Main feed water valve opening degree prediction method, device and control system

Abstract

The application relates to a main feed water valve opening degree prediction method, device and control system. The method comprises the following steps: in the case that a fault main feed water valve is detected, determining the current state of the fault main feed water valve according to the difference between the water level of each evaporator and the evaporator water level setting value and the water level change rate of the non-fault evaporator; in the case that the current state of the fault main feed water valve is a steady state, obtaining the average value of the opening degree of the non-fault main feed water valve and taking the average value as the predicted opening degree of the fault main feed water valve; and in the case that the current state of the fault main feed water valve is not a steady state, determining the predicted opening degree of the fault main feed water valve according to the functional relationship between the main feed water valve section area and the predicted opening degree of the main feed water valve and the main feed water valve section area of the fault main feed water valve. The application can determine the actual opening degree of the fault main feed water valve, so as to guarantee the safe and stable operation of a nuclear power unit.

Description

Technical Field

[0001] This application relates to the field of evaporator water level control technology, and in particular to a method, device and control system for predicting the opening degree of the main feedwater valve. Background Technology

[0002] As one of the most important and sensitive control systems in a nuclear power plant, the stability of the evaporator water level control system is crucial for the safe and stable operation of the nuclear power unit. Statistics show that abnormal evaporator water level control is the leading cause of transient events or automatic reactor shutdowns. In existing evaporator water level control systems, disturbances or transients often occur due to abnormal operation of downstream actuators.

[0003] The actuator at the back end of the evaporator water level control system is the main feedwater valve. The most common failure mode one is valve jamming, where the main feedwater valve is stuck at a specific opening degree, and both automatic and manual control functions are unavailable. Failure mode two is that the valve is not controlled by command signals and continues to open too wide or close too narrowly.

[0004] In the main feedwater valve failure mode, the actual valve opening is unknown. Therefore, the research on the method for judging the actual valve opening under the main feedwater valve failure mode of nuclear power plant evaporator water level has very important engineering significance. It is beneficial to fault response and fault handling, and ensures the safe and stable operation of nuclear power units. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, device, and control system for predicting the opening degree of a faulty main feedwater valve to ensure the safe and stable operation of a nuclear power unit, addressing the aforementioned technical problems.

[0006] Firstly, a method for predicting the opening degree of a main feedwater valve is provided, applied to an evaporator water level control system, the method comprising:

[0007] If a faulty main water supply valve is detected, the current status of the faulty main water supply valve is determined based on the difference between the water level of each evaporator and the evaporator water level setpoint, as well as the rate of change of the water level of the non-faulty evaporators.

[0008] When the current state of the faulty main water supply valve is in a steady state, the average value of the opening of the non-faulty main water supply valve is obtained and used as the predicted opening of the faulty main water supply valve.

[0009] When the current state of the faulty main feedwater valve is not in a steady state, the predicted opening of the faulty main feedwater valve is determined based on the functional relationship between the cross-sectional area of ​​the main feedwater valve and the predicted opening of the main feedwater valve, and the cross-sectional area of ​​the faulty main feedwater valve.

[0010] In one embodiment, the process of determining the cross-sectional area of ​​the main water supply valve includes:

[0011] The main water supply flow rate is determined based on the pressure difference across the main water supply valve; wherein, the pressure difference across the main water supply valve refers to the difference between the inlet pressure before the main water supply valve malfunctions and the inlet pressure after the malfunction, or the difference between the outlet pressure before the main water supply valve malfunctions and the outlet pressure after the malfunction.

[0012] The cross-sectional area of ​​the main water supply valve is determined based on the functional relationship between the main water supply valve cross-sectional area, the main water supply flow rate, and the main water supply velocity, as well as the main water supply flow rate and the main water supply velocity.

[0013] In one embodiment, the process of determining the pressure difference across the main water supply valve includes:

[0014] Obtain the positional difference between the feedwater pump outlet and the steam generator feedwater inlet;

[0015] Obtain the pressure difference between the water supply header and the steam header;

[0016] Based on the mapping relationship between the secondary load and the pressure difference, the first pressure drop on the secondary side of the steam generator and the second pressure drop in the steam pipeline and / or the feedwater pipeline are obtained by fitting.

[0017] The pressure difference across the main feedwater valve is determined based on the pressure difference between the feedwater header and the steam header, the positional difference between the feedwater pump outlet and the steam generator feedwater inlet, the first pressure drop, and the second pressure drop.

