PID (Proportion Integration Differentiation) control method for controlling impulse rotation of saturated steam condensing turbine by pneumatic butterfly valve

Abstract

The invention relates to the technical field of pneumatic butterfly valve control, and discloses a PID (Proportion Integration Differentiation) control method for controlling impulse rotation of a saturated steam condensing turbine by a pneumatic butterfly valve, which ensures that the pneumatic butterfly valve is tightly connected with a steam pipeline without leakage, an actuating mechanism of the pneumatic butterfly valve works normally, the valve can be opened and closed flexibly, and meanwhile, all parts of the turbine are checked to be in a normal state. According to the PID control method for controlling impulse rotation of the saturated steam condensing turbine through the pneumatic butterfly valve, in the using process, the whole impulse rotation process is divided into four impulse rotation processes, the valve opening speed is calculated according to the rotating speed characteristic and the vibration characteristic of the turbine in each process, and therefore the impulse rotation of the saturated steam condensing turbine is controlled. According to the method, the stability of early-stage impact rotation is guaranteed, the rapidness of passing through a high-vibration interval is also guaranteed, and the scientificity, effectiveness and real-time performance of the valve opening are guaranteed through the mode that the pneumatic butterfly valve is combined with smooth opening processing and PID adjustment.

Description

Technical Field

[0001] The invention relates to the technical field of pneumatic butterfly valve control, in particular to a PID control method for controlling the run-up of a saturated steam condensing turbine by a pneumatic butterfly valve. Background Art

[0002] After the heat source steam passes through the steam-water separator, the pure steam enters the turbine through the pneumatic steam regulating butterfly valve. The steam works on the turbine, driving it to rotate. The speed of the turbine can be controlled by adjusting the opening of the valve. The turbine is connected to the synchronous generator through the gear box. The speed of the generator is adjusted by adjusting the gear ratio. After reaching the rated speed, it is connected to the grid for power generation.

[0003] At present, for the start-up of steam condensing turbines, electro-hydraulic control valves are used for speed control. The main principle is that valves are usually equipped with feedback devices to monitor the position of the valve core. This feedback device will feed back the actual position of the valve core to the control system, and the control system will adjust the excitation of the electromagnet according to this position information, so as to achieve precise control of the position of the valve core. This feedback mechanism enables the electro-hydraulic valve to achieve automatic control and adjustment, which can achieve stages including valve opening acceleration adjustment, mid-way control (including mid-way acceleration control, mid-way deceleration control and mid-way flow rate maintenance control) and valve closing deceleration control. Each stage needs to adjust the excitation of the electromagnet according to the actual flow rate, pressure and other parameters to achieve precise control. The existing saturated steam condensing turbine start-up mostly uses electro-hydraulic valves for PID adjustment. Although it can ensure the advantages of high stability, fast response speed and strong adaptability, it is also inevitable that the electro-hydraulic valve control system involves multiple components and complex control logic, which increases the complexity and maintenance difficulty of the system. Professional technicians are required for maintenance and debugging. The electro-hydraulic valve control system usually uses hydraulic oil to transmit power and control signals, so the oil quality requirements are high. If the oil quality is poor, it may affect the stability and life of the system. Due to the complexity and high precision requirements of the electro-hydraulic valve control system, its cost is very high. The method uses ordinary pneumatic butterfly valves combined with multiple stroke PID control to achieve stable stroke of the turbine and solve the shortcomings of complex stroke control logic and high cost of electro-hydraulic valve control of turbines. Summary of the invention

