Method for determining feed water flow of evaporator of nuclear power station and related device

Abstract

The invention discloses a method for determining the feed water flow of an evaporator of a nuclear power station and a related device, and relates to the technical field of thermoelectric conversion, and the method comprises the steps: obtaining the steam flow of an outlet of the evaporator, the secondary loop pressure of the evaporator, and the feed water temperature and nuclear power of an inlet of a main water supply pipe; the specific enthalpy coefficient is determined by looking up a table according to the secondary loop pressure of the evaporator and the feed water temperature, and the specific enthalpy coefficient is the ratio of the steam specific enthalpy to the feed water specific enthalpy; the nuclear power is converted into theoretical steam flow, the theoretical steam flow is used for verifying the steam flow of an evaporator outlet, and if verification passes, the steam flow of the evaporator outlet is used as one of the inputs of the feed water flow soft measurement model; and inputting the specific enthalpy coefficient, the steam flow at the outlet of the evaporator and the secondary loop pressure of the evaporator into a water flow soft measurement model to obtain the theoretical feed water flow. According to the method, high-precision dynamic measurement and calculation of the water supply flow of the evaporator are realized based on the water supply flow soft measurement model.

Description

Technical Field

[0001] The present application relates to the field of thermoelectric conversion technology, and in particular to a method for determining the feed water flow rate of an evaporator of a nuclear power plant and a related device. Background Art

[0002] The evaporator water level control system in nuclear power plants is a critical system for ensuring the safe and stable operation of nuclear power units. Abnormal fluctuations in the evaporator water level can easily trigger an automatic reactor shutdown or transient response, directly impacting the safety and economic efficiency of the nuclear power unit. Currently, the evaporator water level must be controlled by the evaporator's feedwater flow rate.

[0003] Existing technologies use sensors to determine the evaporator feedwater flow rate based on the Venturi tube differential pressure signal. However, under low-load conditions, the sensor's sensitivity to the Venturi tube differential pressure signal decreases significantly, resulting in insufficient accuracy in the evaporator feedwater flow rate measured by the sensor. This, in turn, affects the stability of water level control, reducing the operational safety and economic efficiency of the nuclear power unit.

[0004] Therefore, there is an urgent need for a technology that can improve the accuracy of obtaining the feed water flow rate of the evaporator. Summary of the Invention

[0005] In view of the above problems, this application provides a method and related device for determining the feed water flow rate of the evaporator of a nuclear power plant to achieve the purpose of improving the accuracy of the feed water flow rate of the evaporator. The specific solution is as follows:

[0006] A first aspect of the present application provides a method for determining a feedwater flow rate of an evaporator of a nuclear power plant, comprising:

[0007] Obtain the steam flow rate at the evaporator outlet, the evaporator secondary circuit pressure, the feedwater temperature at the main feedwater pipe inlet, and the nuclear power;

[0008] Using the evaporator secondary circuit pressure and the feed water temperature, a table is used to determine a specific enthalpy coefficient, where the specific enthalpy coefficient is the ratio of the steam specific enthalpy to the feed water specific enthalpy;

[0009] Converting the nuclear power into a theoretical steam flow, using the theoretical steam flow to verify the steam flow at the evaporator outlet, and if the verification passes, using the steam flow at the evaporator outlet as one of the inputs of a feedwater flow soft measurement model;

[0010] The specific enthalpy coefficient, the steam flow rate at the evaporator outlet and the evaporator secondary circuit pressure are input into the water flow soft measurement model to obtain the theoretical water flow rate, wherein the water flow rate soft measurement model is a model pre-constructed based on soft measurement technology, and the water flow rate soft measurement model has a heat transfer efficiency factor and a heat storage coefficient.

[0011] Optionally, the process of obtaining the heat transfer efficiency factor and the heat storage coefficient includes:

[0012] Acquiring a parameter set, wherein the parameter set includes at least a portion of historical operating parameter data of the nuclear power plant;

[0013] Constructing a linear relationship model of the heat transfer efficiency factor and the heat storage coefficient based on the historical operating parameter data;

[0014] Based on the regularization factor, a least squares loss function including a regularization term is constructed;

[0015] The linear relationship model is converted into a matrix form, and model parameters of the linear relationship model in the matrix form are solved based on the least squares loss function to obtain an optimal estimated value of the heat transfer efficiency factor and an optimal estimated value of the heat storage coefficient;

[0016] Based on the sliding time window training and the anomaly detection mechanism, the optimal estimated value of the heat transfer efficiency factor and the optimal estimated value of the heat storage coefficient are corrected to obtain the heat transfer efficiency factor and the heat storage coefficient.

[0017] Optionally, the method further includes:

[0018] Determine the load status of the power generation system;

[0019] If the load state is a low load state, controlling the water level of the evaporator based on the theoretical water supply flow rate;

[0020] If the load state is a high load state, the water level of the evaporator is controlled based on the feed water flow rate measured by the sensor of the venturi tube.

[0021] Optionally, controlling the water level of the evaporator based on the theoretical water supply flow rate includes:

[0022] Determine the linearly increasing intervention coefficient according to the duration of the control switching phase from the high load state to the low load state;

[0023] determining a first water supply flow rate that is gradually reduced during the control switching phase based on the linearly increasing intervention coefficient, the theoretical water supply flow rate, and the water supply flow rate measured by the sensor of the venturi tube;

[0024] In the control switching stage, the water level of the evaporator is controlled by using the first water supply flow rate;

[0025] After the control switching phase is completed, the water level of the evaporator is controlled using the theoretical water supply flow rate.