[0018] In one embodiment, determining the main feedwater flow rate based on the pressure difference across the main feedwater valve includes:

[0019] Obtain the product of the preset constant, the pressure difference across the main water supply valve, and the gravitational acceleration;

[0020] Obtain the square root of the product value;

[0021] The product of the flow coefficient and the root of the square is obtained and used as the main feedwater velocity.

[0022] In one embodiment, the process of determining whether the current state of the faulty main water supply valve is in a steady state includes:

[0023] The current state of the faulty main water supply valve is determined to be steady state if at least one of the following conditions is met: the water level change rate of the non-faulty evaporator is not greater than the standard value of the water level change rate of the non-faulty evaporator, and the absolute value of the difference between the water level of each evaporator and the evaporator water level set value is not greater than the standard value of the water level deviation of the non-faulty evaporator.

[0024] In one embodiment, the method further includes:

[0025] Adjust the evaporator water level corresponding to the faulty main feedwater valve based on the predicted opening degree determined under the condition that the current state of the faulty main feedwater valve is in a steady state.

[0026] If the evaporator water level does not reach the preset water level within the preset time after adjustment, the evaporator water level corresponding to the faulty main water valve will be adjusted according to the predicted opening determined when the current state of the faulty main water valve is not in a steady state.

[0027] Secondly, a main feedwater valve opening prediction device is provided, applied to an evaporator water level control system, the device comprising:

[0028] The status determination module is used to determine the current status of the faulty main water supply valve when a faulty main water supply valve is detected, based on the difference between the water level of each evaporator and the evaporator water level setpoint, as well as the rate of change of the water level of the non-faulty evaporators.

[0029] The opening prediction module is used to predict the opening of the faulty main feedwater valve by using the average opening of the non-faulty evaporator main feedwater valve as the current steady state.

[0030] The opening prediction module is also used to determine the predicted opening of the faulty main water supply valve based on the functional relationship between the cross-sectional area of ​​the main water supply valve and the predicted opening of the main water supply valve, and the cross-sectional area of ​​the faulty main water supply valve, when the current state of the faulty main water supply valve is not in a steady state.

[0031] Thirdly, an evaporator water level control system is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described in the first aspect.

[0032] Fourthly, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect.

[0033] Fourthly, a computer program product is provided, comprising a computer program that, when executed by a processor, implements the steps of the method described in the first aspect.

[0034] In the above embodiments, under the main feedwater valve failure mode, it is determined whether the main feedwater valve is in a steady state. In a steady state, predicting the opening of the faulty main feedwater valve using the opening of the non-faulty main feedwater valve is extremely simple. In a non-steady state, determining the predicted opening of the faulty main feedwater valve based on the functional relationship between the main feedwater valve cross-sectional area and the predicted opening, and using the cross-sectional area of ​​the faulty main feedwater valve, allows for timely monitoring of the actual valve opening under the main feedwater valve failure mode. Knowing the actual valve opening under the main feedwater valve failure mode is beneficial for fault response and handling.

[0035] In addition, the method provided in this embodiment can improve the reliability of the evaporator water level control system, significantly reduce evaporator water level disturbances caused by main feedwater valve malfunctions, and significantly reduce the risk of reactor automatic shutdown due to main feedwater valve malfunctions, thus ensuring the safe and stable operation of the nuclear power unit. Furthermore, the method provided in this embodiment has significant prospects for promotion and application; the technologies involved in the project have good versatility and can be promoted and applied in nuclear power units at multiple sites. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart illustrating a method for predicting the opening degree of the main water supply valve in one embodiment.

[0038] Figure 2 This is another flowchart illustrating the main water supply valve opening prediction method in one embodiment;

[0039] Figure 3 This is a schematic diagram of the main water supply valve opening prediction method in one embodiment;

[0040] Figure 4 This is a schematic diagram illustrating the composition of the steam-water pressure difference in one embodiment;

[0041] Figure 5 This is a curve showing the steady-state value of the actual valve opening under the fault mode of the main water supply valve in one embodiment.