[0004] Based on the technical problems existing in the background technology, the present invention provides the following technical solutions: a PID control method for controlling the run-up of a saturated steam condensing turbine by a pneumatic butterfly valve, comprising the following steps: S1. Check equipment connection and parameter settings Ensure that the pneumatic butterfly valve is tightly connected to the steam pipeline without leakage, and that its actuator works properly and the valve can be opened and closed flexibly. At the same time, check that all components of the turbine are in normal condition, and that the relevant sensors work properly and can accurately collect system operation data; S2. Data collection and error calculation During the turbine run-up process, the actual speed of the turbine is collected in real time through the speed sensor installed on the turbine, the valve positioner detects the valve opening and closing degree, and the vibration sensor detects the vibration value. These data will be fed back to the control system, and the set value of the data will be compared with the actual data to calculate the error signal; S3, PID control calculation Add the control outputs of the three links of proportion, integration and differentiation to get the total control signal, which will be used to control the opening of the pneumatic butterfly valve; S4, four-stroke Through the whole four-stroke method, the turbine speed is connected to the grid; S5, feedback adjustment PID parameters According to the actual operation conditions of the turbine during the run-up process, if there are problems such as overshoot, oscillation or excessive steady-state error, the PID parameters are adjusted.

[0005] Preferably, in step S1, the system includes a controller, a set of pneumatic butterfly valves and valve positioners, a turbine, a speed sensor, and a vibration sensor. When the system starts, all component parameters are initialized and the current speed is read. When the speed is 0 and the controller receives a power-on signal, the smooth opening module calculates the valve smooth opening and outputs it to the pneumatic butterfly valve. The pneumatic butterfly valve slowly opens and feeds back the feedback signal of the valve positioner to the controller, and the speed signal and vibration signal are also fed back to the controller.

[0006] Preferably, in step S2, the turbine speed setting value SP set Compare with the actual speed SP and calculate the speed error E sp =SP set -SP, set the valve opening value to OP set Compare with the actual opening and closing degree OP and calculate the valve opening and closing error E op =OP set -OP, also set the vibration value to N set Compare with the actual vibration value N and calculate the vibration value error E n =N set -N, these error signals will be used as inputs to the PID controller.

[0007] Preferably, in step S3, the proportional link calculates the proportional coefficient Kp and speed error E sp , calculate the proportional control output up=K p E sp The proportional link directly generates a control signal according to the current error, so that the opening of the pneumatic butterfly valve changes accordingly, and the integral control output uI is calculated. The output of the integral link uI=K i ∫0 t E n d n , where K i =K p / T i Integral control is to eliminate the steady-state error of the system. As time accumulates, as long as the error exists, the integral control output will continue to increase or decrease, prompting the opening of the pneumatic butterfly valve to continue to adjust until the speed error is zero. Calculate the differential control output uD, uD=K d dE sp / dt, where K d =K p T d The differential control output is related to the rate of change of the error. When the turbine speed is close to the set value and the speed rises too quickly, the differential control output will generate a reverse control signal to appropriately reduce the opening of the pneumatic butterfly valve to avoid speed overshoot. The control outputs of the three links of proportional, integral and differential are added together to obtain the total control signal u=up+uI+uD. This control signal will be used to control the opening of the pneumatic butterfly valve.

[0008] Preferably, in step S4, before the start of the rush, the controller determines the rush condition once, and when the system vacuum, valve control signal and feedback signal are OK, the controller uses the smooth opening calculation module to calculate the opening of the pneumatic butterfly valve and slowly increases it (OP1% / 1s, where OP1 is the valve opening per second output by the smooth calculation module of the first rush), when the speed reaches the set value (SP1-100) RPM, wherein the speed is set lower than SP1100 because when PID intervenes in the control, PID oscillation causes system instability, the PID1 module reads the valve feedback signal and the turbine speed signal to perform PID automatic adjustment, and then determines the second rush condition, when the condition does not meet the requirement, the PID adjustment is continued, and when the condition is met, the second rush begins.

[0009] Preferably, in step S4, when entering the second stroke, due to the rotation and vibration characteristics of the turbine, when it is at 4000~5000rpm, the vibration value will be at a high value, so it is required to quickly increase the valve opening to cross the high vibration range, and the process is: the sliding opening calculation module calculates the valve opening and quickly opens the valve (OP2 / s, where OP2 is the valve opening per second output by the second stroke smoothing calculation module, OP2>OP1), the system detects the vibration value through the vibration sensor, and reads the speed value at the same time, when the turbine quickly crosses the high vibration range and the speed reaches (SP2-100) RPM, the PID2 module is connected to the control, adjusts the valve opening, and then determines the second stroke condition. When the condition does not meet the requirements, the PID adjustment is continued. When the conditions are met, the third stroke is entered.

