Feed water recirculation valve adjusting control method and system

Abstract

The invention relates to the technical field of automatic control of thermal power generating units, and discloses a feed water recirculation valve adjusting control method and system.The method comprises the steps that when the unit target load, the unit actual power generation load and the unit feed water flow meet preset requirements, a feed water recirculation adjusting valve is opened and closed, and the unit target load and the unit actual power generation load meet the preset requirements; in the opening and closing process, the opening degree of the water supply recirculation adjusting valve is adjusted based on a parallelogram flow control strategy, and the parallelogram flow control strategy is designed with an adjusting return difference of opening and closing of the valve. During the low-load operation period of the unit, when the feed water flow is low, a control strategy of automatically opening and closing the feed water recirculation regulating valve is designed; the water supply recirculation control of a parallelogram flow control strategy is designed, it is guaranteed that when the water supply flow of the unit is low, the water supply flow of the unit is stable in the opening and closing process of the recirculation adjusting valve, stable transition of the water supply recirculation adjusting system is achieved, and the reliability and safety of the water supply system in the low-load period of the thermal power generating unit are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic control of thermal power units, and particularly to a control method and system for a feed water recirculation regulating valve. Background Art

[0002] With the rapid development of new energy power generation in China, the proportion of new energy in the power grid has been increasing rapidly year by year, resulting in problems such as new energy consumption and power system peak shaving, and the demand for improving the balancing regulation ability has become increasingly prominent, restricting the construction and development of the new power system.

[0003] While new energy has grown rapidly, thermal power generation has also experienced great development. Although the proportion of thermal power in China's power source structure has been decreasing year by year, the power generation still occupies a dominant position. Improving the peak shaving ability of thermal power is an urgent task for current flexibility improvement. Thermal power units need to have the ability to operate at deep peak shaving and low loads, which will be the main work for subsequent improvement of thermal power unit capabilities. The power grid urgently requires existing thermal power units to have the function of deep peak shaving and low load operation, and must improve the flexibility of thermal power units to meet the requirements of the power grid. Therefore, in order to meet the requirements of the power system for the deep peak shaving width of thermal power units and further improve the ability of the feed water system of thermal power units to adapt to deep peak shaving, a control strategy for the recirculation valve of the steam-driven feed water pump during low load operation of thermal power units equipped with a single steam-driven feed water pump is designed. For the conventional control strategy of the recirculation flow valve of the steam-driven feed water pump, PID regulation control or manual adjustment by operators is adopted. During the opening and closing process of the recirculation control valve, it is easy to cause large fluctuations in the feed water flow of the unit. For units designed with a single steam-driven feed water pump, once the feed water flow fluctuates greatly to the feed water flow protection set value, it will cause the unit to shut down, bringing greater safety risks to the safe operation of thermal power units. Summary of the Invention

[0004] In view of this, the present invention provides a control method and system for a feed water recirculation regulating valve to solve the problem that the conventional control strategy of the recirculation flow valve of the steam-driven feed water pump is easy to cause large fluctuations in the feed water flow of the unit.

[0005] In a first aspect, the present invention provides a control method for a feed water recirculation regulating valve, the method comprising:

[0006] When the target load of the unit, the actual power generation load of the unit, and the feed water flow of the unit meet the first preset requirement, open the feed water recirculation regulating valve, and during the opening process, adjust the opening of the feed water recirculation regulating valve based on the parallelogram flow control strategy, and the parallelogram flow control strategy is designed with an adjustment dead zone for valve opening and closing;

[0007] When the unit target load, the actual power generation load of the unit, and the feed water flow of the unit meet the second preset requirement, close the feed water recirculation regulating valve, and adjust the opening of the feed water recirculation regulating valve based on the parallelogram flow control strategy during the closing process.

[0008] A control method for a feed water recirculation regulating valve provided by the present invention designs an automatic opening and closing control strategy for the feed water recirculation regulating valve during low load operation of the unit when the feed water flow is low; considering that the feed water flow has a large disturbance during the opening and closing processes of the recirculation regulating valve, a feed water recirculation control with a parallelogram flow control strategy is designed. This control strategy designs a dead zone for the opening and closing of the recirculation regulating valve, eliminates the coupling phenomenon of the feed water flow, ensures the stability of the feed water flow of the unit during the opening and closing processes of the recirculation regulating valve when the feed water flow of the unit is low, realizes the smooth transition of the feed water recirculation regulation system, and improves the reliability and safety of the feed water system during low load periods of thermal power units.