[0042] Figure 6 This is a structural block diagram of the main water supply valve opening prediction device in one embodiment. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0044] A steam generator is a vertical, naturally circulating device that produces saturated steam. Reactor coolant flows within heat transfer tubes, transferring heat to the secondary loop water outside the tubes. The secondary loop water circulates naturally within the steam generator; as it flows past the heat transfer tubes, a portion of the water becomes saturated steam, which is then supplied to the main turbine and auxiliary facilities. The purpose of the steam generator water level regulation system is to maintain the secondary side water level at the required setpoint. Evaporator water level control mainly includes main feedwater pump speed control and main feedwater valve opening control. The control system mainly consists of the evaporator, main feedwater pump, main feedwater valve, and corresponding piping.

[0045] As one of the most important and sensitive control systems in a nuclear power plant, the stability of the evaporator water level control system is crucial for the safe and stable operation of the nuclear power unit. Statistics show that abnormal evaporator water level control is the leading cause of transient events or automatic reactor shutdowns. Existing evaporator water level control systems incorporate redundancy in their front-end sensors and intermediate controllers, significantly improving the reliability of the front-end and intermediate stages. However, the non-redundant design of the back-end actuators remains a weak point. Abnormalities in the operation of these back-end actuators often cause disturbances or transients in the control system.

[0046] The actuator at the back end of the evaporator water level control system is the main feedwater valve, which is theoretically a pneumatic regulating valve. The most common failure mode is valve jamming, where the main feedwater valve becomes stuck at a specific opening, rendering both automatic and manual control functions unavailable. Another failure mode is that the valve is unresponsive to command signals, continuously opening or closing excessively. Numerous nuclear power plants, both domestically and internationally, have experienced evaporator water level control anomalies due to main feedwater valve malfunctions, severely triggering automatic reactor shutdowns. The response time allowed to operators after a main feedwater valve failure is extremely limited; in most cases, the time between the failure and automatic reactor shutdown is ≤10 minutes.

[0047] Analysis of typical fault data leads to the conclusion that when the main feedwater valve malfunctions, the actual opening degree of the main feedwater valve is less than the required opening degree. Small, and the pressure difference between the soda and water is small. The flow rate remained basically unchanged, resulting in a decrease in water supply. The water level in the evaporator has dropped. The water level in the evaporator continues to decline. With evaporator water level setpoint The deviation gradually increases. Main feedwater valve opening demand signal. Under the integral action of the regulating system, the valve continuously opens, reaching its maximum opening of 100%. Since the actual opening of the main feedwater valve does not change, without intervention, the reactor protection logic for the evaporator water level will be directly triggered. Nuclear unit B triggered the reactor automatic shutdown signal. When the main feedwater valve malfunctions, its actual opening is less than the required opening. The opening may be too small or too large. Therefore, the main feedwater valve opening requirement signal... The evaporator water level varies depending on the valve opening, whether it is continuously opened or closed under the integral action of the regulating system. The direction of opening or closing is related to the instantaneous steam-water deviation of the valve. The rates of change also differ considerably.

[0048] Since the actual opening degree of the main feedwater valve is unknown during the main feedwater valve failure mode, the research on the method for judging the actual valve opening degree under the main feedwater valve failure mode of the evaporator water level in nuclear power plants has very important engineering significance. It is beneficial to fault response and fault handling, and ensures the safe and stable operation of nuclear power units.

[0049] Based on this, this application provides a method, device and control system for predicting the opening degree of the main water supply valve.

[0050] The term "non-faulty evaporator" refers to the evaporator corresponding to a non-faulty feedwater valve, while "faulty evaporator" refers to the evaporator corresponding to a faulty feedwater valve. Similarly, the term "non-faulty main feedwater valve" refers to the main feedwater valve corresponding to a non-faulty evaporator, while "faulty main feedwater valve" refers to the main feedwater valve corresponding to a faulty evaporator.

[0051] In one exemplary embodiment, such as Figure 1 As shown, a method for predicting the opening degree of the main feedwater valve is provided. Taking the application of this method to the aforementioned evaporator water level control system as an example, the method includes the following steps 102 to 106. Wherein:

[0052] Step 102: If a faulty main water supply valve is detected, determine the current state of the faulty main water supply valve based on the difference between the water level of each evaporator and the evaporator water level setpoint, as well as the rate of change of the water level of the non-faulty evaporators.

[0053] The current state includes both steady-state and unsteady-state conditions. This step is used to determine whether the faulty main water supply valve is in a steady state.

[0054] Among them, when a fault signal of the main feedwater valve is detected, the faulty main feedwater valve corresponding to the faulty main feedwater valve and the faulty evaporator corresponding to the faulty main feedwater valve can be identified.