[0010] Preferably, in step S4, the controller determines the conditions for the third start-up, and uses the smooth opening calculation module to calculate the opening of the pneumatic butterfly valve and slowly increases it (OP3% / 1s, where OP3 is the valve opening per second output by the smooth calculation module for the third start-up). When the speed reaches the set value (SP3-100RPM), the PID3 module reads the valve feedback signal and the turbine speed signal to perform PID automatic adjustment, and then determines the conditions for the fourth start-up. When the conditions do not meet the requirements, PID adjustment is continued. When the conditions are met, the fourth start-up is entered.

[0011] Preferably, in step S4, the controller determines the conditions for the fourth start-up, and uses the smooth opening calculation module to calculate the opening of the pneumatic butterfly valve and slowly increases it (OP4% / 1s, where OP4 is the valve opening per second output by the fourth start-up smoothing calculation module). When the speed reaches the set value (SP4-100), the PID4 module reads the valve feedback signal and the turbine speed signal to perform PID automatic adjustment, and then determines the conditions for the fourth start-up. When the conditions do not meet the requirements, PID adjustment is continued. When the conditions are met, the power generation and grid connection stage is entered.

[0012] Preferably, in step S5, if overshoot occurs (i.e., the speed exceeds the set value), the differential time constant T can be appropriately increased. d Or reduce the proportionality factor K p If the steady-state error is too large, the integral time constant T can be appropriately increased. d Or the proportionality factor K p Through continuous feedback adjustment, the turbine run-up process can reach the set speed more smoothly and quickly, and maintain stable operation.

[0013] Compared with the prior art, the present invention provides a PID control method for controlling the run-up of a saturated steam condensing turbine by a pneumatic butterfly valve, which has the following beneficial effects: The PID control method of the pneumatic butterfly valve controlling the start-up of a saturated steam condensing turbine divides the entire start-up process into four start-up processes, and calculates the valve opening speed according to the speed characteristics and vibration characteristics of the turbine in each process, thereby ensuring both the stability of the early start-up and the rapidity of crossing the high vibration range.