[0026] Optionally, the water level of the evaporator is controlled by using the feed water flow rate measured by the venturi tube-based sensor, including:

[0027] Determine the linear decreasing intervention coefficient according to the duration of the control switching phase from the low load state to the high load state;

[0028] determining a second water supply flow rate that is gradually increased during the control switching phase based on the linearly decreasing intervention coefficient, the theoretical water supply flow rate, and the water supply flow rate measured by the sensor of the venturi tube;

[0029] In the control switching stage, the water level of the evaporator is controlled by using the second water supply flow rate;

[0030] After the control switching phase is completed, the water level of the evaporator is controlled by using the water feed flow rate measured by the sensor of the venturi tube.

[0031] Optionally, the process of controlling the water level of the evaporator includes:

[0032] A first-order inertia function that determines the rate of change of valve opening based on a set inertia time;

[0033] During a control switching phase when the power generation system changes from a low-load state to a high-load state, the opening of the valve of the main water supply pipe is controlled according to the theoretical water supply flow rate, and the rate of change of the valve opening is limited by the first-order inertia function. After the control switching phase of the power generation system ends, the opening of the valve of the main water supply pipe is controlled according to the water supply flow rate measured by the sensor of the venturi tube;

[0034] During the control switching stage when the power generation system changes from a high-load state to a low-load state, the opening of the valve of the main water supply pipe is controlled according to the water flow rate measured by the sensor of the venturi tube, and the valve opening change rate is limited by the first-order inertia function. After the control switching stage of the power generation system ends, the opening of the valve of the main water supply pipe is controlled according to the theoretical water flow rate.

[0035] A second aspect of the present application provides a device for determining a feedwater flow rate of an evaporator of a nuclear power plant, comprising:

[0036] Data acquisition module, used to obtain the steam flow rate at the evaporator outlet, the evaporator secondary circuit pressure, the feed water temperature at the main feed water pipe inlet, and the nuclear power;

[0037] a table lookup module, configured to use the evaporator secondary circuit pressure and the feed water temperature to look up a table to determine a specific enthalpy coefficient, wherein the specific enthalpy coefficient is a ratio of the steam specific enthalpy to the feed water specific enthalpy;

[0038] a verification module, configured to convert the nuclear power into a theoretical steam flow, verify the steam flow at the evaporator outlet using the theoretical steam flow, and use the steam flow at the evaporator outlet as one of the inputs of a feedwater flow soft measurement model if the verification passes;

[0039] The data processing module is used to input the specific enthalpy coefficient, the steam flow rate at the evaporator outlet and the evaporator secondary circuit pressure into the water flow soft measurement model to obtain the theoretical water flow rate, wherein the water flow rate soft measurement model is a model pre-constructed based on soft measurement technology, and the water flow rate soft measurement model has a heat transfer efficiency factor and a heat storage coefficient.

[0040] A third aspect of the present application provides a computer program product comprising computer-readable instructions, which, when executed on an electronic device, enables the electronic device to implement the method for determining the feed water flow rate of an evaporator of a nuclear power plant according to the first aspect or any implementation of the first aspect.

[0041] A fourth aspect of the present application provides an electronic device, comprising at least one processor and a memory connected to the processor, wherein:

[0042] The memory is used to store computer programs;

[0043] The processor is used to execute the computer program so that the electronic device can implement the method for determining the feed water flow rate of the evaporator of the nuclear power plant according to the first aspect or any implementation of the first aspect.

[0044] In a fifth aspect, the present application provides a computer storage medium, which carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can determine the feed water flow rate of the evaporator of the nuclear power plant according to the above-mentioned first aspect or any implementation of the first aspect.

[0045] By means of the above technical solution, the present application provides a method and related device for determining the feedwater flow rate of the evaporator of a nuclear power plant. By introducing the specific enthalpy coefficient, heat transfer efficiency factor and heat storage coefficient, the evaporator outlet steam flow rate and the evaporator secondary circuit pressure, feedwater temperature and nuclear power and other parameters are input into a feedwater flow soft measurement model pre-built based on soft measurement technology to achieve high-precision soft measurement of the evaporator feedwater flow rate. Compared with the prior art that determines the evaporator feedwater flow rate based on the venturi tube differential pressure signal, the present application reduces the dependence on physical flow meters, reduces measurement errors and maintenance costs. Secondly, the actual steam flow rate is verified by using the theoretical steam flow rate during the measurement process, which improves the reliability and robustness of the measurement results, can adapt to changes in the operating conditions of the nuclear power plant, ensure the stability and accuracy of the feedwater flow rate calculation, and thus improve the safety and economy of the evaporator operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above and other features, advantages, and aspects of the various embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and that the originals and elements are not necessarily drawn to scale.

[0047] Figure 1 A flow chart of a method for determining the feed water flow rate of an evaporator of a nuclear power plant provided in this application;

[0048] Figure 2 A flow chart of a water flow soft measurement model provided in this application;

[0049] Figure 3 A schematic structural diagram of a device for determining the feed water flow rate of an evaporator of a nuclear power plant provided in this application;

[0050] Figure 4 This is a schematic block diagram of an electronic device provided in this application. DETAILED DESCRIPTION

[0051] The following describes the embodiments of the present application in conjunction with the accompanying drawings. The terms used in the implementation methods of the present application are only used to explain the specific embodiments of the present application and are not intended to limit the present application.

[0052] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0053] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, and this is merely a way of distinguishing the objects of the same attributes when describing them in the embodiments of the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0054] This application provides a method for determining the feed water flow rate of an evaporator of a nuclear power plant, such as Figure 1 , the method may include the following steps:

[0055] S101: Obtain the steam flow rate at the evaporator outlet, the evaporator secondary circuit pressure, the feed water temperature at the main feed water pipe inlet, and the core power.

[0056] In this embodiment, a nuclear power plant refers to a power plant that uses nuclear reactors to generate heat and convert it into electricity. One of the key components is the evaporator (also known as a steam generator). The evaporator is a vertical, natural circulation device that produces saturated steam. Reactor coolant flows through heat transfer tubes, transferring heat to the secondary water outside the tubes. This secondary water circulates naturally within the evaporator. As it flows through the heat transfer tubes, a portion of the water becomes saturated steam, which is then supplied to the main steam turbine and auxiliary facilities.

