A method for optimizing cut and parallel pump of coal-fired unit feed water pump

Abstract

The application discloses a kind of coal-fired unit feed water pump cut, and the optimization method of parallel pump includes: based on distributed control system, sets up program-controlled operation logic, completes cut, and parallel pump logic design step sequence;Operation instruction module outputs cut, and parallel pump program-controlled operation instruction and judges whether it satisfies the preset allowable condition, when program-controlled operation allowable condition satisfies, operation instruction is sent out;Drive module outputs skip number and skip trigger pulse control program-controlled step sequence, step execution is completed feedback to drive module;Drive module according to predetermined step sequence outputs next skip number and skip trigger pulse, finally outputs instruction drive function group equipment start-stop.The application realizes feed water pump one-key automatic cut, and parallel pump through the optimization of logic, through the redesign of program-controlled step sequence, reduce step sequence, shorten program-controlled completion time, through the modification of logic configuration, reduce the work intensity of operating personnel, increase operation safety, stability and flexibility.

Description

Technical Field

[0001] This invention relates to the field of thermal engineering control logic design and application technology in thermal power plants, specifically to an optimization method for switching and synchronizing feedwater pumps in coal-fired units. Background Technology

[0002] The most crucial operation for coal-fired power generating units during flexible peak shaving under ultra-low load conditions is the switching and merging of feedwater pumps. This involves equipment including feedwater pumps, engineering workstations, configuration logic, pressure transmitters, turbine feedwater pump speeds, recirculation electric valves, recirculation control valves, and more. Under ultra-low load conditions, the unit's operating status is inherently unstable, requiring operators to closely monitor equipment parameters and adjust operating conditions promptly. Switching and merging feedwater pumps under ultra-low load conditions during flexible peak shaving involves numerous operational steps. It requires continuously modifying output feedwater pump commands and recirculation control valve commands based on equipment parameters such as feedwater pump instructions, speed, feedwater header pressure, feedwater pump outlet pressure, and feedwater flow rate. All of this is done manually by operators, resulting in a large workload and insufficient flexibility. Summary of the Invention

[0003] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by this invention is that the existing methods for switching and connecting water pumps have complex operation steps and require constant adjustment of parameter settings, and how to optimize the one-click automatic switching and connecting of water pumps.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for optimizing the switching and paralleling of feedwater pumps in coal-fired power units, comprising:

[0007] Based on the distributed control system, programmable operation logic was established, and the design sequence of switching and merging pump logic was completed.

[0008] The operation instruction module outputs the switching and parallel pump programmable operation instructions and determines whether the preset allowable conditions are met. When the programmable operation allowable conditions are met, the operation instruction is issued.

[0009] The driver module outputs the step number and step trigger pulse to control the programmable step sequence, and the complete execution of the step is fed back to the driver module.

[0010] The drive module outputs the next jump step number and jump trigger pulse according to the predetermined step sequence, and finally outputs the command to drive the function group device to start and stop.

[0011] As a preferred embodiment of the optimized method for switching and merging feedwater pumps in coal-fired power units according to the present invention, the pump switching logic design steps include:

[0012] Pump switching begins; switch from A water pump mode to manual mode.

[0013] A command to reduce the speed of the water pump;

[0014] Pause the deceleration and wait for the water flow to stabilize;

[0015] Continue to reduce the speed of water pump A;

[0016] Pump A's pump tripping process is complete.

[0017] As a preferred embodiment of the optimized method for switching and merging feedwater pumps in coal-fired power units according to the present invention, the preset allowable conditions for the pump switching logic design steps include:

[0018] The preset allowable conditions for the pump switching logic design steps include:

[0019] The conditions under which the A-type water pump mode can be switched to manual mode at the start of the pump switching process are as follows:

[0020] When the load is below 300MW, both A and B feedwater pumps are in automatic mode. The recirculation electric valve of feedwater pump A is fully open and the recirculation regulating valve is manually operated with an opening greater than 65 degrees. The inlet flow and outlet pressure of feedwater pumps A and B are both in good condition, the outlet main pipe pressure is in good condition, the outlet electric valves of feedwater pumps A and B are both fully open, and the deviation between the outlet pressure of feedwater pumps A and B and the outlet main pipe pressure is no greater than 0.1MPa.

