CN114017379A

CN114017379A - Automatic control system and method for high-speed and low-speed switching process of air feeder

Info

Publication number: CN114017379A
Application number: CN202111308702.2A
Authority: CN
Inventors: 沈乾坤; 安朝榕; 宋国鹏; 金国强; 王辰昱; 张振伟; 胡亚敏; 吴恒运; 孟阳
Original assignee: Xian Thermal Power Research Institute Co Ltd
Current assignee: Xian Thermal Power Research Institute Co Ltd
Priority date: 2021-11-05
Filing date: 2021-11-05
Publication date: 2022-02-08
Anticipated expiration: 2041-11-05
Also published as: WO2023078351A1; CN114017379B

Abstract

The invention discloses an automatic control system and a method for a high-low speed switching process of an air feeder, which can keep the output of the air feeder unchanged in the high-low speed switching process by a dynamic feedforward prediction technology so as to keep the stability of the total air volume in the high-low speed switching process; meanwhile, the correction theory of inverse function is facilitated, a correction loop of the high-low speed switching process of the air feeder is added in a feedforward loop controlled by an induced draft fan, so that the output of the induced draft fan is basically stable in the high-low speed switching process of the air feeder, and the stability of the negative pressure of a hearth, the total air volume and the oxygen volume in the high-low speed switching process of the air feeder is ensured; the automatic control system and the method greatly shorten the high-low speed switching time of the air feeder, greatly reduce the operation amount of operators, realize the whole automatic control of air feeding and air induction, and further lay the foundation for responding the requirement of the quick load of the power grid.

Description

Automatic control system and method for high-speed and low-speed switching process of air feeder

Technical Field

The invention relates to the technical field of automatic control of thermal power stations, in particular to an automatic control system and method for a high-speed and low-speed switching process of an air feeder.

Background

With the continuous deepening of the policy of energy conservation and consumption reduction in China, the requirement of the thermal power plant on energy conservation of main auxiliary equipment of the unit is higher and higher. The high-low speed motor is applied to thermal power generating units in China, and the motor is connected to a low-speed running state under the working condition of low load or specific load of the units, so that a fan or a pump runs in a low-speed energy-saving mode; under the high load working condition or the abnormal working condition of the unit, the motor is switched to a high-speed state to operate so as to meet the output requirement of the unit.

At the present stage, the switching of high-speed and low-speed motors in an electrical loop is very mature in China, the influence of a water pump related system on the operation of a unit in the high-speed and low-speed switching process is small, the requirement on an automatic control loop in the switching process is not high, and the automatic control of the switching process is realized; the disturbance of the high-speed and low-speed switching process of the fan on the system is large, and if the control is improper in the switching process, the safe operation of the unit is affected; most of power plant fans are not perfect in control logic design, so that the fan switching process is completely manually operated by operators, and even in some power plants, the fans are operated in a high-speed mode in a whole period due to safety considerations.

The switching process of the high speed and the low speed of the fan, particularly the switching process of the high speed and the low speed of the blower is the most complicated. When the high speed and the low speed of the air feeder are switched, the work capacity of the air feeder can be changed greatly instantly, the conventional air feeding control logic controls an air feeding regulation instruction through PID (proportion integration differentiation), so that the total air volume tracks the total air volume instruction, and the conventional PID control is difficult to realize the purpose of rapidly tracking the total air volume instruction; in order to match the load requirements of the unit before switching, operators can manually and quickly operate the adjusting baffle of the air feeder so that the total air volume meets the requirements of the current working condition; meanwhile, because the conventional induced air control logic comprises an air supply instruction feedforward loop, the influence of a high-speed and low-speed switching process is not considered, the instruction of the induced draft fan is inevitably changed greatly in the high-speed and low-speed switching process of the air supply fan, and further, the negative pressure and the combustion working condition of a hearth are greatly disturbed, so that the related parameters of a unit are greatly fluctuated; the negative pressure fluctuation of the hearth reaches more than +/-300 Pa, the total air quantity fluctuation is more than +/-3 percent, and the oxygen quantity fluctuation is more than +/-1 percent.

Disclosure of Invention

The invention aims to overcome the problems and provide an automatic control system and method for the high-low speed switching process of an air feeder, which basically keeps the output of the air feeder unchanged in the switching process by a dynamic feedforward prediction technology, is beneficial to an inverse function correction theory, increases a correction loop for controlling feedforward of an air feeding instruction of the high-low speed switching process on an induced draft fan, realizes automatic control of air feeding in a full load section, greatly shortens the switching time, and simultaneously ensures the stability of total air volume, hearth pressure and combustion working condition so as to adapt to the requirement of quick load response of a power grid.

The purpose of the invention is realized by the following technical scheme:

an automatic control system for high-low speed switching process of a blower comprises a total air volume input 1, a total air volume instruction input 2, wherein the total air volume input 1 and the total air volume instruction input 2 are respectively connected to an input PV and an input SP of a first proportional-integral-derivative controller 3, an output of the first proportional-integral-derivative controller 3 is connected to a first input of a first second output balance block 4, a second input of the first second output balance block 4 is connected with an output TOUT of a first adder 6, a third input of the first second output balance block 4 is connected with an output TOUT of a second adder 7, outputs of the first second output balance block 4 are respectively connected to a first input of the first adder 6 and a first input of the second adder 7, an output of a first offset manual operation station 5 is respectively connected with a second input of the first adder 6 and a second input of the second adder 7, the output of the first adder 6 is connected to the input N of the fifth analog quantity switcher 8, the first constant 9 is connected to the input Y of the fifth analog quantity switcher 8, the switching condition of the fifth analog quantity switcher 8 is connected to the blower a damper full-off command input 10, the output of the fifth analog quantity switcher 8, i.e., the blower a damper adjustment command, is connected to the first input of the third multiplier 18, the second input of the third multiplier 18 is connected to the output of the seventh analog quantity switcher 17, the input N of the seventh analog quantity switcher 17 is the second constant 16, the input Y of the seventh analog quantity switcher 17 is the output of the fifth function converter 15, the input of the fifth function converter 15 is connected to the output of the fifth analog quantity switcher 8, the switching condition of the seventh analog quantity switcher 17 is connected to the output of the third logic and 13, the inputs of the third logic AND 13 are respectively connected with a high-speed operation input 11 of the blower A and a low-speed stop input 12 of the blower A, the output of the third multiplier 18 is connected with the input of a first hand station 19, and the output of the first hand station 19 is connected with a damper regulation instruction output 20 of the blower A;