[0055] The evaporator water level setpoint can be set according to actual needs.

[0056] In some embodiments, the main feedwater valve is determined to be in a steady state when the rate of change of water level in the non-faulty evaporators is less than a preset rate of change, and the difference between the water level of each evaporator and the evaporator water level setpoint is less than a preset difference. In some embodiments, the main feedwater valve is determined to be in a non-steady state when the rate of change of water level in the non-faulty evaporators is greater than or equal to a preset rate of change, and / or the difference between the water level of any evaporator and the evaporator water level setpoint is greater than or equal to a preset difference.

[0057] Step 104: When the current state of the faulty main feedwater valve is in a steady state, obtain the average value of the opening of the non-faulty main feedwater valve and use it as the predicted opening of the faulty main feedwater valve.

[0058] For example, if there are 3 main water supply valves, including 1 faulty main water supply valve and 2 non-faulty main water supply valves, then the average opening of the 2 non-faulty main water supply valves is used as the predicted opening of the faulty main water supply valve. In the formula This is the opening signal of the non-faulty main feedwater valve corresponding to the non-faulty evaporator No. 1. This is the opening signal of the main feedwater valve corresponding to the non-faulty evaporator No. 2. The predicted opening degree of the faulty main water supply valve.

[0059] Step 106: When the current state of the faulty main feedwater valve is not in a steady state, determine the predicted opening of the faulty main feedwater valve based on the functional relationship between the cross-sectional area of ​​the main feedwater valve and the predicted opening of the main feedwater valve, and the cross-sectional area of ​​the faulty main feedwater valve.

[0060] The cross-sectional area of ​​the main water supply valve refers to the area of ​​the internal flow channel of the valve on a specific cross section.

[0061] The cross-sectional area of ​​the main feedwater valve that caused the malfunction can be obtained through actual measurement or simulation. For example, the cross-sectional area of ​​the main feedwater valve can be calculated based on the main feedwater flow rate and velocity.

[0062] The functional relationship between the cross-sectional area of ​​the main feedwater valve and the predicted opening degree of the main feedwater valve can be obtained by fitting historical data. In one embodiment, the cross-sectional area of ​​the main feedwater valve... Predicted opening degree of main water supply valve The corresponding functional relationships are as follows: .in, The opening characteristics of the main feedwater valve, namely the opening command signal of the main feedwater valve (which can be understood as the predicted opening in this embodiment) and the cross-sectional area of ​​the main feedwater valve. To ensure accuracy, the corresponding functional relationship can be obtained by fitting a higher-order function. .

[0063] The predicted opening degree of the faulty main feedwater valve determined in step 106 can be understood as the initial value of the actual valve opening degree under the faulty main feedwater valve mode. The determination of the initial value of the actual valve opening degree under the faulty main feedwater valve mode is mainly used to promptly grasp the actual valve opening value under the faulty main feedwater valve mode in the early stage of the main feedwater valve fault.

[0064] The predicted opening degree of the faulty main feedwater valve determined in step 104 can be understood as the actual valve opening value under the faulty mode of the main feedwater valve, which is accurately determined after the evaporator water level is stabilized.

[0065] In the above embodiments, under the main feedwater valve failure mode, it is determined whether the main feedwater valve is in a steady state. In a steady state, predicting the opening of the faulty main feedwater valve using the opening of the non-faulty main feedwater valve is extremely simple. In a non-steady state, determining the predicted opening of the faulty main feedwater valve based on the functional relationship between the main feedwater valve cross-sectional area and the predicted opening, and using the cross-sectional area of ​​the faulty main feedwater valve, allows for timely monitoring of the actual valve opening under the main feedwater valve failure mode. Knowing the actual valve opening under the main feedwater valve failure mode is beneficial for fault response and handling.

[0066] In addition, the method provided in this embodiment can improve the reliability of the evaporator water level control system, significantly reduce evaporator water level disturbances caused by main feedwater valve malfunctions, and significantly reduce the risk of reactor automatic shutdown due to main feedwater valve malfunctions, thus ensuring the safe and stable operation of the nuclear power unit. Furthermore, the method provided in this embodiment has significant prospects for promotion and application; the technologies involved in the project have good versatility and can be promoted and applied in nuclear power units at multiple sites.