[0009] In an optional implementation manner, adjusting the opening of the feed water recirculation regulating valve based on the parallelogram flow control strategy includes:

[0010] Determine the automatic opening function of the feed water recirculation regulating valve according to the operating conditions during the opening process of the feed water recirculation regulating valve;

[0011] Determine the automatic closing function of the feed water recirculation regulating valve according to the operating conditions during the closing process of the feed water recirculation regulating valve;

[0012] During the opening process of the feed water recirculation regulating valve, adjust the opening of the feed water recirculation regulating valve according to the automatic opening function of the feed water recirculation regulating valve;

[0013] During the closing process of the feed water recirculation regulating valve, adjust the opening of the feed water recirculation regulating valve according to the automatic closing function of the feed water recirculation regulating valve, and the difference between the automatic closing function of the water recirculation regulating valve and the automatic opening function of the feed water recirculation regulating valve is the adjustment dead zone.

[0014] In an optional implementation manner, when the unit target load, the actual power generation load of the unit, and the feed water flow of the unit meet the first preset requirement, opening the feed water recirculation regulating valve includes:

[0015] When any one of the two conditions that the unit target load is less than the first preset value, the actual power generation load of the unit is less than the second preset value, and the feed water flow of the unit is less than the third preset value is satisfied, issue an instruction to open the feed water recirculation regulating valve to open the feed water recirculation regulating valve, and the first preset value is less than the second preset value.

[0016] In an optional implementation manner, when the unit target load, the actual power generation load of the unit, and the feed water flow of the unit meet the second preset requirement, closing the feed water recirculation regulating valve includes:

[0017] When any one of the following two conditions is met: the target load of the unit is greater than the fourth preset value, the actual power generation load of the unit is greater than the fifth preset value, and the feed water flow rate of the unit is greater than the sixth preset value, an instruction to close the feed water recirculation regulating valve is issued to close the feed water recirculation regulating valve, and the fourth preset value is greater than the fifth preset value.

[0018] In an alternative embodiment, the method further includes:

[0019] When any one of the following five conditions is met: the feed water flow rate of the unit is greater than the third preset value, the feed water recirculation regulating valve instruction is greater than the seventh preset value, the feed water recirculation regulating valve feedback is greater than the eighth preset value, the condition for requesting to close the feed water recirculation regulating valve is triggered, and the selection switch is out of service, the instruction to open the feed water recirculation regulating valve is reset.

[0020] In an alternative embodiment, the method further includes:

[0021] When any one of the following four conditions is met: the target load of the unit, the actual power generation load of the unit, and the feed water flow rate of the unit do not meet the closing conditions of the feed water recirculation regulating valve, the feed water recirculation regulating valve instruction is less than the ninth preset value, the feed water recirculation regulating valve feedback is less than the ninth preset value, the condition for requesting to open the feed water recirculation regulating valve is triggered, and the selection switch is out of service, the instruction to close the feed water recirculation regulating valve is reset.

[0022] In a second aspect, the present invention provides a feed water recirculation regulating valve control system, which includes:

[0023] An opening control module, configured to open the feed water recirculation regulating valve when the target load of the unit, the actual power generation load of the unit, and the feed water flow rate of the unit meet the first preset requirements, and adjust the opening of the feed water recirculation regulating valve based on a parallelogram flow control strategy during the opening process, and the parallelogram flow control strategy is designed with an adjustment dead zone for valve opening and closing;

[0024] A closing control module, configured to close the feed water recirculation regulating valve when the target load of the unit, the actual power generation load of the unit, and the feed water flow rate of the unit meet the second preset requirements, and adjust the opening of the feed water recirculation regulating valve based on a parallelogram flow control strategy during the closing process.

[0025] A feed water recirculation regulating valve control system provided by the present invention designs an automatic opening and closing control strategy for the feed water recirculation regulating valve during the low-load operation of the unit when the feed water flow rate is low. Considering the opening and closing processes of the recirculation regulating valve, a parallelogram control strategy is adopted, and an opening and closing hysteresis of the valve is designed. During the switching process, a smooth transition can be achieved, ensuring the stable process of the feed water flow rate during the low-flow process of the unit and improving the operation safety of the unit. The application of this invention patent in the production process improves the automation level of the unit and also provides safety guarantee for the thermal power unit when auxiliary equipment fails and trips during deep peak shaving and low load.

[0026] In a third aspect, the present invention provides a computer device, including: a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to execute the feed water recirculation regulating valve control method according to the first aspect or any corresponding embodiment thereof.

