Control method and system

Abstract

To provide a control method and a system capable of controlling a controlled object value with good followability to a target value.SOLUTION: Defining a control factor, which is a value that can be manipulated in controlling the controlled object value, and a variable factor, which is a value other than the control factor that can have the greatest influence on the controlled object value, the controlled object value is controlled by controlling the control factor according to the variable factor. In controlling the control factor, an influence factor, which is a value that can affect at least one of the controlled object value and the control factor, can be added. The control factor can be defined as a function of the variable factor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for controlling a certain controlled value so that it coincides with or approaches a target value, and a system for executing the same. [Background technology]

[0002] For example, in a sludge treatment facility, a feeder for temporarily storing dehydrated cake to be fed to the incinerator is provided between a storage tank for storing dehydrated cake and an incinerator for incinerating the dehydrated cake, and the dehydrated cake is supplied from the storage tank to the supply port of the feeder by a first pump, and the dehydrated cake is discharged from the discharge port of the feeder by a second pump and fed into the incinerator.

[0003] In the feeder, the amount of dehydrated cake stored must be kept approximately constant so that the stored dehydrated cake does not exceed the allowable amount and overflow, or the feeder does not become empty and interfere with the operation of the second pump. In other words, the amount of dehydrated cake stored in the feeder must be set as a control target value, and it must be controlled so that it coincides with a target value or does not deviate significantly from the target value.

[0004] Incidentally, examples of prior art documents that describe technology relating to control of the supply amount of stored material in such facilities include Patent Document 1 listed below. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2-249812 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned facilities, in order to keep the amount of dehydrated cake, which is the controlled value, close to the target value, a common method is to monitor the amount of the stored material in the feeder and adjust the operation of the first pump accordingly. If the amount of stored material is less than the target value or is decreasing, the rotation speed of the first pump is increased to increase the amount of stored material supplied per hour, and if the amount of stored material is more than the target value or is increasing, the rotation speed is decreased to decrease the amount supplied.

[0007] However, this method has a problem that the control of the storage amount through the supply amount is poor in response to the storage amount of the storage material in the feeder. For example, when the discharge amount of the second pump is increased significantly in a short time, the rotation speed of the first pump is increased after a decrease in the storage amount in the feeder is measured, and as a result, when the storage amount in the feeder increases beyond the target value, the rotation speed of the first pump is decreased, and when the storage amount falls below the target value again, the rotation speed of the first pump is increased again. By repeating this control, the storage amount gradually converges to the target value while fluctuating up and down. In other words, the tracking ability of the control target value to the target value is poor, and it becomes temporarily unstable due to fluctuations in the factor (discharge amount) that affects the control target value.

[0008] In view of the above circumstances, the present invention provides a control method and system capable of controlling a control object value with good tracking ability to a target value. [Means for solving the problem]

[0009] The present invention provides a control method for controlling a control object value by defining a control factor, which is a value that can be manipulated to control the control object value, and a fluctuation factor, which is a value other than the control factor that has the greatest effect on the control object value, and controlling the control factor in response to the fluctuation factor, This applies to equipment equipped with a storage section for storing a substance, The amount of the stored matter in the storage unit is set as the control target value, The control factor is the supply amount of the stored material to the storage section or a value related thereto; The discharge amount of the stored matter from the storage portion or a value related thereto is treated as the fluctuation factor; The control factor is defined as a function of the fluctuation factor, and a correction value C according to the operation status of the equipment is added to the function, The correction value is based on C=1, When the control target value is smaller than the target value, when the control target value is on a decreasing trend, the control factor is From the designed supply amount of the stored material to the storage section or a value related thereto If there are few 、 The correction value is set at a value C>1 under at least one of the following conditions: When the control target value is greater than the target value, when the control target value is on the increase, the control factor is From the designed supply amount of the stored material to the storage section or a value related thereto In many cases 、 The present invention relates to a control method, characterized in that the correction value is set to a value C<1 under at least one of the conditions above.

