JP4801420B2 - Control device, control method, and control program - Google Patents

Description

  The present invention relates to a control device, a control method, and a control program.

FIG. 1 shows a schematic configuration of a general once-through exhaust heat boiler. As shown in FIG. 1, the once-through exhaust heat boiler includes a main pipe system 60 in which a economizer 61, a furnace water cooling wall 62, a primary superheater 63, and a secondary superheater 64 are sequentially arranged. In the main pipe system 60, an overheat reducer 65 is provided between the primary superheater 63 and the secondary superheater 64. Furthermore, the spray water piping 70 which bypasses the economizer 61, the furnace water cooling wall 62, and the primary superheater 63, and supplies a part of water supply to the superheat reducer 65 as spray water is provided.
The spray water pipe 70 includes an IS valve 71 for adjusting the flow rate of the spray water supplied to the superheat reducer 65, and an ISPR valve for controlling the difference between the pressure of the spray water pipe and the pressure of the main pipe system to a set value. 72 is provided.
The feed water flow rate sent to the once-through exhaust heat boiler is adjusted by a boiler feed pump 81 provided at the inlet of the once-through exhaust heat boiler. Furthermore, the piping connecting the boiler feed pump 81 and the economizer 61 is provided with a movable nozzle 82 that is opened and closed by a boiler load.

In the above-described once-through type exhaust heat boiler, conventionally, opening control of the boiler feed pump 81, the IS valve 71, the ISPR valve 72, and the like has been mainly performed by PID control and program control.
For example, in Patent Document 1, a boiler outlet steam temperature is detected, a deviation between this detected value and a preset temperature set value is calculated, and this deviation is given to a PID controller, thereby providing an outlet of the superheater. A technique for calculating a feed water flow rate that maintains a steam temperature within a set range is disclosed.

Patent Document 2 discloses a technique for adjusting the flow rate of the spray water supplied to the secondary superheater 64 by performing PI control of the IS valve 71 so that the steam temperature at the boiler outlet is within a predetermined range. ing.
Japanese Patent Laid-Open No. 2004-19961 JP 2002-323203 A

As described above, conventionally, PID control and program control have been mainly used as a control method in a plant or the like.
However, in PID control and program control, when the control target or its control environment changes rapidly, there arises a problem that the control target cannot be quickly followed.
For example, in the once-through type exhaust heat boiler, when the boiler load is changed, the movable nozzle 82 is operated, and when the open state is changed to the closed state, or the closed state is changed to the open state, the influence of the movable nozzle 82 causes the main pipe. Since the pressure of the system 60 changes abruptly, the pressure of the spray water pipe 70 needs to promptly follow the pressure change of the main system 60.

However, in the PID control, a control delay occurs due to the control characteristics, so that the ISPR valve 72 cannot be controlled in response to a rapid pressure change, and the pressure of the spray water pipe 70 is controlled by the main pipe system 60. There was a problem that it was not possible to follow the pressure. In PID control, it is conceivable to set a high gain in order to eliminate the control delay. However, if the gain is set high, a hunting phenomenon occurs and a problem arises that stable control cannot be realized. .
Such a problem is not limited to the above-described control of the ISPR valve 72, but is a problem common to all control methods when the control object or the environment where the control object is placed changes rapidly.

  The present invention has been made to solve the above-described problem. When the control object or the control environment of the control object changes suddenly, the control object quickly follows the rapid fluctuation to realize stable control. It is an object of the present invention to provide a control device, a control method, and a control program that can be executed.

In order to solve the above problems, the present invention employs the following means.
The present invention provides a control device that controls the control target by controlling an operation amount of the adjusting unit that affects the control target, and includes a first control that changes the operation amount of the adjusting unit at a predetermined rate. Means, second control means for changing the amount of operation of the adjusting means based on deviation, detection means for detecting that a predetermined disturbance that changes the control object or its control environment has occurred, and the disturbance Based on a comparison result between a deviation between the actual measurement value of the control target and the target value and a preset first specified value in a predetermined period after the occurrence of the Control means for alternately selecting the two control means, and the predetermined period is set to be substantially equal to or longer than the period until the influence of the control object due to the occurrence of the disturbance is eliminated. Providing equipment To.

According to the above configuration, the first control unit that changes the operation amount of the adjustment unit at a predetermined rate and the second control unit that changes the operation amount of the adjustment unit based on the deviation are in accordance with the behavior of the control target. Therefore, the optimum control can be performed according to the situation of the control target. Thereby, for example, even when a large fluctuation occurs in the control environment of the control target, the control target can quickly follow the fluctuation by setting the predetermined rate of the first control means to an appropriate value. It becomes possible to make it.
In addition, for example, switching between the first control means and the second control means may be performed according to time. However, in this method, if the characteristics of the controlled object change due to deterioration over time, an error occurs. It becomes difficult to maintain the original accuracy. However, by monitoring the behavior of the controlled object as in the present invention and switching the control means in accordance with this behavior, control can be performed with high accuracy even when the characteristics change due to aging degradation or the like. It can be carried out.
In addition, since the selection unit alternately selects the first control unit and the second control unit only within a predetermined period after the occurrence of the disturbance, the predetermined period has elapsed since the occurrence of the disturbance. Later, it becomes possible to control the operation amount of the adjusting means by a control method suitable for controlling the controlled object. Here, the predetermined period is set to be approximately equal to or longer than the period until the influence of the control target due to the occurrence of the disturbance disappears. Moreover, it is also possible to employ the second control means as the control means after a predetermined period has elapsed.

In the above control device, the selection unit is configured such that the deviation between the actual measurement value of the control target and the target value is equal to or less than the first specified value , and the differential value of the deviation is equal to or less than a preset second specified value. Preferably, the first control means is selected, and the second control means is selected when the deviation is greater than the first specified value or the differential value of the deviation is greater than the second specified value .

