A method and system for controlling feedwater to a once-through steam generator

Abstract

This application relates to the field of nuclear energy science and engineering, and particularly to a method and system for controlling feedwater in a direct-current steam generator. The control method includes: establishing a first mapping relationship between feedwater pressure and feedwater flow rate of the pump-valve system based on collected operating parameters of the direct-current steam generator; obtaining a steam pressure deviation value based on the current steam pressure value and the steam pressure setpoint; obtaining a steam superheat deviation value based on the current steam pressure value, the current steam temperature value, and the steam superheat threshold of the direct-current steam generator; obtaining the required feedwater pump speed and the required feedwater valve opening value based on the steam superheat deviation value, the steam pressure deviation value, and the first mapping relationship; and adjusting the feedwater pump to the required speed value and the feedwater valve to the required opening value. This application provides a method and system for controlling feedwater in a direct-current steam generator to solve the problem in related technologies of the inability to quickly and accurately control the outlet steam parameters of a direct-current steam generator.

Description

Technical Field

[0001] This application relates to the field of nuclear energy science and engineering, and in particular to a method and system for controlling feedwater in a direct current steam generator. Background Technology

[0002] Steam generators are an important component of steam power plants. Marine power plants use once-through steam generators. Because once-through steam generators have very small water capacity and heat load, their buffering capacity is limited. Changes in feedwater will have a rapid and significant impact on the pressure and temperature of the outlet steam. Therefore, the feedwater control process of once-through steam generators must meet the following requirements: (1) high control accuracy; (2) fast feedwater adjustment speed, with as few repetitive actions as possible during the adjustment process.

[0003] However, the coupling effect of the pump and valve system makes it more complicated to accurately regulate the feedwater flow rate or feedwater pressure, which directly affects the control accuracy of the outlet steam parameters of the DC steam generator.

[0004] In related technologies, methods for handling pump-valve coupling effects often employ decoupling algorithms such as feedforward compensation, diagonal matrix method, and identity matrix method to approximate the pump-valve system, separating the roles of the feedwater valve and feedwater pump in the control system. However, these decoupling algorithms decouple the transfer functions of the feedwater valve and feedwater pump. Since pump-valve systems are typically nonlinear systems, the transfer functions mentioned in the literature are obtained by linearizing the system at a specific operating point. This means that the transfer function changes with each adjustment of the pump-valve system, implying that decoupling algorithms are practically useless in industrial applications and have significant limitations in engineering applications. They fail to effectively resolve the coupling effects and cause repeated oscillations in the control process of the DC steam generator. Summary of the Invention

[0005] This application provides a method and system for controlling the feedwater of a DC steam generator, in order to solve the problem in related technologies that the outlet steam parameters of a DC steam generator cannot be controlled quickly and accurately.

[0006] To achieve the above objectives, in a first aspect, a method for controlling the feedwater of a direct-flow steam generator is provided, comprising the following steps:

[0007] Based on the collected operating parameters of the DC steam generator, a first mapping relationship between the feedwater pressure and the feedwater flow rate of the pump and valve system is established.

[0008] The steam pressure deviation value is obtained based on the current steam pressure value and the steam pressure set value of the DC steam generator;

[0009] Based on the current steam pressure and temperature values ​​of the DC steam generator, as well as the steam superheat threshold, the steam superheat deviation value is obtained.

[0010] Based on the steam superheat deviation value, steam pressure deviation value, and the first mapping relationship, obtain the required values ​​for the feedwater pump speed and the feedwater valve opening.

[0011] Adjust the water pump to the required speed and the water valve to the required opening.

[0012] In some embodiments, based on the collected operating parameters of the DC steam generator, a first mapping relationship between the feedwater pressure and the feedwater flow rate of the pump-valve system is established, specifically including:

[0013] Based on the collected operating parameters of the DC steam generator, the second mapping relationship between the head of the feedwater pump and the feedwater flow rate at different speeds was obtained, as well as the third mapping relationship between the pressure difference of the feedwater valve and the feedwater flow rate at different opening degrees.

[0014] Based on the second and third mapping relationships, a first mapping relationship is established between the water supply pressure and the water supply flow rate of the pump and valve system.