[0057] The steam flow rate at the evaporator outlet refers to the mass flow rate of steam delivered from the evaporator to the turbine. It can be measured in kg / s or t / h. It is a key parameter for determining evaporation efficiency and system operating load and can be measured in real time by a mass flow meter installed on the evaporator outlet piping. The evaporator secondary circuit refers to the internal water side of the evaporator. The pressure in the evaporator secondary circuit affects the water saturation temperature and steam enthalpy. This pressure can be measured using a high-precision pressure transmitter and transmitted to the control system in real time. The feedwater temperature at the main feedwater inlet refers to the temperature of the main feedwater entering the evaporator. It is expressed in degrees Celsius and is a key input parameter for the feedwater enthalpy lookup table. This temperature can be measured by a temperature sensor or thermocouple and, combined with the pressure, can be used to determine the feedwater enthalpy. Nuclear power refers to the total thermal power released by a nuclear reactor per unit time. It is measured in MW (megawatts) and is calculated by the reactor instrumentation and control system based on neutron flux and other parameters. Nuclear power determines the thermal energy supply and indirectly affects steam production. By combining multiple source parameters such as the steam flow rate at the evaporator outlet, secondary circuit pressure, feed water temperature and nuclear power, the dependence on a single sensor is avoided and the accuracy and reliability of the feed water flow measurement soft measurement are improved.

[0058] S102: Using the evaporator secondary circuit pressure and feed water temperature, determine the specific enthalpy coefficient by looking up the table. The specific enthalpy coefficient is the ratio of the steam specific enthalpy to the feed water specific enthalpy.

[0059] In this example, specific enthalpy is a fundamental parameter in thermodynamics, representing the thermal energy per unit mass of a fluid, typically expressed in kJ / kg. Specific enthalpy is an important indicator of energy changes during the thermal energy conversion process and is crucial for analyzing and modeling nuclear power plant thermal systems.

[0060] Specifically, steam specific enthalpy refers to the thermal energy per unit mass of steam at a specific pressure and temperature. Since steam generation in nuclear power plants originates from the heating of feed water by the evaporator, steam specific enthalpy generally represents the evaporator's ability to transfer heat to the secondary circuit water. The specific value of steam specific enthalpy depends on the thermodynamic state of the steam, particularly the pressure. In this embodiment, the operating pressure of the evaporator's secondary circuit can be used as a lookup input parameter to obtain the specific enthalpy of saturated steam at the corresponding pressure from a table of thermodynamic properties of water and water vapor.

[0061] The specific enthalpy of feedwater refers to the thermal energy per unit mass of feedwater in its thermodynamic state before it enters the evaporator. In nuclear power systems, the temperature of the main feedwater is usually low, but its enthalpy also changes with temperature.

[0062] In this embodiment, the specific enthalpy of the feed water corresponding to the temperature at the main feed water pipe inlet can be determined under constant pressure conditions by measuring the temperature at the main feed water pipe inlet and combining it with a standard thermodynamic property table. It should be noted that in the thermodynamic property table, the enthalpy value is generally listed based on a constant pressure process.

[0063] Specifically, in this method, the table lookup strategy is as follows: given the evaporator secondary circuit pressure, find the specific enthalpy value corresponding to the saturated steam at this pressure , given the feed water temperature, assuming its pressure is much lower than the saturation pressure, find the specific enthalpy of liquid water at that temperature Through the above two operations, the steam specific enthalpy and the feed water specific enthalpy can be obtained respectively, and then the specific enthalpy coefficient can be calculated. The calculation formula is: specific enthalpy coefficient . This ratio is used to measure the relative heat energy required for the unit mass of feed water to be evaporated into steam. Generally speaking, this value is usually greater than 1, indicating that the heat content of steam is significantly higher than that of liquid feed water. The higher the specific enthalpy coefficient, the greater the heat conversion capacity required by the evaporator under this operating condition. In this embodiment, the specific enthalpy coefficient serves as one of the important input parameters of the subsequent soft measurement model, reflecting the trend of changes in the heat transfer efficiency of the system under the current thermal state, which helps to dynamically correct the estimated value of the feed water flow rate, and improve the response accuracy of the soft measurement model and the real-time performance of the system control.

[0064] S103: The nuclear power is converted into a theoretical steam flow, and the theoretical steam flow is used to verify the steam flow at the evaporator outlet. If the verification passes, the steam flow at the evaporator outlet is used as one of the inputs of the feedwater flow soft measurement model.

[0065] In this embodiment, the theoretical steam flow rate refers to the steam mass flow rate that should be generated in the secondary circuit under the current thermal power conditions of the nuclear reactor, assuming ideal evaporator heat transfer and zero heat loss in all links. This parameter is derived from the principle of conservation of thermodynamic energy and can be used to verify the rationality of the actually measured steam flow rate, thereby improving the reliability of the measurement data.

[0066] The calculation formula for the theoretical steam flow is: .in is the theoretical steam flow rate, is the nuclear power rate, Evaporator thermal efficiency, which indicates the efficiency of the evaporator in converting the heat energy of the primary coolant into the heat energy of the secondary steam, can range from 0.85 to 0.95. The specific value can be obtained through regression analysis or long-term statistics of historical nuclear power plant operating data to ensure calculation accuracy.