In the above control device, the selection means is configured such that the deviation between the actual measurement value of the control target and the target value is not less than the first specified value and the differential value of the deviation is not less than a second specified value set in advance. Preferably, the first control means is selected, and the second control means is selected when the deviation is less than the first specified value or the differential value of the deviation is less than the second specified value .

  Thus, since the first control means and the second control means are alternately selected in consideration of not only the deviation but also the deviation differential value, the two control means can be switched at a more suitable timing. Become. For example, when the control means is selected based only on the deviation, the switching timing from the first control means to the second control means tends to be delayed, and the control target is changed after the control means is switched. There is a possibility that the behavior will not be stable. In such a case, by selecting the control means in consideration of the differential value of the deviation, the state of the controlled object can be grasped more accurately and the accuracy can be improved.

  In the control device, the predetermined rate of the first control means is the amount of operation of the adjusting means corresponding to the target value of the control target set before the occurrence of the disturbance and after the occurrence of the disturbance. It is preferable that the difference is set to be equal to or larger than a value obtained by dividing a difference from the operation amount of the adjusting unit corresponding to the set target value to be controlled by the predetermined period.

  In this way, the predetermined rate corresponds to the operation amount of the adjusting unit corresponding to the target value to be controlled set before the disturbance occurs and the adjusting unit corresponding to the target value to be controlled set after the disturbance occurs. Is set to a value that is equal to or greater than the difference between the manipulated variable and the predetermined amount of time, even if the measured value of the controlled object greatly exceeds or falls below the target value due to the influence of disturbance, After a predetermined period, it is possible to reliably bring the measured value close to the target value. As a result, it becomes possible to quickly follow the control object in accordance with a change in the control environment of the control object.

The present invention provides a control method for indirectly controlling the control target by controlling an operation amount of the adjustment unit that affects the control target, wherein the operation amount of the adjustment unit is changed at a predetermined rate. first control mode and the operation amount of the adjustment means may be set and a second control mode for changing on the basis of the deviation in advance, a predetermined disturbance giving fluctuation to the control object or the control environment is detected The first control mode based on a comparison result between a deviation between the actual measurement value of the control target and the target value and a preset first specified value in a predetermined period after the disturbance is detected. And the second control mode are alternately selected, and the predetermined period is set to be approximately equal to or longer than the period until the influence of the control target due to the occurrence of the disturbance is eliminated. provide.

  According to the above method, the first control mode for changing the operation amount of the adjusting means at a predetermined rate and the second control mode for changing the operation amount of the adjusting means based on the deviation are in accordance with the behavior of the control target. Therefore, optimal control can be performed according to the status of the control target. As a result, even if a large variation occurs in the controlled object or its control environment, it becomes possible to cause the controlled object to quickly follow the variation.

The present invention is a control program for indirectly controlling the control object by controlling the operation amount of the adjustment means that affects the control object, and changes the operation amount of the adjustment means at a predetermined rate. a first control process for the operation amount of the adjustment means may be stored in the storage means and a second control process vary based on the deviation, a predetermined giving fluctuation to the control object or a controlled environment When a disturbance is detected, in a predetermined period after the disturbance is detected, based on a comparison result between a deviation between the actually measured value of the control target and the target value and a preset first specified value, While causing the computer to execute a process of alternately selecting the first control process and the second control process, the predetermined period is almost the same as the period until the influence of the control target due to the occurrence of the disturbance is eliminated. same Or to provide a control program that is set further to.

  A first control process for changing the operation amount of the adjusting means at a predetermined rate by executing the arithmetic processing by the program with hardware resources, and a second control for changing the operation amount of the adjusting means based on the deviation. It is possible to switch between processes according to the behavior of the control target. As a result, it is possible to perform optimal control according to the status of the control target, and it is possible to realize stable control. As a result, even if a large variation occurs in the controlled object or its control environment, the controlled object can promptly follow the variation.

The present invention provides a main pipe system in which at least an evaporator and a superheater are disposed, a spray water pipe for supplying spray water to the main pipe system, and a pressure of the spray water pipe provided in the spray water pipe. Adjusting means for adjusting the operating amount of the adjusting means, and control means for controlling the pressure of the spray water pipe by controlling the operating amount of the adjusting means, wherein the control means sets the operating amount of the adjusting means at a predetermined rate. a first control means for changing, a second control means for changing based on the operation amount of the adjustment means in deviation, a predetermined disturbance giving fluctuating pressure or in controlled environment of the spray water piping occurs detecting means for detecting that, in the period from the generation is detected in the predetermined the disturbance, a comparison result of the first specified value set in advance and the deviation between the pressure and the target value of the spray water pipe Based on the first control means and a selection means for alternately selecting said second control means, the predetermined period is the period until the effect of the control object is received by the occurrence of the disturbance is eliminated Provide a waste heat boiler that is set to approximately the same or higher .

According to the above configuration, the first control means for changing the operation amount of the adjusting means at a predetermined rate and the second control means for changing the operation amount of the adjusting means based on the deviation are controlled by the pressure of the spray water pipe. Since it selects and employ | adopts alternately according to a behavior, it becomes possible to implement optimal control according to the condition of the pressure of spray water piping.
As a result, the pressure of the spray water pipe quickly follows the pressure of the main pipe system even if the pressure of the spray water pipe or the control environment thereof greatly fluctuates due to a large fluctuation in the pressure of the main pipe system. It becomes possible to make it.
In the exhaust heat boiler, the disturbance is a disturbance generated by opening and closing a movable nozzle provided between the main pipe system and a water supply pump supplying water to the main pipe system according to a boiler load, In the case where the movable nozzle is in an opening operation, the means selects the first control means when a deviation between the pressure of the spray water pipe and the pressure of the main pipe system is not more than the first specified value. , deviation selects the second control means is greater than said first predetermined value, said movable nozzle is in the closing operation, the deviation is the first in the case of more than the first predetermined value select control unit, the deviation may be configured to select the second control means when lower than the first predetermined value.
In the exhaust heat boiler, the disturbance is a disturbance generated by opening and closing a movable nozzle provided between the main pipe system and a water supply pump supplying water to the main pipe system according to a boiler load, When the movable nozzle is in an opening operation, the means has a deviation between the pressure of the spray water pipe and the pressure of the main pipe system not more than the first specified value, and a differential value of the deviation is not more than zero. selects the first control means when, deviation is greater than said first predetermined value, or selects the second control means when the differential value of the deviation is greater than zero, the movable nozzle There when a closing operation, the deviation is the first predetermined value or more, and the differential value of the deviation to select the first control means when the above zero, the deviation is the first predetermined value Or the differential value of the deviation is It may be selected the second control means when less than.

