ADRR controller is designed. First, a transient process is arranged, utilizing a nonlinear tracking differentiator to monotonically follow the input signal within a finite time. Second, a nonlinear error feedback rate is used to eliminate system errors. Then, an extended observer is designed to classify disturbances acting on the controlled object whose mathematical model cannot be obtained as unknown disturbances. In the absence of a disturbance mathematical model and the inability to measure the disturbance, the disturbance can be estimated solely through the input and output information of the controlled object. Finally, the online water level estimation result is input to the ADRR controller to eliminate the unknown disturbances in the steam generator and control the steam generator water level at the setpoint.

[0073] Experiment 1:

[0074] At 500s, a disturbance of -2% in steam flow is introduced at 100% power plateau. Figure 6 (a) The feedwater flow rate, steam flow rate, feedwater temperature, and primary inlet temperature measured by the sensor, as well as the estimated steam content and circulation flow rate. The water level estimate, measurement error, and estimation error are respectively as follows: Figure 6 As shown in (b). Figure 6 As shown in (a), the unmeasurable state variables of steam holdup and circulation flow rate were estimated. As the steam flow rate decreases, the steam holdup decreases, and the circulation flow rate increases. From... Figure 6 (b) It can be seen that the maximum estimation error of the water level at 100% power level is less than 0.7%, indicating high estimation accuracy. Under steam flow disturbances, a nonlinear dynamic model can obtain more accurate water level information than traditional sensor measurements alone.

[0075] Experiment 2:

[0076] At 500s, a disturbance of -2% in feedwater flow was introduced at the 50% power plateau. Figure 7 (a) The feedwater flow rate, steam flow rate, feedwater temperature, and primary inlet temperature measured by the sensor, as well as the estimated steam content and circulation flow rate. The water level estimate, measurement error, and estimation error are respectively as follows: Figure 7 As shown in (b). Figure 7 As shown in (a), with a decrease in feedwater flow rate, the primary side inlet temperature and feedwater temperature remain unchanged. The height of the subcooled zone decreases, the height of the boiling zone increases, the proportion of saturated steam increases, the proportion of saturated water decreases, and the steam content gradually increases. The outlet boundary of the steam generator is pressure; the increase in generated saturated steam leads to an increase in the steam space pressure, resulting in a slight increase in the outlet steam flow rate. As the water level increases, the system's circulation power increases, leading to an increase in the circulating flow. Figure 7 (b) It can be seen that as the feedwater flow rate decreases, the water level gradually decreases, and the estimated water level can quickly approach the true value. The mean absolute error of the estimated water level is smaller than that of the measured water level, and the root mean square error of the estimated water level is smaller than that of the measured water level. Under feedwater disturbance, online state estimation using a steam generator can obtain a more accurate water level than traditional sensor-based measurements.

[0077] Experiment 3:

[0078] The simulation starts at 0s, with all boundary conditions maintaining the steady-state equilibrium values. The initial water level is 14m (50% water level). At 500s, a disturbance is introduced to reduce the steam generator water level setpoint by 0.3m (5.9%), which continues until the simulation ends. Figure 8 (a) Figure 8 (b) Figure 8 (c) and Figure 8 As shown in (d), the feedwater flow rate responds quickly, the steam generator water level tracks the set value, the overshoot during the disturbance process is 3.1%, which is less than 30%, the disturbance process attenuation rate is 0, which is less than 1 / 10, the main feedwater regulating valve operates smoothly, the bypass feedwater regulating valve does not operate, and the control performance meets the requirements.

[0079] See Figure 3 This diagram illustrates the online state estimation platform for a steam generator in this invention. The platform utilizes signals measured by multiple sensors. During steam generator operation, the sensors measure feedwater flow rate, steam flow rate, primary inlet temperature, feedwater temperature, water level, steam pressure, and primary outlet temperature. All of these measurements serve as inputs to the steam generator state estimation platform. Based on a nonlinear dynamic model and sensor measurement data, an unscented Kalman filter algorithm is used to perform online state estimation of the steam generator's water level, steam content, and circulation flow rate.

[0080] See Figure 4 This is a schematic diagram of the steam generator in this invention, including a cylinder 1 equipped with a measuring device; the measuring device includes a wide-range water level differential pressure transmitter 4 and a narrow-range water level differential pressure transmitter 7; a U-shaped tube 3 and a steam-water separator 2 are arranged inside the cylinder 1; a primary side inlet 5 and a primary side outlet 6 are provided on the cylinder 1, which are respectively connected to the two ends of the U-shaped tube 3 for the primary side coolant to flow in and out of the U-shaped tube 3; a secondary side feedwater inlet 8 is also provided on the cylinder 1 for the secondary side feedwater to flow into the cylinder 1; the secondary side feedwater absorbs heat from the primary side coolant inside the cylinder 1 and then flows into the steam-water separator 2; the secondary side feedwater inlet 8 is connected to a feedwater regulating valve.