[0021] The condition for allowing the A water pump to reduce its speed is that the A water pump is controlled in manual mode.

[0022] The permissible conditions for pausing deceleration and waiting for the water supply flow to stabilize are: the deviation between the outlet pressure of water pump B and the outlet main pipe pressure is greater than 0.1 MPa, and the deviation between the outlet pressure of water pump A and the outlet main pipe pressure is greater than 1 MPa, lasting for 3 seconds.

[0023] The permissible condition for the command to continue reducing the speed of the feedwater pump A is: the deviation between the actual feedwater flow rate and the set feedwater flow rate is not greater than 20t / h;

[0024] The permissible conditions for the completion of the pump switching program of the A water supply pump are: when the speed of the A water supply pump is less than 2900 r / min or the A water supply pump command is less than 1.

[0025] As a preferred embodiment of the optimized method for switching and merging feedwater pumps in coal-fired power units according to the present invention, the preset operation instructions for the pump switching logic design steps include:

[0026] The operation command to switch the A water pump from manual mode to manual mode is as follows: Click the start button on the A water pump control screen to switch the A water pump control mode to manual mode.

[0027] The operation command for the A water supply pump speed reduction command is: start pump cut-off, the A water supply pump command starts to decrease according to the A water supply pump cut-off speed reduction control, starting from the set value G1;

[0028] The operation command to pause deceleration and wait for the water supply flow to stabilize is: temporarily stop the A water supply pump speed control and temporarily stop the A water supply pump command.

[0029] The operation instruction for continuing to reduce the speed of water pump A is as follows: the water pump A instruction continues to decrease the speed of water pump A according to the water pump A cut-off and speed reduction control, starting from the set value G1.

[0030] The operation command for the A water supply pump tripping program is: A water supply pump tripping completed, program control ended.

[0031] As a preferred embodiment of the optimized method for switching and simulating feedwater pumps in coal-fired power units according to the present invention, the pump simulating logic design steps include:

[0032] A water pump starts running in parallel; command to increase the speed of A water pump.

[0033] Pause the rate increase and wait for the water supply to stabilize;

[0034] Continue to increase the speed command of water pump A;

[0035] Once the water supply flow rate of the water pump stabilizes, switch the control of water pump A to automatic mode.

[0036] A water supply pump was connected and the pumping program was completed.

[0037] As a preferred embodiment of the optimized method for switching and merging feedwater pumps in coal-fired power units according to the present invention, the preset allowable conditions for the merging logic design steps include:

[0038] The permissible conditions for the command to increase the speed of feedwater pump A upon starting parallel operation are as follows: the load is higher than 240MW; both feedwater pumps A and B are in automatic mode; the recirculation electric valve of feedwater pump A is fully open and the recirculation regulating valve is manually operated with an opening greater than 65°; the outlet flow rate and outlet pressure of feedwater pump A / B are both within acceptable limits; the outlet main pipe pressure is within acceptable limits; the outlet electric valves of feedwater pumps A and B are both fully open; the deviation between the outlet pressure of feedwater pump B and the outlet main pipe pressure is no greater than 0.1MPa; the deviation between the outlet pressure of feedwater pump A and the outlet main pipe pressure is greater than 1MPa; the actual feedwater flow rate deviates from the set feedwater flow rate by no more than 20t / h; and the outlet main pipe pressure is within acceptable limits.

[0039] The permissible conditions for pausing the speed increase and waiting for the water supply to stabilize are: the deviation between the outlet pressure of water pump A and the outlet main pipe pressure is less than 0.5 MPa and the deviation between the outlet pressure of water pump B and the outlet main pipe pressure is less than 0.5 MPa.