[0067] Specifically, the calculated theoretical steam flow rate Comparable with the actual measured steam flow For comparison. If the deviation between the two is within the set allowable range (such as ±2%), the measurement value is considered credible; if the deviation exceeds the limit, the anomaly detection mechanism can be triggered, indicating that there may be problems such as sensor drift, blockage or data distortion. When the verification passes, the steam flow measured at the evaporator outlet is used as one of the input parameters of the feed water flow soft measurement model; if the verification fails, the data of the measurement point can be temporarily eliminated and replaced with the model prediction value or other redundant measurement signals to ensure the validity of the soft measurement model input. By continuously comparing the theoretical value with the measured value, it can also be used to evaluate the trend of changes in the heat transfer efficiency of the evaporator, helping operation and maintenance personnel to discover potential scaling, dirt deposition, heat exchange tube blockage and other problems, so as to carry out inspection and maintenance in advance.

[0068] S104: Input the specific enthalpy coefficient, the steam flow rate at the evaporator outlet, and the evaporator secondary circuit pressure into the water flow soft measurement model to obtain the theoretical water flow rate, wherein the water flow soft measurement model is a model pre-built based on soft measurement technology, and the water flow soft measurement model has a heat transfer efficiency factor and a heat storage coefficient.

[0069] In this embodiment, the soft measurement model of this embodiment is a method for estimating process variables that cannot be directly measured or are difficult to measure accurately based on the mathematical relationship between observable variables. Unlike traditional hardware measurement methods, soft measurement technology relies on historical operating data, process mechanism models, or a mathematical model established by combining the two, rather than relying on direct measurement of target variables by physical sensors. Figure 2 shown.

[0070] Specifically, based on the law of conservation of energy, that is, the steam output energy remains equal to the feedwater input energy and the system energy storage change, a soft measurement calculation method for feedwater flow is established, and its formula is: ,in The theoretical water flow rate calculated in real time, is the secondary circuit pressure, express For the instantaneous rate of change at time t, is the thermal efficiency factor, is the heat storage coefficient. and It can be obtained through training with historical data. Through this soft measurement model, this embodiment can achieve continuous, real-time, and accurate estimation of the main feed water flow without relying on high-cost hardware flow meters. This technical solution effectively improves the control system's adjustment accuracy for the evaporator's water level, while enhancing the system's fault tolerance for sensor failures, significantly reducing maintenance costs and downtime risks. In addition, by introducing the heat transfer efficiency factor and heat storage coefficient, the model can accurately correct the inertia effect of the evaporator during dynamic load changes, thereby further improving the estimation accuracy during non-steady-state operation stages such as start-stop and power increase and decrease, providing a strong guarantee for the stability and reliability of the system operation.

[0071] In one embodiment, the process of obtaining the heat transfer efficiency factor and the heat storage coefficient includes:

[0072] Acquiring a parameter set, the parameter set including at least a portion of historical operating parameter data of the nuclear power plant;

[0073] A linear relationship model of heat transfer efficiency factor and heat storage coefficient is constructed based on historical operating parameter data;

[0074] Based on the regularization factor, a least squares loss function including a regularization term is constructed;

[0075] The linear relationship model is transformed into a matrix form, and the model parameters of the matrix linear relationship model are solved based on the least squares loss function to obtain the optimal estimated value of the heat transfer efficiency factor and the optimal estimated value of the heat storage coefficient;

[0076] Based on the sliding time window training and anomaly detection mechanism, the optimal estimated values ​​of the heat transfer efficiency factor and the heat storage coefficient are corrected to obtain the heat transfer efficiency factor and the heat storage coefficient.

[0077] The parameter set includes at least some of the historical operating parameter data of the nuclear power plant, which can be obtained through the nuclear power plant's digital instrumentation and control system. Sampling is performed during stable operating conditions, with a sampling period of ≤1s. The parameter list is shown in Table 1.

[0078] Secondly, the acquired data is preprocessed to remove the start-up and shutdown periods and load mutation periods, and finally the data is normalized. In this method, the theoretical heat balance flow is defined as: , where the parameters in brackets are non-essential parameters. The feed water temperature can increase the accuracy of the calculation, but it will increase the complexity of the algorithm and needs to be determined according to the real-time situation. Based on the above parameters, a linear relationship model of the heat transfer efficiency factor and the heat storage coefficient can be established as follows: ,in Indicates the rate of change of secondary side pressure, which is used to reflect transient effects caused by system dynamic processes such as load changes and valve opening and closing.

[0079] Table 1 Parameter list

[0080]

[0081] In order to improve the identification reliability and suppress parameter overfitting, the least squares loss with a quadratic regularization term is adopted as the objective function.

[0082] The least squares loss function is as follows: ,

[0083] The loss consists of two parts: one is the mean square error between the measured data and the model prediction, which is used to ensure that the model fits the observed data. is the mean square error between the observed value and the model predicted value, which is used to approximate the actual reference water flow rate , minimizing this part can make the model fit better on the training data, where is the number of data points, indicating the total number of data samples, The data index indicates that the current calculation is the samples, Indicates the Secondary circuit pressure versus time for each sample The second is the quadratic penalty term for the identification parameters , which can impose a quadratic penalty on the parameter size, with the goal of preventing the parameter from becoming too large or unstable, thereby reducing overfitting, improving generalization ability, and enhancing numerical stability, especially when there is collinearity between independent variables or insufficient samples. Parameters Determines the penalty strength. The larger the value, the more the parameter is shrunk to 0, and vice versa, the closer it is to ordinary least squares. In this application, the parameter The default value is 0.01 to prevent overfitting. The partial derivative of the loss with respect to the parameter can be set to zero to obtain the normal equation: , so the closed-form solution is: ,in , , we can get the optimal estimated value of the heat transfer efficiency factor and the optimal estimated value of the heat storage coefficient, where is the identity matrix, for To address equipment aging or internal evaporator structure issues, this application uses a sliding time window training process to automatically recalculate the heat transfer efficiency factor and heat storage coefficient using the latest data to ensure accuracy. If the soft-measured value deviates from the reference flow rate by more than 2% for three consecutive hours, retraining mode is immediately triggered to recalculate the heat transfer efficiency factor and heat storage coefficient.