[0014] The PID control method for controlling the saturated steam condensing turbine by the pneumatic butterfly valve ensures the scientificity, effectiveness and real-time performance of the valve opening by using the pneumatic butterfly valve combined with smooth opening processing and PID regulation during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a system architecture diagram of the present invention; Figure 2 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0017] See also Figure 1-2 The present invention provides a technical solution: a PID control method for controlling the saturated steam condensing turbine by a pneumatic butterfly valve, comprising the following steps: S1. Check equipment connection and parameter settings Ensure that the pneumatic butterfly valve is tightly connected to the steam pipeline without leakage, and its actuator works normally, and the valve can be opened and closed flexibly. At the same time, check that all components of the turbine should be in normal state, and the relevant sensors work normally and can accurately collect system operation data. The system includes a controller, a set of pneumatic butterfly valves and valve positioners, a turbine, a speed sensor, and a vibration sensor. At the beginning of the system, all component parameters are initialized and the current speed is read. When the speed is 0 and the controller receives the start-up signal, the smooth opening module calculates the valve smooth opening and outputs it to the pneumatic butterfly valve. The pneumatic butterfly valve opens slowly and feeds back the feedback signal of the valve positioner to the controller. At the same time, the speed signal and vibration signal are also fed back to the controller; S2. Data collection and error calculation During the turbine run-up process, the actual speed of the turbine is collected in real time through the speed sensor installed on the turbine, the valve positioner detects the valve opening and closing degree, and the vibration sensor detects the vibration value. These data will be fed back to the control system, and the set value of the data will be compared with the actual data, and the error signal will be calculated. The set value SP of the turbine speed set Compare with the actual speed SP and calculate the speed error E sp =SP set -SP, set the valve opening value to OP set Compare with the actual opening and closing degree OP and calculate the valve opening and closing error E op =OP set -OP, also set the vibration value to N set Compare with the actual vibration value N and calculate the vibration value error E n =N set -N, these error signals will be used as inputs to the PID controller; S3, PID control calculation Add the control outputs of the three links of proportion, integration and differentiation to get the total control signal, which will be used to control the opening of the pneumatic butterfly valve. The proportional link is calculated according to the proportional coefficient K p and speed error E sp , calculate the proportional control output up=K p E sp The proportional link directly generates a control signal according to the current error, so that the opening of the pneumatic butterfly valve changes accordingly, and the integral control output uI is calculated. The output of the integral link uI=K i ∫0 t E n d n , where K i =K p / T i Integral control is to eliminate the steady-state error of the system. As time accumulates, as long as the error exists, the integral control output will continue to increase or decrease, prompting the opening of the pneumatic butterfly valve to continue to adjust until the speed error is zero. Calculate the differential control output uD, uD=K d dE sp / dt, where K d =K p T d , the differential control output is related to the rate of change of the error. When the turbine speed is close to the set value and the speed rises too fast, the differential control output will generate a reverse control signal to appropriately reduce the opening of the pneumatic butterfly valve to avoid speed overshoot. The control outputs of the three links of proportional, integral and differential are added together to obtain the total control signal u=up+uI+uD, which will be used to control the opening of the pneumatic butterfly valve; S4, four-stroke Through the whole four-time rush-start method, the speed of the turbine is connected to the grid. Before the rush-start begins, the controller determines the rush-start condition. When the system vacuum, valve control signal and feedback signal are OK, the controller uses the smooth opening calculation module to calculate the opening of the pneumatic butterfly valve and slowly increases it (OP1% / 1s, where OP1 is the valve opening per second output by the first rush-start smooth calculation module). When the speed reaches the set value (SP1-100) RPM, the reason for setting the speed lower than SP1100 is that when PID intervenes in control, PID oscillation causes system instability. The PID1 module reads the valve feedback signal and the turbine speed signal for P ID is automatically adjusted, and then the second impulse condition is determined. When the condition does not meet the requirement, PID adjustment is continued. When the condition is met, the second impulse is entered. When entering the second impulse, due to the rotation and vibration characteristics of the turbine, when it is between 4000 and 5000 rpm, the vibration value will be at a high value, so it is required to quickly increase the valve opening to cross the high vibration range. The process is as follows: the sliding opening calculation module calculates the valve opening and quickly opens the valve (OP2 / s, where OP2 is the valve opening per second output by the second impulse smoothing calculation module, OP2>OP1). The system detects the vibration value through the vibration sensor and reads the speed value at the same time. When the valve When the engine passes through the high vibration zone quickly and smoothly, when the speed reaches (SP2-100) RPM, the PID2 module is connected to the control, adjusts the valve opening, and then determines the second rush condition. When the condition does not meet the requirement, the PID adjustment is continued. When the condition is met, it enters the third rush. The controller determines the third rush condition. The controller uses the smooth opening calculation module to calculate the pneumatic butterfly valve opening and slowly increases it (OP3% / 1s, where OP3 is the valve opening per second output by the third rush smooth calculation module). When the speed reaches the set value (SP3-100RPM), the PID3 module reads the valve feedback signal and the turbine speed signal for PID automatic Adjust, and then determine the fourth rush condition. When the condition does not meet the requirements, continue PID adjustment. When the condition is met, enter the fourth rush. The controller determines the fourth rush condition. The controller uses the smooth opening calculation module to calculate the opening of the pneumatic butterfly valve and slowly increases it (OP4% / 1s, where OP4 is the valve opening per second output by the fourth rush smooth calculation module). When the speed reaches the set value (SP4-100), the PID4 module reads the valve feedback signal and the turbine speed signal for PID automatic adjustment, and then determines the fourth rush condition. When the condition does not meet the requirements, continue PID adjustment. When the condition is met, enter the power generation and grid connection stage; S5, feedback adjustment PID parameters According to the actual operation of the turbine during the run-up process, if there are problems such as overshoot, oscillation or excessive steady-state error, adjust the PID parameters. If overshoot occurs (i.e. the speed exceeds the set value), the differential time constant T can be appropriately increased. d Or reduce the proportionality factor K p If the steady-state error is too large, the integral time constant T can be appropriately increased. d Or the proportionality factor K p Through continuous feedback adjustment, the turbine run-up process can reach the set speed more smoothly and quickly, and maintain stable operation.