[0040] The condition for continuing to increase the speed command of water pump A is that the deviation between the actual water flow rate and the set water flow rate is not greater than 20t / h;

[0041] The conditions under which the automatic control of water pump A is allowed to be activated when the water flow rate of the waiting water pump is stable are as follows: the deviation between the outlet pressure of water pump A and the outlet main pipe pressure is less than 0.2 MPa, the deviation between the inlet flow rates of water pumps A and B is less than 50 t / h, and the deviation between the actual water flow rate and the set water flow rate is not greater than 20 t / h.

[0042] The permissible condition for the A water supply pump to be connected in parallel is: the A water supply pump is connected in parallel.

[0043] As a preferred embodiment of the optimized method for switching and merging feedwater pumps in coal-fired power units according to the present invention, the preset operation instructions for the merging logic design steps include:

[0044] The operation command for starting the A water supply pump in parallel and increasing the speed of the A water supply pump is as follows: Click the start button on the A water supply pump parallel control screen, the A water supply pump will start to increase its speed, and the A water supply pump command will increase according to the A water supply pump parallel pump speed increase control starting from the set value G2.

[0045] The operation command to pause the speed increase and wait for the water supply to stabilize is: temporarily stop water supply pump A and control the pump speed increase, and the command to temporarily stop water supply pump A is increased.

[0046] The operation command to continue increasing the speed command of water pump A is: the command for water pump A continues to increase starting from the set value G2;

[0047] The operation command for automatically controlling water pump A when the water flow rate of the waiting water pump is stable is: Automatic activation of water pump A speed control.

[0048] The operation command for the A water supply pump to be connected and the program control to be completed is: A water supply pump connection completed, program control ends.

[0049] As a preferred embodiment of the optimized method for switching and merging feedwater pumps in coal-fired power units according to the present invention, the method further includes: the A feedwater pump command continuing to increase from the set value G2, and limiting the amplitude by using the B feedwater pump command to float up by 10%.

[0050] As a preferred embodiment of the optimization method for switching and merging feedwater pumps of coal-fired power units according to the present invention, wherein: when any step in the switching and merging sequence does not meet the allowed conditions, the next step needs to be manually determined and an automatic allow protection condition is set; when the program control operation needs to be interrupted, it is restored to the initial state through the drive module.

[0051] As a preferred embodiment of the optimization method for switching and merging feedwater pumps of coal-fired power units described in this invention, the output of the programmable step sequence is implemented by the step sequence module. The step sequence module executes the mask defined in the function block according to the step number and step trigger pulse output by the drive module, in the order of reset, shield, jump, step hold, next step, timer hold, and finally outputs the command to drive the function group equipment to start and stop.

[0052] The beneficial effects of this invention are as follows: The optimized method for switching and merging feedwater pumps in coal-fired power units provided by this invention meets the needs of flexible and deep peak shaving under ultra-low loads, reduces the workload of operators, increases flexibility, and provides safety and stability. Through optimization of the configuration logic in the DCS engineering station, one-click automatic switching and merging of feedwater pumps is achieved. The program control sequence is redesigned, reducing the number of steps and shortening the program control completion time. Furthermore, the feedwater pump's acceleration and deceleration rates and the deviation between the feedwater pump and the main pipe pressure can be flexibly modified based on long-term operational experience. Modification of the logic configuration reduces the workload of operators and increases operational safety, stability, and flexibility. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0054] Figure 1 The overall flowchart of a method for optimizing the switching and paralleling of feedwater pumps in a coal-fired power unit, provided in the first embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram of the pump switching program control in a method for optimizing the switching and merging of feedwater pumps in a coal-fired power unit, provided in the second embodiment of the present invention.

[0056] Figure 3 This is a logic diagram of the output pump switching programmable sequence instructions in a method for optimizing the switching and merging of feedwater pumps in a coal-fired power unit, provided in the second embodiment of the present invention.

[0057] Figure 4 The second embodiment of the present invention provides a method for optimizing the switching and merging of feedwater pumps in a coal-fired power unit, which outputs a next step control diagram in the pump switching program control.

[0058] Figure 5 This is a schematic diagram of the judgment logic steps in the pump switching program control of a method for optimizing the switching and merging of feedwater pumps in a coal-fired power unit, provided in the second embodiment of the present invention.