[0067] In some embodiments, please refer to Figure 2 The process of determining the cross-sectional area of ​​the main water supply valve includes:

[0068] Step 202: Determine the main water supply flow rate based on the pressure difference across the main water supply valve; wherein, the pressure difference across the main water supply valve refers to the difference between the inlet pressure before the main water supply valve malfunctions and the inlet pressure after the malfunction, or the difference between the outlet pressure before the main water supply valve malfunctions and the outlet pressure after the malfunction.

[0069] In one embodiment, the functional relationship between the pressure difference across the main feedwater valve and the main feedwater flow rate can be obtained by fitting historical data. Then, based on the functional relationship between the pressure difference across the main feedwater valve and the main feedwater flow rate, and the calculated pressure difference across the main feedwater valve, the main feedwater flow rate can be determined.

[0070] In one embodiment, the product of a preset constant, the pressure difference across the main feedwater valve, and gravitational acceleration is obtained; the square root of this product is obtained; and the product of the flow coefficient and the square root of this product is obtained and used as the main feedwater velocity. For example, the main feedwater velocity... Pressure difference across the main water supply valve The corresponding functional relationship is as follows: .in, The flow coefficient of the fluid. It represents gravitational acceleration.

[0071] Step 204: Determine the cross-sectional area of ​​the main water supply valve based on the functional relationship between the main water supply valve cross-sectional area, the main water supply flow rate, and the main water supply velocity, as well as the main water supply flow rate and the main water supply velocity.

[0072] Based on the principles of fluid mechanics, the main feedwater flow rate is established. Cross-sectional area of ​​the main water supply valve and main water supply flow rate The functional relationship is as follows: Based on this functional relationship, the main feedwater velocity calculated in step 202, and the measured main feedwater flow rate, the cross-sectional area of ​​the main feedwater valve can be determined. The determined cross-sectional area of ​​the main water supply valve Used in step 106 to determine the predicted opening degree of the faulty main water supply valve.

[0073] The above embodiment uses a simple and efficient method to determine the cross-sectional area of ​​the main water supply valve based on the functional relationship between the main water supply valve cross-sectional area, the main water supply flow rate, and the main water supply velocity, as well as the main water supply flow rate and the main water supply velocity. This method allows for quick and easy calculation of the main water supply valve cross-sectional area.

[0074] In some embodiments, please refer to Figure 3 The process of determining the pressure difference across the main water supply valve includes:

[0075] Step 302: Obtain the positional difference between the outlet of the feedwater pump and the feedwater inlet of the steam generator.

[0076] Step 304: Obtain the pressure difference between the water supply header and the steam header.

[0077] Step 306: Based on the mapping relationship between the secondary load and the pressure difference, the first pressure drop on the secondary side of the steam generator and the second pressure drop in the steam pipeline and / or the feedwater pipeline are fitted to obtain the results.

[0078] Step 308: Determine the pressure difference across the main feedwater valve based on the pressure difference between the feedwater header and the steam header, the positional difference between the feedwater pump outlet and the steam generator feedwater inlet, the first pressure drop, and the second pressure drop.

[0079] The initial value of the actual valve opening under the main feedwater valve fault mode is determined by the steam-water pressure difference, which is one of the variables involved in the calculation. and main water supply flow The actual valve opening under the fault mode of the main feedwater valve is obtained by calculating the differential pressure opening.

[0080] Please see Figure 4 The steam-water pressure difference shown A schematic diagram illustrating the pressure difference between the water supply header and the steam header, showing the steam-water pressure difference. Composed of four parts ( , , and )composition. The positional difference between the feedwater pump outlet and the steam generator feedwater inlet is a constant value. The pressure difference across the main water supply valve. The pressure drop on the secondary side of the steam generator (i.e., the first pressure drop) varies with the load, thus conforming to a mapping relationship. , This represents the load of the second circuit. The first voltage drop remains constant at a stable load plateau. The pressure drop (i.e., the second pressure drop) in the steam and water supply lines varies with the load, i.e., it conforms to the mapping relationship. .

[0081] To ensure high accuracy, , All were obtained by fitting high-order functions.

[0082] The pressure difference across the main feedwater valve can be obtained from the above components. : .

[0083] The above embodiments simulate the functional relationship between the pressure difference across the main feedwater valve and the main feedwater flow rate, and the steam-water pressure difference. The functional relationship between other components in the pressure difference between the main water supply pipe and the steam pipe (i.e., the pressure difference between the main water supply pipe and the steam pipe) and the pressure difference before and after the main water supply valve is used to achieve the effect of quickly obtaining the main water supply flow rate based on measured data and functional relationships.