[0010] The present invention provides a control method for controlling a control object value by defining a control factor, which is a value that can be manipulated to control the control object value, and a fluctuation factor, which is a value other than the control factor that has the greatest effect on the control object value, and controlling the control factor in response to the fluctuation factor, This applies to equipment equipped with a flow rate regulator that adjusts the flow rate of the target object. An actual measurement value of a flow rate of the object discharged from the flow rate adjustment unit is set as the control target value, A value related to a flow rate of an object that can be manipulated by the flow rate adjusting unit is set as the control factor; A target value of the flow rate of the object discharged from the flow rate adjustment unit is treated as the fluctuation factor; The control factor is defined as a function of the fluctuation factor, and a correction value C according to the operation status of the equipment is added to the function, The correction value is based on C=1, When the control target value is smaller than the target value, when the control target value is on a decreasing trend, the control factor is From the design flow rate of the object that can be operated in the flow rate adjustment unit or a value related thereto, If there are few 、The correction value is set at a value C>1 under at least one of the following conditions: When the control target value is greater than the target value, when the control target value is on the increase, the control factor is From the design flow rate of the object that can be operated in the flow rate adjustment unit or a value related thereto, In many cases 、 The present invention relates to a control method, characterized in that the correction value is set to a value C<1 under at least one of the conditions above.

[0011] In the control method of the present invention, when controlling the control factor, an influencing factor which is a value that can affect at least one of the control target value and the control factor can be taken into consideration.

[0013] In the control method of the present invention, the correction value can be calculated using at least one of the control object value and an influencing factor, which is a value that can affect at least one of the control object value and the control factor, as a variable.

[0016] The present invention also relates to a control system configured to be able to execute the above-mentioned control method. Effect of the Invention

[0017] According to the control method and system of the present invention, it is possible to obtain the excellent effect of controlling a control object value with good tracking ability with respect to a target value. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing an example (first embodiment) of the configuration of a control system according to an embodiment of the present invention. [Diagram 2] 11 is a graph showing an example of a relationship between a control factor and a fluctuation factor, and explaining correction of a proportionality coefficient. [Diagram 3] 11 is a graph showing an example of fluctuations in supply amount and storage amount relative to fluctuations in discharge amount assumed when control according to the present invention is performed. [Figure 4]11 is a graph showing an example of fluctuations in supply amount and storage amount with respect to fluctuations in discharge amount assumed when control is performed by a conventional method, as a reference example of the present invention. [Diagram 5] 11 is a graph showing the variation in supply amount and storage amount with respect to the variation in discharge amount observed when control according to the present invention is implemented. [Figure 6] 1 is a flowchart illustrating an example of a procedure of a control method according to an embodiment of the present invention. [Figure 7] FIG. 4 is a schematic diagram showing another example (second embodiment) of the configuration of a control system according to the present invention. [Figure 8] FIG. 11 is a schematic diagram showing yet another example (third embodiment) of the configuration of a control system according to the present invention. [Figure 9] 4 is a graph illustrating an example of the relationship between the opening degree of a regulator valve and a flow rate. [Figure 10] 4 is a graph illustrating an example of the relationship between the opening degree of a regulator valve and a flow rate. [Figure 11] 13 is a graph illustrating an example of a relationship between a control factor and a fluctuation factor and correction of a coefficient in the third embodiment. [Figure 12] 13 is a graph illustrating another example of the relationship of the control factor to the fluctuation factor and correction of the coefficient in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0020] FIG. 1 shows an example (first embodiment) of the configuration of a system capable of implementing the control method of the present invention, and assumes the case where the present invention is applied to a sludge treatment facility. The material (dehydrated cake D) stored in a storage tank 1 is transferred to a feeder 2 serving as a storage section for temporarily storing the material D, and then fed into an incinerator 3. A first pump 4 and a second pump 5 are provided between the storage tank 1 and the feeder 2, and between the feeder 2 and the incinerator 3, respectively, and the dehydrated cake D is supplied from the storage tank 1 to the feeder 2 by the first pump 4, and is discharged from the feeder 2 by the second pump 5 and fed into the incinerator 3. The first pump 4 is, for example, a screw pump, and the second pump 5 is, for example, a single-shaft eccentric pump.