[0015] In some embodiments, the second mapping relationship and the third mapping relationship are plotted in the same coordinate system. The intersection of the second mapping relationship and the third mapping relationship is the current feedwater pump speed value and feedwater valve opening value corresponding to the feedwater flow rate and feedwater pressure in the DC steam generator. The first mapping relationship includes the intersection point.

[0016] In some embodiments, the second and third mapping relationships are obtained by least squares fitting.

[0017] In some embodiments, the steam superheat deviation value is obtained based on the current steam pressure and temperature values ​​of the DC steam generator, as well as the steam superheat threshold. Specifically, this includes:

[0018] Obtain the saturated steam temperature value under the current steam pressure, and calculate the difference between the saturated steam temperature value and the current steam temperature value to obtain the current steam superheat.

[0019] The steam superheat deviation value is obtained by subtracting the current steam superheat from the superheat threshold.

[0020] In some embodiments, the required values ​​for the feedwater pump speed and feedwater valve opening are obtained based on the steam superheat deviation, pressure deviation, and a first mapping relationship, specifically including:

[0021] Calculate the required feedwater pressure and feedwater flow rate based on the steam pressure deviation and steam superheat deviation values.

[0022] Based on the water supply pressure demand, water supply volume demand, and the first mapping relationship, the water supply pump speed demand and water supply valve opening demand are obtained.

[0023] In some embodiments, the required values ​​for the water supply pump speed and the water supply valve opening are obtained based on the required water supply pressure, the required water supply volume, and a first mapping relationship. Specifically, this includes:

[0024] Input the water supply pressure requirement value into the first mapping relationship to obtain the water supply pump speed requirement value, and input the water supply volume requirement value into the first mapping relationship to obtain the water supply valve opening requirement value.

[0025] In some embodiments, the water pump is adjusted to the required speed value, and the water valve is adjusted to the required opening value, specifically including:

[0026] Based on the measured speed of the water pump and the required speed of the water pump, the speed deviation value is obtained, and the speed of the water pump is adjusted accordingly.

[0027] Based on the measured opening value of the water supply valve and the required opening value of the water supply valve, the opening deviation value is obtained, and the opening of the water supply valve is adjusted accordingly.

[0028] Secondly, a feedwater control system for a DC steam generator is provided, comprising:

[0029] The first module is used to: establish a first mapping relationship between the feedwater pressure and the feedwater flow rate of the pump and valve system based on the collected operating parameters of the DC steam generator;

[0030] The second module is used to: obtain the steam superheat deviation based on the current steam temperature and current steam pressure of the DC steam generator, as well as the superheat threshold.

[0031] The third module is used to: obtain the pressure deviation value based on the current steam pressure and the target pressure value;

[0032] The fourth module is used to: obtain the required values ​​of feedwater pump speed and feedwater valve opening based on the steam superheat deviation, pressure deviation, and the first mapping relationship;

[0033] The fifth module is used to adjust the water pump to the required speed and the water valve to the required opening.

[0034] In some embodiments, the water pump and water valve are connected in parallel with the DC steam generator, and a pressure measuring sensor and a temperature sensor are connected to the outlet of the DC steam generator.

[0035] The beneficial effects of the technical solution provided in this application include:

[0036] This application provides a method and system for controlling the feedwater of a DC steam generator. By collecting the operating parameters of the DC steam generator under normal operating conditions, a first mapping relationship between the feedwater pressure and the feedwater flow rate is established in the pump valve system. Then, the steam pressure value of the DC steam generator is measured, and the difference between it and the set value of the steam pressure is used to obtain the steam pressure deviation value. A similar method is used to obtain the steam superheat deviation value.

[0037] Among them, the steam pressure deviation value and the steam superheat deviation value are the parts that need to be corrected. Based on the first mapping relationship, and referring to the steam superheat deviation value and the pressure deviation value, the required speed value of the feed water valve and the required opening value of the feed water pump are obtained by calculation and adjustments are made.