[0059] Figure 6 This is a schematic diagram of the next step logic in the pump switching program control of a method for optimizing the switching and merging of feedwater pumps in a coal-fired power unit, provided in the second embodiment of the present invention.

[0060] Figure 7 The second embodiment of the present invention provides a control diagram for the speed control of feedwater pump A in the control program of the switching and paralleling optimization method for feedwater pumps of a coal-fired power unit;

[0061] Figure 8 A schematic diagram of the parallel pump control program for an optimization method of switching and paralleling feedwater pumps in a coal-fired power unit, provided in the second embodiment of the present invention;

[0062] Figure 9 This is a logic diagram of the output parallel pump control step sequence instruction in a method for optimizing the switching and paralleling of feedwater pumps in a coal-fired power unit, provided in the second embodiment of the present invention.

[0063] Figure 10 The second embodiment of the present invention provides a method for optimizing the switching and paralleling of feedwater pumps in a coal-fired power unit, which outputs a next step control diagram in the paralleling control process.

[0064] Figure 11 This is a schematic diagram of the judgment logic steps in the pump switching program control of a method for optimizing the switching and merging of feedwater pumps in a coal-fired power unit, provided in the second embodiment of the present invention.

[0065] Figure 12 This is a schematic diagram of the next step logic in the pump paralleling programmable control of a method for optimizing the switching and paralleling of feedwater pumps in a coal-fired power unit, provided in the second embodiment of the present invention.

[0066] Figure 13 This is a pump switching operation screen for a method of optimizing the switching and paralleling of feedwater pumps in a coal-fired power unit, provided in the second embodiment of the present invention.

[0067] Figure 14 The second embodiment of the present invention provides a method for optimizing the switching and paralleling of feedwater pumps in a coal-fired power unit, showing the paralleling operation screen. Detailed Implementation

[0068] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0069] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0070] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0071] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0072] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0073] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0074] Example 1

[0075] Reference Figure 1As an embodiment of the present invention, a method for optimizing the switching and paralleling of feedwater pumps in a coal-fired power unit is provided, comprising:

[0076] S1: Based on the distributed control system, establish the programmable operation logic and complete the design steps of the switching and merging pump logic;

[0077] Furthermore, the pump switching logic design steps include:

[0078] Pump switching begins; switch from A water pump mode to manual mode.

[0079] A command to reduce the speed of the water pump;

[0080] Pause the deceleration and wait for the water flow to stabilize;

[0081] Continue to reduce the speed of water pump A;

[0082] Pump A's pump tripping process is complete.

[0083] Furthermore, the parallel pump logic design steps include:

[0084] A water pump starts running in parallel; command to increase the speed of A water pump.

[0085] Pause the rate increase and wait for the water supply to stabilize;

[0086] Continue to increase the speed command of water pump A;

[0087] Once the water supply flow rate of the water pump stabilizes, switch the control of water pump A to automatic mode.

[0088] A water supply pump was connected and the pumping program was completed.

[0089] S2: The operation instruction module outputs the switching and parallel pump programmable operation instruction and determines whether the preset allowable conditions are met. When the programmable operation allowable conditions are met, the operation instruction is issued.

[0090] Furthermore, the allowable conditions and operation instructions for each step in the pump switching logic design sequence include:

[0091] (1) Start switching the pumps, switch from A water pump mode to manual mode.

[0092] Allowed conditions:

[0093] The load is less than 300MW;

[0094] Both water pumps A and B are in automatic mode; the electric recirculation valve of water pump A is fully open and the manual recirculation valve is open at a degree greater than 65.

[0095] There are no issues with the inlet flow rate and outlet pressure of the A / B water supply pumps;

[0096] The pressure in the outlet header pipe is free of defects.

[0097] The electric valves at the outlets of both A and B water pumps are fully open.

[0098] The deviation between the outlet pressure of the A / B water supply pump and the outlet header pressure shall not exceed 0.1 MPa.

[0099] Operation instructions:

[0100] Click the "Start" button on the "Switch A Pump Control" screen for water pump A;

[0101] A. Water pump control mode switched to manual mode

[0102] (2) Command to reduce the speed of water pump A

[0103] Permitted condition: A. Water supply pump is controlled in manual mode.

