A boiler master feedforward control system and method with make-up valve participation

Abstract

This invention provides a boiler main control feedforward control system and method with the participation of the steam supplement valve in regulation. By using a combination of function conversion module, rate limiting module, multiplication block, and amplitude limiting module, the valve opening of the steam turbine steam supplement valve has a feedforward effect on the boiler main control. This compensates in advance for energy losses caused by reduced unit efficiency and increased heat consumption due to the opening of the steam supplement valve, improves the regulation quality of the boiler main control after the steam supplement valve is opened, reduces the deviation of controlled parameters such as main steam pressure and main steam temperature, significantly improves the unit's operational stability and rapid load-bearing capacity after the steam supplement valve is opened, and reduces the number of times the unit is subject to grid testing by improving the AGC response index, thus indirectly improving the unit's operating efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of coal-fired power plants, specifically relating to a boiler main control feedforward control system and method with the participation of a steam injection valve in regulation. Background Technology

[0002] The coordinated control of ultra-supercritical units adopts a strategy of basic feedforward quantity + closed-loop correction. The feedforward functions of coal quantity, feedwater and air quantity corresponding to the load command are generated according to the boiler turbine calculation and are based on the unit design efficiency. Their accuracy is crucial for maintaining the basic energy balance of the boiler turbine when the load changes during coordinated control.

[0003] Steam turbines designed with supplementary steam valves (such as those from Shanghai Turbine) can improve the unit's operating economy by eliminating the pre-throttling design of the high-pressure regulating valve during THA (Transmission Allergy) conditions. They can also increase the steam intake to meet the turbine's load requirements when the high-pressure regulating valve is fully open due to insufficient steam parameters. However, due to the different steam intake methods, when the supplementary steam valve is open for power regulation, the steam flow direction entering the turbine from the supplementary steam valve disturbs the original axial steam flow. Furthermore, the temperature and pressure differences between the two steam flows reduce the efficiency of the turbine's high-pressure cylinder and increase the heat rate, severely reducing the unit's efficiency. Under the same load command, the energy provided by the boiler cannot change in time, resulting in significant energy imbalance between the boiler and turbine sides. Conventional boiler control can only passively adjust after the main steam pressure drops, usually causing large deviations in main steam pressure and significant deviations in the unit's main controlled parameters from their rated values. This leads to a decrease in the unit's load-carrying capacity, seriously affecting the unit's operational safety, economy, and AGC (Automatic Gain Control) response indicators. Summary of the Invention

[0004] The purpose of this invention is to provide a boiler main control feedforward control system and method with the participation of the steam supplement valve in regulation, which solves the above-mentioned shortcomings in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a boiler main control feedforward control system with steam replenishment valve participation in regulation, comprising a first function conversion module and a second function conversion module. The input of the first function conversion module is connected to an analog steam replenishment valve command for conversion. The input of the second function conversion module is connected to an analog load command for conversion. The outputs of the first and second function conversion modules are connected to the boiler main control feedforward value affected by the steam replenishment valve command.

[0007] Preferably, a rate limiting module is provided between the output of the first function conversion module and the feedforward value of the boiler main control affected by the steam replenishment valve command.

[0008] Preferably, the input terminal of the steam replenishment valve command affecting the boiler main control feedforward value is also connected to a multiplication module.

[0009] Preferably, the output of the first function conversion module is connected to the input of the multiplication module.

[0010] Preferably, the output of the second function conversion module is connected to the input of the multiplication module.

[0011] A boiler main control feedforward control method involving the participation of a steam supplement valve in regulation includes the following steps:

[0012] The analog steam valve command and the analog load command were converted separately to obtain two calculated values;

[0013] The two calculated values ​​are used as the boiler main control supplementary steam valve command to influence the boiler main control feedforward value.

[0014] Preferably, the specific method for using the two calculated values ​​as the boiler main control supplementary steam valve command to influence the boiler main control feedforward value is as follows:

[0015] When the load is 80%, the adjustment command for the steam replenishment valve is multiplied by a coefficient of 1.2.

[0016] When the load is 50%, the adjustment command for the steam replenishment valve is multiplied by a coefficient of 1.0.