[0021] The operation of the first pump 4, the second pump 5, and the incinerator 3 is controlled by a control unit 6. The control unit 6 is a device that monitors and controls the operation of each part of the facility, and controls the on / off and rotation speed of the first and second pumps 4, 5 by inputting operation signals to the motors 4a, 5a of the first and second pumps 4, 5. In addition, signals indicating the rotation speed are input to the control unit 6 from the motors 4a, 5a at any time.

[0022] The feeder 2 is provided with a level meter 7 as a controlled object measuring part for measuring the amount of the dehydrated cake D stored therein. The controlled object measuring part (level meter) 7 is, for example, an ultrasonic distance sensor. The measured amount of the dehydrated cake D is inputted to the control part 6 as a measurement signal from the level meter 7. In addition, as the controlled object measuring part or level meter for measuring the amount of the stored material as a controlled object value in the equipment such as the first embodiment, any device may be adopted as long as it is a device capable of measuring the amount of the stored material. The level meter may be, for example, a laser type in addition to an ultrasonic type. In addition, in the case of a level meter, the amount of the stored material is measured as a height, but a device other than a level meter may be used as the controlled object measuring part, and the amount of the stored material may be measured as a weight or a volume, for example.

[0023] The storage tank 1 is provided with a moisture content meter 8 as a property measuring unit for measuring the property of the dehydrated cake D supplied from the first pump 4 to the feeder 2. The connection between the storage tank 1 and the first pump 4 is provided with a load cell 9 as a weight measuring unit for measuring the weight of the dehydrated cake D in the storage tank 1 to be applied to the inlet of the first pump 4. The measured values ​​of the moisture content meter 8 and the load cell 9 are input to the control unit 6 as measurement signals. These values ​​are used as values ​​(influencing factors) that may affect the storage amount and supply amount of the dehydrated cake D, and are used to control the supply amount of the dehydrated cake D, which will be described later. As the property measuring unit and the weight measuring unit, various devices other than the moisture content meter and the load cell may be used as long as the property and weight of the dehydrated cake D can be appropriately measured. For example, a viscometer may be used instead of the moisture content meter to measure the viscosity as a property of the dehydrated cake D.

[0024] Here, for convenience of explanation, in this first embodiment, the rotation speed of the first pump 4 is treated as a "control factor" and the rotation speed of the second pump 5 is treated as a "variation factor". The control factor refers to a value that can be manipulated when controlling the control target value (in this first embodiment, the amount of dehydrated cake D stored in the feeder 2), and in this first embodiment, it is the supply amount of dehydrated cake D in the first pump 4 or a value related thereto (for example, the rotation speed of the first pump 4, or the rotation speed and output of the motor 4a). The variation factor refers to a value other than the control factor that can have the greatest effect on the control target value, and in this first embodiment, it is the discharge amount of dehydrated cake D in the second pump 5 or a value related thereto (for example, the rotation speed of the second pump 5, or the rotation speed and output of the motor 5a. Alternatively, a flow meter (not shown) may be provided on the path of the dehydrated cake D from the second pump 5 to the incinerator 3, and the measured value thereof may be used). The greatest feature of the present invention is, as will be described below, that in keeping the control object value (the amount of stored material (dehydrated cake) D in the storage section (feeder) 2) close to the target value, the control factor (the rotational speed of the first pump 4) is controlled in accordance with the fluctuation factor (the discharge amount of the stored material D in the second pump 5), and that in keeping the control object value close to the target value, the control factor is defined as a function of the fluctuation factor. In other words, the control factor is directly correlated with the fluctuation factor rather than being fed back to the control object value, and the largest factor to be considered in determining the control factor is the fluctuation factor rather than the control object value.

[0025] Of course, the variables of the function defining the control factor may incorporate the controlled object value in addition to the fluctuation factor, or may incorporate various other values ​​(referred to as "influencing factors") that may affect the controlled object value or the control factor. In the case of this first embodiment, the properties of the dehydrated cake D, which is the stored matter (values ​​measured by the property measuring unit (moisture content meter 8)) and the weight of the dehydrated cake D at the inlet of the first pump 4 (values ​​measured by the weight measuring unit (load cell 9)) are treated as influencing factors, and by taking these influencing factors into account when calculating the control factor, the control factor is corrected to a more appropriate value according to the operating situation, and the controlled object value is controlled with high precision.