[0104] Operation command: Start pump cut-off. The A feed water pump command will be executed according to the A feed water pump cut-off speed reduction control, which will start to decrease from the set value G1.

[0105] (3) Pause deceleration and wait for the water flow rate to stabilize:

[0106] Permissible conditions: The pressure deviation between the outlet pressure of water pump B and the outlet main pipe is greater than 0.1 MPa, and the pressure deviation between the outlet pressure of water pump A and the outlet main pipe is greater than 1 MPa, lasting for 3 seconds.

[0107] Operation command: Temporarily stop the A water supply pump speed control, and temporarily stop the A water supply pump command by decreasing the speed.

[0108] (4) Continue to reduce the speed of water pump A

[0109] Permissible conditions: The deviation between the actual water supply flow rate and the set water supply flow rate shall not exceed 20t / h.

[0110] Operation command: The A water pump command continues to decrease the speed control according to the A water pump cut-off speed control, starting from the set value G1.

[0111] (5) Pump tripping of water supply pump A completed.

[0112] Permissible conditions: When the speed of water pump A is less than 2900 r / min or the command of water pump A is less than 1.

[0113] Operation command: Pump A has been switched off, program control has ended.

[0114] It should be noted that the default setting for value G1 is 0.05% per second, and this command size can be flexibly modified online.

[0115] Furthermore, the allowable conditions and operation instructions for each step in the pump switching logic design sequence include:

[0116] (1) When pump A starts running in parallel, the command to increase the speed of pump A is executed.

[0117] Permitted conditions: Load exceeds 240MW;

[0118] Both water pumps A and B are in automatic mode;

[0119] A. The electric recirculation valve of the water pump is fully open, and the manual recirculation valve is opened to a degree greater than 65.

[0120] There are no issues with the outlet flow rate and outlet pressure of the A / B feed water pump booster pump;

[0121] The pressure in the outlet header pipe is free of defects.

[0122] The electric valves at the outlets of both A and B water pumps are fully open.

[0123] The deviation between the outlet pressure of pump B and the outlet main pipe pressure shall not exceed 0.1 MPa;

[0124] The deviation between the outlet pressure of pump A and the outlet main pipe pressure is greater than 1 MPa;

[0125] The actual water supply flow rate deviates from the set water supply flow rate by no more than 20t / h. There is no problem with the pressure in the main pipe.

[0126] Operation instructions:

[0127] Click the "Start" button on the "Parallel A Pump Control" screen for water pump A;

[0128] Water pump A starts to increase its speed. The command for water pump A is to increase the speed control of water pump A according to the set value G2.

[0129] (2) Pause the rate increase and wait for the water supply to stabilize.

[0130] Allowable conditions: The deviation between the outlet pressure of pump A and the outlet main pipe pressure is less than 0.5 MPa and the deviation between the outlet pressure of pump B and the outlet main pipe pressure is less than 0.5 MPa.

[0131] Operation command: Temporarily stop water pump A and increase pump speed control. The command to temporarily stop water pump A is added.

[0132] (3) Continue to increase the speed command of water pump A.

[0133] Permissible conditions: The deviation between the actual water supply flow rate and the set water supply flow rate shall not exceed 20t / h.

[0134] Operation command: A. Water pump command continues to increase starting from the set value G2.

[0135] (4) Wait for the water supply flow rate of the water pump to stabilize, and then switch the control of water pump A to automatic.

[0136] Permissible conditions: The deviation between the outlet pressure of water pump A and the outlet main pipe pressure is less than 0.2 MPa, and the deviation between the inlet flow rates of water pumps A and B is less than 50 t / h, and the deviation between the actual water flow rate and the set water flow rate is not greater than 20 t / h.

[0137] Operation command: A. Automatic activation of water pump speed control.

[0138] (5) Pump A is connected to the pump control program and completed.

[0139] Permissible conditions: Pump A is in operation and pumping is complete.

[0140] Operation command: Pump A is in operation and pumping is complete; program control ends.