[0038] Since the control method provided in this application controls the feedwater of the DC steam generator based on the pump and valve performance curves, it can quickly find the target values ​​of feedwater flow rate and feedwater pressure based on the pump and valve performance curves and adjust them, effectively overcoming the coupling effect between the pump and valve systems, improving the adjustment process, and enabling relatively fast and accurate control of the outlet steam parameters of the DC steam generator. Therefore, it can solve the problem in related technologies that cannot quickly and accurately control the outlet steam parameters of the DC steam generator. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A flowchart illustrating the control principle of the DC steam generator feedwater control method provided in this application embodiment;

[0041] Figure 2 This is a schematic diagram of the pump-valve decoupling control adjustment process at a certain node provided in an embodiment of this application.

[0042] In the diagram: 1. DC steam generator; 2. Feed water pump; 3. Feed water valve; 4. Speed ​​sensor; 5. Opening degree sensor; 6. Pressure sensor; 7. Temperature sensor; 8. First controller; 9. Second controller; 10. Third controller; 11. Fourth controller. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] This application provides a method for controlling the feedwater of a DC steam generator, which can solve the problem in related technologies that cannot quickly and accurately control the outlet steam parameters of a DC steam generator.

[0045] See Figures 1 to 2 As shown in the figure, this application provides a method for controlling the feedwater of a DC steam generator, including the following steps:

[0046] S1. Based on the collected operating parameters of DC steam generator 1, establish the first mapping relationship between the feed water pressure and the feed water flow rate of the pump valve system;

[0047] Specifically, during the water supply control process, there is a severe coupling effect between the water supply pump 2 and the water supply valve 3. That is, when the water supply flow rate is adjusted, the change in the opening of the water supply valve causes a change in the pressure difference across the water supply valve 3, which in turn causes an adjustment in the speed of the water supply pump 2. Similarly, when the water supply pressure is adjusted, the change in the speed of the water supply pump 2 will also cause a change in the water supply flow rate, so the opening of the water supply valve 3 also needs to be adjusted.

[0048] Therefore, in this embodiment, the DC steam generator 1 is first brought to normal operation, and the speed of the feedwater pump 2 and the opening of the feedwater valve 3 are changed to obtain the first mapping relationship between the feedwater pressure and the feedwater flow rate of the pump and valve system, i.e., as follows. Figure 2 As shown, the arrows point to the adjustment process of pump-valve decoupling control;

[0049] Furthermore, establishing the first mapping relationship between the water supply pressure and the water supply flow rate of the pump and valve system specifically includes the following steps:

[0050] S101. Based on the collected operating parameters of the DC steam generator 1, obtain the second mapping relationship between the head of the feedwater pump 2 and the feedwater flow rate at different speeds, and the third mapping relationship between the pressure difference of the feedwater valve 3 and the feedwater flow rate at different openings.

[0051] Based on the second and third mapping relationships, a first mapping relationship is established between the water supply pressure and the water supply flow rate of the pump and valve system.

[0052] Specifically, when establishing the second mapping relationship, the DC steam generator 1 is made to run normally, and the speed of the feed water pump 2 is kept constant. The flow rate and head data of the feed water pump 2 at this speed are measured. The curve is fitted by the least squares method to obtain the data at different speeds and to obtain the relationship between head and feed water flow rate.

[0053] Furthermore, by changing the rotational speed of the water pump 2, multiple sets of flow rate and head curves were obtained through fitting.

[0054] Specifically, when establishing the third mapping relationship, the DC steam generator 1 is made to operate normally and the opening degree of the feedwater valve 3 is kept constant. Similarly, based on the engineering operation data of the feedwater valve 3, the relationship between the pressure difference of the feedwater valve 3 and the feedwater flow rate is obtained by fitting using the least squares method.

[0055] Furthermore, by changing the opening degree of water supply valve 3, the relationship between the pressure difference and water supply flow rate of multiple sets of water supply valve 3 under different opening degrees was obtained through fitting.

[0056] The second and third mapping relationships are based on the rotational speed of the water pump 2 and the opening range of the water valve 3 during normal operation, and the rotational speed and opening interval are selected accordingly.

[0057] S102. Plot the second mapping relationship and the third mapping relationship in the same coordinate system. The intersection of the second mapping relationship and the third mapping relationship is the current speed value of the feed water pump 2 and the opening value of the feed water valve 3 corresponding to the feed water flow rate and feed water pressure in the DC steam generator 1. The first mapping relationship includes the intersection point.

