Automatic start-stop control system and method for electric feed pump of coal-fired unit

Abstract

According to the automatic start-stop control system and method for the electrically-driven feed pump of the coal-fired unit, the system is mainly used for automatically starting or stopping all devices of an electrically-driven feed pump system, automatic start-stop of the electrically-driven feed pump system is achieved, and automatic start-stop of the electrically-driven feed pump system is achieved by inputting a recirculation adjusting valve of the electrically-driven feed pump. Automatic control of the inlet flow of the electric feed pump is achieved, whether equipment operates normally or not is automatically judged according to feedback of the operation state of the equipment, the equipment failed to start is fed back to operation personnel in time, operation can be handled in time, frequent operation of the operation personnel is reduced, and the automation degree of a unit water supply system is improved. The unit operation reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic control of coal-fired generator sets, and in particular to an automatic start-stop control system and method for all equipment in an electric feedwater pump system of a coal-fired generator set. Background Art

[0002] During the startup of large coal-fired power units, there are many systems, complex processes and heavy workloads, especially in the initial startup phase, when system inspections and startup operations are numerous and cumbersome. The electric water supply pump also faces the same problems in the initial startup phase, which increases the frequency of operations by operators during the startup process and also increases the risk of misoperation by operators.

[0003] In the prior art, if the configuration system of the automatic adjustment variable speed switch of the steam pump recirculation valve of the thermal power unit disclosed in the publication number CN112984490A includes the steam pump inlet flow signal terminal, the inertia link function block, the first function conversion block, the second function conversion block, the large value function block, the small value function block, the subtraction block, the rate limiting block, the high and low judgment block, the analog switching block, the first analog constant block, the second analog constant block, the rate limiting block and the valve regulating device, the system can effectively avoid the frequent disturbance of the recirculation valve switch. The automatic control object in this document is the steam pump. In the power plant, the feed water pump is used to boost the water pressure. The driving mode of the boiler feed water pump is generally divided into two working driving modes: the motor and the steam turbine, and is further divided into a fixed speed feed water pump and a variable speed feed water pump. Simply put, the electric feed water pump is driven by electricity, while the steam-driven feed water pump is generally driven by the steam turbine to rotate through the shaft to drive the steam-driven pump to rotate. Most motors use AC motors, so the speed of the feedwater pump is fixed. The boiler feedwater regulation is adjusted by "throttling". The fixed-speed feedwater pump adjusts the flow rate by the throttle valve opening at the pump outlet. The higher the speed, the greater the throttling loss of the throttle valve. However, the throttling adjustment feedwater pump is easy to operate and maintain, and is suitable for medium and low specific speeds and small capacity pumps. The variable-speed feedwater pump adjusts the flow rate by changing the speed of the water pump, and the throttling loss is reduced. The regulating valve has good working conditions and long life, and can be started at low speed, but the equipment is more complex, the investment cost is high, and the maintenance is large. It is suitable for large-capacity pumps. At present, the feedwater pumps used in large-capacity power plants use speed regulation to improve the economic efficiency of operation. There are two types of stepless speed regulation: electric speed-controlled feedwater pumps and steam-driven feedwater pumps. There are essential differences in the working principles of steam pumps and electric feedwater pumps, and the control methods cannot be universal. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to design the automatic start and stop of each device in the electric water supply pump system to realize the automatic start and stop of the electric water supply pump.

[0005] The present invention solves the above technical problems through the following technical means:

[0006] An automatic start-stop control system for an electric feedwater pump of a coal-fired unit, including an automatic control of a recirculation valve of an electric feedwater pump; the automatic control of the recirculation valve of the electric feedwater pump includes: the analog electric feedwater pump inlet flow is connected to the input of a lead-lag module LDLG; the output of the lead-lag module LDLG is respectively connected to the input of a function conversion module FX1 and the input of a function conversion module FX2; the output of the function conversion module FX1 is connected to the input X1 of a maximum module MAX, the output of the function conversion module FX2 is connected to the input X2 of a minimum module MIN, the output of the maximum module MAX is connected to the input X1 of the minimum module MIN, and the output of the minimum module MIN is respectively connected to the input The input X2 of the large module MAX and the input X of the rate limiting module RLMT are connected; the inlet flow of the analog electric water supply pump is connected to the input of the function conversion module FX3 and the input of the alarm module 1 respectively, the output of the function conversion module FX3 is connected to the increase rate limit of the rate limiting module RLMT, the output of the rate limiting module RLMT is connected to the input X1 of the analog switching selection module ASELV, and the output of the analog switching selection module ASELV is connected to the input of the analog handheld operator module MA1; the inlet flow of the analog electric water supply pump is connected to the input of the limit module ALM1, and the lower limit output of the limit module ALM1 is connected to the input X1 of the logic OR module OR1.