[0026] A specific control method will be described. In the case of a sludge treatment facility as described above, in order to maintain the amount of dehydrated cake D stored in feeder 2, which is the controlled value, at a constant value, the supply amount of dehydrated cake D by first pump 4 may be controlled to be equal to the discharge amount by second pump 5. Therefore, the control factor (the rotation speed of first pump 4), which is a value related to the supply amount of dehydrated cake D, is defined as a function of a fluctuation factor (the rotation speed of second pump 5), which is a value related to the discharge amount. In the case of the example shown here, it is sufficient to define this function as a simple linear proportional equation as follows, and the control factor can be easily calculated according to the value of the fluctuation factor using such a calculation equation. (Control factor) = A × C × (Variation factor) … Equation (1)

[0027] In the above formula, A is a preset coefficient, and can be determined as a design value such that the supply amount of dehydrated cake D by the first pump 4 and the discharge amount of dehydrated cake D by the second pump 5 are equal, taking into consideration, for example, the design relationship between the rotation speed and the conveyance amount in the first pump 4 and the design relationship between the rotation speed and the conveyance amount in the second pump 5. In other words, in terms of design, if the first pump 4 is operated with the proportionality coefficient of the control factor for the fluctuation factor set to A, the supply amount and discharge amount to the feeder 2 are balanced, and the storage amount of dehydrated cake D can be kept constant.

[0028] However, depending on the actual operating conditions, there may be cases where the two do not match even if the fluctuation factor and the control factor are simply made proportional by a fixed coefficient. For example, if the first pump 4 is a screw pump and the second pump 5 is a single-shaft eccentric pump, the second pump 5, which is a single-shaft eccentric pump, can transport the amount of dehydrated cake D that is approximately proportional to the rotation speed, but the first pump 4, which is a screw pump, may have a possibility that the transport amount of dehydrated cake D per rotation speed varies depending on the amount and properties of the dehydrated cake D stored in the storage tank 1. For example, when a large amount of dehydrated cake D is stored in the storage tank 1, a large amount of dehydrated cake D is pushed into the first pump 4 by its own weight, so that the transport amount is larger even if the rotation speed is the same, and the supply amount to the storage section (feeder 2) is larger than when the storage amount in the storage tank 1 is small. Also, if the dehydrated cake D is hard, it is difficult to cut out by the first pump 4, so the transport amount is smaller, and if the dehydrated cake D is soft, the transport amount is larger.

[0029] Therefore, in the case of this first embodiment, a variable C is set on the right side of the above formula as a correction value that is taken into account depending on the operating conditions of the equipment, and this allows control to be performed that is suited to the operating conditions at each time. This correction value C is calculated using an appropriate control method such as fuzzy control, PID control, or logic control, with influencing factors (measurements from the property measuring unit (moisture content meter 8) and weight measuring unit (load cell 9)) as variables (note that the calculation method for the correction value C is not limited to these, and other control methods and calculation methods may also be used as appropriate).

[0030] In addition to these influencing factors, the control object value (the amount of dehydrated cake D stored in the feeder 2) may also be used as a variable in calculating the correction value C. For example, the accuracy of control of the control object value can be further improved by controlling the correction value C to be larger when the control object value is smaller than the target value or is on a downward trend, and to be smaller when the control object value is large or is on an upward trend.

[0031] In addition, only one of the influencing factors or the controlled value may be used to calculate the correction value C. Also, only some of the examples given here may be used as the influencing factors, or other values ​​may be used as appropriate instead of or in addition to them. For example, other sensors (not shown) may be provided, and their measured values ​​may be used as the influencing factors.

[0032] In this way, by defining the control factor as an appropriate function in advance, the control factor can be appropriately calculated by simple calculation processing when control is executed.