[0058] Specifically, the performance curves of the pumps and valves are as follows: Figure 1 As shown, the arrow indicates the adjustment process of pump-valve decoupling control. The intersection point of the pump-valve curves (the intersection point of the second mapping relationship and the third mapping relationship) is the operating point. By inputting the water flow rate and pressure values, the operating point can be found, and the corresponding speed of water pump 2 and opening value of water valve 3 can be obtained. The input water flow rate and water pressure values ​​are allowed to correspond to the nearest operating point within a certain error range.

[0059] Specifically, Figure 1 In this context, ω represents the rotational speed of water pump 2, and μ represents the opening degree of water supply valve 3. Figure 2 The intersection of the second and third mapping relationships is the operating point, which represents the current speed of the water pump 2 and the opening degree of the water valve 3 corresponding to the water flow rate and water pressure in the pipeline.

[0060] When the speed of water pump 2 is constant, the relationship between its head and flow rate is as follows:

[0061] H i =a0+a1*Q i +a2*Q i 2Where H is the head, Q is the flow rate, and a0, a1, and a2 are constants;

[0062] Specifically, the subscript i of Q and H represents a certain rotational speed value, and a0, a1, and a2 are related to the rotational speed values ​​of water pump 2. When the rotational speed of water pump 2 is constant (determined to a specific value), a definite head-flow curve is obtained.

[0063] When the rotational speed changes, the values ​​of a0, a1, and a2 also change. That is, after the rotational speed of water pump 2 changes, a new head-flow curve (second mapping relationship) is obtained.

[0064] Furthermore, combined Figure 2 As shown, Figure 2 The graph shows the relationship between QP and ωP, where ω1 and ω2 are curves at two different speeds of the water pump 2.

[0065] When the opening degree of water supply valve 3 is constant, the relationship between its pressure difference and flow rate is as follows:

[0066] H i =b0*Q i 2 Where H is the head, Q i Let b be the flow rate, and b0 be a constant.

[0067] Specifically, the subscript i of Q and H represents a certain opening value, and b0 is related to the opening value of water supply valve 3. When the opening of water supply valve 3 is constant (determined to a specific value), a definite head-flow curve is obtained.

[0068] When the opening degree changes, the value of b0 also changes. That is, after the opening degree of water supply valve 3 changes, a new head-flow curve (third mapping relationship) is obtained.

[0069] Furthermore, combined Figure 2 As shown, Figure 2 The graph shows the relationship between QP and μ1 and μ2, which are curves for two different opening degrees of the water supply valve 3.

[0070] Specifically, Figure 2 The graph shows the relationship between flow rate Q and pressure P. In the two curves above, the head H is the pressure difference (P). 出口 -P 入口 Set the pressure value at the inlet (P). 入口 The value is constant; only the pressure at the outlet (P) needs to be known. 出口 It can be directly converted into Figure 2 The vertical axis represents the pressure value (P value). The pressure value at the outlet is a known value, obtained by adjusting the speed of the water pump 2 and the opening of the water valve 3. The pressure value at the inlet is a constant value, so this method is feasible.

[0071] S2. Obtain the steam pressure deviation value based on the current steam pressure value and the steam pressure set value of DC steam generator 1;

[0072] Specifically, the steam pressure deviation value can be obtained by subtracting the current steam pressure value from the steam pressure setpoint. The current steam pressure value can be obtained by installing a pressure sensor 6 at the outlet of the DC steam generator 1.

[0073] S3. Based on the current steam pressure and temperature values ​​of DC steam generator 1, and the steam superheat threshold, obtain the steam superheat deviation value.

[0074] Specifically, first obtain the saturated steam temperature value under the current steam pressure, then subtract the saturated steam temperature value from the measured current steam temperature value to obtain the current steam superheat; then, based on the current steam superheat, subtract the superheat threshold value to obtain the steam superheat deviation value.

[0075] Specifically, the steam superheat needs to be controlled within the superheat threshold range. Therefore, when the current steam superheat exceeds the superheat threshold, the difference between the two (the steam superheat deviation value) is the parameter that needs to be adjusted.