[0081] See Figure 5This invention discloses a method, system, and apparatus for steam generator water level control based on fusion estimation, comprising three steam generators, three main feedwater regulating valves, three bypass feedwater regulating valves, two main feedwater pumps, and feedwater pipelines. The three steam generators share two main feedwater pumps, and each steam generator is equipped with one main feedwater regulating valve and one bypass feedwater regulating valve for water level regulation. Primary-side coolant flows into the UTSG, transferring heat to the secondary-side fluid, and then flows out of the UTSG. Secondary-side feedwater flows into the UTSG, absorbs heat from the primary-side coolant, and becomes a vapor-liquid two-phase mixture, flowing into the steam-water separator. Saturated steam separated from the steam-water separator enters the steam space, driving the turbine to generate electricity. Saturated water separated from the steam-water separator mixes with the feedwater and flows into the descending section. Because the UTSG is located inside the containment vessel, the radiation dose level is very high, making it difficult to use electronic devices. Water level measuring instruments placed inside the pressure vessel are also unsuitable, as are conventional liquid level measuring instruments with high maintenance space requirements, such as ultrasonic or radar instruments. Therefore, for the measurement stage, the differential pressure level measurement principle is typically used to measure the pressure difference between the upper and lower ends of the UTSG, and then the water level is calculated. Water level measuring instruments mainly include wide-range and narrow-range differential pressure level transmitters. Traditional UTSG water level calculations are calibrated under specific operating conditions, and deviations in these calibration conditions can lead to significant errors in the measurement results. In this invention, the steam generator sensor measurement information includes feedwater flow rate, feedwater temperature, steam flow rate, steam pressure, primary side inlet temperature, and primary side outlet temperature. The sensor measurement information is input to the state estimation platform, which provides the estimated water level value. The deviation between the water level setpoint and the estimated water level value is input to the active disturbance rejection controller (ADRC). The deviation between the steam flow rate measurement value and the feedwater flow rate measurement value is also input to the ADRC. The ADRC outputs the opening degrees of the main and auxiliary feedwater regulating valves, thereby changing the feedwater flow rate entering the steam generator to maintain the water level at the setpoint. The water level control system uses the deviation between the estimated water level of the steam generator and the set value as the input of the active disturbance rejection controller (ADRC). The deviation between the steam flow rate and the feedwater flow rate is also used as the input of the ADRC. The ADRC calculates and outputs the opening degree of the feedwater regulating valve. The feedwater regulating valve then changes the feedwater flow rate, thereby maintaining the water level of the steam generator at the set value.

[0082] The working principle of this invention is as follows:

[0083] Based on the operating mechanism of the steam generator, a nonlinear dynamic model is derived and established based on the conservation equations of mass, energy, and momentum, serving as prior knowledge for the online state estimation platform. Secondly, state estimation is performed using multi-source sensor measurement information and the nonlinear dynamic model. An unscented Kalman filter algorithm is used to fuse and estimate the input parameters, thus designing an online state estimation platform for the steam generator. Finally, an active disturbance rejection controller (ADDC) is designed based on control objectives such as water level overshoot and settling time. Firstly, a transient process is arranged, utilizing a nonlinear tracking differentiator to monotonically follow the input signal within a finite time. Secondly, a nonlinear error feedback rate is adopted to eliminate system errors. An extended observer is designed to classify disturbances acting on the controlled object whose mathematical model cannot be obtained as unknown disturbances. Even without a disturbance mathematical model and without the ability to measure the disturbance, the disturbance can be estimated solely through the input and output information of the controlled object. Finally, the online water level estimation result is input into the ADDC water level control system to eliminate the unknown disturbances in the steam generator and control the steam generator water level at the set value.

[0084] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the water level of a steam generator based on fusion estimation, characterized in that, Includes the following steps: Establish a nonlinear dynamic model to obtain prior knowledge; The establishment of the nonlinear dynamic model includes: （1） （2） （3） in, P i To control the inlet working fluid pressure, Pa; W i To control the inlet flow rate of the working medium, kg·s -1 ; W o To control the flow rate of the working fluid at the outlet, kg·s -1 ; A To control the volumetric flow area, m 2 ; L Let m be the length of the control volume; ρ To control the average density of the working fluid, kg·m -3 ; h To control the average enthalpy of the working fluid, J·kg -1 ; h o To control the outlet enthalpy of the working fluid, J·kg -1 ; P To control the average pressure of the working fluid, Pa; h i To control the inlet enthalpy of the working fluid, J·kg -1 ; ρ o To control the density of the working fluid at the outlet, kg·m -3 g is the acceleration due to gravity, in m·s². -2 ; θ The angle between the control volume and the horizontal plane is expressed in rad. C f This is the fluid flow resistance coefficient; Dh The hydraulic diameter; Based on prior knowledge and information measured by multiple sensors, state estimation is performed using an online state estimation platform to obtain online state estimation results; Based on the online state estimation results and control objective requirements, the water level of the steam generator is controlled by combining an active disturbance rejection water level control system. The specific method for building the online state estimation platform is as follows: During the operation of the steam generator, the information measured by the multi-source sensors includes parameters such as actual feedwater flow rate, actual steam flow rate, actual primary inlet temperature, actual feedwater temperature, actual water level, actual steam pressure, and actual primary outlet temperature. The parameters of actual water flow rate, actual steam flow rate, actual primary inlet temperature, actual water temperature, actual water level, actual steam pressure, and actual primary outlet temperature are used as inputs to the online state estimation platform. The parameters of actual water flow rate, actual steam flow rate, actual primary inlet temperature, and actual water temperature are used as inputs to the nonlinear dynamic model. The parameters for calculating water level, steam pressure, primary side outlet temperature, steam content, and circulation flow rate are obtained through a nonlinear dynamic model and used as inputs for the online state estimation platform. An online state estimation platform for a steam generator was designed by using the unscented Kalman filter algorithm to fuse and estimate the input parameters, and to perform online state estimation of the steam generator's water level, steam content, and circulation flow rate.