[0007] Furthermore, the electric water supply pump tripping is respectively connected to the input X2 of the logic OR module OR1 and the input X of the pulse output module TIMER, the output of the logic OR module OR1 is connected to the tracking switch of the analog hand operator module MA1; the output of the pulse output module TIMER is connected to the input X1 of the logic OR module OR2.

[0008] Furthermore, the switch quantity electric water supply pump inlet flow rate is connected to the input X2 of the logic or module OR2, and the output of the logic or module OR2 is connected to the manual switch of the analog hand operator module MA1.

[0009] Furthermore, the position feedback of the analog electric water supply pump recirculation valve is connected to the feedback value of the analog hand operator module MA1, the output of the analog hand operator module MA1 is respectively connected to the input X2 of the analog switching selection module ASELV and the given instruction of the analog electric water supply pump recirculation valve, and the manual status display of the analog hand operator module MA1 is respectively connected to the selection signal of the analog switching selection module ASELV and the manual mode of the switch electric water supply pump recirculation valve.

[0010] Furthermore, the deceleration rate limit of the rate limiting module RLMT is 100.

[0011] Furthermore, the function conversion module FX1F(x)=(0,100;145,100;190,0;300,0).

[0012] Furthermore, the function conversion module FX2F(x)=(0,100;155,100;220,0;300,0).

[0013] Furthermore, the function conversion module FX3F(x)=(0,100; 200,100; 250,50; 350,20).

[0014] Furthermore, the lower limit of the limiting module ALM1 is set to 97.

[0015] The present invention also provides an automatic start and stop control method for an electric water supply pump of a coal-fired unit. First, an operating personnel determines whether the on-site equipment has the starting conditions, and then enters the sequential control starting screen. The start-up begins, and it is determined that the equipment is in the automatic position. After the automatic position is confirmed, the electric door on the inlet of the electric water supply pump is opened. After the electric door on the inlet of the electric water supply pump is fully opened, the electric water supply pump recirculation regulating valve is continued to be opened, and the instruction is given to 100%. After the recirculation regulating valve is fully opened, the first-stage tap electric valve of the electric water supply pump and the second-stage tap electric valve of the electric water supply pump are closed. After the two tap electric valves are fully closed, the electric door on the outlet of the electric water supply pump is continued to be closed. After the electric door on the outlet of the electric water supply pump is fully closed, the electric water supply pump is started, the electric water supply pump is running, and the electric door on the outlet of the electric water supply pump is opened. After the electric door on the outlet of the electric water supply pump is fully opened, the electric water supply pump recirculation regulating valve is automatically controlled. After the automatic control of the electric water supply pump recirculation regulating valve has been put into operation, the automatic start sequential control of the electric water supply pump ends.

[0016] The advantages of the present invention are:

[0017] The present invention proposes an automatic start-stop control system for an electric water feed pump of a coal-fired unit. According to the operation mode of the operating personnel, the system equipment can be started at any time to realize one-key start and stop of the electric water feed pump system, and each device in the system can be automatically started or stopped in an orderly manner, and automatic control of the recirculation regulating valve of the electric water feed pump can be realized. Through the feedback of equipment operation data, the operating state of the equipment is continuously adjusted, and the control instructions of the valve are adjusted to make the inlet flow control of the electric water feed pump more stable. Through this system control, the equipment can not only be started and stopped safely and stably, but also the model can be used to automatically determine whether the equipment is operating normally. The equipment that fails to start and stop is promptly fed back to the operating personnel for processing, thereby reducing the frequent operations of the operating personnel, improving the degree of automation of the unit, and increasing the safety and reliability of the unit operation.

[0018] The present invention is more stable during the startup process of the electric water supply pump, reduces system disturbances, reduces water supply fluctuations, and makes the system more stable; an automatic start and stop control program is added to improve the degree of automation of the water supply system; a function broken line control algorithm is used to reduce disturbances, and the broken line function can be continuously debugged to make the control more accurate and faster. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of the control method in an embodiment of the present invention.