[0033] Fig. 2 shows an example of a proportional relationship when the control factor is controlled as a proportional value to the fluctuation factor as described above. When C=1, control is performed according to the relationship shown by the solid line in the figure (proportionality coefficient=A). When the amount of dehydrated cake D stored in the feeder 2 (control target value) is less than the target value, when the amount of storage is on a decreasing trend, when the dehydrated cake D is hard and the amount of conveyance by the first pump 4 is small, when the weight added to the first pump 4 by the dehydrated cake D in the storage tank 1 is small and the amount of conveyance by the first pump 4 is small, etc., the correction value C is set to a value greater than 1 (see the dashed line in the figure). On the other hand, when the amount of dehydrated cake D stored in the feeder 2 is greater than the target value, when the amount is increasing, when the dehydrated cake D is soft and the amount of the dehydrated cake D transported by the first pump 4 is large, or when the weight of the dehydrated cake D in the storage tank 1 added to the first pump 4 is large and the amount of the dehydrated cake D transported by the first pump 4 is large, the correction value C is set to a value smaller than 1 (see the dashed line in the figure). Note that the specific correction value C is appropriately determined by fuzzy control or the like as described above. Also, the correction value C may be appropriately set to an upper limit value and a lower limit value, or the upper limit value and the lower limit value may be made variable.

[0034] In this way, when the fluctuation factor is set as a value related to the discharge amount and the control factor is set as a value related to the supply amount, and the control factor is changed according to the fluctuation factor, the storage amount, which is the controlled value, can be controlled with good tracking to the fluctuation of the discharge amount, as shown in FIG. 1 ~t2 At time t 3 ~t 4 In the case where the discharge amount fluctuates in this way, by changing the supply amount in accordance with the fluctuation in the discharge amount as described above (see the middle part), it is possible to precisely keep the controlled value (storage amount) close to the target value even if the discharge amount fluctuates (see the bottom part).

[0035] In contrast, in the conventional control in which the supply amount is changed according to the storage amount, the storage amount has a low ability to follow the fluctuation of the discharge amount. An example of the fluctuation of the supply amount and the storage amount that is assumed in such a case is shown as a reference example in FIG. 4. In this reference example, 1 ~t 2 When the discharge rate (top row) increases, the storage rate (bottom row) decreases first, and in response, the supply rate (middle row) is increased. As a result, the storage rate increases beyond the target value, and the supply rate is then decreased. By repeating this process, the storage rate fluctuates up and down, gradually approaching the target value. 3 ~t 4 Similarly, when the discharge rate is decreased, the storage amount fluctuates significantly before converging to the target value. In this way, with the conventional control method, it takes time for the storage amount to stabilize in response to fluctuations in the discharge rate.

[0036] FIG. 5 shows the results of actual measurements of the supply amount and the storage amount with respect to the discharge amount in the first embodiment. In this actual operation, the second pump 5 is driven at a time t 0 After the operation is turned on at time t 5 The discharge rate is increased rapidly from time t 6 ~t 7 After that, the discharge rate gradually increases (see the upper dashed line).

[0037] The supply amount of the first pump 4 quickly follows such a fluctuation in the discharge amount, and while it fluctuates, it generally fluctuates in balance with the discharge amount (see the solid line in the upper part). 0 After that, it is maintained close to the target value (see the lower part). Unlike the reference example shown in Figure 4, which takes time to converge, it quickly follows the increase or decrease in the discharge rate.

[0038] The procedure for executing the above control method in a system can be summarized in a flowchart such as that shown in FIG.

[0039] First, a target value for the control object value (amount of dehydrated cake D stored in feeder 2) is set (step S1). Next, a coefficient A is set to be used for controlling the control factor (the rotation speed of first pump 4) against the fluctuation factor (the rotation speed of second pump 5) (step S2). An actual measurement value of the control object value (measurement value of level meter 7) is obtained (step S3), and an influencing factor (measurement value of moisture content meter 8 and load cell 9) is obtained (step S4). A correction value C is calculated based on the values ​​obtained in steps S3 and S4 (step S5).

[0040] Once the value corresponding to the fluctuation factor (the rotation speed of the second pump 5) is obtained (step S6), it is multiplied by the coefficient A and the correction value C to calculate the value corresponding to the control factor (the rotation speed of the first pump 4) (step S7). Based on this control factor, the operation of the first pump 4, which is the controlled device, is controlled (step S8). In other words, the motor 4a is controlled so that the rotation speed of the first pump 4 becomes the value calculated in step S7. Returning to step S3, the subsequent steps are repeated.