[0141] It should be noted that the default setting for value G2 is 0.05% per second, and this command value can be flexibly modified online. The acceleration / deceleration rate and other setpoints of the water pump command can all be modified online. After multiple runs, more reasonable parameters can be obtained through calculation and experience. These parameters can be optimized directly online without stopping the system for configuration, thus increasing flexibility.

[0142] Furthermore, to prevent excessive commands from A water pump during the pumping process, the command of B water pump is increased by 10% during the speed-up to limit its speed and ensure its safety. Through logic configuration, the possibility of human error is reduced.

[0143] S3: The driver module outputs the step number and step trigger pulse to control the programmable step sequence. Once the step is completed, feedback is sent back to the driver module.

[0144] Furthermore, if any step in the cutting and pumping sequence fails to meet the permitted conditions, the next step requires manual confirmation, and automatic permission protection conditions are set. When the programmed operation needs to be interrupted, the system is restored to the initial state via the drive module.

[0145] S4: The drive module outputs the next jump step number and jump step trigger pulse according to the predetermined step sequence, and finally outputs the command to drive the function group device to start and stop.

[0146] Furthermore, the output of the programmable step sequence is implemented by the step sequence module. The step sequence module executes the mask defined in the function block according to the step number and step trigger pulse output by the drive module, in the order of reset, mask, jump, step hold, next step, timer hold, and finally outputs the command to drive the function group device to start and stop.

[0147] Example 2

[0148] Reference Figure 2-14 As an embodiment of the present invention, a method for optimizing the switching and paralleling of feedwater pumps in coal-fired power units is provided. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through application experiments.

[0149] like Figure 3 The pump switching programmable operation sequence block receives the step number and step pulse command from the drive block and outputs the step sequence command logic.

[0150] like Figure 4 Once the step is completed, feedback is sent to the driver module for logical judgment, and the output is returned to the driver module, along with the next step number.

[0151] like Figure 5-6 This refers to the judgment logic steps for pump switching program control.

[0152] During pump switching and paralleling operations, the load is generally low, and equipment parameters are easily disturbed and unstable. Therefore, when configuring one-click pump switching, attention must be paid to control safety. The system should allow for manual intervention during the switching process, requiring manual confirmation before proceeding to the next step if conditions are not met, and should include automatic allowance protection conditions. The automatic allowance protection conditions are set as follows: Figure 6 During the process of switching off pump A, if the outlet pressure of pump B deviates from the outlet main pipe pressure by more than 0.1 MPa, or if the outlet pressure of pump A deviates from the outlet main pipe pressure by more than 1 MPa, and this continues for 3 seconds, the pump switching and speed reduction control of pump A will be temporarily stopped. The pump A command to reduce speed will be temporarily stopped until the actual water flow rate deviates from the set water flow rate by no more than 20 t / h. At this point, the pump A command will continue to decrease at 0.05% per second according to the pump switching and speed reduction control of pump A, ensuring the stability of operating parameters.

[0153] Upon initiating pump cutoff, the A feedwater pump command, in accordance with the A feedwater pump cutoff speed reduction control, begins by decreasing the speed by 0.05% per second. Figure 7 Its rotational speed can be flexibly modified online as needed, without the need for configuration download.

[0154] Increase operability and reduce risks caused by improper parameter settings during actual operation.

[0155] like Figure 9 The pump programmable operation sequence module receives the step number and step pulse command from the drive module and outputs the step sequence command logic.

[0156] like Figure 10 Once the step is completed, feedback is sent to the driver module for logical judgment, and the output is returned to the driver module, along with the next step number.

[0157] like Figure 11-12 The judgment logic steps for parallel pump programmable control.

[0158] During the pump merging process, the A feedwater pump command, according to the A feedwater pump merging speed control, begins to increase its speed at 0.05% per second. Figure 7 The acceleration rate is flexibly adjustable, and a 10% limit is set by another pump to prevent overshoot, thus increasing safety and reliability.