[0017] When the load is 30%, the conversion command for the supplementary steam valve is multiplied by a coefficient of 0.8.

[0018] Preferably, the function for converting analog steam replenishment valve commands is:

[0019] F(X,Y)=F(0,0;24,23;41,28;50,30;100,30);

[0020] The function for converting analog load commands is:

[0021] F(X,Y)=F(300,0.6;500,1;800,1.2;1000,1.2).

[0022] Preferably, after the analog steam replenishment valve command is converted, the calculated value is subjected to rate limiting processing, specifically:

[0023] The growth rate limit is 30.

[0024] The deceleration rate limit is 20.

[0025] Preferably, the two calculated values ​​should be subject to limit processing before being used as boiler main control feedforward values ​​by the boiler main control supplementary steam valve command. Specifically:

[0026] If the input value is between 0 and 26, then the original input value will be output.

[0027] If the input value is greater than 26, then output 26;

[0028] When the input value is less than 0, the output is 0.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] This invention provides a boiler main control feedforward control system with the participation of the steam supplement valve in regulation. By adding the calculated value converted from the steam supplement valve command as the feedforward of the boiler main control, it compensates in advance for the energy loss caused by the reduction in unit efficiency and the increase in heat consumption after the steam supplement valve is opened. This effectively improves the regulation quality of steam pressure and steam temperature after the steam supplement valve is opened, significantly improves the unit's operational stability and rapid load-bearing capacity after the steam supplement valve is opened, and reduces the number of times the unit is subject to grid assessment by improving the AGC response index, thus indirectly improving the unit's operating efficiency.

[0031] Furthermore, by setting a rate limiting module, it is possible to prevent large and rapid fluctuations caused by the sudden opening or closing of the steam injection valve.

[0032] Furthermore, by multiplying the steam replenishment valve conversion command by the corresponding coefficient according to different loads, variable gain control of the feedforward quantity can be achieved to adapt to the differences in unit characteristics under different load conditions. Attached Figure Description

[0033] Figure 1 This is a design diagram of the logic configuration scheme of the present invention. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings:

[0035] refer to Figure 1 The boiler main control feedforward control system with the participation of the supplementary steam valve in regulation, as described in this invention, calculates a value from the input of the supplementary steam valve command and the load command by using a combination of function conversion module, rate limiting module, multiplication block, and amplitude limiting module. This value serves as one of the feedforward parameters for the boiler main control, which compensates for the energy loss caused by the reduced unit efficiency and increased heat consumption after the supplementary steam valve is opened. This keeps the main controlled parameters of the unit stable, improves the regulation quality of the boiler main control, and ensures the safe and stable operation of the unit.

[0036] The boiler main control feedforward control system with steam replenishment valve participation in regulation according to the present invention includes:

[0037] Analog inputs: Steam replenishment valve command (0-100) and load command.

[0038] Analog output: The steam replenishment valve command affects the boiler main control feedforward value.

[0039] The analog steam replenishment valve command (0-100) is connected to the input of the first function conversion module, with the function F(X,Y) = F(0,0; 24,23; 41,28; 50,30; 100,30). The output of the first function conversion module is connected to the input of the rate limiting module, setting the acceleration rate limit to 30 and the deceleration rate limit to 20. Setting a certain rate for the opening speed of the steam replenishment valve command aims to prevent large and rapid fluctuations caused by sudden opening or closing of the steam replenishment valve. Several previous modifications are also needed. The output of the rate limiting module is connected to the input of the multiplication module.

[0040] The analog load command is connected to the input of the second function conversion module, with the function F(X,Y) = F(300,0.6; 500,1; 800,1.2; 1000,1.2). The output of the second function conversion module is connected to the input of the multiplication module. Specifically: when the load is 80%, the conversion command for the supplementary steam valve is multiplied by a coefficient of 1.2; when the load is 50%, the conversion command for the supplementary steam valve is multiplied by a coefficient of 1.0; and when the load is 30%, the conversion command for the supplementary steam valve is multiplied by a coefficient of 0.8. The purpose is to achieve variable gain control of the feedforward quantity to adapt to the differences in unit characteristics at different load segments.