[0084] The above results indicate that the heat transfer efficiency factor and heat storage coefficient obtained through the above process not only reflect the actual operating state of the evaporator but also adapt to different loads, temperatures, and pressures. Compared with fixed-parameter models, this method significantly reduces feedwater flow estimation errors in long-term operation and improves the stability and safety of evaporator water level control.

[0085] In one embodiment, the method for determining the feed water flow rate of the evaporator of the nuclear power plant further includes:

[0086] Determine the load status of the power generation system;

[0087] If the load state is low, the water level of the evaporator is controlled based on the theoretical feed water flow rate;

[0088] If the load state is a high load state, the water level of the evaporator is controlled based on the feed water flow rate measured by the sensor of the venturi tube.

[0089] The load state refers to the ratio of the current power output level of the nuclear power unit to the designed rated power, and can generally be divided into a low-load state and a high-load state. In this application, the low-load state can be 30% of the standard power, and the rest of the time is a high-load state. In the low-load state, due to the low nuclear power, relatively small fluctuations in steam production, and low flow rate in the water supply pipeline, the measurement accuracy of the Venturi flowmeter may be affected by factors such as a low Reynolds number and a weak pressure difference, causing it to decrease. Therefore, this embodiment preferably adopts a water level control strategy based on the theoretical water supply flow rate.

[0090] Under high load conditions, the unit's steam production is high and the feedwater flow rate is high. The differential pressure signal from the Venturi flowmeter is stable and well above the lower limit of the instrument's range. At this point, its measurement accuracy meets operational requirements. Therefore, this embodiment preferably adopts a water level control strategy based on Venturi tube sensor measurements.

[0091] From the above, it can be concluded that this control strategy solves the problem of accuracy degradation of a single measurement method under all operating conditions by intelligently switching the measurement method under different load conditions. It not only improves the stability and safety of water level control, but also optimizes the operating economy, and realizes accurate, fast and safe closed-loop control of the water level of the nuclear power plant evaporator under all operating conditions.

[0092] In one embodiment, controlling the water level of the evaporator based on the theoretical feed water flow rate includes:

[0093] Determine the linearly increasing intervention coefficient according to the duration of the control switching phase from the high load state to the low load state;

[0094] Determining a first water supply flow rate that is gradually reduced during a control switching phase based on a linearly increasing intervention coefficient, a theoretical water supply flow rate, and a water supply flow rate measured by a sensor of the venturi tube;

[0095] In the control switching stage, the water level of the evaporator is controlled by using the first water supply flow rate;

[0096] After the control switching stage is completed, the water level of the evaporator is controlled using the theoretical water flow rate.

[0097] When the nuclear power plant's power generation system switches from a high-load state to a low-load state, this method introduces a linearly increasing intervention coefficient to ensure smooth control transition in order to ensure the smoothness of the evaporator's water level regulation process and avoid drastic water level fluctuations caused by sudden changes in the control signal. Specifically, the start time of the control switching phase can be determined in the following two ways:

[0098] 1) Nuclear rate signal determination:

[0099] When the core power drops from greater than the set high load threshold to and below the low load threshold, the system determines that it has entered the high load to low load switching stage.

[0100] 2) Operation mode signal determination:

[0101] When the unit switches from full-power generation to peak load regulation or low-power operation, a control switchover is automatically triggered. The duration of the control switchover phase can be set based on historical operating data or engineering experience, for example, 30 to 120 seconds, to ensure a smooth adjustment process.

[0102] Specifically, the linear increasing intervention coefficient is defined as: , , in the linear increasing control strategy, the linear increasing intervention coefficient It increases linearly from 0 to 1, and is used to gradually introduce the theoretical water flow control signal, where: is the time that the control switching phase from high load state to low load state has run. is the total duration of the control switching phase from high load state to low load state. When the control is completely dependent on the measurement value of the venturi tube, When , the control is completely dependent on the theoretical water flow value. When the first water flow rate is used, it is defined as: ,in is the theoretical water flow rate, The feedwater flow rate measured by the sensor of the venturi tube.

[0103] From the above, we can conclude that the control strategy proposed in this application achieves smooth switching between high- and low-load measurement modes through a linearly increasing intervention coefficient. This not only retains the high response speed of the Venturi tube during the initial switching phase, but also gradually introduces the low-load accuracy advantage of the soft-sensing model to form an optimal signal combination for all operating conditions. This improves water level stability during load switching and enhances the control system's robustness to disturbances such as power fluctuations and signal anomalies, ensuring nuclear safety while balancing equipment protection and long-term operational efficiency.

[0104] In one embodiment, the water level of the evaporator is controlled based on the feed water flow rate measured by the sensor of the venturi tube, including:

[0105] Determine the linear decreasing intervention coefficient according to the duration of the control switching phase from the low load state to the high load state;

[0106] Determining a second feed water flow rate that is gradually increased during a control switching phase based on a linearly decreasing intervention coefficient, a theoretical feed water flow rate, and a feed water flow rate measured by a sensor of the venturi tube;

[0107] During the control switching phase, the water level of the evaporator is controlled by using the second feed water flow rate;

[0108] After the control switching phase is completed, the water level of the evaporator is controlled by using the feed water flow measured by the sensor of the venturi tube.

[0109] Specifically, the linearly decreasing intervention coefficient is defined as: , , in the linear decreasing control strategy, the linear decreasing intervention coefficient The feed water flow rate measured by the sensor used to gradually introduce the venturi tube decreases linearly from 1 to 0, where, is the time that the control switching phase from low load state to high load state has run, is the total duration of the control switching phase from low load state to high load state. When the control is completely dependent on the theoretical water flow value, When , control is completely dependent on the measurement value of the venturi tube. When the second water flow rate is used, it is defined as: ,in is the theoretical water flow rate, The feedwater flow rate measured by the sensor of the venturi tube.