the output of the second adder 7 is connected to the input N of the sixth analog quantity switching device 21, the first constant 9 is connected to the input Y of the sixth analog quantity switching device 21, the switching condition of the sixth analog quantity switching device 21 is connected to the blower B damper full-off command input 23, the output of the sixth analog quantity switching device 21, i.e., the blower B damper adjustment command, is connected to the first input of the fourth multiplier 31, the second input of the fourth multiplier 31 is connected to the output of the eighth analog quantity switching device 30, the input N of the eighth analog quantity switching device 30 is the second constant 16, the input Y of the eighth analog quantity switching device 30 is the output of the sixth function converter 28, the input of the sixth function converter 28 is connected to the output of the sixth analog quantity switching device 21, the switching condition of the eighth analog quantity switching device 30 is connected to the output of the fourth logic and 26, the inputs of the fourth logical product 26 are respectively connected with a high-speed operation input 24 of the blower B and a low-speed stop input 25 of the blower B, the output of the fourth multiplier 31 is connected with the input of a second manual operation station 32, and the output of the second manual operation station 32 is connected with a damper regulation instruction output 33 of the blower B;

the load command input 37 is connected to the inputs of a first function converter 38, a second function converter 39, a third function converter 41, and a fourth function converter 42, respectively, the output of the first function converter 38 is connected to the input Y of the first analog quantity switch 40, the output of the second function converter 39 is connected to the input N of the first analog quantity switch 40, the output of the third function converter 41 is connected to the input Y of the second analog quantity switch 43, the output of the fourth function converter 42 is connected to the input N of the second analog quantity switch 43, the switching condition of the first analog quantity switch 40 and the switching condition of the second analog quantity switch 43 are connected to the output of a first logic and 36, the inputs of the first logic and 36 are connected to the high-speed operation input 11 of the blower a and the high-speed operation input 24 of the blower B, respectively, the output of the first analog quantity switch 40 is connected to the first input of the first multiplier 50, the second input of the first multiplier 50 is connected to the output of the third analog quantity switch 48, the input Y of the third analog quantity switch 48 is connected to the third constant 47, the input N of the third analog quantity switch 48 is connected to the fourth constant 49, the output of the second analog quantity switch 43 is connected to the first input of the second multiplier 54, the second input of the second multiplier 54 is connected to the output of the fourth analog quantity switch 53, the input Y of the fourth analog quantity switch 53 is connected to the fifth constant 51, the input N of the fourth analog quantity switch 53 is connected to the sixth constant 52, the switching condition of the third analog quantity switch 48 and the switching condition of the fourth analog quantity switch 53 are connected to the outputs of the second logic and 46, the inputs of the second logical product 46 are connected to the blower a automatic control input 44 and the blower B automatic control input 45, respectively, the output of the first multiplier 50 is connected to the input KP of the first pid controller 3, and the output of the second multiplier 54 is connected to the input TI of the first pid controller 3;

a furnace negative pressure input 55, a furnace negative pressure set point input 56, respectively connected to the input PV and the input SP of a second pid controller 57, the output of the second pid controller 57 being connected to a first input of a second secondary output weight 58, a second input of the second secondary output weight 58 being connected to the output TOUT of a fourth adder 59, a third input of the second secondary output weight 58 being connected to the output TOUT of a fifth adder 60, the output of the second secondary output weight 58 being connected to a first input of a fourth adder 59 and a first input of the fifth adder 60, respectively, the output of the second biasing hand 61 being connected to a second input of the fourth adder 59 and a second input of the fifth adder 60, respectively,

the output of the fourth adder 59 is connected to the input N of a thirteenth analog quantity switcher 63, the first constant 9 is connected to the input Y of the thirteenth analog quantity switcher 63, the switching condition of the thirteenth analog quantity switcher 63 is connected to the full-closed instruction input 62 of the movable vane of the induced draft fan a, the output of the thirteenth analog quantity switcher 63 is connected to the input of a third manual station 65, and the output of the third manual station 65 is connected to the movable vane adjustment instruction output 66 of the induced draft fan a;

an output OUT of the fifth adder 60 is connected to an input N of a fourteenth analog quantity switcher 68, the first constant 9 is connected to an input Y of the fourteenth analog quantity switcher 68, a switching condition of the fourteenth analog quantity switcher 68 is connected with a movable vane full-closing instruction input 67 of an induced draft fan B, an output of the fourteenth analog quantity switcher 68 is connected to an input of a fourth hand station 70, and an output of the fourth hand station 70 is connected to a movable vane regulation instruction output 71 of the induced draft fan B;

the negative pressure set value and actual value deviation input 97 is connected to the inputs of a seventh function converter 98 and an eighth function converter 99, respectively, the output of the seventh function converter 98 is connected to the first input of a fifth multiplier 100, the second input of the fifth multiplier 100 is connected to the output of a ninth analog quantity switcher 96, the input Y of the ninth analog quantity switcher 96 is connected to a seventh constant 94, the input N of the ninth analog quantity switcher 96 is connected to an eighth constant 95, the output of the eighth function converter 99 is connected to the first input of a sixth multiplier 104, the second input of the sixth multiplier 104 is connected to the output of a tenth analog quantity switcher 102, the input Y of the tenth analog quantity switcher 102 is connected to a ninth constant 101, the input N of the tenth analog quantity switcher 102 is connected to a tenth constant 103, the switching condition of the ninth analog quantity switcher 96 and the switching condition of the tenth analog quantity switcher 102 are connected with the output of a fifth logical sum 93, the input of the fifth logical sum 93 is respectively connected with the automatic control input 91 of the induced draft fan A and the automatic control input 92 of the induced draft fan B, the output of a fifth multiplier 100 is connected to the input KP of the second proportional-integral-derivative controller 57, and the output of a sixth multiplier 104 is connected to the input TI of the second proportional-integral-derivative controller 57;