[0041] The control method described above is merely an example. For example, when calculating the control factor according to the variable factor, the function to be set is not limited to the proportional formula as described above. For example, a constant term or other variable term may be provided on the right side of the proportional formula, or a quadratic function, exponential function, or other various functions may be set. In addition, the procedure shown in FIG. 6 is also variable, and the order of steps may be changed as appropriate, some steps may be omitted, or other steps may be added.

[0042] Furthermore, the control method is not limited to the sludge treatment facility described above. The present invention can be widely applied to facilities that have a "control target value" that needs to be kept close to a target value, a "variation factor" that significantly affects the control target value, and an element that can be operated according to the variation factor and can be regarded as a "control factor" that can be used to control the control target value.

[0043] 7 shows another example (second embodiment) of the configuration of a system capable of implementing the control method of the present invention, and assumes the case in which the present invention is applied to a facility that pumps water from a water tank. Water W stored in water tank 10 is pumped out and sent to the outside by the operation of pump 11. Pump 11 is controlled to turn on and off and to rotate at a speed according to an operation signal input from control unit 12, and functions as a flow rate adjustment unit that adjusts the flow rate of the target object.

[0044] A water level gauge 13 is attached to the water tank 10 to measure the level of the water W in the water tank 10. A flow meter 14 is provided downstream of the pump 11 to measure the amount of water W discharged from the pump 11. Measurement values ​​from the water level gauge 13 and the flow meter 14 are input to the control unit 12 as measurement signals.

[0045] In the second embodiment, the discharge amount of the object (water W), i.e., the actual value of the flow rate measured by the flow meter 14, is treated as the value to be controlled. That is, the flow meter 14 corresponds to the controlled object measurement unit. Also, the fluctuation factor is the target value of the discharge amount.

[0046] The control factor is a value related to the flow rate of an object that can be operated in the flow rate adjustment unit (pump 11), and in this second embodiment, it is the rotation speed input to the pump 11 as an operation signal. That is, the rotation speed used to control the operation of the pump 11 is defined as a function with the target value of the discharge amount as a variable. In addition, the measured value of the water level gauge 13 is used as the influencing factor. In this case, as in the control in the first embodiment, it is sufficient to set a proportional formula as the function (see FIG. 2 and the above formula (1)). As the coefficient A, a value set in advance in consideration of the relationship between the designed rotation speed and discharge amount of the pump 11 can be used. Then, the water level in the water tank 10 (the measured value of the water level gauge 13) is used as the influencing factor, and a correction value C is calculated by taking into account the fluctuation factor (target value of the discharge amount) and the like as necessary. In this way, the rotation speed of the pump 11 is controlled while correcting the proportional coefficient as shown in FIG. 2.

[0047] In this type of control, for example, when the demand for water W downstream of pump 11 increases and the target value (variation factor) is suddenly set higher than the current actual value (control target value) of the discharge rate grasped as the measurement value of flowmeter 14, the rotation speed (control factor) of pump 11 is increased in response to the variation of this variation factor, so that the actual discharge rate can be varied with good tracking relative to the target value of the discharge rate. In addition, at that time, the coefficient can be corrected by taking into account the water level in water tank 10 as an influencing factor. For example, when the water level in water tank 10 is high and high water pressure is applied to the inlet of pump 11, it is considered that the amount of water W transported per rotation speed of pump 11 will be large, and such a factor can also be taken into account in the operation control of pump 11.

[0048] The control in the second embodiment can be executed in a procedure similar to that shown in Fig. 6. However, in the case of the second embodiment, since the "target value of the control object value" is the fluctuation factor, step S1 is not required.

[0049] Fig. 8 shows yet another example (third embodiment) of the configuration of a system capable of implementing the control method of the present invention. This third embodiment also assumes a facility in which water is pumped from a water tank, and much of the configuration is common to the second embodiment shown in Fig. 7, but in this third embodiment, a regulator valve 15 for regulating the flow rate is provided downstream of the pump 11, and the discharge amount of water W is controlled by the opening of this regulator valve 15. The opening of the regulator valve 15 is controlled by input of an opening signal from the control unit 12. That is, in this third embodiment, the regulator valve 15 corresponds to the flow rate adjustment unit.