[0027] In a fourth aspect, the present invention provides a computer-readable storage medium, on which computer instructions are stored. The computer instructions are used to cause a computer to execute the feed water recirculation regulating valve control method according to the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required to be used in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 is a layout diagram of partial structural equipment of the feed water system of a thermal power unit according to an embodiment of the present invention;

[0030] Figure 2 is a flowchart of the feed water recirculation regulating valve control method according to an embodiment of the present invention;

[0031] Figure 3 is a logic diagram of the automatic opening and reset request of the feed water recirculation regulating valve according to an embodiment of the present invention;

[0032] Figure 4 is a logic diagram of the automatic closing and reset request of the feed water recirculation regulating valve according to an embodiment of the present invention;

[0033] Figure 5 is a schematic diagram of the parallelogram control strategy of the feed water recirculation regulating valve according to an embodiment of the present invention;

[0034] Figure 6 It is a structural block diagram of a feed water recirculation regulating valve control system device according to an embodiment of the present invention;

[0035] Figure 7 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Specific embodiments

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] As Figure 1 shown is a layout diagram of partial structural equipment of a feed water system of a thermal power unit. The main equipment includes a deaerator, a steam-driven feed water pre-pump, a steam-driven feed water pump, a feed water pump steam turbine, a drain isolation valve 1 for the pre-filter of the feed water pump, a check valve 2 for the outlet pipeline of the feed water tapping, an air release valve 3 for the outlet pipeline of the feed water pump, an air release valve 4 for the outlet pipeline of the feed water pump, a check valve 5 for the outlet of the feed water pump, an electric valve 6 for the outlet of the feed water pump, an electric bypass valve 7 for the outlet of the feed water pump, an electric bypass valve 8 for the outlet of the feed water pump, a high-pressure heater bypass pneumatic three-way valve 9, an electric gate valve 10 before the feed water recirculation regulating valve, an air release valve 11 for the feed water recirculation pipeline, a feed water recirculation regulating valve 12, an electric gate valve 13 after the feed water recirculation regulating valve, a drain isolation valve 14 for the pre-filter of the feed water pre-pump, an electric gate valve 15 for the feed water pipeline, a check valve 16 for the feed water recirculation pipeline, an air release valve 17 for the feed water recirculation pipeline, and other equipment. The feed water recirculation system refers to the pipeline and valves leading from the outlet of the feed water pump to the feed water recirculation interface of the deaerator. Its function is to pump all or part of the water back to the deaerator during unit startup or low load to increase the flow rate of the feed water pump, avoid cavitation of the feed water pump, and reduce noise and vibration. The minimum flow recirculation pipelines at the feed water outlet are respectively connected to the deaerator and are equipped with minimum flow regulating valves to ensure that the flow rate of the feed water flowing through the feed water pump during low load and low feed water flow conditions of the unit is greater than the minimum flow rate allowed for starting the feed water pump, and to ensure the normal feed water flow rate of the unit, and to ensure that the unit does not shut down abnormally due to feed water flow problems.

[0038] Feed water control is one of the important controls of an ultra-supercritical unit. The fluctuation of the feed water flow rate of a once-through boiler directly affects important parameters such as unit load, steam temperature, steam pressure, and steam enthalpy value, which is not conducive to the safe and economic operation of the unit. Especially during the low load period of the unit, when the feed water flow rate is low, the feed water disturbance is relatively large during the opening and closing process of the feed water recirculation regulating valve, affecting the safe operation of the unit.

[0039] To this end, the present invention provides a control method for a feed water recirculation regulating valve. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0040] In this embodiment, a control method for a feed water recirculation regulating valve is provided, which can be applied to the feed water recirculation system of the feed water system of a thermal power unit. Figure 2 It is a flowchart of the control method for the feed water recirculation regulating valve according to the embodiment of the present invention, as Figure 2 shown, and this process includes the following steps:

[0041] Step S1, when the unit target load, the actual power generation load of the unit, and the feed water flow of the unit meet the first preset requirement, open the feed water recirculation regulating valve, and during the opening process, adjust the opening of the feed water recirculation regulating valve based on the parallelogram flow control strategy. The parallelogram flow control strategy is designed with adjustment deadbands for valve opening and closing.

[0042] Specifically, the feed water recirculation regulating valve control system based on the parallelogram flow control strategy mainly aims at the opening and closing control of the recirculation regulating valve in the feed water system of the thermal power unit during low load periods. During the low load period of the thermal power unit, for the automatic opening control strategy design of the feed water recirculation regulating valve, when the unit target load, the actual power generation load, and the feed water flow of the unit meet certain requirements, an instruction to open the feed water recirculation regulating valve is automatically issued. When the feed water flow of the unit, the recirculation regulating valve instruction, and the recirculation regulating valve feedback meet certain requirements, the opening instruction is automatically reset.

[0043] Step S2, when the unit target load, the actual power generation load of the unit, and the feed water flow of the unit meet the second preset requirement, close the feed water recirculation regulating valve, and during the closing process, adjust the opening of the feed water recirculation regulating valve based on the parallelogram flow control strategy.

[0044] Specifically, when the unit target load, the actual power generation load of the unit, and the feed water flow of the unit meet certain requirements, an instruction to close the feed water recirculation regulating valve is automatically issued, and when certain conditions are met, the closing instruction of the recirculation regulating valve is automatically reset. During the opening and closing processes of the feed water recirculation regulating valve, a double broken line is designed. Based on the parallelogram flow control strategy, there is a certain adjustment deadband during the opening and closing processes of the feed water recirculation regulating valve, ensuring the stability of the feed water flow of the unit during the action process of the recirculation regulating valve and improving the reliability of the unit operation. The embodiment of the present invention improves the automation level of the unit, ensures the operation safety during the low load period of the unit, and has achieved good results in actual production applications.