the output of the fifth analog quantity switching device 8, i.e. the adjustment command of the blower a, is connected to the input of the ninth function switching device 76, the output of the ninth function switching device 76 is connected to the input Y of the twelfth analog quantity switching device 78, the input N of the twelfth analog quantity switching device 78 is connected to the second constant 16, the switching condition of the twelfth analog quantity switching device 78 is connected to the output of the seventh logic and 74, and the inputs of the seventh logic and 74 are connected to the high-speed operation input 11 of the blower a and the low-speed stop input 12 of the blower a, respectively; the output of the twelfth analog quantity switcher 78 is connected to the first input of the eighth multiplier 80, the second input of the eighth multiplier 80 is connected to the blower a damper adjustment command input 20, the output of the sixth analog quantity switcher 21, i.e., the blower B adjustment command, is connected to the input of the tenth function converter 85, the output of the tenth function converter 85 is connected to the input Y of the eleventh analog quantity switcher 87, the input N of the eleventh analog quantity switcher 87 is connected to the second constant 16, the switching condition of the eleventh analog quantity switcher 87 is connected to the output of the sixth logical sum 83, and the inputs of the sixth logical sum 83 are connected to the blower B high speed operation input 24 and the blower B low speed stop input 25, respectively; the output of the eleventh analog switch 87 is connected to a first input of a seventh multiplier 89, a second input of the seventh multiplier 89 is connected to the blower B damper adjustment command input 33, the outputs of the eighth multiplier 80 and the seventh multiplier 89 are connected to first and second inputs of a third adder 90, respectively, and the output of the third adder 90 is connected to the input FF of the second pid controller 57.

The control method of the automatic control system for the high-speed and low-speed switching process of the air feeder comprises the following steps:

step 1, judging whether the running state of the air blower A is high-speed running, low-speed running, high-speed to low-speed switching or low-speed to high-speed switching according to a high-speed running input 11 of the air blower A and a low-speed stopping input 12 of the air blower A;

judging whether the operation state of the blower B is high-speed operation, low-speed operation, high-speed to low-speed switching or low-speed to high-speed switching according to a high-speed operation input 24 of the blower B and a low-speed stop input 25 of the blower B;

step 2, when the blower A runs at a low speed, the output of the seventh analog quantity switcher 17 in air supply control and the output of the twelfth analog quantity switcher 78 in air induction control are both the second constant 16, when the blower B runs at a low speed, the output of the eighth analog quantity switcher 30 in air supply control and the output of the eleventh analog quantity switcher 87 in air induction control are both the second constant 16, namely, the air supply control and the air induction control are consistent with the conventional control; meanwhile, preparing conditions for feedforward automatic control of switching the air feeder from low speed to high speed;

step 3, in the process that the air feeder A is switched from low-speed operation to high-speed operation, after the low-speed switch of the air feeder A is switched off, the high-speed switch of the air feeder A is switched on immediately, the rotating speed of the air feeder A rises rapidly, and the output of the air feeder A increases rapidly; at this time, the output of the seventh analog quantity switcher 17 is quickly switched to the output of the fifth function converter 15 by the second constant 16, and the output of the fifth function converter 15 is determined according to the output of the fifth analog quantity switcher 8, that is, the blower a adjustment instruction; when the air volume increase caused by the rapid increase of the rotating speed of the air blower A is matched with the air volume decrease caused by the rapid decrease of the regulating baffle of the air blower A, the air volume disturbance of the air blower A in the process of switching from low-speed operation to high-speed operation can be inhibited;

in the process of switching the blower A from low-speed operation to high-speed operation, the inverse function theory is adopted to correct the control feedforward of the induced draft fan A, namely the instruction of adjusting the baffle of the blower A is corrected, namely the instruction correction coefficient of the adjustment baffle of the blower A in the control feedforward of the induced draft fan A is quickly switched from the second constant 16 to the output of the ninth function converter 76, the control feedforward correction coefficient switching time of the induced draft fan A, namely the switching time of the twelfth analog quantity switcher 78 from the input N to the input Y, is consistent with the output switching time of the blower, namely the switching time of the seventh analog quantity switcher 17 from the input N to the input Y, so that the control feedforward of the induced draft fan A in the switching process is kept stable under the condition that the output of the blower A is kept unchanged, the balance of the delivery and induced draft fans is finally ensured, and the aim of maintaining the stable negative pressure is achieved;

and 4, switching the low-speed operation of the air blower B to the high-speed operation, and switching off the low-speed switch of the air blower B. Switching on a high-speed switch of the air blower B immediately, wherein the rotating speed of the air blower B rises rapidly, and the output of the air blower B increases rapidly; at this time, the output of the eighth analog quantity switcher 30 is quickly switched from the second constant 16 to the output of the sixth function converter 28; when the air volume increase caused by the rapid increase of the rotating speed of the air blower B is matched with the air volume decrease caused by the rapid decrease of the regulating baffle of the air blower B, the air volume disturbance in the process of switching the low-speed operation of the air blower B to the high-speed operation can be inhibited;