[0159] The operation screen for cutting and parallel pump control is controlled by the programmable controller. Figure 13 and Figure 14 When the conditions for programmable operation are met, a red checkmark appears before the condition description. Press the "Start" button to start the programmable operation of the switch and parallel pumps. As the steps proceed, the corresponding step box flashes red. When the conditions for the next step are met, the program will automatically jump to the next step. This continues until the entire programmable process is completed. The programmable logic then returns to its initial state, waiting for the next programmable start.

[0160] This invention modifies the configuration logic to complete the operation with a single click, reducing the number of operation steps and sequences, simplifying operation, reducing the workload of operators, and increasing the stability and controllability of the equipment.

[0161] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for optimizing the switching and paralleling of feedwater pumps in a coal-fired power unit, characterized in that, include: Based on the distributed control system, programmable operation logic was established, and the design steps for pump switching and pump merging logic were completed. The operation instruction module outputs the switching and parallel pump programmable operation instructions and determines whether the preset allowable conditions are met. When the programmable operation allowable conditions are met, the operation instruction is issued. The driver module outputs the step number and step trigger pulse to control the programmable step sequence, and the complete execution of the step is fed back to the driver module. The drive module outputs the next jump step number and jump trigger pulse according to the predetermined step sequence, and finally outputs the command to drive the function group device to start and stop. The pump switching logic design steps include: Pump switching begins; switch from A water pump mode to manual mode. A command to reduce the speed of the water pump; Pause the deceleration and wait for the water flow to stabilize; Continue to reduce the speed of water pump A; A water pump tripping program completed; The preset allowable conditions for the pump switching logic design steps include: The conditions under which the A-type water pump mode can be switched to manual mode at the start of the pump switching process are as follows: When the load is below 300MW, both A and B feedwater pumps are in automatic mode. The recirculation electric valve of feedwater pump A is fully open and the recirculation regulating valve is manually operated with an opening greater than 65 degrees. The inlet flow and outlet pressure of feedwater pumps A and B are both in good condition, the outlet main pipe pressure is in good condition, the outlet electric valves of feedwater pumps A and B are both fully open, and the deviation between the outlet pressure of feedwater pumps A and B and the outlet main pipe pressure is no greater than 0.1MPa. The condition for allowing the A water pump to reduce its speed is that the A water pump is controlled in manual mode. The permissible conditions for pausing deceleration and waiting for the water supply flow to stabilize are: the deviation between the outlet pressure of water pump B and the outlet main pipe pressure is greater than 0.1 MPa, and the deviation between the outlet pressure of water pump A and the outlet main pipe pressure is greater than 1 MPa, lasting for 3 seconds. The permissible condition for the command to continue reducing the speed of the feedwater pump A is: the deviation between the actual feedwater flow rate and the set feedwater flow rate is not greater than 20t / h; The permissible conditions for the completion of the pump switching program of water supply pump A are: when the speed of water supply pump A is less than 2900 r / min or the command of water supply pump A is less than 1.

2. The method for optimizing the switching and paralleling of feedwater pumps in coal-fired power units as described in claim 1, characterized in that: The preset operation instructions for the pump switching logic design sequence include: The operation command to switch the A water pump from manual mode to manual mode is as follows: Click the start button on the A water pump control screen to switch the A water pump control mode to manual mode. The operation command for the A water supply pump speed reduction command is: start pump cut-off, the A water supply pump command starts to decrease according to the A water supply pump cut-off speed reduction control, starting from the set value G1; The operation command to pause deceleration and wait for the water supply flow to stabilize is: temporarily stop the A water supply pump speed control, and temporarily stop the A water supply pump command by decreasing the speed. The operation command for continuing to reduce the speed of water pump A is as follows: the water pump A command continues to decrease the speed of water pump A according to the water pump A cut-off and speed reduction control, starting from the set value G1. The operation command for the A water supply pump tripping program is: A water supply pump tripping completed, program control ended.

3. The method for optimizing the switching and paralleling of feedwater pumps in coal-fired power units as described in claim 1, characterized in that: The parallel pump logic design steps include: A water pump starts running in parallel; command to increase the speed of A water pump. Pause the rate increase and wait for the water supply to stabilize; Continue to increase the speed command of water pump A; Once the water supply flow rate of the water pump stabilizes, switch the control of water pump A to automatic mode. A water supply pump was connected and the pumping program was completed.