[0110] From the above, we can conclude that the control strategy in this application achieves a shockless transition from low to high load through a linearly decreasing intervention coefficient. Initially, it utilizes theoretical flow to suppress disturbances, and later, it combines this with a Venturi tube for rapid response, balancing accuracy and dynamic performance. This creates a symmetrical logic with the linearly increasing strategy for high-to-low load switching, simplifying system implementation and maintenance. The water level remains within a safe range throughout the entire process, avoiding the risks of flooding and drying up, and improving the safety and stability of the unit's operation.

[0111] In one embodiment, the process of controlling the water level of the evaporator includes:

[0112] A first-order inertia function that determines the rate of change of valve opening based on a set inertia time;

[0113] During the control switching phase when the power generation system changes from a low-load state to a high-load state, the valve opening of the main water supply pipe is controlled according to the theoretical water supply flow rate, and the first-order inertia function is used to limit the rate of change of the valve opening;

[0114] After the control switching phase of the power generation system is completed, the opening of the valve of the main water supply pipe is controlled according to the water flow rate measured by the sensor of the venturi tube.

[0115] During the control switching phase when the power generation system changes from a high-load state to a low-load state, the opening of the valve of the main water supply pipe is controlled according to the water flow rate measured by the sensor of the venturi tube, and the rate of change of the valve opening is limited by the first-order inertia function;

[0116] After the control switching phase of the power generation system is completed, the opening of the valve of the main water supply pipe is controlled according to the theoretical water supply flow rate.

[0117] In order to avoid the rapid opening and closing and water level shock caused by the direct action of the control signal on the valve, this embodiment defines a first-order inertia function, which is defined as follows: ,in is the inertia time. When the value is large, the valve action is relatively smooth, which is suitable for large inertia and large capacity systems; when Smaller values ​​result in faster response but may introduce water level fluctuations. A value of 30s is recommended to balance control response speed and system stability, where s represents the Laplace operator. For example, when a nuclear power plant's power generation system switches from a high-load to a low-load state, the control signal uses the theoretical feedwater flow rate. Without the addition of a first-order inertia link, the control signal directly controls the valve opening, which can easily lead to large water level fluctuations in the evaporator. In this case, an inertia link is introduced to smooth the control signal before inputting it to the valve. This gradually establishes the flow rate required for high-load operation during the transition phase, while also preventing significant water level fluctuations caused by sudden load increases.

[0118] When the power generation system of a nuclear power plant switches from a high-load state to a low-load state, the control signal uses the actual feed water flow rate measured by the Venturi tube. After being processed by the first-order inertia link, the output value valve can maintain the rapid response capability under large flow conditions during the transition period, while preventing the water level from suddenly dropping or overshooting caused by directly switching to the theoretical flow.

[0119] As can be seen from the above, the control strategy in this application achieves smooth adjustment of valve opening through a first-order inertia function, suppressing water level fluctuations and ensuring a stable transition during load switching. The system also exhibits bidirectional adaptability, maintaining a stable water level regardless of high or low load switching. Valve velocity limiting protects the actuator, reduces mechanical shock, and extends equipment life.

[0120] A method for determining the feed water flow rate of an evaporator of a nuclear power plant provided by an embodiment of the present application has been described above. The following will introduce an apparatus for determining the feed water flow rate of an evaporator of a nuclear power plant that performs the above method.

[0121] See also Figure 3 , Figure 3 This is a schematic diagram of a device for determining the feed water flow rate of an evaporator in a nuclear power plant provided in an embodiment of the present application. Figure 3 As shown, the device for determining the feed water flow rate of the evaporator of the nuclear power plant includes:

[0122] Data acquisition module 301, used to obtain the steam flow rate at the evaporator outlet, the evaporator secondary circuit pressure, the feed water temperature at the main feed water pipe inlet, and the core power;

[0123] A table lookup module 302 is used to use the evaporator secondary circuit pressure and feed water temperature to look up a table to determine the specific enthalpy coefficient, which is the ratio of the steam specific enthalpy to the feed water specific enthalpy;

[0124] Verification module 303, used to convert nuclear power into theoretical steam flow, use the theoretical steam flow to verify the steam flow at the evaporator outlet, and if the verification passes, use the steam flow at the evaporator outlet as one of the inputs of the feedwater flow soft measurement model;

[0125] The data processing module 304 is used to input the specific enthalpy coefficient, the steam flow rate at the evaporator outlet and the evaporator secondary circuit pressure into the water flow soft measurement model to obtain the theoretical water flow rate, wherein the water flow soft measurement model is a model pre-built based on soft measurement technology, and the water flow soft measurement model has a heat transfer efficiency factor and a heat storage coefficient.

[0126] In one embodiment, the data acquisition module 301 is specifically configured to:

[0127] Acquiring a parameter set, the parameter set including at least a portion of historical operating parameter data of the nuclear power plant;

[0128] A linear relationship model of heat transfer efficiency factor and heat storage coefficient is constructed based on historical operating parameter data;

[0129] Based on the regularization factor, a least squares loss function including a regularization term is constructed;

[0130] The linear relationship model is transformed into a matrix form, and the model parameters of the matrix linear relationship model are solved based on the least squares loss function to obtain the optimal estimated value of the heat transfer efficiency factor and the optimal estimated value of the heat storage coefficient;

[0131] Based on the sliding time window training and anomaly detection mechanism, the optimal estimated values ​​of the heat transfer efficiency factor and the heat storage coefficient are corrected to obtain the heat transfer efficiency factor and the heat storage coefficient.

[0132] In one embodiment, the data processing module 304 is specifically configured to:

[0133] Determine the load status of the power generation system;

[0134] If the load state is low, the water level of the evaporator is controlled based on the theoretical feed water flow rate;

[0135] If the load state is a high load state, the water level of the evaporator is controlled based on the feed water flow rate measured by the sensor of the venturi tube.