[0084] In some embodiments, the process of determining whether the current state of the faulty main water supply valve is in a steady state includes:

[0085] The current state of the faulty main water supply valve is determined to be steady state if at least one of the following conditions is met: the rate of change of water level of the non-faulty evaporator is not greater than the standard value of the rate of change of water level of the non-faulty evaporator, and the absolute value of the difference between the water level of each evaporator and the evaporator water level setpoint is not greater than the standard value of the water level deviation of the non-faulty evaporator.

[0086] In other words, if the following three conditions are met simultaneously, it is determined that the evaporator water level has entered a steady state, and the current state of the faulty main water supply valve is steady state.

[0087] The three conditions include: ; ; .

[0088] in, The standard value for the rate of water level change of a non-faulty evaporator is obtained by multiplying the maximum rate of water level change of the evaporator during steady-state operation at full power by the uncertainty coefficient. The standard value for the water level deviation of a non-faulty evaporator is obtained by multiplying the maximum deviation of the evaporator water level during full-power steady-state operation by the uncertainty coefficient.

[0089] Please see Figure 5 The diagram shows the steady-state value judgment curve of the actual valve opening under the main feedwater valve failure mode. If the water level of the non-faulty evaporator does not change significantly, that is, there is no obvious upward or downward trend, and the water levels of the faulty and non-faulty evaporators are consistent with the evaporator water level setpoint... If the values ​​match, it can be determined that the evaporator water level has reached a steady state.

[0090] In the above embodiments, by determining whether the evaporator water level is controlled stably, it is determined whether the main feedwater valve has entered a steady state under fault mode. This method is stable and reliable, and is conducive to accurately determining the status of the faulty main feedwater valve.

[0091] In some embodiments, the main feedwater valve opening prediction method further includes:

[0092] Step 1: Based on the predicted opening degree determined when the main feedwater valve is in a steady state, adjust the evaporator water level corresponding to the main feedwater valve.

[0093] As can be seen from the above description, the predicted opening degree determined when the current state of the faulty main feedwater valve is steady is more accurate. Therefore, the evaporator water level should be adjusted based on the predicted opening degree determined when the current state of the faulty main feedwater valve is steady.

[0094] Step 2: If the evaporator water level does not reach the preset water level within the preset time after adjustment, adjust the evaporator water level corresponding to the faulty main water supply valve according to the predicted opening determined when the current state of the faulty main water supply valve is not in a steady state.

[0095] The preset water level can be understood as a preset water level range.

[0096] If the evaporator water level has not reached the preset water level after adjusting the predicted opening based on the steady state, then the predicted opening determined under the non-steady state condition will be used to adjust the evaporator water level.

[0097] In the above embodiments, understanding the actual valve opening under the main water supply valve failure mode is beneficial for timely adjustment of the evaporator water level, enabling faster fault response and handling.

[0098] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0099] Please see Figure 6 Based on the same inventive concept, this application also provides a main feedwater valve opening prediction device 60 for implementing the main feedwater valve opening prediction method described above. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more embodiments of the main feedwater valve opening prediction device 60 provided below can be found in the limitations of the main feedwater valve opening prediction method above, and will not be repeated here.

[0100] The main feedwater valve opening prediction device 60 is used in the evaporator water level control system. The device 60 includes:

[0101] The status determination module 61 is used to determine the current status of the faulty main water supply valve when a faulty main water supply valve is detected, based on the difference between the water level of each evaporator and the evaporator water level setpoint, as well as the rate of change of the water level of the non-faulty evaporators.

[0102] The opening prediction module 62 is used to predict the opening of the faulty main feedwater valve by using the average opening of the non-faulty evaporator main feedwater valve as the current state of the faulty main feedwater valve when the current state of the faulty main feedwater valve is in a steady state.

[0103] The opening prediction module 62 is also used to determine the predicted opening of the faulty main water supply valve based on the functional relationship between the cross-sectional area of ​​the main water supply valve and the predicted opening of the main water supply valve, and the cross-sectional area of ​​the faulty main water supply valve, when the current state of the faulty main water supply valve is not in a steady state.