[0050] Accordingly, in this third embodiment, the opening of the adjustment valve 15 is treated as the control factor. The controlled value, the fluctuation factor, and the influencing factor are, as in the second embodiment, the discharge rate of water W (measured value of flow meter 14), the target value of the discharge rate, and the water level in the water tank 10 (measured value of water level meter 13), respectively.

[0051] In this case, the control factor cannot necessarily be controlled with a simple linear proportional relationship to the fluctuation factor as shown in Figure 2 or the above formula (1). This is because there is usually no proportional relationship between the valve opening and flow rate. For example, with a globe valve, the relationship between the opening and flow rate (flow rate characteristics of a control valve) is as shown in Figure 9, and with a diaphragm valve, the flow rate characteristics are as shown in Figure 10. When using such a valve as a flow rate regulator, the control factor as a function with the fluctuation factor as a variable must be set to a function other than a proportional relationship or a linear function, as shown in Figures 11 and 12, for example (note that Figure 11 corresponds to the flow rate characteristics in Figure 9, and Figure 12 corresponds to the flow rate characteristics in Figure 10, respectively).

[0052] 11, when the fluctuation factor is x, the control factor f(x) can be expressed by, for example, the following approximate formula (quadratic function): In the following formula (2), p and q are coefficients, and r is a constant. f(x)=C×(px 2 +qx+r) …Equation (2)

[0053] 12, the control factor f(x) can be expressed by, for example, the following approximate formula (quartic function): In the following formula (3), p, q, r, and s are coefficients, and t is a constant. f(x)=C×(px 4 +qx 3 +rx 2 +sx+t) …Formula (3)

[0054] In either case, by varying the correction value C, the coefficient is adjusted as shown by the dashed or dashed lines in Figures 11 and 12, thereby making it possible to make the control factor (the rotation speed of pump 11) follow the fluctuation factor (the target value of the discharge volume) and quickly bring the controlled value (the actual measured value of the discharge volume) closer to the target value.

[0055] In the above formulas (1) to (3), the correction value C is multiplied by the entire right side of the function, but the setting of the correction value can be changed as appropriate when implementing the invention. For example, a correction value can be set only for some terms, the correction value can be used as an addition / subtraction value rather than a multiplication value, or a different correction value can be used for each term.

[0056] The control in the third embodiment can be executed in a procedure similar to that shown in FIG. 6. However, in the third embodiment, as in the second embodiment, the "target value of the controlled value" is the fluctuation factor, and step S1 is not necessary. In the third embodiment, the fluctuation factor and the control factor are not simply proportional to each other, so that it is not enough to set the value of one coefficient in step S2. For example, it may be necessary to set the function itself or to set the coefficients of multiple terms. In addition, it is also possible that, for example, a different correction value needs to be set for each of multiple terms in calculating the correction value (step S5).

[0057] As described above, in the control method of each of the above embodiments, a control factor, which is a value that can be manipulated to control a control target value, and a fluctuation factor, which is a value other than the control factor that has the greatest effect on the control target value, are defined, and the control factor is controlled according to the fluctuation factor to control the control target value. In this way, by controlling the control factor to fluctuate according to the fluctuation factor, the control target value can be controlled with good tracking ability to the fluctuation of the fluctuation factor.

[0058] In each embodiment, when controlling the control factor, an influencing factor, which is a value that can affect at least one of the control target value and the control factor, is taken into consideration. In this way, control can be performed that is suited to the driving situation at each time.

[0059] In each embodiment, the control factor is defined as a function of the fluctuation factor, so that the supply amount can be appropriately calculated by a simple calculation process.

[0060] In each embodiment, a correction value according to the operating condition of the equipment is added to the function, so that the supply amount can be calculated more appropriately by simple calculation processing.

[0061] In each embodiment, the correction value is calculated using at least one of the control target value and the control factor, which is an influencing factor that can affect at least one of the control target value and the control factor, as a variable. In this way, control suited to the driving situation at each time can be performed.