[0136] In one embodiment, the data processing module 304 is specifically configured to:

[0137] Determine the linearly increasing intervention coefficient according to the duration of the control switching phase from the high load state to the low load state;

[0138] Determining a first water supply flow rate that is gradually reduced during a control switching phase based on a linearly increasing intervention coefficient, a theoretical water supply flow rate, and a water supply flow rate measured by a sensor of the venturi tube;

[0139] In the control switching stage, the water level of the evaporator is controlled by using the first water supply flow rate;

[0140] After the control switching stage is completed, the water level of the evaporator is controlled using the theoretical water flow rate.

[0141] In one embodiment, the data processing module 304 is specifically configured to:

[0142] Determine the linear decreasing intervention coefficient according to the duration of the control switching phase from the low load state to the high load state;

[0143] Determining a second feed water flow rate that is gradually increased during a control switching phase based on a linearly decreasing intervention coefficient, a theoretical feed water flow rate, and a feed water flow rate measured by a sensor of the venturi tube;

[0144] During the control switching phase, the water level of the evaporator is controlled by using the second feed water flow rate;

[0145] After the control switching phase is completed, the water level of the evaporator is controlled by using the feed water flow measured by the sensor of the venturi tube.

[0146] In one embodiment, the data processing module 304 is specifically configured to:

[0147] A first-order inertia function that determines the rate of change of valve opening based on a set inertia time;

[0148] During the control switching phase when the power generation system changes from a low-load state to a high-load state, the valve opening of the main water supply pipe is controlled according to the theoretical water supply flow rate, and the first-order inertia function is used to limit the rate of change of the valve opening;

[0149] After the control switching phase of the power generation system is completed, the opening of the valve of the main water supply pipe is controlled according to the water flow rate measured by the sensor of the venturi tube.

[0150] During the control switching phase when the power generation system changes from a high-load state to a low-load state, the opening of the valve of the main water supply pipe is controlled according to the water flow rate measured by the sensor of the venturi tube, and the rate of change of the valve opening is limited by the first-order inertia function;

[0151] After the control switching phase of the power generation system ends, the opening of the valve of the main water supply pipe is controlled according to the theoretical water supply flow rate.

[0152] An electronic device is also provided in an embodiment of the present application. Figure 4 , which shows a schematic diagram of the structure of an electronic device suitable for implementing the method for determining the feedwater flow rate of an evaporator in a nuclear power plant according to an embodiment of the present application. The electronic device in the embodiment of the present application may include, but is not limited to, fixed terminals such as mobile phones, laptop computers, PDAs (personal digital assistants), PADs (tablet computers), desktop computers, and the like. Figure 4The electronic device shown is merely an example and should not limit the functions and scope of use of the embodiments of the present application.

[0153] like Figure 4 As shown, the electronic device may include a processing device (e.g., a central processing unit, a graphics processing unit, etc.) 601, which can perform various appropriate actions and processes based on programs stored in a read-only memory (ROM) 602 or programs loaded from a storage device 608 into a random access memory (RAM) 603. When the electronic device is powered on, the RAM 603 also stores various programs and data required for the operation of the electronic device. The processing device 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0154] Typically, the following devices may be connected to the I / O interface 605: an input device 606 including, for example, a touch screen, a touchpad, a keyboard, a mouse, a camera, a microphone, an accelerometer, a gyroscope, etc.; an output device 607 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; a storage device 608 including, for example, a memory card, a hard disk, etc.; and a communication device 609. The communication device 609 may allow the electronic device to communicate with other devices wirelessly or by wire to exchange data. Figure 4 The electronic device is shown with various devices, but it should be understood that it is not required to implement or possess all of the devices shown. More or fewer devices may be implemented or possessed instead.

[0155] An embodiment of the present application also provides a computer program product including computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements a method for determining the feed water flow rate of an evaporator of any nuclear power plant provided in the embodiment of the present application.

[0156] A computer-readable storage medium is also provided in an embodiment of the present application. The storage medium carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement a method for determining the feed water flow rate of an evaporator of any nuclear power plant provided in an embodiment of the present application.

[0157] It should also be noted that the device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed across multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. In addition, in the drawings of the device embodiments provided in this application, the connection relationship between the modules indicates that there is a communication connection between them, which can be specifically implemented as one or more communication buses or signal lines.

[0158] Through the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course can also be implemented by special hardware including application-specific integrated circuits, special CPUs, special memories, special components, etc. In general, all functions performed by computer programs can be easily implemented with corresponding hardware, and the specific hardware structures used to implement the same function can also be diverse, such as analog circuits, digital circuits or special circuits, etc. However, for the present application, software program implementation is a better implementation method in most cases. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a readable storage medium, such as a computer's floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk or optical disk, etc., and includes a number of instructions to enable a computer device (which can be a personal computer, training equipment, or network equipment, etc.) to execute the methods described in each embodiment of the present application.

[0159] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product.

[0160] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, a computer, a training device or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website, a computer, a training device or a data center. The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a training device, a data center, etc. that includes one or more available media integrations. The available medium can be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

Claims

1. A method for determining the feed water flow rate of an evaporator of a nuclear power plant, characterized in that: include: Obtain the steam flow rate at the evaporator outlet, the evaporator secondary circuit pressure, the feedwater temperature at the main feedwater pipe inlet, and the nuclear power; Using the evaporator secondary circuit pressure and the feed water temperature, a table is used to determine a specific enthalpy coefficient, where the specific enthalpy coefficient is the ratio of the steam specific enthalpy to the feed water specific enthalpy; Converting the nuclear power into a theoretical steam flow, using the theoretical steam flow to verify the steam flow at the evaporator outlet, and if the verification passes, using the steam flow at the evaporator outlet as one of the inputs of a feedwater flow soft measurement model; The specific enthalpy coefficient, the steam flow rate at the evaporator outlet and the evaporator secondary circuit pressure are input into the water flow soft measurement model to obtain the theoretical water flow rate, wherein the water flow rate soft measurement model is a model pre-constructed based on soft measurement technology, and the water flow rate soft measurement model has a heat transfer efficiency factor and a heat storage coefficient.