in the process that the blower B is switched from low-speed operation to high-speed operation, an inverse function theory is adopted to correct the control feedforward of the induced draft fan B, namely the instruction of adjusting the baffle of the blower B is corrected, namely the instruction correction coefficient of the adjustment baffle of the blower B in the control feedforward of the induced draft fan B is quickly switched from a second constant 16 to the output of a tenth function converter 85, the control feedforward correction coefficient switching time of the induced draft fan B, namely the switching time of switching the eleventh analog quantity switcher 87 from the input N to the input Y, is consistent with the output switching time of the blower, namely the switching time of switching the eighth analog quantity switcher 30 from the input N to the input Y, so that the control feedforward of the induced draft fan B in the switching process is kept stable under the condition that the output of the blower B is kept unchanged, the balance of the output of the feeding and induced draft fans is finally ensured, and the aim of keeping the stable negative pressure is fulfilled;

step 5, when the blower A, B runs at a high speed, the adjusting instruction of the blower A, B passes through the fifth function converter 15 and the sixth function converter 28 respectively to obtain the adjusting baffle instruction of the blower A, B, the control method is similar to the conventional control scheme, and meanwhile, the feedforward automatic control preparation condition for switching the blower from the high speed to the low speed is provided;

step 6, in the process that the air feeder A is switched from high-speed operation to low-speed operation, the high-speed switch of the air feeder A is switched off, and when the high-speed switch of the air feeder A is switched off for a certain time, the low-speed switch of the air feeder A is automatically switched on; the output of the air feeder A is reduced in the process that the rotating speed of the air feeder A is idle; at this time, the output of the seventh analog quantity switcher 17 is switched to the second constant 16 after being limited by the output of the fifth function switcher 15 at a certain rate, and the output of the fifth function switcher 15 is determined by the output of the fifth analog quantity switcher 8, namely, the adjustment instruction of the blower a, so as to predict the optimal adjustment baffle opening correction coefficient of the blower a to adapt to the current total air volume demand; when the air volume reduction caused by the reduction of the rotating speed of the air blower A is matched with the air volume increase caused by the increase of the regulating baffle of the air blower A, the air volume disturbance in the process of switching the air blower A from high-speed operation to low-speed operation can be inhibited;

in the process of switching the blower A from high-speed operation to low-speed operation, an inverse function theory is adopted to correct the control feedforward of the induced draft fan A, namely the instruction of adjusting the baffle of the blower A is corrected, namely the instruction correction coefficient of the adjustment baffle of the blower A in the control feedforward of the induced draft fan A is limited by a certain speed and then is switched to a second constant 16 by the output of the ninth function converter 76, the control feedforward correction coefficient switching time of the induced draft fan A, namely the switching time of the twelfth analog quantity switch 78 from the input Y to the input N, is consistent with the output switching time of the blower, namely the switching time of the seventh analog quantity switch 17 from the input Y to the input N, so that the control feedforward of the induced draft fan A in the switching process is kept stable under the condition that the output of the blower A is kept unchanged, the balance of the output of the induced draft fan A is ensured, and the aim of maintaining the stable negative pressure is finally achieved;

step 7, in the process that the air feeder B is switched from high-speed operation to low-speed operation, firstly, a high-speed switch of the air feeder B is switched off, and when the high-speed switch of the air feeder B is switched off for a certain time, a low-speed switch of the air feeder B is automatically switched on; the output of the blower B is reduced in the process of idling the rotating speed of the blower B; at this time, the output of the eighth analog quantity switcher 30 is switched to the second constant 16 after being limited by the output of the sixth analog quantity switcher 28 at a certain rate, and the output of the sixth analog quantity switcher 28 is determined by the output of the sixth analog quantity switcher 21, namely, the adjustment command of the blower B, so as to predict the optimal adjustment baffle opening correction coefficient of the blower B to adapt to the current total air volume demand; when the air volume reduction caused by the reduction of the rotating speed of the blower B is matched with the air volume increase caused by the increase of the regulating baffle of the blower B, the air volume disturbance in the process of switching the high-speed operation of the blower B to the low-speed operation can be inhibited;

in the process that the blower B is switched from high-speed operation to low-speed operation, an inverse function theory is adopted to correct the control feedforward of the induced draft fan B, namely, the instruction of the baffle of the blower B is adjusted by the induced draft fan B, namely, the instruction correction coefficient of the baffle of the blower B in the control feedforward of the induced draft fan B is limited by a certain speed rate and then is switched to a second constant 16 by the output of the tenth function converter 85, the switching time of the feedforward correction coefficient of the induced draft fan B, namely, the switching time of the eleventh analog quantity switcher 87 from input Y to input N is consistent with the switching time of the output of the blower, namely, the switching time of the eighth analog quantity switcher 30 from input Y to input N, so that the feedforward controlled by the induced draft fan B in the switching process is kept stable under the condition that the output of the blower B is kept unchanged, the balance of the output of the induced draft fan is ensured, and the aim of keeping the stable negative pressure is finally achieved;

step 8, because the blower A, B adjusts the nonlinearity of the baffle, add the fifth function converter 15, the sixth function converter 28 to revise in the blowing control, guarantee the accuracy of the dynamic feedforward quantity in the process of switching the high-low speed of the blower A, B; meanwhile, the inverse functions of the fifth function converter 15 and the sixth function converter 28, namely the ninth function converter 76 and the tenth function converter 85, are added in the induced draft control, so that the induced draft control feedforward is kept stable under the condition that the output of the air feeder is kept unchanged, the output of the air feeder and the output of the induced draft fan are balanced, and the aim of keeping the negative pressure stable is fulfilled finally;

the response characteristic of the adjusting baffle of the air feeder in the high-speed operation process of the air feeder is different from the response characteristic of the adjusting baffle of the air feeder in the low-speed operation process of the air feeder, and control parameters with different high and low speeds are adopted in control so as to ensure the rapidity and the stability of air feeding control in a full-load section.