  Advantageous Effects of Invention According to the present invention, when the control target or its control environment changes greatly, the control target can be made to quickly follow the rapid fluctuation, and stable control can be realized.

Hereinafter, an embodiment in which the control device according to the present invention is applied to control of the operation amount of the ISPR valve 72 of the general once-through exhaust heat boiler shown in FIG. 1 will be described with reference to the drawings.
As shown in FIG. 1, the once-through type exhaust heat boiler has a main pipe system 60 in which a economizer 61, a furnace water cooling wall 62, a primary superheater 63, and a secondary superheater 64 are sequentially arranged, and sprays on the main pipe system 60. And a spray water pipe 70 for supplying water.
In the spray water pipe 70, an IS valve 71 for adjusting the flow rate of the spray water supplied to the superheat reducer 65, and the difference between the pressure of the spray water pipe 70 and the pressure of the main pipe system 60 are controlled to a set value. An ISPR valve 72 is provided. A movable nozzle 82 that is opened and closed by a boiler load is provided in a pipe 80 that connects the boiler feed pump 81 and the economizer 61.
In the once-through type exhaust heat boiler having the above configuration, the opening degree of the ISPR valve 72 is controlled by a control device (not shown) in order to control the difference between the pressure of the spray water pipe 70 and the pressure of the main pipe system 60 to a set value. The

  The control device controls the pressure of the spray water pipe 70 by controlling the opening degree of the ISPR valve 72 which affects the pressure of the spray water pipe 70 as described above. For example, as shown in FIG. In addition, the first control unit 1 that changes the opening degree of the ISPR valve 72 at a predetermined rate, and the opening degree of the ISPR valve, the deviation between the pressure of the spray water pipe and the pressure of the main pipe system (hereinafter simply referred to as “deviation ΔP”). According to the pressure of the spray water pipe, the disturbance control section 3 for detecting that the movable nozzle 82 that changes the pressure control of the spray water pipe is activated, and the pressure of the spray water pipe. A selection unit 4 that alternately selects the first control unit 1 and the second control unit 2 is provided.

The control device further includes a hold unit 6, a deviation comparison unit 7, a deviation differential value comparison unit 8, and a determination unit 5. The hold unit 6 outputs an ON signal in a predetermined period from when the disturbance detection unit 3 detects that the movable nozzle is activated.
The deviation comparison unit 7 compares the deviation ΔP with a predetermined specified value, and outputs a comparison signal corresponding to the comparison result. For example, when the movable nozzle is in an opening operation, the deviation comparison unit 7 is configured so that the deviation ΔP is equal to or less than a specified value, that is, the difference between the deviation ΔP and the specified value (hereinafter, this difference (ΔP−specified value)). Is referred to as “ISPR valve deviation”) is equal to or less than zero, an ON signal is output, and an OFF signal is output when the deviation ΔP is greater than a specified value, that is, when the ISPR valve deviation is greater than zero. Further, when the movable nozzle is in the closing operation, an ON signal is output when the ISPR valve deviation is zero or more, and an OFF signal is output when the ISPR valve deviation is less than zero.
The deviation differential value comparison unit 8 outputs a comparison signal corresponding to the differential value of the ISPR valve deviation (hereinafter simply referred to as “deviation differential value”). For example, when the movable nozzle is open, the deviation differential value comparison unit 8 outputs an on signal when the deviation differential value is less than or equal to zero, and outputs an off signal when the deviation differential value is greater than zero. To do. Further, when the movable nozzle is in the closing operation, an ON signal is output when the deviation differential value is zero or more, and an OFF signal is output when the deviation differential value is less than zero.
The determination unit 5 acquires outputs from the hold unit 6, the deviation comparison unit 7, and the deviation differential value comparison unit 8 as input signals, and outputs a logical product of these signals. That is, the ON signal is output only when all the input signals are ON.

The signal switching unit 9 outputs the rate change target value 10 to the first control unit 1 when an ON signal is given from the determination unit 5. On the other hand, when an OFF signal is given from the determination unit 5, the current ISPR valve opening command held in the latch unit 11 is output to the second control unit 2.
Thus, the first control unit 1 generates and outputs an ISPR valve opening command for changing the opening of the ISPR valve at a predetermined rate given by the signal switching unit 9. On the other hand, based on the current ISPR valve opening and the deviation ΔP, the second control unit 2 obtains an operation amount that makes the deviation ΔP a specified value by a proportional integration calculation, and obtains the calculation result as the ISPR valve opening. Output as a command.

  The selection unit 4 selects and outputs the ISPR valve opening command from the first control unit 1 during the period when the ON signal is given from the determination unit 5, and the OFF signal is given from the determination unit 5. During this period, the ISPR valve opening command from the second control unit 2 is selected and output.

The control of the operation amount of the ISPR valve by the control device having such a configuration will be described with reference to FIG. FIG. 3 shows the control of the ISPR valve when the movable nozzle is controlled from the closed state to the open state.
As shown in FIG. 3, first, when the movable nozzle is controlled to be open at time T <b> 1, the disturbance detection unit 3 in FIG. 2 detects the start of operation of the movable nozzle, and an on signal is output from the hold unit 6. . This ON signal is maintained for a predetermined period (for example, 360 seconds) as shown in FIG. For example, the predetermined period is set to be approximately equal to or longer than the period until the pressure fluctuation of the main pipe system caused by the operation of the movable nozzle is stabilized.