[0045] When the thermal power unit is at low load, the control of the feed water system needs to solve the problem of coordinating the control of the feed water pump and the feed water recirculation valve to control the fluctuation of the feed water flow rate of the unit. Through the coordinated control of the feed water pump and the feed water recirculation valve, the safety risk of single auxiliary equipment operation can be avoided at low load, and the feed water flow rate of the unit can be stably controlled to meet the control requirements during the low load operation of the unit. The original control strategy determines the opening of the recirculation valve according to the feed water flow rate at the inlet of the feed water pump. When the feed water flow rate is low, it is fully opened, which will cause great disturbance to the feed water control and is likely to cause the feed water flow rate low protection action at low load. The embodiment of the present invention adopts a parallelogram flow control strategy. There will be an adjustment dead zone during the adjustment process of the recirculation valve. Due to the existence of the adjustment dead zone, this coupling phenomenon can be alleviated to a great extent. When selecting the dead zone of the parallelogram, it should be noted to avoid the initial opening of the recirculation valve. In order to ensure the stable change of the feed water flow rate during the deep peak shaving process of the unit, the original PI control logic of the steam pump recirculation regulating valve is cancelled and modified to automatically open and close according to the unit load and the conversion of the steam pump inlet flow rate.

[0046] A control method for a feed water recirculation regulating valve provided by the present invention designs an automatic opening and closing control strategy for the feed water recirculation regulating valve during the low load operation of the unit when the feed water flow rate is low; considering that the feed water flow rate is greatly disturbed during the opening and closing processes of the recirculation regulating valve, a feed water recirculation control with a parallelogram flow control strategy is designed. This control strategy designs the dead zone for the opening and closing of the recirculation regulating valve, eliminates the feed water flow coupling phenomenon, ensures the stability of the feed water flow rate of the unit during the opening and closing processes of the recirculation regulating valve when the feed water flow rate of the unit is low, realizes the smooth transition of the feed water recirculation regulating system, and improves the reliability and safety of the feed water system during the low load period of the thermal power unit.

[0047] In an optional implementation manner, when adjusting the opening of the feed water recirculation regulating valve based on the parallelogram flow control strategy during the opening process, the following steps are included:

[0048] Step S11, determine the automatic opening function of the feed water recirculation regulating valve according to the working conditions during the opening process of the feed water recirculation regulating valve.

[0049] Step S12, during the opening process of the feed water recirculation regulating valve, adjust the opening of the feed water recirculation regulating valve according to the automatic opening function of the feed water recirculation regulating valve.

[0050] When adjusting the opening of the feed water recirculation regulating valve based on the parallelogram flow control strategy during the closing process, the following steps are included:

[0051] Step S21, determine the automatic closing function of the feed water recirculation regulating valve according to the working conditions during the closing process of the feed water recirculation regulating valve.

[0052] Step S22, during the closing process of the water supply recirculation regulating valve, the opening of the water supply recirculation regulating valve is adjusted according to the automatic closing function of the water supply recirculation regulating valve, and the difference between the automatic closing function of the water supply recirculation regulating valve and the automatic opening function of the water supply recirculation regulating valve is the adjustment hysteresis.

[0053] Specifically, during the control process of the feedwater recirculation regulating valve, in the low-load stage of the unit, due to the low total amount of boiler feedwater, the opening or closing of the recirculation regulating valve has a more obvious impact on the feedwater flow. During the load reduction process, if the recirculation regulating valve is opened too quickly, the feedwater flow will drop too quickly, causing the water-coal ratio to be out of balance, the temperature at the intermediate point to be abnormal, and even causing the boiler to overheat and operate at the upper limit or the feedwater flow rate to operate at the lower limit; if the recirculation regulating valve is opened too slowly, when the feedwater pump speed drops rapidly with the load, the outlet flow is likely to reach the minimum recirculation flow regulation opening value, affecting the stable operation of the feedwater system, and easily causing the boiler feedwater flow rate to operate at the lower limit. Therefore, the switching rate of the feedwater recirculation regulating valve needs to be set correctly. When the unit feedwater flow is low, fully opening the feedwater recirculation regulating valve will cause a large disturbance to the unit feedwater control, especially when the unit is under low load, it is easy to cause the unit feedwater flow rate to operate at the low MFT.