Compared with the prior art, the invention has the following advantages:

1) on the basis of researching the response characteristics of the adjusting baffle of the air feeder, the dynamic feedforward prediction technology is adopted to adapt the rotating speed change of the air feeder to the output change of the air feeder caused by the opening change of the adjusting baffle of the air feeder, so that the output of the air feeder is basically maintained unchanged in the switching process, and the air volume and the combustion condition in the switching process are ensured to be stable;

2) by utilizing an inverse function theory, a processing loop of controlling the feedforward quantity of the induced draft fan by the air supply instruction in the high-speed and low-speed switching process is increased, the stability of the feedforward quantity of the induced draft fan under the condition that the output of the air supply fan is not changed is ensured, and the stability of negative pressure is further ensured;

3) the air supply control is put into an automatic control mode in a full-load section, the disturbance to a system is small in the high-speed and low-speed switching process, the switching time is greatly reduced, and the requirement of a unit on quick response to a power grid is facilitated;

4) the application range is wide: the control method is suitable for automatic control logic design of high-speed and low-speed switching processes of all fans of the power plant, and can effectively inhibit disturbance of the high-speed and low-speed switching processes on system operation parameters and quickly respond to AGC requirements.

Drawings

Fig. 1 is a logic diagram of the blowing control of the automatic control system and method for the high/low speed switching process of the blower according to the present invention.

Fig. 2 is an induced air control logic diagram of an automatic control system and method for high and low speed switching process of a blower according to the present invention.

In the figure:

PID-proportional integral derivative controller f (x) -function converter; sigma-adder

BALANCER-2 output balance x-multiplier;

constant number

T-analog quantity switcher M/A-manual operator AND-logical AND

-an offset hand station

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

As shown in fig. 1 and fig. 2, the automatic control system for high and low speed switching process of blower of the present invention comprises a total air volume input 1, a total air volume command input 2, the total air volume input 1 and the total air volume command input 2 are respectively connected to an input PV and an input SP of a first pid controller 3, an output of the first pid controller 3 is connected to a first input of a first second output balance block 4, a second input of the first second output balance block 4 is connected to an output TOUT of a first adder 6, a third input of the first second output balance block 4 is connected to an output TOUT of a second adder 7, outputs of the first second output balance block 4 are respectively connected to a first input of the first adder 6 and a first input of the second adder 7, an output of the first offset manual station 5 is respectively connected to a second input of the first adder 6 and a second input of the second adder 7, the output of the first adder 6 is connected to the input N of the fifth analog quantity switcher 8, the first constant 9 is connected to the input Y of the fifth analog quantity switcher 8, the switching condition of the fifth analog quantity switcher 8 is connected to the blower a damper full-off command input 10, the output of the fifth analog quantity switcher 8, i.e., the blower a damper adjustment command, is connected to the first input of the third multiplier 18, the second input of the third multiplier 18 is connected to the output of the seventh analog quantity switcher 17, the input N of the seventh analog quantity switcher 17 is the second constant 16, the input Y of the seventh analog quantity switcher 17 is the output of the fifth function converter 15, the input of the fifth function converter 15 is connected to the output of the fifth analog quantity switcher 8, the switching condition of the seventh analog quantity switcher 17 is connected to the output of the third logic and 13, the inputs of the third logic AND 13 are respectively connected with a high-speed operation input 11 of the blower A and a low-speed stop input 12 of the blower A, the output of the third multiplier 18 is connected with the input of a first hand station 19, and the output of the first hand station 19 is connected with a damper regulation instruction output 20 of the blower A;

a furnace negative pressure input 55, a furnace negative pressure set point input 56, connected to the input PV and the input SP, respectively, of a second pid controller 57, the output of the second pid controller 57 being connected to a first input of a second output counterbalance 58, the second input of the second output counterbalance 58 being connected to the output TOUT of a fourth adder 59, the third input of the second output counterbalance 58 being connected to the output TOUT of a fifth adder 60, the output of the second output counterbalance 58 being connected to the first input of a fourth adder 59 and the first input of the fifth adder 60, respectively, the output of the second biasing hand 61 being connected to the second input of the fourth adder 59 and the second input of the fifth adder 60, respectively, the output of the fourth adder 59 being connected to the input N of a thirteenth analog quantity switch 63, the first constant 9 is connected to the input Y of the thirteenth analog quantity switcher 63, the switching condition of the thirteenth analog quantity switcher 63 is connected with the full-closed instruction input 62 of the movable vane of the induced draft fan a, the output of the thirteenth analog quantity switcher 63 is connected to the input of the third hand station 65, and the output of the third hand station 65 is connected to the movable vane regulation instruction output 66 of the induced draft fan a;

As shown in fig. 1 and fig. 2, the control method of the automatic control system for the high-low speed switching process of the blower according to the present invention includes the following steps:

the response characteristic of the adjusting baffle of the air blower in the high-speed operation process of the air blower is inevitably different from the response characteristic of the adjusting baffle of the air blower in the low-speed operation process of the air blower.

Claims

1. The utility model provides a forced draught blower high-low speed switching process automatic control system which characterized in that: comprises a total air volume input (1), a total air volume instruction input (2), wherein the total air volume input (1) and the total air volume instruction input (2) are respectively connected to an input PV and an input SP of a first proportional-integral-derivative controller (3), an output of the first proportional-integral-derivative controller (3) is connected to a first input of a first second output balance block (4), a second input of the first second output balance block (4) is connected with an output TOUT of a first adder (6), a third input of the first second output balance block (4) is connected with an output TOUT of a second adder (7), outputs of the first second output balance block (4) are respectively connected to a first input of the first adder (6) and a first input of the second adder (7), an output of a first offset hand station (5) is respectively connected with a second input of the first adder (6) and a second input of the second adder (7), the output of the first adder (6) is connected to the input N of a fifth analog quantity switcher (8), the first constant (9) is connected to the input Y of the fifth analog quantity switcher (8), the switching condition of the fifth analog quantity switcher (8) is connected with the blower A regulation baffle full-close command input (10), the output of the fifth analog quantity switcher (8), namely the blower A regulation command, is connected to the first input of a third multiplier (18), the second input of the third multiplier (18) is connected with the output of a seventh analog quantity switcher (17), the input N of the seventh analog quantity switcher (17) is the second constant (16), the input Y of the seventh analog quantity switcher (17) is the output of a fifth function converter (15), the input of the fifth function converter (15) is connected with the output of the fifth analog quantity switcher (8), the switching condition of a seventh analog quantity switcher (17) is connected with the output of a third logical AND (13), the input of the third logical AND (13) is respectively connected with a high-speed operation input (11) of a blower A and a low-speed stop input (12) of the blower A, the output of a third multiplier (18) is connected with the input of a first hand station (19), and the output of the first hand station (19) is connected with a regulating baffle command output (20) of the blower A;