Further, at time T1 in FIG. 3, the pressure 80 at the boiler feed pump outlet suddenly decreases due to the opening operation of the movable nozzle 82 shown in FIG. 1, so the current pressure in the spray water pipe 70 and the pressure in the main pipe system 60 Deviation [Delta] P ([pressure of main pipe system]-[pressure of spray water piping]) is equal to or less than a specified value. Accordingly, an ON signal is output from the deviation comparison unit 7 shown in FIG.
Furthermore, since the behavior of the deviation ΔP is larger than the correcting operation of the second control unit of the ISPR valve, the deviation tends to increase. For this reason, the deviation differential value also becomes zero or less, and an ON signal is output from the deviation differential value comparison unit 8.

  As a result, all inputs to the determination unit 5 are ON signals, and the ON signal is output from the determination unit 5 to the signal switch 9 and the selection unit 4. Thereby, the rate target value 10 is given from the signal switching unit 9 to the first control unit 1. The first control unit 1 generates and outputs an ISPR valve opening command for changing the opening of the ISPR valve at a predetermined rate given by the signal switching unit 9. As a result, as shown in the period from time T1 to time T2 in FIG. 3, the ISPR valve opening command increases at a predetermined rate. At this time, the predetermined rate is the amount of operation of the adjusting means corresponding to the target value of the controlled object set before the occurrence of the disturbance and the adjusting means corresponding to the target value of the controlled object set after the occurrence of the disturbance. It is preferably set to be equal to or greater than a value obtained by dividing the difference from the operation amount by a predetermined period. For example, in this embodiment, the target value θcl of the ISPR valve opening command set when the movable nozzle is in the closed state and the target value θop of the ISPR valve opening command set when the movable nozzle is in the open state. Is preferably set to a value equal to or greater than a value obtained by dividing the difference by the predetermined period (that is, the period during which the ON signal is output from the hold unit 6).

  For example, the target value θcl of the ISPR valve opening command when the movable nozzle is in the closed state and the target value θop of the ISPR valve opening command when the movable nozzle is in the open state are known values as the static characteristics of the boiler. . By setting a predetermined rate to such a value, it is possible to reliably bring the ISPR valve opening command close to the target value after a predetermined period has elapsed.

  When the ISPR valve is quickly opened at a predetermined rate in this way, the pressure in the spray water pipe 70 rises, the pressure difference ΔP with the main pipe system 60 gradually recovers, and the behavior of the deviation ΔP is observed at time T2. When turning upward, the output of the deviation derivative comparison unit 8 shown in FIG. 2 is switched to an off signal.

  As a result, the output of the determination unit 5 is inverted to an off signal, and the off signal is output to the signal switch 9 and the selection unit 4. When the signal switching unit 9 receives the off signal, the signal switching unit 9 outputs the current ISPR valve opening held in the latch unit 11 to the second control unit 2. Based on the current ISPR valve opening and the deviation ΔP, the second control unit 2 obtains an operation amount that makes the deviation ΔP a specified value by a proportional integration calculation, and uses the calculation result as an ISPR valve opening command. Output. The selector 4 selects and outputs the ISPR valve opening command from the second controller 2. As a result, as shown at times T2 to T3 in FIG. 3, the operation amount of the ISPR valve increases with a gentle slope by the PI control.

  Even after switching from the control by the first control unit 1 to the PI control by the second control unit 2 at the time T2, the difference ΔP shows an upward trend, becomes a specified value or more at the time T3, and thereafter shows an upward trend. maintain. Then, at time T4, when the influence of the response delay due to the PI control by the second control unit 2 becomes large, and the pressure change of the spray water pipe cannot catch up with the pressure change of the main pipe system, the deviation starts to expand, The differential value is negative. As a result, the deviation ΔP gradually begins to decrease. At time T5, when all the outputs of the hold unit 6, the deviation comparison unit 7, and the deviation differential value comparison unit 8 are turned on again, the output of the determination unit 5 is changed from the off signal. Invert to ON signal. As a result, the rate change target value 10 is selected by the signal selection unit 9 and supplied to the first control unit 1. As a result, the ISPR valve opening command generated by the first controller 1 is selected by the selector 4 and output. Thereby, at time T5 in FIG. 3, the ISPR valve opening command increases at a predetermined rate.

  Then, by alternately selecting the first control unit 1 and the second control unit 2 according to the behavior of the deviation ΔP as described above, as shown after time 5 in FIG. The behavior of the deviation ΔP becomes stable. At time T6, when a predetermined period elapses from the detection of the movable nozzle operation and the output of the hold unit 6 is switched to the off signal, the determination unit 5 maintains the off signal until the movable nozzle is activated again. Thereby, after the time T6, the control by the second control unit 2 is performed.

  Next, FIG. 4 shows an example of a specific internal circuit of the control device according to the present embodiment. As shown in this figure, reference numeral 21 denotes a movable nozzle opening operation detection unit that outputs an ON signal when it is detected that the movable nozzle is opening, and reference numeral 22 denotes an ON signal when the input signal is an ON signal. Is a hold unit that maintains 360 seconds, reference 23 is a comparator that outputs an ON signal when the ISPR valve opening is 75% or less, and reference 24 is an ON signal when the ISPR valve opening is 15% or more. Is a comparator that outputs Reference numeral 25 denotes a movable nozzle closing operation detection unit that outputs an ON signal when it detects that the movable nozzle is closing, and reference numeral 26 denotes a hold that maintains the ON signal for 360 seconds when the input signal is an ON signal. Part.

Reference numeral 27 is a comparator that outputs an ON signal when the deviation ΔP between the pressure of the spray water pipe 70 and the pressure of the main pipe system 60 is equal to or less than a specified value, and reference numeral 28 is a differentiator that calculates a deviation differential value. Is a comparator that outputs an ON signal when the differential derivative value is less than or equal to zero.
Reference numeral 30 is a comparator that outputs an ON signal when the deviation ΔP is greater than or equal to a specified value, reference numeral 31 is a differentiator that calculates the deviation differential value, and reference numeral 32 is an ON signal that is output when the differential value is zero or more. It is a comparator to output.