[0054] Therefore, a parallelogram flow control strategy is adopted to reserve an adjustment hysteresis during the unit's feed water recirculation regulation process. Under the action of the adjustment hysteresis, the coupling phenomenon of the feed water flow when opening or closing the feed water recirculation regulating valve can be alleviated to a great extent; and the feed water recirculation regulating valve is slowly closed at a certain rate when the feed water pump increases its speed and the feed water flow increases; and the feed water recirculation regulating valve is slowly opened at a certain rate when the feed water pump decreases its speed and the feed water flow decreases, which also effectively avoids the risk of cavitation in the unit's feed water pump.

[0055] When the unit feedwater pump speed increases and the feedwater flow rate increases, the automatic closing rate of the feedwater recirculation regulating valve is carried out according to the function F(x)1. Function F(x)1 is determined by the unit feedwater flow rate for the feedwater recirculation regulating valve opening under the condition of the feedwater recirculation regulating valve opening process. Exemplarily, the design points of function F(x)1 are (400,100), (500,75), (600,50), (700,25), (800,0). When the unit feedwater pump speed decreases and the feedwater flow rate decreases, the automatic opening rate of the feedwater recirculation regulating valve is carried out according to the function F(x)2. Function F(x)2 is determined by the unit feedwater flow rate for the feedwater recirculation regulating valve opening under the condition of the feedwater recirculation regulating valve closing process. Exemplarily, the design points of function F(x)2 are (650,0), (550,25), (450,50), (350,75), (250,100).

[0056] like Figure 3As shown in the figure, it is a schematic diagram of the parallelogram control strategy for the feedwater recirculation regulating valve. This control strategy is for the feedwater recirculation control based on the parallelogram control strategy. When the feedwater flow rate of the unit is relatively low, the opening amplitude of the feedwater recirculation regulating valve changes with the change of the feedwater flow rate. Two command lines are added to the control loop of the recirculation regulating valve as the opening reference command lines for the feedwater recirculation flow regulating valve. When the feedwater flow rate of the unit is relatively high, the opening curve of the feedwater recirculation regulating valve is not selected, and the recirculation regulating valve remains closed. As the feedwater flow rate of the unit gradually decreases and the condition for the curve of the feedwater recirculation regulating valve to be put into operation is met, the parallelogram control strategy is automatically selected and put into operation. The selection of the opening curves F(x)1 and F(x)2 of the feedwater recirculation regulating valve can adopt a pre-established combination method. The two opening curves mainly enable the feedwater flow rate to quickly match the unit load, which is obtained through the actual operating parameters of the unit. The two opening curves reserve an adjustment dead zone, alleviating the coupling phenomenon of the feedwater flow rate during the opening and closing processes of the recirculation regulating valve, and avoiding the phenomenon of large fluctuations in the feedwater flow rate during the opening and closing processes.

[0057] In an alternative embodiment, when the target load of the unit, the actual power generation load of the unit, and the feedwater flow rate of the unit meet the first preset requirement, the feedwater recirculation regulating valve is opened, including the following steps:

[0058] Step S13, when any one of the two conditions that the target load of the unit is less than the first preset value, the actual power generation load of the unit is less than the second preset value, and the feedwater flow rate of the unit is less than the third preset value is satisfied, an instruction to open the feedwater recirculation regulating valve is issued to open the feedwater recirculation regulating valve, and the first preset value is less than the second preset value.

[0059] Specifically, the design of the control strategy for automatically opening the feedwater recirculation regulating valve is as Figure 4 shown. HLALM is a high and low limit alarm logic block, which is used to check the high and low limits of the input and set the corresponding switch indication bits. Among them, the HLALM logic block 301 sets the output value of D2 to 1 when the target load of the unit is less than 300 MW; the HLALM logic block 302 sets the output value of D2 to 1 when the actual power generation load of the unit is less than 310 MW; the HLALM logic block 303 sets the output value of D2 to 1 when the feedwater flow rate of the unit is less than 510 t / h. AND is an AND logic block, and the AND logic block 309 simultaneously satisfies that the target load of the unit is less than 300 MW and the actual power generation load of the unit is less than 310 MW. LEADLAG is a lead-lag logic block, and the design time of the LEADLAG logic block 307 is 3 s to prevent instantaneous fluctuations in the feedwater flow rate signal. FSTOUT is an input first-out logic block, and when the first-out condition is satisfied, an instruction signal is output. The FSTOUT logic block 310 realizes the display of the first-out condition for automatically opening the feedwater recirculation regulating valve. When the first-out condition is satisfied, an instruction to automatically open the recirculation regulating valve is issued.

[0060] Further, in the control strategy for automatically opening the feedwater recirculation regulating valve, when any of the following conditions is met, the feedwater recirculation regulating valve automatically opens: 1) the unit target load < 300 MW and the unit actual power generation load < 310 MW; 2) the unit feedwater flow < 510 t / h. Among them, the first preset value is 300 MW, the second preset value is 310 MW, and the third preset value is 510 t / h.