[0041] The output of the multiplication module is connected to the input of the limiting module. The upper limit is set to 26 and the lower limit is set to 0. The purpose is to output the original input value when the input value is between 0 and 26; output 26 when the input value is greater than 26; and output 0 when the input value is less than 0. The purpose of setting the limiting module is to prevent the feedforward value from being too large when the steam supplement valve opening is too large, which would affect the quality of boiler main control regulation.

[0042] The output of the limiting module and the analog steam replenishment valve command affect the connection of the boiler main control feedforward value.

[0043] This invention, under the premise of normal operation of the original boiler main control feedforward control system, adds the calculated value converted from the steam supplement valve command as the feedforward of the boiler main control. This compensates for the energy loss caused by the reduced unit efficiency and increased heat consumption after the steam supplement valve is opened, effectively improving the regulation quality of steam pressure and steam temperature after the steam supplement valve is opened. It also significantly improves the unit's operational stability and rapid load-bearing capacity after the steam supplement valve is opened. By improving the AGC response index, it reduces the number of times the unit is subject to grid assessment, and indirectly improves the unit's operating efficiency.

Claims

1. A boiler master feed forward control system with make-up valve participation, characterized by, The first function conversion module and the second function conversion module are included, wherein the input end of the first function conversion module is connected with the analog quantity supplementary valve instruction for converting the analog quantity supplementary valve instruction; the input end of the second function conversion module is connected with the analog quantity load instruction for converting the analog quantity load instruction; the output ends of the first function conversion module and the second function conversion module are connected with the supplementary valve instruction influence boiler master control feedforward value.

2. A boiler master feed forward control system with make-up valve participation regulation as claimed in claim 1 wherein, The rate limiting module is arranged between the output end of the first function conversion module and the supplementary valve instruction influence boiler master control feedforward value.

3. A boiler master feed forward control system with make-up valve participation regulation as claimed in claim 1 wherein, The input end of the supplementary valve instruction influence boiler master control feedforward value is also connected with the multiplication module.

4. A boiler master feed forward control system with make-up valve participation regulation as claimed in claim 3 wherein, The output end of the first function conversion module is connected with the input one of the multiplication module.

5. A boiler master feed forward control system with make-up valve participation regulation as claimed in claim 3 wherein, The output end of the second function conversion module is connected with the input two of the multiplication module.

6. A method of feed forward control of a boiler master control with participation of a steam supplement valve, characterized by The method of the boiler master control feedforward control system with the supplementary valve participating in the adjustment according to claim 1 comprises the following steps: The analog quantity supplementary valve instruction and the analog quantity load instruction are converted respectively to obtain two calculation values; The two calculation values are used as the supplementary valve instruction influence boiler master control feedforward value of the boiler master control.

7. A boiler master feed forward control method with make-up valve participation according to claim 6, characterized in that, The specific method of using the two calculation values as the supplementary valve instruction influence boiler master control feedforward value of the boiler master control is as follows: When the load is equal to 80%, the supplementary valve conversion instruction is multiplied by the coefficient 1.2; When the load is equal to 50%, the supplementary valve conversion instruction is multiplied by the coefficient 1.0; When the load is equal to 30%, the supplementary valve conversion instruction is multiplied by the coefficient 0.

8.

8. A boiler master feed forward control method with make-up valve participation regulation as claimed in claim 6 wherein, The function for converting the analog quantity supplementary valve instruction is as follows: F(X,Y)=F(0,0;24,23;41,28;50,30;100,30); The function for converting the analog quantity load instruction is as follows: F(X,Y)=F(300,0.6;500,1;800,1.2;1000,1.2).

9. A boiler master feed forward control method with make-up valve participation regulation as claimed in claim 6 wherein, After the analog quantity supplementary valve instruction is converted, the obtained calculation value is subjected to rate limiting processing, and specifically: The increasing rate limiting value is 30; The decreasing rate limiting value is 20.

10. A boiler master feed forward control method with make-up valve participation regulation as claimed in claim 6 wherein, Before the two calculation values are used as the supplementary valve instruction influence boiler master control feedforward value of the boiler master control, the calculation values should be subjected to limiting value processing, and specifically: When the input value satisfies 0-26, the original input value is outputted; When the input value is greater than 26, 26 is outputted; When the input value is less than 0, 0 is outputted.

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