  Reference numerals 33 to 38 are AND circuits. Reference numeral 39 is a delay circuit that outputs the output of the AND circuit 37 with a delay of 0.5 seconds, and reference numeral 40 is a delay circuit that outputs the output of the AND circuit 38 with a delay of 0.5 seconds. Reference numeral 41 is a signal generator as a lower limit value of the PI controller of 10% at normal times, reference numeral 42 is a signal generator as a lower limit value of the PI controller of the rate change target value 70% when the movable nozzle is opened, and reference numeral 43 is A signal generator as an upper limit value of the PI controller of 100% at normal time, and a signal generator 44 is an upper limit value of the PI controller of the rate change target value 20% when the movable nozzle is closed.

Reference numeral 45 denotes a signal switch for selecting a signal from the signal generator 42 when the input signal is an on signal, and selection of the current ISPR valve opening when the input signal is an off signal, and reference numeral 46 is an input signal for the on signal. In this case, the signal selector 45 selects a signal from the signal switch 45, and selects a signal from the signal generator 41 in the case of an off signal. Reference numeral 47 denotes a signal switch for selecting a signal from the signal generator 44 when the input signal is an on signal, and selection of the current ISPR valve opening when the input signal is an off signal, and reference numeral 48 is an input signal for the on signal. In this case, the signal selector 47 selects a signal from the signal switch 47 and selects a signal from the signal generator 43 in the case of an off signal. Reference numeral 49 denotes a PI controller that performs PI control based on an ISPR valve deviation (deviation ΔP−specified value) within a range between an upper limit value and a lower limit value, and generates and outputs an ISPR valve opening command.
Here, for example, a circuit element having a switching rate as a parameter may be used as the signal switching unit 46 or the like.

  In such a circuit, when an opening operation of the movable nozzle is detected, an ON signal is output from the movable nozzle opening operation detection unit 21 to the hold unit 22, and the ON signal is output from the hold unit 22 to the AND circuit 33 for 360 seconds. Is output. Further, when the ISPR valve opening is 75% or less, the deviation ΔP is less than the specified value, and the deviation differential value is zero or less, the outputs of the comparators 23, 27, and 29 become ON signals. The outputs of the circuits 33 and 35 are ON signals, and the output of the AND circuit 37 is an ON signal. On the other hand, since the outputs of the comparators 24, 30, and 32 are OFF signals, the outputs of the AND circuits 34 and 36 are OFF signals, and the output of the AND circuit 38 is an OFF signal.

When the output of the AND circuit 37 becomes an ON signal, an ON signal is output to the signal switch 46, and an ON signal is output to the signal switch 45 after 0.5 seconds.
When the ON signal is input, the signal switch 46 selects the signal from the signal switch 45 and outputs it to the PI controller 49. Here, since the current ISPR valve opening command is selected from the signal switch 45 during the 0.5 second from the ON signal input, and the signal from the signal generator 42 is selected after 0.5 second, These signals are selected by the signal switch 46 as they are, and are output to the PI controller 49 as lower limit values. On the other hand, when the OFF signal is input from the AND circuit 38, the signal switch 48 selects the signal from the signal generator 43 and outputs it to the PI controller 49.

As a result, the current ISPR valve opening is input to the PI controller 49 as a lower limit value for the first 0.5 seconds, and then a 70% signal is input, while a 100% signal is input as the upper limit value. Is entered.
Thereby, from the PI controller 49, for example, first, the lower limit value is raised to the current ISPR valve opening degree, and the opening degree is reached to the target opening degree of 70% at a rate set based on the raised lower limit value. An ISPR valve opening command for increasing the output is output. This operation corresponds to, for example, the period from time T1 to time T2 in FIG.

Next, in a period in which the output of the hold unit 22 is maintained as an on signal, the output of the AND circuit 35 turns into an off signal when the deviation ΔP is greater than a specified value or the deviation differential value is greater than or equal to zero. Therefore, the output of the AND circuit 37 is an off signal. As a result, an off signal input signal is applied to the signal switchers 45 and 46. When the off signal is input, the signal generator 46 selects the signal from the signal generator 41 and outputs it to the PI controller 49. As a result, the PI controller 49 receives a 10% signal as the lower limit value and a 100% signal as the upper limit value.
As a result, the PI controller 49 performs a proportional integral calculation based on the ISPR valve deviation (deviation ΔP−specified value) with reference to the ISPR valve opening when the AND circuit 37 is inverted from the ON signal to the OFF signal. This result is output as an ISPR valve opening command. Note that the operation in this period corresponds to, for example, the period from time T2 to time T5 illustrated in FIG.

When the deviation ΔP is equal to or smaller than the specified value and the deviation differential value is equal to or smaller than zero during the period in which the output of the hold unit 22 is maintained as the ON signal, the output of the AND circuit 35 turns to the ON signal, and the AND circuit 37. The output becomes an ON signal again. Accordingly, as described above, from the PI controller 49, first, the lower limit value is raised to the current ISPR valve opening degree, and the target opening degree is set to 70% at a rate set based on the raised lower limit value. An ISPR valve opening command for increasing the opening is output.
When the ISPR valve opening is 75% or more, or when 360 seconds have elapsed from the start of operation of the movable nozzle, the output of the comparator 23 or the output of the hold unit 22 is inverted to the OFF signal, and the outputs of the AND circuits 33 and 37 Is inverted to the off signal. Thus, thereafter, the PI controller 49 outputs an ISPR valve opening command by proportional integral calculation with an upper limit of 100%.

  Even when the movable nozzle is closed, the same operation as described above is performed. In this case, when it is detected that the movable nozzle is closed, the ON signal is held by the hold unit 26 in 360 seconds from the time of detection. Further, when the ISPR valve is 15% or more, the deviation ΔP is the specified value or more and the deviation differential value is zero or more, the output of the AND circuit 37 is an OFF signal and the output of the AND circuit 38 is an ON signal. Accordingly, 10% is selected by the signal switching unit 46 and input to the PI controller 49 as the lower limit value.