[0061] In an alternative embodiment, when the unit target load, the unit actual power generation load, and the unit feedwater flow meet the second preset requirements, the feedwater recirculation regulating valve is closed, including the following steps:

[0062] Step S23, when either of the two conditions that the unit target load is greater than the fourth preset value and the unit actual power generation load is greater than the fifth preset value, and the unit feedwater flow is greater than the sixth preset value is satisfied, a command to close the feedwater recirculation regulating valve is issued to close the feedwater recirculation regulating valve, and the fourth preset value is greater than the fifth preset value.

[0063] Specifically, the control strategy for automatically closing the feedwater recirculation regulating valve is designed as Figure 5 shown. Among them, the HLALM logic block 401 sets the output value of D1 to 1 when the unit target load is greater than 340 MW; the HLALM logic block 302 sets the output value of D1 to 1 when the unit actual power generation load is greater than 330 MW. The AND logic block 403 simultaneously satisfies that the unit target load is greater than 340 MW and the unit actual power generation load is greater than 330 MW. The LEADLAG logic block 405 is designed with a time of 3 s to prevent instantaneous fluctuations of the feedwater flow signal. The HLALM logic block 406 sets the output value of D1 to 1 when the unit feedwater flow is greater than 570 t / h. The FSTOUT logic block 404 realizes the display of the first-out condition for automatically closing the feedwater recirculation regulating valve. When the first-out condition is satisfied, a command to close the feedwater recirculation regulating valve is issued.

[0064] Further, in the control strategy for automatically closing the feedwater recirculation regulating valve, when any of the following conditions is met, the feedwater recirculation regulating valve automatically closes: 1) the unit target load > 340 MW and the unit actual power generation load > 330 MW; 2) the unit feedwater flow > 570 t / h. Among them, the fourth preset value is 340 MW, the fifth preset value is 330 MW, and the sixth preset value is 570 t / h.

[0065] In an alternative embodiment, the method further includes:

[0066] Step S14, when any of the five conditions that the unit feedwater flow is greater than the third preset value, the feedwater recirculation regulating valve command is greater than the seventh preset value, the feedwater recirculation regulating valve feedback is greater than the eighth preset value, the condition for requesting to close the feedwater recirculation regulating valve is triggered, and the selection switch exits is satisfied, the command to open the feedwater recirculation regulating valve is reset.

[0067] Specifically, the reset opening logic design of the feed water recirculation regulating valve is as follows Figure 4 shown. When the feed water flow rate of the unit is greater than 510 t / h, the HLALM logic block 304 sets the D1 output value to 1. When the command of the feed water recirculation flow regulating valve is greater than 99%, the HLALM logic block 305 sets the D1 output value to 1. When the feedback of the feed water recirculation flow regulating valve is greater than 95%, the HLALM logic block 306 sets the D1 output value to 1. D / MA is a selection setting logic block, and the D / MA logic block 308 selects to exit the opening control of the feed water recirculation regulating valve. The FSTOUT logic block 311 resets the opening command of the feed water recirculation flow valve when the conditions are met.

[0068] Furthermore, in the reset opening logic of the feed water recirculation regulating valve, when any of the following conditions is met, the reset opening command is executed: 1) the feed water flow rate of the unit > 510 t / h, 2) the command of the feed water recirculation flow regulating valve > 99%, 3) the feedback of the feed water recirculation flow regulating valve > 95%, 4) the condition for requesting to close the recirculation regulating valve is triggered, 5) the selection switch exits. Among them, the seventh preset value is 99%, and the eighth preset value is 95%.

[0069] In an alternative embodiment, the method further includes:

[0070] Step S24, when any one of the four conditions that the target load of the unit, the actual power generation load of the unit, and the feed water flow rate of the unit do not meet the closing condition of the feed water recirculation regulating valve, the command of the feed water recirculation regulating valve is less than the ninth preset value, the feedback of the feed water recirculation regulating valve is less than the ninth preset value, the condition for requesting to open the feed water recirculation regulating valve is triggered, and the selection switch exits is met, the closing command of the feed water recirculation regulating valve is reset.

[0071] Specifically, the reset closing logic design of the feed water recirculation regulating valve is as follows Figure 5As shown in the figure, where NOT is a NOT logic block. The NOT logic block 407 realizes that neither the unit target load nor the actual power generation load of the unit satisfies the condition for automatically closing the feedwater recirculation regulating valve. The NOT logic block 408 realizes that the feedwater flow of the unit does not satisfy the condition for automatically closing the feedwater recirculation regulating valve. The AND logic block 409 realizes that the unit target load, the actual power generation load of the unit, and the feedwater flow of the unit all do not satisfy the condition for automatically closing the feedwater recirculation regulating valve. The HLALM logic block 410 sets the output value of D2 to 1 when the feedwater recirculation flow regulating valve command is less than 5%. The HLALM logic block 411 sets the output value of D2 to 1 when the feedback of the feedwater recirculation flow regulating valve is less than 5%. The AND logic block 412 simultaneously satisfies that both the command and the feedback of the feedwater recirculation flow regulating valve are less than 5%. The D / MA logic block 413 selects to exit the control for closing the feedwater recirculation regulating valve. The FSTOUT logic block 414 resets the closing command of the feedwater recirculation flow valve when the condition is satisfied.