[0020] Figure 2 It is a schematic diagram of the automatic control principle in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] refer to Figure 1The automatic start-stop control system of the electric feedwater pump of a coal-fired unit described in the present invention includes an automatic control of the recirculation valve of the electric feedwater pump; the automatic control of the recirculation valve of the electric feedwater pump includes: the analog electric feedwater pump inlet flow is connected to the input of the lead-lag module LDLG, and the lag time constant of the lead-lag module LDLG is set to 5, the purpose is to make the value of the inlet flow of the electric feedwater pump lag by 5 seconds, and reduce the change rate of the inlet flow of the electric feedwater pump. The output of the lead-lag module LDLG is respectively connected to the input of the function conversion module FX1 and the input of the function conversion module FX2, the function conversion module FX1F(x)=(0,100;145,100;190,0;300,0); the function conversion module FX2F(x)=(0,100;155,100;220,0;300,0), the purpose is to convert an electric feedwater pump recirculation valve opening according to the inlet flow of the electric feedwater pump. The output of the function conversion module FX1 is connected to the input X1 of the maximum module MAX, the output of the function conversion module FX2 is connected to the input X2 of the minimum module MIN, the output of the maximum module MAX is connected to the input X1 of the minimum module MIN, and the output of the minimum module MIN is respectively connected to the input X2 of the maximum module MAX and the input X of the rate limiting module RLMT. The analog electric water supply pump inlet flow is respectively connected to the input of the function conversion module FX3 and the input of the alarm module 1, and the function conversion module FX3F(x)=(0,100;200,100;250,50;350,20); the output of the function conversion module FX3 is connected to the increase rate limit of the rate limiting module RLMT, and the deceleration rate limit of the rate limiting module RLMT is 100. The purpose is to convert the switch rate of an electric pump recirculation valve through the inlet flow of the electric water supply pump to prevent the valve from opening or closing quickly and causing disturbances to the system. The output of the rate limiting module RLMT is connected to the input X1 of the analog switching selection module ASELV, and the output of the analog switching selection module ASELV is connected to the input of the analog handheld operator module MA1. The inlet flow of the analog electric feedwater pump is connected to the input of the limit module ALM1, the lower limit of the limit module ALM1 is set to 97, the lower limit output of the limit module ALM1 is connected to the input X1 of the logic or module OR1, and the trip of the electric feedwater pump is connected to the input X2 of the logic or module OR1 and the input X of the pulse output module TIMER, respectively, the pulse time is set to 3, and the output of the logic or module is connected to the tracking switch of the analog handheld operator module MA1. The purpose is that when the inlet flow of the electric feedwater pump is less than 97t / h or the electric feedwater pump trips, the steam pump recirculation regulating valve is directly fully opened.The output of the pulse output module TIMER is connected to the input X1 of the logic or module OR2, the switch quantity electric water supply pump inlet flow quality is connected to the input X2 of the logic or module OR2, and the output of the logic or module OR2 is connected to the manual switch of the analog hand operator module MA1, so that when the electric water supply pump trips or the inlet flow of the electric water supply pump is of poor quality, the electric water supply pump recirculation regulating valve is switched from automatic mode to manual mode. The analog electric water supply pump recirculation valve position feedback is connected to the feedback value of the analog hand operator module MA1, and the output of the analog hand operator module MA1 is respectively connected to the input X2 of the analog switching selection module ASELV and the analog electric water supply pump recirculation valve given instruction, and the manual state display of the analog hand operator module MA1 is respectively connected to the selection signal of the analog switching selection module ASELV and the manual mode of the switch quantity electric water supply pump recirculation valve, so that when the electric water supply pump recirculation regulating valve is switched from automatic mode to manual mode, the electric water supply pump recirculation valve given instruction maintains the current instruction.

[0023] The electric water supply pump automatic stop sequence begins. First, the electric water supply pump recirculation regulating valve is switched from automatic to manual control, and the electric water supply pump recirculation regulating valve is slowly opened. The instruction is given to 100%, and then the electric water supply pump outlet electric valve is closed to stop the electric water supply pump. Then the electric water supply pump is stopped and the electric water supply pump automatic stop sequence ends.

[0024] This embodiment also proposes a method for automatically starting and stopping an electric feedwater pump of a coal-fired unit. Figure 2 As shown, specifically, according to the operation mode of the operating personnel, the system equipment can be started at any time, the electric water supply pump system can be started and stopped with one button, and each device in the system can be automatically started or stopped in an orderly manner, and the automatic control of the electric water supply pump recirculation regulating valve can be realized. Through the feedback of equipment operation data, the operating status of the equipment is continuously adjusted, and the control instructions of the valve are adjusted to make the inlet flow control of the electric water supply pump more stable. Through this system control, the equipment can not only be started and stopped safely and stably, but also the model can be used to automatically determine whether the equipment is operating normally. The equipment that fails to start and stop will be promptly fed back to the operating personnel for processing, reducing the frequent operations of the operating personnel, improving the degree of automation of the unit, and increasing the safety and reliability of the unit operation.