[0076] S4. Based on the steam superheat deviation value, steam pressure deviation value, and the first mapping relationship, obtain the required speed value of feedwater pump 2 and the required opening value of feedwater valve 3.

[0077] S401. Calculate the required water pressure and water flow based on the steam pressure deviation and steam superheat deviation.

[0078] Specifically, the DC steam generator 1 is connected to a first controller 8 and a second controller 9 to calculate the water supply pressure demand value and the water supply volume demand value.

[0079] Obtain the current steam pressure value at the outlet of DC steam generator 1, calculate the deviation between the steam pressure setpoint and the current steam pressure value, obtain the correction value for PID adjustment of pressure parameters, and output the feedwater pressure demand value through PID.

[0080] Obtain the current steam temperature and current steam pressure, calculate the current steam superheat, and calculate the deviation from the superheat threshold (step S3) to obtain the correction value for PID control of the superheat parameter, and output the water supply demand value through PID.

[0081] S402. Based on the water supply pressure demand value, water supply volume demand value and the first mapping relationship, the speed demand value of water supply pump 2 and the opening degree demand value of water supply valve 3 are obtained.

[0082] Specifically, the water pressure demand value is input into the first mapping relationship to obtain the speed demand value of the water pump 2, and the water flow demand value is input into the first mapping relationship to obtain the opening degree demand value of the water valve 3.

[0083] Combination Figure 2 As shown, the first mapping relationship and the second mapping relationship are plotted in the same coordinate system, with the water flow rate as the horizontal axis and the water pressure as the vertical axis. The intersection of the first mapping relationship and the second mapping relationship is the operating point. The water flow rate and water pressure at this point are the target values ​​for the final adjustment. At this point, the current speed of the water pump 2 and the opening degree of the water valve 3 corresponding to the water flow rate and pressure in the pipeline can also be obtained.

[0084] S5. Adjust the water pump 2 to the required speed value and the water valve 3 to the required opening value.

[0085] Furthermore, the water pump 2 is connected to a speed sensor 4 to measure the real-time speed of the water pump 2. Based on the measured speed value of the water pump 2 and the required speed value of the water pump 2, the speed deviation value is obtained, and the speed of the water pump 2 is adjusted. Specifically, the speed deviation value is input into the PID module, and the control electrical signal of the frequency converter is output to adjust the speed of the water pump 2.

[0086] Furthermore, the water supply valve 3 is connected to an opening sensor 5 to measure the real-time opening of the water supply valve 3. Based on the measured opening value of the water supply valve 3 and the required opening value of the water supply valve 3, the opening deviation value is obtained, and the opening of the water supply valve 3 is adjusted. Specifically, the opening deviation value is input into the PID module, and the control electrical signal of the regulating valve actuator is output to adjust the opening of the water supply valve 3.

[0087] Specifically, if the outlet pressure and flow rate of the pipeline need to meet the requirements simultaneously, it is necessary to adjust the speed of the water pump 2 and the opening of the water valve 3. Combined with... Figure 2 As shown, the intersection of the second and third mapping relationships corresponds to the flow rate Q and pressure P values ​​on the horizontal and vertical axes, as well as the speed ω of the water pump 2 and the opening value μ of the water valve 3 at the intersection of the curves.

[0088] Combination Figure 2 As shown, when the required outlet flow rate is Q1 and the required outlet pressure is P1, the speed of the water pump 2 needs to be adjusted to ω1 and the opening of the water valve 3 needs to be adjusted to μ1; when the required outlet flow rate is Q2 and the required outlet pressure is P2, the speed of the water pump 2 needs to be adjusted to ω2 and the opening of the water valve 3 needs to be adjusted to μ2.

[0089] This application provides a method for controlling the feedwater of a DC steam generator. By collecting the operating parameters of the DC steam generator under normal operating conditions, a first mapping relationship between the feedwater pressure and the feedwater flow rate is established in the pump valve system. Then, the steam pressure value of the DC steam generator 1 is measured, and the difference between the steam pressure and the set steam pressure value is used to obtain the steam pressure deviation value. A similar method is used to obtain the steam superheat deviation value.