[0072] Further, in the reset closing logic of the feedwater recirculation regulating valve, when any of the following conditions is satisfied, the reset closing command is issued: 1) The flow and load conditions do not satisfy the condition for closing the recirculation regulating valve. 2) The feedwater recirculation flow regulating valve command < 5% and the feedwater recirculation flow regulating valve feedback < 5%. 3) The request to open the recirculation condition is triggered. 4) The selection switch exits. Wherein, the ninth preset value is 5%.

[0073] In the embodiment of the present invention, during the opening and closing process of the feedwater recirculation regulating valve when the unit is at low load and the feedwater flow is low, the necessary conditions for automatically opening and closing the feedwater recirculation regulating valve are designed, and at the same time, the reset conditions for resetting the opening and closing commands of the feedwater recirculation regulating valve are designed, realizing the functions of automatically opening and closing the feedwater recirculation regulating valve and automatic reset.

[0074] In this embodiment, a feedwater recirculation regulating valve control system is also provided. This system is used to implement the above-mentioned embodiments and preferred implementation manners, and those that have been described will not be repeated. As used hereinafter, the term "module" can be a combination of software and / or hardware that realizes a predetermined function. Although the systems described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0075] This embodiment provides a feedwater recirculation regulating valve control system, as Figure 6 shown, including:

[0076] An opening control module 61, configured to open the feedwater recirculation regulating valve when the unit target load, the actual power generation load of the unit, and the feedwater flow of the unit meet the first preset requirements, and adjust the opening of the feedwater recirculation regulating valve based on the parallelogram flow control strategy during the opening process. The parallelogram flow control strategy is designed with an adjustment dead zone for valve opening and closing.

[0077] The closing control module 62 is used to close the feedwater recirculation regulating valve when the unit target load, the actual power generation load of the unit, and the feedwater flow rate of the unit meet the second preset requirements, and adjust the opening of the feedwater recirculation regulating valve based on the parallelogram flow control strategy during the closing process.

[0078] The further function descriptions of the above-mentioned various modules and units are the same as those in the corresponding embodiments above, and will not be elaborated here.

[0079] The feedwater recirculation regulating valve control system in this embodiment is presented in the form of functional units. Here, the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and a memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0080] A feedwater recirculation regulating valve control system provided by the present invention designs an automatic opening and closing control strategy for the feedwater recirculation regulating valve during the low-load operation of the unit when the feedwater flow rate is low; considering the opening and closing processes of the recirculation regulating valve, a parallelogram control strategy is adopted, and an opening hysteresis for valve opening or closing is designed. During the switching process, it can transition smoothly, ensuring the smooth process of the feedwater flow rate during the low-flow process of the unit and improving the operating safety of the unit. The application of this invention patent in the production process improves the automation level of the unit and also provides a safety guarantee for the main auxiliary equipment trip during deep peak shaving and low load of thermal power units.

[0081] The embodiment of the present invention also provides a computer device having the above Figure 6 shown feedwater recirculation regulating valve control system.

[0082] Please refer to Figure 7 , Figure 7 which is a schematic structural diagram of a computer device provided by an optional embodiment of the present invention. As shown in Figure 7As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting the components, including a high-speed interface and a low-speed interface. Each component communicates with each other using different buses and can be installed on a common motherboard or in other ways as needed. The processor can process instructions executed within the computer device, including instructions stored in the memory or on the memory to display graphical information of the GUI on an external input / output device (such as a display device coupled to the interface). In some alternative embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a set of blade servers, or a multi-processor system). Figure 7 Take one processor 10 as an example in Figure 7 .

[0083] The processor 10 can be a central processing unit, a network processor, or a combination thereof. Among them, the processor 10 can further include a hardware chip. The above hardware chip can be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The above programmable logic device can be a complex programmable logic device, a field programmable gate array, a generic array logic, or any combination thereof.

[0084] Among them, the memory 20 stores instructions executable by at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiments.

[0085] The memory 20 can include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created according to the use of the computer device. In addition, the memory 20 can include high-speed random access memory and can also include non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some alternative embodiments, the memory 20 can optionally include a memory remotely set relative to the processor 10, and these remote memories can be connected to the computer device through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0086] The memory 20 can include volatile memory, such as random access memory; the memory can also include non-volatile memory, such as flash memory, a hard disk, or a solid-state drive; the memory 20 can also include a combination of the above types of memory.