the output of the second adder (7) is connected to the input N of a sixth analog quantity switcher (21), the first constant (9) is connected to the input Y of the sixth analog quantity switcher (21), the switching condition of the sixth analog quantity switcher (21) is connected to the blower B regulation damper full-close command input (23), the output of the sixth analog quantity switcher (21), i.e., the blower B regulation command, is connected to the first input of a fourth multiplier (31), the second input of the fourth multiplier (31) is connected to the output of an eighth analog quantity switcher (30), the input N of the eighth analog quantity switcher (30) is the second constant (16), the input Y of the eighth analog quantity switcher (30) is the output of a sixth function converter (28), the input of the sixth function converter (28) is connected to the output of the sixth analog quantity switcher (21), the switching condition of the eighth analog quantity switcher (30) is connected with the output of a fourth logical AND (26), the input of the fourth logical AND (26) is respectively connected with a high-speed operation input (24) of the blower B and a low-speed stop input (25) of the blower B, the output of a fourth multiplier (31) is connected to the input of a second manual station (32), and the output of the second manual station (32) is connected to a damper regulation instruction output (33) of the blower B;

the load command input (37) is respectively connected to the input of a first function converter (38), a second function converter (39), a third function converter (41) and a fourth function converter (42), the output of the first function converter (38) is connected to the input Y of a first analog quantity switch (40), the output of the second function converter (39) is connected to the input N of the first analog quantity switch (40), the output of the third function converter (41) is connected to the input Y of a second analog quantity switch (43), the output of the fourth function converter (42) is connected to the input N of the second analog quantity switch (43), the switching condition of the first analog quantity switch (40) and the switching condition of the second analog quantity switch (43) are both connected with the output of a first logic and (36), and the input of the first logic and (36) is respectively connected with the high-speed operation input (11) of the blower A and the high-speed operation input (11) of the blower B The operational input (24) is connected, the output of the first analog quantity switch (40) is connected to the first input of the first multiplier (50), the second input of the first multiplier (50) is connected to the output of the third analog quantity switch (48), the input Y of the third analog quantity switch (48) is connected to the third constant (47), the input N of the third analog quantity switch (48) is connected to the fourth constant (49), the output of the second analog quantity switch (43) is connected to the first input of the second multiplier (54), the second input of the second multiplier (54) is connected to the output of the fourth analog quantity switch (53), the input Y of the fourth analog quantity switch (53) is connected to the fifth constant (51), the input N of the fourth analog quantity switch (53) is connected to the sixth constant (52), the switching condition of the third analog quantity switch (48) and the switching condition of the fourth analog quantity switch (53) are connected to the fifth constant (51), the input N of the fourth analog quantity switch (53) is connected to the sixth constant (52), and the switching condition of the third analog quantity switch (48) and the fourth analog quantity switch (53) are connected to the fourth constant Two logic AND (46) outputs are connected, the second logic AND (46) inputs are respectively connected with a blower A automatic control input (44) and a blower B automatic control input (45), the output of a first multiplier (50) is connected to an input KP of a first proportional-integral-derivative controller (3), and the output of a second multiplier (54) is connected to an input TI of the first proportional-integral-derivative controller (3);

a furnace negative pressure input (55), a furnace negative pressure set point input (56) respectively connected to the input PV and the input SP of a second PID controller (57), the output of the second PID controller (57) being connected to a first input of a second two-output counterweight (58), a second input of the second two-output counterweight (58) being connected to the output TOUT of a fourth summer (59), a third input of the second two-output counterweight (58) being connected to the output TOUT of a fifth summer (60), the output of the second two-output counterweight (58) being respectively connected to a first input of the fourth summer (59) and a first input of the fifth summer (60), the output of the second offset hand station (61) being respectively connected to a second input of the fourth summer (59) and a second input of the fifth summer (60), the output of the fourth adder (59) is connected to the input N of a thirteenth analog quantity switcher (63), the first constant (9) is connected to the input Y of the thirteenth analog quantity switcher (63), the switching condition of the thirteenth analog quantity switcher (63) is connected with the full-closed instruction input (62) of the movable blade of the induced draft fan A, the output of the thirteenth analog quantity switcher (63) is connected to the input of a third manual station (65), and the output of the third manual station (65) is connected to the movable blade adjusting instruction output (66) of the induced draft fan A;

the output OUT of the fifth adder (60) is connected to the input N of a fourteenth analog quantity switcher (68), the first constant (9) is connected to the input Y of the fourteenth analog quantity switcher (68), the switching condition of the fourteenth analog quantity switcher (68) is connected with the full-closed instruction input (67) of the movable blade of the induced draft fan B, the output of the fourteenth analog quantity switcher (68) is connected to the input of a fourth manual station (70), and the output of the fourth manual station (70) is connected to the regulation instruction output (71) of the movable blade of the induced draft fan B;