[0090] Among them, the steam pressure deviation value and the steam superheat deviation value are the parts that need to be corrected. Based on the first mapping relationship, and referring to the steam superheat deviation value and the pressure deviation value, the required speed value of the feed water pump 2 and the required opening value of the feed water valve 3 are obtained by calculation and adjustments are made.

[0091] Since the control method provided in this application controls the feedwater of the DC steam generator 1 based on the pump and valve performance curves, it can quickly find the target values ​​of feedwater flow rate and feedwater pressure based on the pump and valve performance curves and adjust them, effectively overcoming the coupling effect between the pump and valve systems, improving the adjustment process, and enabling faster and more accurate control of the outlet steam parameters of the DC steam generator. Therefore, it can solve the problem in related technologies that cannot quickly and accurately control the outlet steam parameters of the DC steam generator.

[0092] This application also provides a DC steam generator feedwater control system for implementing any of the above-described DC steam generator feedwater control methods, combined with... Figure 1 As shown, it includes:

[0093] The first module is used to: establish a first mapping relationship between the feed water pressure and the feed water flow rate of the pump valve system based on the collected operating parameters of the DC steam generator 1;

[0094] The second module is used to: obtain the steam superheat deviation based on the current steam temperature and current steam pressure of the DC steam generator 1, as well as the superheat threshold.

[0095] The third module is used to: obtain the pressure deviation value based on the current steam pressure and the target pressure value;

[0096] The fourth module is used to: obtain the required speed of the feedwater pump 2 and the required opening of the feedwater valve 3 based on the steam superheat deviation, pressure deviation, and the first mapping relationship;

[0097] The fifth module is used to adjust the water pump 2 to the required speed value and the water valve 3 to the required opening value.

[0098] Specifically, the second or third module includes a pressure sensor 6 and a temperature sensor 7, which are connected to the DC steam generator 1 and used to measure the current steam pressure and current steam temperature of the DC steam generator 1.

[0099] Furthermore, one end of the pressure sensor 6 is connected to the DC steam generator 1, and the other end is connected to the first controller 8. The first controller 8 is used to process the above steps S2 and S4, obtain the steam pressure deviation value, and calculate the feedwater pressure demand value; and one end of the temperature sensor 7 is connected to the DC steam generator 1, and the other end is connected to the second controller 9. The second controller 9 is used to process the above steps S3 and S4, obtain the steam superheat deviation value, and calculate the feedwater flow rate demand value.

[0100] Optionally, a PID module is built into the first controller 8 or the second controller 9.

[0101] In some optional embodiments, the feedwater pump 2 and feedwater valve 3 are connected to the DC steam generator 1 as follows: Figure 1 As shown in the parallel connection, both superheat control and pressure control adopt cascade control methods: feedwater pump 2 is connected to a third controller 10, which calculates the corresponding electrical signal based on the speed of feedwater pump 2, so that feedwater pump 2 can make adjustments; feedwater valve 3 is connected to a fourth controller 11, which calculates the corresponding electrical signal based on the opening degree of feedwater valve 3, so that feedwater valve 3 can make adjustments; this can maintain the stability of the speed of feedwater pump 2 and the opening degree of feedwater valve 3 under the presence of disturbances, improve the regulation process, and meet the functional requirement of keeping the outlet steam parameter tracking setpoint stable.

[0102] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0103] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0104] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for controlling feedwater in a direct-flow steam generator, characterized in that, It includes the following steps: Based on the collected operating parameters of the DC steam generator (1), a first mapping relationship between the feed water pressure and the feed water flow rate of the pump valve system is established. Based on the current steam pressure value and the steam pressure set value of the DC steam generator (1), the steam pressure deviation value is obtained; Based on the current steam pressure and current steam temperature of the DC steam generator (1), and the steam superheat threshold, the steam superheat deviation value is obtained. Based on the steam superheat deviation value, steam pressure deviation value and the first mapping relationship, obtain the required speed value of the feedwater pump (2) and the required opening value of the feedwater valve (3); Adjust the water pump (2) to the required speed value and the water valve (3) to the required opening value.