[0087] The computer device further includes a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0088] Embodiments of the present invention also provide a computer-readable storage medium. The methods according to the embodiments of the present invention can be implemented in hardware, firmware, or be implemented as computer code that can be recorded on a storage medium, or be implemented as computer code that is originally stored in a remote storage medium or a non-transitory machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the methods described herein can be stored as such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code, and when the software or computer code is accessed and executed by the computer, the processor, or the hardware, the methods shown in the above embodiments are implemented.

[0089] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A water supply recirculation valve control method, characterized in that: The method comprises: When the target load of the unit, the actual power generation load of the unit, and the feed water flow of the unit meet the first preset requirement, the feed water recirculation regulating valve is opened, and the opening of the feed water recirculation regulating valve is adjusted based on the parallelogram flow control strategy during the opening process, and the parallelogram flow control strategy is designed with a regulating hysteresis of valve opening and closing; When the unit target load, the unit actual power generation load, and the unit feed water flow meet the second preset requirement, the feed water recirculation regulating valve is closed, and during the closing process, the feed water recirculation regulating valve opening is adjusted based on the parallelogram flow control strategy.

2. The water supply recirculation valve control method according to claim 1, characterized in that: The opening of the feedwater recirculation regulating valve is adjusted based on the parallelogram flow control strategy, including: According to the working conditions of the water supply recirculation regulating valve opening process, determine the automatic opening function of the water supply recirculation regulating valve; According to the working conditions of the water supply recirculation regulating valve during closing, the automatic closing function of the water supply recirculation regulating valve is determined; During the opening process of the water supply recirculation regulating valve, the opening degree of the water supply recirculation regulating valve is adjusted according to the automatic opening function of the water supply recirculation regulating valve; During the closing process of the water supply recirculation regulating valve, the opening of the water supply recirculation regulating valve is adjusted according to the automatic closing function of the water supply recirculation regulating valve, and the difference between the automatic closing function of the water supply recirculation regulating valve and the automatic opening function of the water supply recirculation regulating valve is the adjustment hysteresis.

3. The water supply recirculation valve control method according to claim 1, characterized in that: When the unit target load, the unit actual power generation load, and the unit feed water flow rate meet the first preset requirement, the feed water recirculation regulating valve is opened, including: When any one of the following two conditions is met: the target load of the unit is less than the first preset value, the actual power generation load of the unit is less than the second preset value, and the feed water flow rate of the unit is less than the third preset value, an instruction to open the feed water recirculation regulating valve is issued to open the feed water recirculation regulating valve, and the first preset value is less than the second preset value.

4. The water supply recirculation valve control method according to claim 1, characterized in that: When the unit target load, the unit actual power generation load, and the unit feed water flow rate meet the second preset requirement, the feed water recirculation regulating valve is closed, including: When any one of the following two conditions is met: the target load of the unit is greater than the fourth preset value, the actual power generation load of the unit is greater than the fifth preset value, and the water supply flow rate of the unit is greater than the sixth preset value, an instruction to close the water supply recirculation regulating valve is issued to close the water supply recirculation regulating valve, and the fourth preset value is greater than the fifth preset value.

5. The water supply recirculation valve control method according to claim 3 is characterized in that: The method further comprises: When any one of the following five conditions is met: the unit's feed water flow rate is greater than the third preset value, the feed water recirculation regulating valve instruction is greater than the seventh preset value, the feed water recirculation regulating valve feedback is greater than the eighth preset value, the request to close the feed water recirculation regulating valve condition is triggered, and the switch is selected to exit, the feed water recirculation regulating valve instruction is reset to open.

6. The water supply recirculation valve control method according to claim 4, characterized in that: The method further comprises: When the target load of the unit, the actual power generation load of the unit and the water supply flow rate of the unit do not meet the closing conditions of the water supply recirculation regulating valve, the water supply recirculation regulating valve instruction is less than the ninth preset value and the water supply recirculation regulating valve feedback is less than the ninth preset value, the condition for requesting to open the water supply recirculation regulating valve is triggered, and the selection switch exits, any of the four conditions is met, the instruction to close the water supply recirculation regulating valve is reset.

7. A water supply recirculation valve control system, characterized in that: The system comprises: The opening control module is used to open the feed water recirculation regulating valve when the unit target load, the unit actual power generation load, and the unit feed water flow meet the first preset requirement, and adjust the opening of the feed water recirculation regulating valve based on the parallelogram flow control strategy during the opening process, wherein the parallelogram flow control strategy is designed with a regulating hysteresis of valve opening and closing; The closing control module is used to close the feed water recirculation regulating valve when the unit target load, the unit actual power generation load, and the unit feed water flow meet the second preset requirement, and adjust the opening of the feed water recirculation regulating valve based on the parallelogram flow control strategy during the closing process.

8. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the water recirculation valve control method according to any one of claims 1 to 6 by executing the computer instructions.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the water recirculation valve control method according to any one of claims 1 to 6.

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