the negative pressure set value and actual value deviation input (97) is respectively connected to the inputs of a seventh function converter (98) and an eighth function converter (99), the output of the seventh function converter (98) is connected to the first input of a fifth multiplier (100), the second input of the fifth multiplier (100) is connected to the output of a ninth analog quantity switcher (96), the input Y of the ninth analog quantity switcher (96) is connected to a seventh constant (94), the input N of the ninth analog quantity switcher (96) is connected to an eighth constant (95), the output of the eighth function converter (99) is connected to the first input of a sixth multiplier (104), the second input of the sixth multiplier (104) is connected to the output of a tenth analog quantity switcher (102), the input Y of the tenth analog quantity switcher (102) is connected to a ninth constant (101), the input N of a tenth analog quantity switcher (102) is connected with a tenth constant (103), the switching condition of a ninth analog quantity switcher (96) and the switching condition of the tenth analog quantity switcher (102) are connected with the output of a fifth logical AND (93), the inputs of the fifth logical AND (93) are respectively connected with an automatic control input (91) of an induced draft fan A and an automatic control input (92) of an induced draft fan B, the output of a fifth multiplier (100) is connected with an input KP of a second proportional-integral-derivative controller (57), and the output of a sixth multiplier (104) is connected with an input TI of the second proportional-integral-derivative controller (57);

the output of the fifth analog quantity switcher (8), namely the adjustment command of the blower A, is connected to the input of a ninth function converter (76), the output of the ninth function converter (76) is connected to the input Y of a twelfth analog quantity switcher (78), the input N of the twelfth analog quantity switcher (78) is connected with a second constant (16), the switching condition of the twelfth analog quantity switcher (78) is connected with the output of a seventh logic AND (74), and the input of the seventh logic AND (74) is respectively connected to the high-speed operation input (11) of the blower A and the low-speed stop input (12) of the blower A; the output of the twelfth analog quantity switcher (78) is connected to the first input of the eighth multiplier (80), the second input of the eighth multiplier (80) is connected with the blower A regulation baffle command input (20), the output of the sixth analog quantity switcher (21), namely the blower B regulation command, is connected to the input of the tenth function converter (85), the output of the tenth function converter (85) is connected to the input Y of the eleventh analog quantity switcher (87), the input N of the eleventh analog quantity switcher (87) is connected with the second constant (16), the switching condition of the eleventh analog quantity switcher (87) is connected with the output of the sixth logical sum (83), and the inputs of the sixth logical sum (83) are respectively connected to the blower B high-speed operation input (24) and the blower B low-speed stop input (25); the output of the eleventh analog quantity switcher 87 is connected to the first input of the seventh multiplier 89, the second input of the seventh multiplier 89 is connected to the blower B damper adjustment command input 33, the outputs of the eighth multiplier 80 and the seventh multiplier 89 are connected to the first and second inputs of the third adder 90, respectively, and the output of the third adder 90 is connected to the input FF of the second pid controller 57.

2. The control method of the automatic control system for the high-low speed switching process of the blower according to claim 1, characterized in that: the method comprises the following steps:

step 1, judging whether the running state of the air blower A is high-speed running, low-speed running, high-speed to low-speed switching or low-speed to high-speed switching according to high-speed running input (11) and low-speed stop input (12) of the air blower A;

judging whether the operation state of the blower B is high-speed operation, low-speed operation, high-speed to low-speed switching or low-speed to high-speed switching according to a high-speed operation input (24) of the blower B and a low-speed stop input (25) of the blower B;

step 2, when the air feeder A runs at a low speed, the output of a seventh analog quantity switcher (17) in air feeding control and the output of a twelfth analog quantity switcher (78) in air inducing control are both second constants (16), when the air feeder B runs at a low speed, the output of an eighth analog quantity switcher (30) in air feeding control and the output of an eleventh analog quantity switcher (87) in air inducing control are both second constants (16), namely, the air feeding control and the air inducing control are consistent with the conventional control; meanwhile, preparing conditions for feedforward automatic control of switching the air feeder from low speed to high speed;

step 3, in the process that the air feeder A is switched from low-speed operation to high-speed operation, after the low-speed switch of the air feeder A is switched off, the high-speed switch of the air feeder A is switched on immediately, the rotating speed of the air feeder A rises rapidly, and the output of the air feeder A increases rapidly; at the moment, the output of the seventh analog quantity switcher (17) is quickly switched to the output of a fifth function converter (15) by a second constant (16), and the output of the fifth function converter (15) is determined according to the output of the fifth analog quantity switcher (8), namely the adjustment instruction of the air blower A; when the air volume increase caused by the rapid increase of the rotating speed of the air blower A is matched with the air volume decrease caused by the rapid decrease of the regulating baffle of the air blower A, the air volume disturbance of the air blower A in the process of switching from low-speed operation to high-speed operation can be inhibited;

in the process that the air feeder A is switched from low-speed operation to high-speed operation, an inverse function theory is adopted to correct the control feedforward of the induced draft fan A, namely the adjustment baffle instruction of the air feeder A is corrected, namely the adjustment baffle instruction correction coefficient of the air feeder A in the control feedforward of the induced draft fan A is quickly switched from a second constant (16) to the output of a ninth function converter (76), the control feedforward correction coefficient switching time of the induced draft fan A, namely the switching time of a twelfth analog quantity switcher (78) from input N to input Y is consistent with the output switching time of the air feeder, namely the switching time of a seventh analog quantity switcher (17) from input N to input Y, so that the control feedforward of the induced draft fan A in the switching process is kept stable under the condition that the output of the air feeder A is kept unchanged, the balance of the output of the air feeder and the induced draft fan is finally ensured, and the purpose of keeping the negative pressure stable is achieved;

step 4, in the process that the air feeder B is switched from low-speed operation to high-speed operation, the high-speed switch of the air feeder B is switched on immediately after the low-speed switch of the air feeder B is switched off, the rotating speed of the air feeder B is rapidly increased, and the output of the air feeder B is rapidly increased; at this time, the output of the eighth analog quantity switcher (30) is quickly switched from the second constant (16) to the output of the sixth function converter (28); when the air volume increase caused by the rapid increase of the rotating speed of the air blower B is matched with the air volume decrease caused by the rapid decrease of the regulating baffle of the air blower B, the air volume disturbance in the process of switching the low-speed operation of the air blower B to the high-speed operation can be inhibited;