2. The feedwater control method for a DC steam generator as described in claim 1, characterized in that, Based on the collected operating parameters of the DC steam generator (1), a first mapping relationship between the feedwater pressure and the feedwater flow rate of the pump-valve system is established, specifically including: Based on the collected operating parameters of the DC steam generator (1), the second mapping relationship between the head of the feed water pump (2) and the feed water flow rate at different speeds is obtained, as well as the third mapping relationship between the pressure difference of the feed water valve (3) and the feed water flow rate at different openings. Based on the second and third mapping relationships, a first mapping relationship is established between the water supply pressure and the water supply flow rate of the pump and valve system.

3. The feedwater control method for a DC steam generator as described in claim 2, characterized in that: The second mapping relationship and the third mapping relationship are plotted on the same coordinate system. The intersection of the second mapping relationship and the third mapping relationship is the current speed value of the feed water pump (2) and the opening value of the feed water valve (3) corresponding to the feed water flow rate and feed water pressure in the DC steam generator (1). The first mapping relationship includes the intersection point.

4. The feedwater control method for a DC steam generator as described in claim 2, characterized in that: The second and third mapping relationships were obtained by fitting using the least squares method.

5. The feedwater control method for a DC steam generator as described in claim 1, characterized in that, Based on the current steam pressure and temperature values ​​of the DC steam generator (1), and the steam superheat threshold, the steam superheat deviation value is obtained, specifically including: Obtain the saturated steam temperature value under the current steam pressure, and calculate the difference between the saturated steam temperature value and the current steam temperature value to obtain the current steam superheat. The steam superheat deviation value is obtained by subtracting the current steam superheat from the superheat threshold.

6. The feedwater control method for a DC steam generator as described in claim 1, characterized in that, Based on the steam superheat deviation, pressure deviation, and the first mapping relationship, the required speed of the feedwater pump (2) and the required opening of the feedwater valve (3) are obtained, specifically including: Calculate the required feedwater pressure and feedwater flow rate based on the steam pressure deviation and steam superheat deviation values. Based on the water supply pressure demand, water supply volume demand and the first mapping relationship, the speed demand of the water supply pump (2) and the opening demand of the water supply valve (3) are obtained.

7. The feedwater control method for a DC steam generator as described in claim 6, characterized in that, Based on the water supply pressure demand, water supply volume demand, and the first mapping relationship, the required speed of the water supply pump (2) and the required opening of the water supply valve (3) are obtained, specifically including: Input the water pressure demand value into the first mapping relationship to obtain the speed demand value of the water pump (2), and input the water flow demand value into the first mapping relationship to obtain the opening demand value of the water valve (3).

8. The feedwater control method for a DC steam generator as described in claim 1, characterized in that, Adjust the water pump (2) to the required speed value and the water valve (3) to the required opening value, specifically including: Based on the measured speed of the water pump (2) and the required speed of the water pump (2), the speed deviation value is obtained, and the speed of the water pump (2) is adjusted. Based on the measured opening value of the water supply valve (3) and the required opening value of the water supply valve (3), the opening deviation value is obtained, and the opening of the water supply valve (3) is adjusted.

9. A feedwater control system for a DC steam generator, characterized in that, It includes: The first module is used to: establish a first mapping relationship between the feed water pressure and the feed water flow rate of the pump valve system based on the collected operating parameters of the DC steam generator (1); The second module is used to: obtain the steam superheat deviation based on the current steam temperature and current steam pressure of the DC steam generator (1) and the superheat threshold. The third module is used to: obtain the pressure deviation value based on the current steam pressure and the target pressure value; The fourth module is used to: obtain the required speed of the feedwater pump (2) and the required opening of the feedwater valve (3) based on the steam superheat deviation, pressure deviation and the first mapping relationship; The fifth module is used to: adjust the water pump (2) to the required speed value and adjust the water valve (3) to the required opening value.

10. The DC steam generator feedwater control system as described in claim 9, characterized in that: The water pump (2) and water valve (3) are connected in parallel with the DC steam generator (1), and a pressure measuring sensor (6) and a temperature sensor (7) are connected at the outlet of the DC steam generator (1).

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