[0104] In one embodiment, the process of determining the cross-sectional area of ​​the main water supply valve includes:

[0105] The main feed water flow rate is determined based on the pressure difference across the main feed water valve. The pressure difference across the main feed water valve refers to the difference between the pressure at the inlet before the main feed water valve malfunctions and the pressure at the inlet after the malfunction, or the difference between the pressure at the outlet before the main feed water valve malfunctions and the pressure at the outlet after the malfunction.

[0106] The cross-sectional area of ​​the main water supply valve is determined based on the functional relationship between the main water supply valve cross-sectional area, the main water supply flow rate, and the main water supply velocity, as well as the main water supply flow rate and the main water supply velocity.

[0107] In one embodiment, the process of determining the pressure difference across the main water supply valve includes:

[0108] Obtain the positional difference between the feedwater pump outlet and the steam generator feedwater inlet;

[0109] Obtain the pressure difference between the water supply header and the steam header;

[0110] Based on the mapping relationship between the secondary load and the pressure difference, the first pressure drop on the secondary side of the steam generator and the second pressure drop in the steam pipeline and / or the feedwater pipeline are obtained by fitting.

[0111] The pressure difference across the main feedwater valve is determined based on the pressure difference between the feedwater header and the steam header, the positional difference between the feedwater pump outlet and the steam generator feedwater inlet, the first pressure drop, and the second pressure drop.

[0112] In one embodiment, determining the main feedwater flow rate based on the pressure difference across the main feedwater valve includes:

[0113] Obtain the product of the preset constant, the pressure difference across the main water supply valve, and the gravitational acceleration;

[0114] Get the square root of the product value;

[0115] Obtain the product between the flow coefficient and the root of the square and use it as the main feedwater velocity.

[0116] In one embodiment, the process of determining whether the current state of the faulty main water supply valve is in a steady state includes:

[0117] The current state of the faulty main water supply valve is determined to be steady state if at least one of the following conditions is met: the rate of change of water level of the non-faulty evaporator is not greater than the standard value of the rate of change of water level of the non-faulty evaporator, and the absolute value of the difference between the water level of each evaporator and the evaporator water level setpoint is not greater than the standard value of the water level deviation of the non-faulty evaporator.

[0118] In one embodiment, the main feedwater valve opening prediction device 60 further includes an adjustment module 63. The adjustment module 63 is used to adjust the evaporator water level corresponding to the faulty main feedwater valve based on the predicted opening determined when the current state of the faulty main feedwater valve is in a steady state; if the evaporator water level does not reach the preset water level within a preset time after adjustment, the evaporator water level corresponding to the faulty main feedwater valve is adjusted based on the predicted opening determined when the current state of the faulty main feedwater valve is not in a steady state.

[0119] Each module in the aforementioned main water supply valve opening prediction device 60 can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the operations corresponding to each module.

[0120] In one exemplary embodiment, an evaporator water level control system is provided, including a memory and a processor, the memory storing a computer program that, when executed by the processor, implements the main feedwater valve opening prediction method as provided in any of the preceding embodiments.

[0121] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the main water supply valve opening prediction method as provided in any of the preceding embodiments.

[0122] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the main feedwater valve opening prediction method as provided in any of the preceding embodiments.

[0123] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0124] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0125] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0126] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for predicting the opening degree of a main water supply valve, characterized in that, The method, applied to an evaporator water level control system, includes: If a faulty main water supply valve is detected, the current status of the faulty main water supply valve is determined based on the difference between the water level of each evaporator and the evaporator water level setpoint, as well as the rate of change of the water level of the non-faulty evaporators. When the current state of the faulty main water supply valve is in a steady state, the average value of the opening of the non-faulty main water supply valve is obtained and used as the predicted opening of the faulty main water supply valve. When the current state of the faulty main feedwater valve is not in a steady state, the predicted opening of the faulty main feedwater valve is determined based on the functional relationship between the cross-sectional area of ​​the main feedwater valve and the predicted opening of the main feedwater valve, and the cross-sectional area of ​​the faulty main feedwater valve. The process of determining the cross-sectional area of ​​the main feedwater valve includes: determining the main feedwater flow velocity based on the pressure difference across the main feedwater valve. The pressure difference across the main feedwater valve refers to the difference between the pressure at the inlet before the fault and the pressure at the inlet after the fault, or the difference between the pressure at the outlet before the fault and the pressure at the outlet after the fault. The cross-sectional area of ​​the main water supply valve is determined based on the functional relationship between the main water supply valve cross-sectional area, the main water supply flow rate, and the main water supply velocity, as well as the main water supply flow rate and the main water supply velocity. The functional relationship between the main water supply valve cross-sectional area and the predicted opening degree of the main water supply valve is obtained by fitting a high-order function.