2. The method for determining the feed water flow rate of the evaporator of a nuclear power plant according to claim 1, characterized in that: The process of obtaining the heat transfer efficiency factor and the heat storage coefficient includes: Acquiring a parameter set, wherein the parameter set includes at least a portion of historical operating parameter data of the nuclear power plant; Constructing a linear relationship model of the heat transfer efficiency factor and the heat storage coefficient based on the historical operating parameter data; Based on the regularization factor, a least squares loss function including a regularization term is constructed; The linear relationship model is converted into a matrix form, and model parameters of the linear relationship model in the matrix form are solved based on the least squares loss function to obtain an optimal estimated value of the heat transfer efficiency factor and an optimal estimated value of the heat storage coefficient; Based on the sliding time window training and the anomaly detection mechanism, the optimal estimated value of the heat transfer efficiency factor and the optimal estimated value of the heat storage coefficient are corrected to obtain the heat transfer efficiency factor and the heat storage coefficient.

3. The method for determining the feed water flow rate of the evaporator of a nuclear power plant according to claim 1, characterized in that: Also includes: Determine the load status of the power generation system; If the load state is a low load state, controlling the water level of the evaporator based on the theoretical water supply flow rate; If the load state is a high load state, the water level of the evaporator is controlled based on the feed water flow rate measured by the sensor of the venturi tube.

4. The method for determining the feed water flow rate of the evaporator of a nuclear power plant according to claim 3, characterized in that: The controlling of the water level of the evaporator based on the theoretical water supply flow rate includes: Determine the linearly increasing intervention coefficient according to the duration of the control switching phase from the high load state to the low load state; determining a first water supply flow rate that is gradually reduced during the control switching phase based on the linearly increasing intervention coefficient, the theoretical water supply flow rate, and the water supply flow rate measured by the sensor of the venturi tube; In the control switching stage, the water level of the evaporator is controlled by using the first water supply flow rate; After the control switching phase is completed, the water level of the evaporator is controlled using the theoretical water supply flow rate.

5. The method for determining the feed water flow rate of the evaporator of a nuclear power plant according to claim 3, characterized in that: The water level of the evaporator is controlled by the water flow rate measured by the sensor based on the venturi tube, including: Determine the linear decreasing intervention coefficient according to the duration of the control switching phase from the low load state to the high load state; determining a second water supply flow rate that is gradually increased during the control switching phase based on the linearly decreasing intervention coefficient, the theoretical water supply flow rate, and the water supply flow rate measured by the sensor of the venturi tube; In the control switching stage, the water level of the evaporator is controlled by using the second water supply flow rate; After the control switching phase is completed, the water level of the evaporator is controlled by using the water feed flow rate measured by the sensor of the venturi tube.

6. The method for determining the feed water flow rate of the evaporator of a nuclear power plant according to claim 3, characterized in that: The process of controlling the water level of the evaporator includes: A first-order inertia function that determines the rate of change of valve opening based on a set inertia time; During a control switching phase when the power generation system changes from a low-load state to a high-load state, the opening of the valve of the main water supply pipe is controlled according to the theoretical water supply flow rate, and the rate of change of the valve opening is limited by using the first-order inertia function. After the control switching phase of the power generation system ends, the opening of the valve of the main water supply pipe is controlled according to the water supply flow rate measured by the sensor of the venturi tube; During the control switching stage when the power generation system changes from a high-load state to a low-load state, the opening of the valve of the main water supply pipe is controlled according to the water flow rate measured by the sensor of the venturi tube, and the valve opening change rate is limited by the first-order inertia function. After the control switching stage of the power generation system ends, the opening of the valve of the main water supply pipe is controlled according to the theoretical water flow rate.

7. A device for determining the feed water flow rate of an evaporator of a nuclear power plant, characterized in that: include: Data acquisition module, used to obtain the steam flow rate at the evaporator outlet, the evaporator secondary circuit pressure, the feed water temperature at the main feed water pipe inlet, and the nuclear power; a table lookup module, configured to use the evaporator secondary circuit pressure and the feed water temperature to look up a table to determine a specific enthalpy coefficient, wherein the specific enthalpy coefficient is a ratio of the steam specific enthalpy to the feed water specific enthalpy; a verification module, configured to convert the nuclear power into a theoretical steam flow, verify the steam flow at the evaporator outlet using the theoretical steam flow, and use the steam flow at the evaporator outlet as one of the inputs of a feedwater flow soft measurement model if the verification passes; The data processing module is used to input the specific enthalpy coefficient, the steam flow rate at the evaporator outlet and the evaporator secondary circuit pressure into the water flow soft measurement model to obtain the theoretical water flow rate, wherein the water flow rate soft measurement model is a model pre-constructed based on soft measurement technology, and the water flow rate soft measurement model has a heat transfer efficiency factor and a heat storage coefficient.

8. A computer program product, characterized in that The method comprises computer-readable instructions, which, when executed on an electronic device, enable the electronic device to implement the method for determining the feed water flow rate of an evaporator of a nuclear power plant as claimed in any one of claims 1 to 6.

9. An electronic device, characterized in that: comprising at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs; The processor is configured to execute the computer program so that the electronic device can implement the method for determining the feed water flow rate of the evaporator of the nuclear power plant according to any one of claims 1 to 6.

10. A computer storage medium, characterized in that The storage medium carries one or more computer programs, which, when executed by an electronic device, enable the electronic device to implement the method for determining the feed water flow rate of the evaporator of a nuclear power plant as described in any one of claims 1 to 6.

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