4. The method for optimizing the switching and paralleling of feedwater pumps in coal-fired power units as described in claim 3, characterized in that: The preset allowable conditions for the parallel pump logic design step sequence include: The permissible conditions for the command to increase the speed of feedwater pump A upon starting parallel operation are as follows: the load is higher than 240MW; both feedwater pumps A and B are in automatic mode; the recirculation electric valve of feedwater pump A is fully open and the recirculation regulating valve is manually operated with an opening greater than 65°; the outlet flow rate and outlet pressure of feedwater pump A / B are both within acceptable limits; the outlet main pipe pressure is within acceptable limits; the outlet electric valves of feedwater pumps A and B are both fully open; the deviation between the outlet pressure of feedwater pump B and the outlet main pipe pressure is no greater than 0.1MPa; the deviation between the outlet pressure of feedwater pump A and the outlet main pipe pressure is greater than 1MPa; the actual feedwater flow rate deviates from the set feedwater flow rate by no more than 20t / h; and the outlet main pipe pressure is within acceptable limits. The permissible conditions for pausing the speed increase and waiting for the water supply to stabilize are: the deviation between the outlet pressure of water pump A and the outlet main pipe pressure is less than 0.5 MPa and the deviation between the outlet pressure of water pump B and the outlet main pipe pressure is less than 0.5 MPa. The condition for continuing to increase the speed command of water pump A is that the deviation between the actual water flow rate and the set water flow rate is not greater than 20t / h; The conditions under which the automatic control of water pump A is allowed to be activated when the water flow rate of the waiting water pump is stable are: the deviation between the outlet pressure of water pump A and the outlet main pipe pressure is less than 0.2 MPa, the deviation between the inlet flow rates of water pumps A and B is less than 50 t / h, and the deviation between the actual water flow rate and the set water flow rate is not greater than 20 t / h. The permissible condition for the A water supply pump to be connected in parallel is: the A water supply pump is connected in parallel.

5. The method for optimizing the switching and paralleling of feedwater pumps in coal-fired power units as described in claim 3, characterized in that: The preset operation instructions for the parallel pump logic design sequence include: The operation command for starting the A water supply pump in parallel and increasing the speed of the A water supply pump is as follows: Click the start button on the A water supply pump parallel control screen, the A water supply pump will start to increase its speed, and the A water supply pump command will increase according to the A water supply pump parallel pump speed increase control starting from the set value G2. The operation command to pause the speed increase and wait for the water supply to stabilize is: temporarily stop water supply pump A and control the pump speed increase, and the command to temporarily stop water supply pump A is increased. The operation command to continue increasing the speed command of water pump A is: the command for water pump A continues to increase starting from the set value G2; The operation command for automatically controlling water pump A when the water flow rate of the waiting water pump is stable is: Automatic activation of water pump A speed control. The operation command for the A water supply pump to be connected and the program control to be completed is: A water supply pump connection completed, program control ends.

6. The method for optimizing the switching and paralleling of feedwater pumps in coal-fired power units as described in claim 5, characterized in that: The A water pump command continues to increase starting from the set value G2, and also includes using the B water pump command to float up by a 10% limit.

7. The method for optimizing the switching and paralleling of feedwater pumps in coal-fired power units as described in claim 1 or 4, characterized in that: If any step in the cutting and pumping sequence does not meet the allowed conditions, the next step needs to be manually determined and the automatic allow protection conditions need to be set; when the programmable operation needs to be interrupted, it is restored to the initial state through the drive module.

8. The method for optimizing the switching and paralleling of feedwater pumps in coal-fired power units as described in claim 1, characterized in that: The output of the programmable step sequence is implemented by the step sequence module. The step sequence module executes the mask defined in the function block according to the step number and step trigger pulse output by the drive module, in the order of reset, mask, step, step hold, next step, timer hold, and finally outputs the command to drive the function group device to start and stop.

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