[0018] The PID control method for controlling the start-up of a saturated steam condensing turbine with a moving butterfly valve, during use, divides the entire start-up process into four start-up processes, and calculates the valve opening speed according to the speed characteristics and vibration characteristics of the turbine in each process, thereby ensuring both the stability of the early start-up and the rapidity of crossing the high vibration range. By using a pneumatic butterfly valve in combination with smooth opening processing and PID regulation, the scientificity, effectiveness and real-time nature of the valve opening are ensured.

[0019] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A PID control method for controlling the saturated steam condensing turbine by a pneumatic butterfly valve, characterized in that: The following steps are involved: S1. Check equipment connection and parameter settings Ensure that the pneumatic butterfly valve is tightly connected to the steam pipeline without leakage, and that its actuator works properly and the valve can be opened and closed flexibly. At the same time, check that all components of the turbine are in normal condition, and that the relevant sensors work properly and can accurately collect system operation data; S2. Data collection and error calculation During the turbine run-up process, the actual speed of the turbine is collected in real time through the speed sensor installed on the turbine, the valve positioner detects the valve opening and closing degree, and the vibration sensor detects the vibration value. These data will be fed back to the control system, and the set value of the data will be compared with the actual data to calculate the error signal; S3, PID control calculation Add the control outputs of the three links of proportion, integration and differentiation to get the total control signal, which will be used to control the opening of the pneumatic butterfly valve; S4, four-stroke Through the whole four-stroke method, the turbine speed is connected to the grid; S5, feedback adjustment PID parameters According to the actual operation conditions of the turbine during the run-up process, if there are problems such as overshoot, oscillation or excessive steady-state error, the PID parameters are adjusted.

2. The PID control method for controlling the saturated steam condensing turbine by a pneumatic butterfly valve according to claim 1 is characterized in that: In step S1, the system includes a controller, a set of pneumatic butterfly valves and valve positioners, a turbine, a speed sensor, and a vibration sensor. When the system starts, all component parameters are initialized and the current speed is read. When the speed is 0 and the controller receives a start-up signal, the smooth opening module calculates the valve smooth opening and outputs it to the pneumatic butterfly valve. The pneumatic butterfly valve slowly opens and feeds back the feedback signal of the valve positioner to the controller. At the same time, the speed signal and the vibration signal are also fed back to the controller.

3. The PID control method for controlling the saturated steam condensing turbine by a pneumatic butterfly valve according to claim 1 is characterized in that: In step S2, the turbine speed setting value SP set Compare with the actual speed SP and calculate the speed error E sp =SP set -SP, set the valve opening value to OP set Compare with the actual opening and closing degree OP and calculate the valve opening and closing error E op =OP set -OP, also set the vibration value to N set Compare with the actual vibration value N and calculate the vibration value error E n =N set -N, these error signals will be used as inputs to the PID controller.

4. The PID control method for controlling the saturated steam condensing turbine by a pneumatic butterfly valve according to claim 1 is characterized in that: In step S3, the proportional link calculates the proportional coefficient K p and speed error E sp , calculate the proportional control output up=K p E sp The proportional link directly generates a control signal according to the current error, so that the opening of the pneumatic butterfly valve changes accordingly, and the integral control output uI is calculated. The output of the integral link uI=K i ∫0 t E n d n , where K i =K p / T i Integral control is to eliminate the steady-state error of the system. As time accumulates, as long as the error exists, the integral control output will continue to increase or decrease, prompting the opening of the pneumatic butterfly valve to continue to adjust until the speed error is zero. Calculate the differential control output uD, uD=K d dE sp / dt, where K d =K p T d The differential control output is related to the rate of change of the error. When the turbine speed is close to the set value and the speed rises too quickly, the differential control output will generate a reverse control signal to appropriately reduce the opening of the pneumatic butterfly valve to avoid speed overshoot. The control outputs of the three links of proportional, integral and differential are added together to obtain the total control signal u=up+uI+uD. This control signal will be used to control the opening of the pneumatic butterfly valve.