[0025] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic start-stop control system for an electric feedwater pump of a coal-fired unit, characterized in that: The invention comprises an automatic control system for regulating the recirculation valve of an electric water supply pump; the automatic control system for regulating the recirculation valve of the electric water supply pump comprises: connecting the analog electric water supply pump inlet flow rate with the input of the lead-lag module LDLG; connecting the output of the lead-lag module LDLG with the input of the function conversion module FX1 and the input of the function conversion module FX2 respectively; connecting the output of the function conversion module FX1 with the input X1 of the maximum module MAX, connecting the output of the function conversion module FX2 with the input X2 of the minimum module MIN, connecting the output of the maximum module MAX with the input X1 of the minimum module MIN, connecting the output of the minimum module MIN with the input X2 of the maximum module MAX respectively.

2. The rate limiting module RLMT input X is connected; the analog electric water supply pump inlet flow is connected to the input of the function conversion module FX3 and the input of the alarm module 1 respectively, the output of the function conversion module FX3 is connected to the increase rate limit of the rate limiting module RLMT, the output of the rate limiting module RLMT is connected to the input X1 of the analog switching selection module ASELV, the output of the analog switching selection module ASELV is connected to the input of the analog hand operator module MA1; the analog electric water supply pump inlet flow is connected to the input of the limit module ALM1, and the lower limit output of the limit module ALM1 is connected to the input X1 of the logic OR module OR1.

2. The automatic start-stop control system for an electric water supply pump of a coal-fired unit according to claim 1, characterized in that: The electric water supply pump trip is connected to the input X2 of the logic OR module OR1 and the input X of the pulse output module TIMER respectively. The output of the logic OR module OR1 is connected to the tracking switch of the analog hand operator module MA1; the output of the pulse output module TIMER is connected to the input X1 of the logic OR module OR2.

3. The automatic start-stop control system for an electric water supply pump of a coal-fired unit according to claim 2, characterized in that: The switching quantity electric water supply pump inlet flow rate is connected to the input X2 of the logic OR module OR2, and the output of the logic OR module OR2 is connected to the manual switch of the analog hand operator module MA1.

4. The automatic start-stop control system for an electric water supply pump of a coal-fired unit according to claim 3 is characterized in that: The position feedback of the analog electric water supply pump recirculation valve is connected to the feedback value of the analog hand operator module MA1, the output of the analog hand operator module MA1 is respectively connected to the input X2 of the analog switching selection module ASELV and the given instruction of the analog electric water supply pump recirculation valve, and the manual status display of the analog hand operator module MA1 is respectively connected to the selection signal of the analog switching selection module ASELV and the manual mode of the switch electric water supply pump recirculation valve.

5. An automatic start-stop control system for an electric feedwater pump of a coal-fired unit according to any one of claims 1 to 4, characterized in that: The deceleration rate limit value of the rate limiting module RLMT is 100.

6. An automatic start-stop control system for an electric feedwater pump of a coal-fired unit according to any one of claims 1 to 4, characterized in that: The function conversion module FX1F(x)=(0,100;145,100;190,0;300,0).

7. An automatic start-stop control system for an electric feedwater pump of a coal-fired unit according to any one of claims 1 to 4, characterized in that: The function conversion module FX2F(x)=(0,100;155,100;220,0;300,0).

8. An automatic start-stop control system for an electric feedwater pump of a coal-fired unit according to any one of claims 1 to 4, characterized in that: The function conversion module FX3F(x)=(0, 100; 200, 100; 250, 50; 350, 20).

9. An automatic start-stop control system for an electric water supply pump of a coal-fired unit according to any one of claims 1 to 4, characterized in that: The lower limit of the amplitude limiting module ALM1 is set to 97.

10. A method for automatically starting and stopping an electric feedwater pump of a coal-fired unit, characterized in that: First, the operator determines whether the on-site equipment has the conditions for starting, and then enters the sequential control startup screen. The startup begins, and determines that the equipment is in the automatic position. After the automatic position is confirmed, open the electric door on the electric water supply pump inlet. After the electric door on the electric water supply pump inlet is fully opened, continue to open the electric water supply pump recirculation regulating valve, and give the instruction to 100%. After the recirculation regulating valve is fully opened, close the first-stage tap electric valve of the electric water supply pump and the second-stage tap electric valve of the electric water supply pump. After the two tap electric valves are fully closed, continue to close the electric water supply pump outlet electric door. After the electric water supply pump outlet electric door is fully closed, start the electric water supply pump, and the electric water supply pump is running. Open the electric water supply pump outlet electric door. After the electric water supply pump outlet electric door is fully opened, put the electric water supply pump recirculation regulating valve into automatic control. After the electric water supply pump recirculation regulating valve automatic control has been put into operation, the electric water supply pump automatic start sequential control ends.

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