2. The steam generator water level control method based on fusion estimation according to claim 1, characterized in that, The specific method for fusion estimation is as follows: The calculated water level, steam pressure, and primary side outlet temperature are fused with the actual water level, steam pressure, and primary side outlet temperature using the unscented Kalman filter algorithm to obtain the estimated water level, steam pressure, primary side outlet temperature, steam content, and circulation flow rate after fusion estimation.

3. The steam generator water level control method based on fusion estimation according to claim 1, characterized in that, The design method of the unscented Kalman filter algorithm is as follows: Determine the measurement accuracy of multi-source sensors; Determine the accuracy of the nonlinear dynamic model; An unscented Kalman filter algorithm is designed by deriving parameters for calculating water level, steam pressure, primary side outlet temperature, actual water level, actual steam pressure, actual primary side outlet temperature, estimated water level, estimated steam pressure, estimated primary side outlet temperature, estimated steam content, and estimated circulation flow rate.

4. The steam generator water level control method based on fusion estimation according to claim 1, characterized in that, The design method of the self-disruption-resistant water level control system is as follows: Based on the control objectives of water level overshoot and settling time of the steam generator, an active disturbance rejection controller is designed, and a nonlinear tracking differentiator is used to arrange the transient process. System errors are eliminated by employing a nonlinear error feedback rate. Design an extended observer to eliminate unknown disturbances in the steam generator.

5. The steam generator water level control method based on fusion estimation according to claim 4, characterized in that, The input parameters of the self-disruption level control system include the estimated water level, estimated steam pressure, estimated primary side outlet temperature, estimated steam content, and estimated circulation flow rate.

6. A steam generator water level control system based on fusion estimation, characterized in that, include: Nonlinear dynamic models are established to obtain prior knowledge. The establishment of the nonlinear dynamic model includes: （1） （2） （3） in, P i To control the inlet working fluid pressure, Pa; W i To control the inlet flow rate of the working medium, kg·s -1 ; W o To control the flow rate of the working fluid at the outlet, kg·s -1 ; A To control the volumetric flow area, m 2 ; L Let m be the length of the control volume; ρ To control the average density of the working fluid, kg·m -3 ; h To control the average enthalpy of the working fluid, J·kg -1 ; h o To control the outlet enthalpy of the working fluid, J·kg -1 ; P To control the average pressure of the working fluid, Pa; h i To control the inlet enthalpy of the working fluid, J·kg -1 ; ρ o To control the density of the working fluid at the outlet, kg·m -3 g is the acceleration due to gravity, in m·s². -2 ; θ The angle between the control volume and the horizontal plane is expressed in rad. C f This is the fluid flow resistance coefficient; Dh The hydraulic diameter; The online state estimation platform performs state estimation based on information measured by multi-source sensors and prior knowledge, and obtains the online state estimation result. The specific method for building the online state estimation platform is as follows: During the operation of the steam generator, the information measured by the multi-source sensors includes parameters such as actual feedwater flow rate, actual steam flow rate, actual primary inlet temperature, actual feedwater temperature, actual water level, actual steam pressure, and actual primary outlet temperature. The parameters of actual water flow rate, actual steam flow rate, actual primary inlet temperature, actual water temperature, actual water level, actual steam pressure, and actual primary outlet temperature are used as inputs to the online state estimation platform. The parameters of actual water flow rate, actual steam flow rate, actual primary inlet temperature, and actual water temperature are used as inputs to the nonlinear dynamic model. The parameters for calculating water level, steam pressure, primary side outlet temperature, steam content, and circulation flow rate are obtained through a nonlinear dynamic model and used as inputs for the online state estimation platform. An online state estimation platform for a steam generator was designed by using the unscented Kalman filter algorithm to fuse and estimate the input parameters, and to perform online state estimation of the steam generator's water level, steam content, and circulation flow rate. The active disturbance rejection water level control system controls the water level of the steam generator based on online state estimation results and control target requirements.

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