5. The PID control method for controlling the saturated steam condensing turbine by a pneumatic butterfly valve according to claim 1, characterized in that: In step S4, before the start of the rush, the controller determines the rush condition. When the system vacuum, valve control signal and feedback signal are OK, the controller uses the smooth opening calculation module to calculate the opening of the pneumatic butterfly valve and slowly increases it (OP1% / 1s, where OP1 is the valve opening per second output by the smooth calculation module of the first rush). When the speed reaches the set value (SP1-100) RPM, the reason for setting the speed lower than SP1100 is that when PID intervenes in the control, PID oscillation causes system instability. The PID1 module reads the valve feedback signal and the turbine speed signal to perform PID automatic adjustment, and then determines the second rush condition. When the condition does not meet the requirement, the PID adjustment is continued. When the condition is met, the second rush begins.

6. The PID control method for controlling the saturated steam condensing turbine by a pneumatic butterfly valve according to claim 1, characterized in that: In step S4, when entering the second stroke, due to the rotation and vibration characteristics of the turbine, when it is between 4000 and 5000 rpm, the vibration value will be at a high value, so it is required to quickly increase the valve opening to cross the high vibration range. The process is as follows: the sliding opening calculation module calculates the valve opening and quickly opens the valve (OP2 / s, where OP2 is the valve opening per second output by the second stroke smoothing calculation module, OP2>OP1). The system detects the vibration value through the vibration sensor and reads the speed value at the same time. When the turbine quickly crosses the high vibration range and the speed reaches (SP2-100) RPM, the PID2 module is connected to the control, adjusts the valve opening, and then determines the second stroke condition. When the condition does not meet the requirements, the PID adjustment is continued. When the conditions are met, the third stroke is entered.

7. The PID control method for controlling the saturated steam condensing turbine by a pneumatic butterfly valve according to claim 1, characterized in that: In step S4, the controller determines the conditions for the third stroke, and uses the smooth opening calculation module to calculate the opening of the pneumatic butterfly valve and slowly increases it (OP3% / 1s, where OP3 is the valve opening per second output by the smooth calculation module for the third stroke). When the speed reaches the set value (SP3-100RPM), the PID3 module reads the valve feedback signal and the turbine speed signal to perform PID automatic adjustment, and then determines the conditions for the fourth stroke. When the conditions do not meet the requirements, PID adjustment is continued. When the conditions are met, the fourth stroke is entered.

8. The PID control method for controlling the saturated steam condensing turbine by a pneumatic butterfly valve according to claim 1, characterized in that: In step S4, the controller determines the conditions for the fourth start-up. The controller uses the smooth opening calculation module to calculate the opening of the pneumatic butterfly valve and slowly increases it (OP4% / 1s, where OP4 is the valve opening per second output by the fourth start-up smoothing calculation module). When the speed reaches the set value (SP4-100), the PID4 module reads the valve feedback signal and the turbine speed signal to perform PID automatic adjustment, and then determines the fourth start-up conditions. When the conditions do not meet the requirements, PID adjustment is continued. When the conditions are met, the power generation and grid connection stage is entered.

9. The PID control method for controlling the saturated steam condensing turbine by a pneumatic butterfly valve according to claim 1, characterized in that: In step S5, if overshoot occurs (i.e. the speed exceeds the set value), the differential time constant T can be appropriately increased. d Or reduce the proportionality factor K p If the steady-state error is too large, the integral time constant T can be appropriately increased. d Or the proportionality factor K p Through continuous feedback adjustment, the turbine run-up process can reach the set speed more smoothly and quickly, and maintain stable operation.

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