in the process that the blower B is switched from low-speed operation to high-speed operation, an inverse function theory is adopted to correct a control feedforward of the induced draft fan B, namely a damper adjusting instruction of the blower B is corrected, namely a damper adjusting instruction correction coefficient of the blower B in the control feedforward of the induced draft fan B is quickly switched from a second constant (16) to the output of a tenth function converter (85), the control feedforward correction coefficient switching time of the induced draft fan B, namely the switching time of an eleventh analog quantity switcher (87) from input N to input Y is kept consistent with the output switching time of the blower, namely the switching time of an eighth analog quantity switcher (30) from input N to input Y, so that the control feedforward of the induced draft fan B in the switching process is kept stable under the condition that the output of the blower B is kept unchanged, the balance of the output of the feeding fan and the induced draft fan is finally ensured, and the purpose of keeping the negative pressure stable is achieved;

step 5, when the blower A, B runs at a high speed, the adjusting instruction of the blower A, B passes through a fifth function converter (15) and a sixth function converter (28) respectively to obtain the adjusting baffle instruction of the blower A, B, the control method is similar to the conventional control scheme, and meanwhile, the feedforward automatic control preparation condition for switching the blower from the high speed to the low speed is provided;

step 6, in the process that the air feeder A is switched from high-speed operation to low-speed operation, the high-speed switch of the air feeder A is switched off, and when the high-speed switch of the air feeder A is switched off for a certain time, the low-speed switch of the air feeder A is automatically switched on; the output of the air feeder A is reduced in the process that the rotating speed of the air feeder A is idle; at the moment, the output of the seventh analog quantity switcher (17) is switched to a second constant (16) after being limited by the output of a fifth function converter (15) at a certain speed, and the output of the fifth function converter (15) is determined by the output of a fifth analog quantity switcher (8), namely a blower A adjusting instruction, so as to predict an optimal blower A adjusting baffle opening degree correction coefficient to adapt to the current total air quantity demand; when the air volume reduction caused by the reduction of the rotating speed of the air blower A is matched with the air volume increase caused by the increase of the regulating baffle of the air blower A, the air volume disturbance in the process of switching the air blower A from high-speed operation to low-speed operation can be inhibited;

in the process that the air feeder A is switched from high-speed operation to low-speed operation, an inverse function theory is adopted to correct the control feedforward of the induced draft fan A, namely, the instruction of the baffle of the air feeder A is adjusted by the induced draft fan A, namely, the instruction correction coefficient of the baffle of the air feeder A in the control feedforward of the induced draft fan A is limited by a certain speed rate and then is switched to a second constant (16) by the output of a ninth function converter (76), the control feedforward correction coefficient switching time of the induced draft fan A, namely, the switching time of a twelfth analog quantity converter (78) from input Y to input N is consistent with the output switching time of the air feeder, namely, the switching time of a seventh analog quantity converter (17) from input Y to input N, so that the control feedforward of the induced draft fan A in the switching process is kept stable under the condition that the output of the air feeder A is kept unchanged, the balance of the output of the air feeder and the induced draft fan is ensured, and finally the aim of keeping the negative pressure stable is achieved;

step 7, in the process that the air feeder B is switched from high-speed operation to low-speed operation, firstly, a high-speed switch of the air feeder B is switched off, and when the high-speed switch of the air feeder B is switched off for a certain time, a low-speed switch of the air feeder B is automatically switched on; the output of the blower B is reduced in the process of idling the rotating speed of the blower B; at the moment, the output of the eighth analog quantity switcher (30) is switched to a second constant (16) after being limited by the output of a sixth function converter (28) at a certain speed, and the output of the sixth function converter (28) is determined by the output of a sixth analog quantity switcher (21), namely a blower B adjusting instruction, so as to predict an optimal blower B adjusting baffle opening degree correction coefficient to adapt to the current total air volume requirement; when the air volume reduction caused by the reduction of the rotating speed of the blower B is matched with the air volume increase caused by the increase of the regulating baffle of the blower B, the air volume disturbance in the process of switching the high-speed operation of the blower B to the low-speed operation can be inhibited;

when the blower B is switched from high-speed operation to low-speed operation, the inverse function theory is adopted to correct the control feedforward of the induced draft fan B, namely the instruction of adjusting the baffle of the blower B, the method is characterized in that the instruction correction coefficient of a baffle adjusting instruction of a blower B in the control feedforward of an induced draft fan B is limited by a certain speed rate and then is switched to a second constant (16) by the output of a tenth function converter (85), the switching time of the control feedforward correction coefficient of the induced draft fan B, namely the switching time of an eleventh analog quantity switcher (87) from input Y to input N, is kept consistent with the switching time of the output of the blower, namely the switching time of an eighth analog quantity switcher (30) from input Y to input N, so that the control feedforward of the induced draft fan B in the switching process is kept stable under the condition that the output of the blower B is kept unchanged, the balance of the output of the induced draft fan and the output of the induced draft fan is ensured, and the aim of keeping the negative pressure stable is finally achieved;

step 8, because the blower A, B adjusts the nonlinearity of the baffle, add the fifth function converter (15), the sixth function converter (28) is revised in the blowing control, guarantee the accuracy of the dynamic feedforward quantity in the process of switching the high-low speed of the blower A, B; meanwhile, the inverse functions of a fifth function converter (15) and a sixth function converter (28), namely a ninth function converter (76) and a tenth function converter (85), are added in the induced draft control, so that the induced draft fan control feedforward is kept stable under the condition that the output of the air feeder is kept unchanged, the output of the air feeder and the output of the induced draft fan are balanced, and the aim of maintaining the stability of negative pressure is fulfilled finally;