  On the other hand, in the signal switch 48, the signal from the signal switch 47 is selected and output to the PI controller 49 as an upper limit value. The signal switch 47 selects the ISPR valve opening for the first 0.5 seconds, and then selects the signal from the signal generator 44. As a result, the current ISPR valve opening degree is input to the PI controller 49 in the first 0.5 seconds, and thereafter, 20% is input as the upper limit value.

As a result, the upper limit value is lowered from the PI controller 49 to the current ISPR valve opening degree, and the ISPR valve opening degree is lowered to a target opening degree of 20% at a rate set based on the upper limit value. A command is output. Thereafter, when the deviation ΔP is equal to or less than the specified value or the deviation differential value is equal to or less than zero, the output of the AND circuit 36 is inverted to the OFF signal, and as a result, the output of the AND circuit 38 is also inverted to the OFF signal. As a result, the signal from the signal generator 43 is selected by the selection switch 48, and 100% is input to the PI controller 49 as the upper limit value. As for the lower limit, 10% is input as described above.
As a result, the PI controller 49 performs a proportional integral calculation based on the ISPR valve deviation (deviation ΔP−specified value), and outputs the result as an ISPR valve opening command.

Next, FIGS. 5 to 8 show changes in the state quantities when the ISPR valve of the once-through exhaust heat boiler shown in FIG. 1 is controlled by the control device shown in FIG.
FIGS. 5 and 6 show the transition of the change in each state quantity when the movable nozzle is controlled from the closed state to the open state, and FIGS. 7 and 8 show the transition of each state quantity when the movable nozzle is controlled from the open state to the closed state. Is.
As shown in FIG. 5, it can be seen that when the movable nozzle is operated from the closed state to the open state, the lower limit of the ISPR valve is instantaneously raised to the current ISPR valve opening command value. Further, as shown in FIG. 7, when the movable nozzle is operated from the open state to the closed state, the upper limit of the ISPR valve is instantaneously reduced to the current ISPR valve opening command value.
By this operation, it is possible not only to open and close the rate without any control delay, but also to be able to cope with a change in state due to boiler seasoning or the like. In addition, by alternately selecting the first control unit and the second control unit, controllability that cannot be obtained only by opening the specified rate or proportional integral calculation (during the change of the external environment with a large deviation ΔP, Is controlled as specified). This way of giving the control operation amount can be realized by monitoring the deviation of the controlled object and combining the rate opening / closing operation and the proportional integration operation.

  As described above, according to the control apparatus according to the present embodiment, in the once-through exhaust heat boiler, the movable nozzle 82 is activated by changing the boiler load, and the open state is closed, or the closed state is By changing to the open state, even if the pressure of the boiler feed pump outlet pressure 80 suddenly drops or rises, the opening of the ISPR valve 72 provided in the spray water pipe 70 is quickly adjusted according to this change. Therefore, the pressure of the spray water pipe 70 can be made to quickly follow the change in the pressure 80 at the outlet of the boiler feed pump.

In the above-described embodiment, processing by hardware is assumed as the control device, but it is not necessary to be limited to such a configuration. For example, a configuration in which processing is performed separately by software is possible. In this case, the control device includes a main storage device such as a CPU and a RAM, and a computer-readable recording medium on which a program for realizing all or part of the above processing is recorded. Then, the CPU reads out the program recorded in the storage medium and executes information processing / calculation processing, thereby realizing processing similar to that of the control device described above.
Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

Hereinafter, the software process of the control process will be described with reference to FIG.
FIG. 9 is a flowchart showing a processing procedure related to software processing executed by the control device according to the embodiment of the present invention.
In step SA1, when the start of operation of the movable nozzle is detected, the process proceeds to step SA2 to determine whether or not the movable nozzle is in a closing operation. As a result, when it is a closing operation, the process proceeds to step SA3. In step SA3, the closing operation rate change condition, for example, “the deviation ΔP between the pressure of the main pipe system and the pressure of the spray water pipe is a specified value or more, the deviation differential value is zero or more, and the ISPR valve opening is 15%. It is determined whether or not the above condition is satisfied.

  As a result, when it is determined that the condition for changing the closing operation rate is satisfied, the process proceeds to step SA4, and the ISPR valve opening is changed from the current valve opening to the target opening (for example, 20%) at a specified rate. After implementing the 1st control mode to reduce, it transfers to step SA6. On the other hand, if it is determined in step SA3 that the closing operation rate change condition is not satisfied, the process proceeds to step SA5, and the manipulated variable is calculated by proportional integral calculation based on the ISPR valve deviation (deviation ΔP−specified value). Then, after executing the second control mode in which the operation amount subtracted from the current ISPR valve opening is output as the ISPR valve opening command, the process proceeds to step SA6. In step SA6, it is determined whether or not it is within a predetermined period (eg, 360 seconds) from the start of operation of the movable nozzle. If the predetermined period has not elapsed, the process returns to step SA2 to repeat the above processing. On the other hand, if the predetermined period has elapsed in step SA6, the present process is terminated.

On the other hand, if it is determined in step SA2 that it is not a closing operation, that is, if it is an opening operation, the process proceeds to step SA7. In step SA7, the opening operation rate change condition, for example, “the deviation ΔP between the pressure of the main pipe system and the pressure of the spray water pipe is not more than a specified value, the deviation differential value is not more than zero, and the ISPR valve opening degree is 75%. It is determined whether or not the following condition is satisfied. As a result, when it is determined that the opening operation rate changing condition is satisfied, the process proceeds to step SA8, and the ISPR valve opening is changed from the current valve opening to the target opening (for example, 70%) at a specified rate. The first control mode to be increased is performed, and the process proceeds to step SA6. On the other hand, if it is determined in step SA7 that the above opening operation rate change condition is not satisfied, the process proceeds to step SA9, where the manipulated variable is calculated by proportional-integral calculation based on the ISPR valve deviation (deviation ΔP−specified value). Then, the second control mode in which the operation amount added to the current ISPR valve opening is output as the ISPR valve opening command is executed, and the process proceeds to step SA6. Then, in step SA6, the processes after step SA2 are repeatedly performed until a predetermined period (for example, 360 seconds) elapses from the start of operation of the movable nozzle.
In the period when the movable nozzle operation is not detected in step SA1, the process is terminated without performing this process, and control in the normal mode (for example, generally used control technique, specifically PI control) is performed. Etc.) will be implemented.