2. The method according to claim 1, characterized in that, The process of determining the pressure difference across the main feedwater valve includes: Obtain the positional difference between the feedwater pump outlet and the steam generator feedwater inlet; Obtain the pressure difference between the water supply header and the steam header; Based on the mapping relationship between the secondary load and the pressure difference, the first pressure drop on the secondary side of the steam generator and the second pressure drop in the steam pipeline and / or the feedwater pipeline are obtained by fitting. The pressure difference across the main feedwater valve is determined based on the pressure difference between the feedwater header and the steam header, the positional difference between the feedwater pump outlet and the steam generator feedwater inlet, the first pressure drop, and the second pressure drop.

3. The method according to claim 1, characterized in that, The process of determining the main feedwater flow rate based on the pressure difference across the main feedwater valve includes: Obtain the product of the preset constant, the pressure difference across the main water supply valve, and the gravitational acceleration; Obtain the square root of the product value; The product of the flow coefficient and the root of the square is obtained and used as the main feedwater velocity.

4. The method according to any one of claims 1-3, characterized in that, The process for determining whether the current state of the faulty main water supply valve is in a steady state includes: The current state of the faulty main water supply valve is determined to be steady state if at least one of the following conditions is met: the water level change rate of the non-faulty evaporator is not greater than the standard value of the water level change rate of the non-faulty evaporator, and the absolute value of the difference between the water level of each evaporator and the evaporator water level set value is not greater than the standard value of the water level deviation of the non-faulty evaporator.

5. The method according to any one of claims 1-3, characterized in that, The method further includes: Adjust the evaporator water level corresponding to the faulty main feedwater valve based on the predicted opening degree determined under the condition that the current state of the faulty main feedwater valve is in a steady state. If the evaporator water level does not reach the preset water level within the preset time after adjustment, the evaporator water level corresponding to the faulty main water valve will be adjusted according to the predicted opening determined when the current state of the faulty main water valve is not in a steady state.

6. A main water supply valve opening degree prediction device, characterized in that, The device, used in an evaporator water level control system, comprises: The status determination module is used to determine the current status of the faulty main water supply valve when a faulty main water supply valve is detected, based on the difference between the water level of each evaporator and the evaporator water level setpoint, as well as the rate of change of the water level of the non-faulty evaporators. The opening prediction module is used to predict the opening of the faulty main feedwater valve by using the average opening of the non-faulty evaporator main feedwater valve as the current steady state. The opening prediction module is also used to determine the predicted opening of the faulty main water supply valve based on the functional relationship between the cross-sectional area of ​​the main water supply valve and the predicted opening of the main water supply valve, and the cross-sectional area of ​​the faulty main water supply valve, when the current state of the faulty main water supply valve is not in a steady state. The process of determining the cross-sectional area of ​​the main feedwater valve includes: determining the main feedwater flow velocity based on the pressure difference across the main feedwater valve; wherein the pressure difference across the main feedwater valve refers to the difference between the inlet pressure before the main feedwater valve malfunctions and the inlet pressure after the malfunction, or the difference between the outlet pressure before the main feedwater valve malfunctions and the outlet pressure after the malfunction; determining the main feedwater valve cross-sectional area based on the functional relationship between the main feedwater valve cross-sectional area, the main feedwater flow rate, and the main feedwater flow velocity; the functional relationship between the main feedwater valve cross-sectional area and the predicted opening degree of the main feedwater valve is obtained by fitting a high-order function.

7. The apparatus according to claim 6, characterized in that, The process of determining the pressure difference across the main water supply valve includes: Obtain the positional difference between the feedwater pump outlet and the steam generator feedwater inlet; Obtain the pressure difference between the water supply header and the steam header; Based on the mapping relationship between the secondary load and the pressure difference, the first pressure drop on the secondary side of the steam generator and the second pressure drop in the steam pipeline and / or the feedwater pipeline are obtained by fitting. The pressure difference across the main feedwater valve is determined based on the pressure difference between the feedwater header and the steam header, the positional difference between the feedwater pump outlet and the steam generator feedwater inlet, the first pressure drop, and the second pressure drop.

8. An evaporator water level control system, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

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