  By performing the above-described processing, the same control as that of the control device shown in FIG. 2 or 4 can be realized by processing by software. Moreover, the said process is an example and a process procedure etc. are not restrict | limited to the said content.

In the above embodiment, the case where the control device of the present invention is applied to a once-through exhaust heat boiler has been described. However, in the present invention, the control target or the control environment of the control target is largely changed by a predetermined disturbance means. It is possible to apply to cases. For example, examples of the disturbance means include pump start / stop, fan start / stop, and motor-operated valve opening / closing.
Hereinafter, a part of the application examples will be described. Note that the present invention is not limited to the following application examples.

  FIG. 10 shows a schematic configuration of a fuel supply system that supplies fuel to a furnace in a thermal power plant. In FIG. 10, reference numeral 100 denotes a fuel tank, and a fuel pipe 102 for supplying fuel from the fuel tank 100 to the boiler is provided. In this fuel pipe 102, a plurality of eruption pumps 103a, 103b, 103c are provided in parallel. Further, a pressure regulating valve 104 for keeping the pump outlet pressure PX constant is provided on the boiler side of the fuel injection pumps 103a, 103b, 103c. In such a fuel supply system, the number of activated eruption pumps 103a, 103b, 103c is increased or decreased according to the load on the boiler, but when the eruption pump is activated or the activated eruption pump is changed. When stopping, the pump outlet pressure PX varies. Therefore, the control method of the present invention can be applied to the opening degree control of the pressure regulating valve 104 at the time of starting and stopping of the fuel injection pump.

That is, in the fuel supply system shown in FIG. 10, the pump outlet pressure PX corresponds to the control target of the present invention, and the pressure control valve 104 corresponds to the adjusting means of the present invention. Moreover, starting and stopping of the eruption pumps 103a to 103c correspond to the predetermined disturbance of the present invention.
In addition, the said fuel is not specifically limited, As an example, heavy oil, gas, etc. are mentioned.

  FIG. 11 shows a schematic configuration of a wind flue system for supplying air to a boiler in a thermal power plant. In FIG. 11, reference numeral 105 denotes a furnace, reference numeral 106 denotes a forced air blower (hereinafter referred to as “FDF”) for sending air into the furnace 105, and reference numeral 107 denotes exhaust gas discharged from the furnace to cause furnace pressure Is an induction ventilator (hereinafter referred to as “IDF”) for maintaining a negative pressure. A common air heater 108 is provided in the air duct connecting the FDF 106 and the furnace 105 and the exhaust gas duct connecting the furnace 105 and the IDF 107. Furthermore, a denitration device 109 and the like are provided on the furnace side of the air heater 108 in the exhaust gas duct connecting the furnace 105 and the IDF 107.

  In such a wind flue system, the pressure of the furnace 105 is controlled to a constant value (−10 to −20 mmAq). The pressure adjustment of the furnace 105 is performed by adjusting the pitch of the moving blade 111 provided on the input side of the IDF 107. Is done by controlling. On the other hand, the moving blade 110 provided on the output side of the FDF 106 controls the air flow rate. These controls are conventionally performed by, for example, PI control.

  However, when the IDF 107 and the FDF 106 are started up, the pressure of the furnace greatly fluctuates. Therefore, if PI control is performed in the same manner as in normal times, it is difficult to quickly follow the pressure fluctuation. . Therefore, the control method of the present invention can be applied to the pitch control of the moving blades 110 and 111 when the IDF 107 and the FDF 106 are activated.

  That is, in the wind flue system shown in FIG. 11, the pressure of the furnace 105 corresponds to the control object of the present invention, and the moving blade 111 corresponds to the adjusting means of the present invention. Further, activation and deactivation of the FDF 106 or IDF 107 corresponds to a predetermined disturbance according to the present invention.

FIG. 12 shows a schematic configuration of an auxiliary steam system in a thermal power plant.
In FIG. 12, reference numeral 120 denotes a high-pressure auxiliary steam header, and steam is sent from each part of the thermal power plant. A steam pipe for sending steam to the high-pressure auxiliary steam header 120 is provided with a plurality of pressure control valves 121 and 122 for controlling the steam pressure of the boiler. Furthermore, the steam piping is provided with a plurality of motor-operated valves 123 to 125 that are opened and closed according to the supply and consumption state of steam.

In addition, when the electric valves 123 to 125 are opened and closed, the pressure of the steam pipe may fluctuate greatly. In such a case, the control method of the present invention is applied to the control of the pressure control valves 121 and 122. can do.
That is, in the auxiliary steam supply system shown in FIG. 12, the pressure of the steam pipe corresponds to the control object of the present invention, and the pressure control valves 121 and 122 correspond to the adjusting means of the present invention. Moreover, opening and closing the motor operated valves 123 to 125 provided in the steam pipe corresponds to the predetermined disturbance of the present invention.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

It is a figure showing a schematic structure of a general once-through type exhaust heat boiler. It is a block diagram which shows schematic structure of the control apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating operation | movement of the control apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows an example of the internal circuit of the control apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the effect of the control apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the effect of the control apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the effect of the control apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the effect of the control apparatus which concerns on one Embodiment of this invention. It is the flowchart which showed the process sequence in the case of implement | achieving the process implement | achieved by the control apparatus which concerns on one Embodiment of this invention by software. It is the figure which showed the other example of application of the control apparatus which concerns on one Embodiment of this invention. It is the figure which showed the other example of application of the control apparatus which concerns on one Embodiment of this invention. It is the figure which showed the other example of application of the control apparatus which concerns on one Embodiment of this invention. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st control part 2 2nd control part 3 Disturbance detection part 4 Selection part 5 Determination part 6 Hold part 7 Deviation comparison part 8 Deviation differential value comparison part 9 Signal switching part 10 Rate change target value 11 Latch part 70 Spray water Piping 72 ISPR valve 82 Movable nozzle

Claims (9)

A control device for controlling the control object by controlling an operation amount of an adjusting unit that affects the control object,
First control means for changing an operation amount of the adjusting means at a predetermined rate;
Second control means for changing an operation amount of the adjusting means based on a deviation;
Detecting means for detecting the occurrence of a predetermined disturbance that causes fluctuations in the controlled object or its control environment;
In a predetermined period after the occurrence of the disturbance is detected, based on a comparison result between a deviation between an actual measurement value of the control target and a target value and a preset first specified value, Selection means for alternately selecting the second control means;
With
The control device in which the predetermined period is set to be substantially equal to or longer than a period until the influence of the control target due to the occurrence of the disturbance is eliminated .   The selection means is configured such that when the deviation between the measured value and the target value of the control target is equal to or less than the first specified value and the differential value of the deviation is equal to or less than a second specified value set in advance, 2. The control according to claim 1, wherein a control unit is selected, and the second control unit is selected when the deviation is larger than the first specified value or the differential value of the deviation is larger than the second specified value. apparatus.   The selection means is configured such that when the deviation between the actually measured value and the target value of the control target is equal to or greater than the first specified value and the differential value of the deviation is equal to or greater than a second predetermined value set in advance, 2. The control device according to claim 1, wherein a control unit is selected, and the second control unit is selected when the deviation is less than the first specified value or the differential value of the deviation is less than the second specified value. . The predetermined rate of the first control means is the operation amount of the adjusting means corresponding to the target value of the control target set before the occurrence of the disturbance and the control set after the disturbance has occurred. The control device according to any one of claims 1 to 3 , wherein the control device is set to be equal to or greater than a value obtained by dividing a difference from an operation amount of the adjusting unit corresponding to a target value of an object by the predetermined period. A control method for indirectly controlling the control object by controlling an operation amount of an adjusting unit that affects the control object,
Wherein an operation amount of the first control mode and said adjusting means for the operating amount change at a predetermined rate adjustment means may be set and a second control mode for changing on the basis of the deviation in advance,
When a predetermined disturbance giving fluctuation to the control object or the control environment is detected, in a predetermined period after the disturbance has been detected, a preset and deviation from the target value of the controlled object Based on the comparison result with the first specified value, alternately select the first control mode and the second control mode,
A control method in which the predetermined period is set to be approximately equal to or longer than a period until the influence of the control target due to the occurrence of the disturbance is eliminated . A control program for indirectly controlling the control object by controlling the operation amount of the adjusting means that affects the control object,
A first control process for changing the operation amount of the adjustment means at a predetermined rate, may be stored in the storage means and a second control process vary based on the deviation of the operation amount of the adjustment means,
When a predetermined disturbance giving fluctuation to the control object or the control environment is detected, in a predetermined period after the disturbance has been detected, a preset and deviation from the target value of the controlled object Based on the comparison result with the first specified value, the computer executes a process of alternately selecting the first control process and the second control process,
A control program in which the predetermined period is set to be substantially equal to or longer than a period until the influence of the control target due to the occurrence of the disturbance is eliminated . A main pipe system in which at least an evaporator and a superheater are arranged;
Spray water piping for supplying spray water to the main pipe system;
An adjusting means provided in the spray water pipe for adjusting the pressure of the spray water pipe;
Control means for controlling the pressure of the spray water pipe by controlling the operation amount of the adjusting means,
The control means includes
First control means for changing an operation amount of the adjusting means at a predetermined rate;
And second control means for changing based on the operation amount of the adjustment means in deviation,
Detecting means for detecting the occurrence of a predetermined disturbance that varies the pressure of the spray water pipe or its control environment;
Based on a comparison result between a deviation between the pressure of the spray water pipe and the target value and a preset first specified value in a predetermined period after the occurrence of the disturbance is detected , Selection means for alternately selecting the second control means;
With
The exhaust heat boiler in which the predetermined period is set to be approximately equal to or longer than a period until the influence of the control target due to the occurrence of the disturbance is eliminated . The disturbance is a disturbance generated by opening and closing a movable nozzle provided between the main pipe system and a water supply pump for supplying water to the main pipe system according to a boiler load,
In the case where the movable nozzle is in an opening operation, the selection unit is configured to switch the first control unit when a deviation between the pressure of the spray water pipe and the pressure of the main pipe system is equal to or less than the first specified value. selected, the deviation to select the second control means is greater than said first predetermined value, said in the movable nozzle closing operation, wherein when the deviation is equal to or greater than the first predetermined value a The exhaust heat boiler according to claim 7 , wherein one control means is selected, and the second control means is selected when the deviation is less than the first specified value. The disturbance is a disturbance generated by opening and closing a movable nozzle provided between the main pipe system and a water supply pump for supplying water to the main pipe system according to a boiler load,
When the movable nozzle is in the opening operation, the selection means has a deviation between the pressure of the spray water pipe and the pressure of the main pipe system equal to or less than the first specified value, and a differential value of the deviation is zero. It selects the first control means when the following deviation is greater than said first predetermined value, or selects the second control means when the differential value of the deviation is greater than zero,
When the movable nozzle is closing operation, the deviation is the first predetermined value or more, and the differential value of the deviation to select the first control means when the above zero, the deviation is the first The exhaust heat boiler according to claim 7, wherein the second control means is selected when the deviation value is less than 1 specified value or the differential value of the deviation is less than zero.

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