[0062] In some embodiments, the present invention is applied to equipment equipped with a storage section 2 that stores a stored material (dehydrated cake) D, and the amount of the stored material D in the storage section 2 is treated as the controlled value, the amount of the stored material supplied to the storage section 2 or a value related thereto is treated as the control factor, and the amount of the stored material D discharged from the storage section 2 or a value related thereto is treated as the fluctuation factor. In this way, the above-mentioned effects can be achieved in the equipment equipped with the storage section 2 that stores the stored material D.

[0063] In some embodiments, the present invention is applied to equipment equipped with a flow rate adjustment unit (pump 11, control valve 15) that adjusts the flow rate of the object (water) W, and the actual measured value of the flow rate of the object W discharged from the flow rate adjustment units 11, 15 is treated as the control target value, a value related to the flow rate of the object that can be manipulated in the flow rate adjustment units 11, 15 is treated as the control factor, and a target value of the flow rate of the object W discharged from the flow rate adjustment units 11, 15 is treated as the fluctuation factor. In this way, the above-mentioned operational effects can be achieved in equipment equipped with the flow rate adjustment units 11, 15 that adjust the flow rate of the object W.

[0064] Furthermore, since the control system of each embodiment is configured to be able to execute the above-mentioned control method, the above-mentioned operational effects can be achieved in the system.

[0065] Therefore, according to the above embodiment, the control object value can be controlled with good tracking ability with respect to the target value.

[0066] Incidentally, the control method and system of the present invention are not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0067] 2. Storage section 11 Flow rate regulator (pump) 15 Flow rate adjustment section (control valve) D Retention material (dehydrated cake) W Object (Water)

Claims

1. A control method for controlling a control object value by defining a control factor, which is a value that can be manipulated to control a control object value, and a fluctuation factor, which is a value other than the control factor that has the greatest effect on the control object value, and controlling the control factor in response to the fluctuation factor, comprising: This applies to equipment equipped with a storage section for storing a substance, The amount of the stored matter in the storage unit is set as the control target value, The control factor is the supply amount of the stored material to the storage section or a value related thereto; The discharge amount of the stored matter from the storage portion or a value related thereto is treated as the fluctuation factor; The control factor is defined as a function of the fluctuation factor, and a correction value C according to the operation status of the equipment is added to the function, The correction value is based on C=1, The correction value is set to a value of C>1 under at least one of the following conditions: when the control object value is smaller than the target value; when the control object value is on a decreasing trend; and when the control factor is smaller than the designed supply amount of the stored material to the storage unit or a value related thereto; A control method characterized in that the correction value is set to a value C<1 under at least one of the following conditions: when the control object value is greater than a target value, when the control object value is tending to increase, and when the control factor is greater than the designed supply amount of the stored material to the storage section or a value related thereto.

2. A control method for controlling a control object value by defining a control factor, which is a value that can be manipulated to control a control object value, and a fluctuation factor, which is a value other than the control factor that has the greatest effect on the control object value, and controlling the control factor in response to the fluctuation factor, comprising: This applies to equipment equipped with a flow rate regulator that adjusts the flow rate of the target object. An actual measurement value of a flow rate of the object discharged from the flow rate adjustment unit is set as the control target value, A value related to a flow rate of an object that can be manipulated by the flow rate adjusting unit is set as the control factor; A target value of the flow rate of the object discharged from the flow rate adjustment unit is treated as the fluctuation factor; The control factor is defined as a function of the fluctuation factor, and a correction value C according to the operation status of the equipment is added to the function, The correction value is based on C=1, The correction value is set to a value C>1 under at least one of the following conditions: when the control object value is smaller than a target value; when the control object value is on a decreasing trend; and when the control factor is smaller than a design flow rate of an object that can be operated in the flow rate adjustment unit or a value related thereto; A control method characterized in that the correction value is set to a value C<1 under at least one of the following conditions: when the control object value is greater than a target value, when the control object value is on an increasing trend, and when the control factor is greater than the design flow rate of the object that can be operated in the flow adjustment unit or a value related thereto.

3. When controlling the control factor, an influencing factor that is a value that can affect at least one of the control target value and the control factor is taken into consideration.

3. The control method according to claim 1 or 2,

4. The correction value is calculated using at least one of the control target value and the control factor as a variable, or an influencing factor that is a value that can affect at least one of the control target value and the control factor.

3. The control method according to claim 1 or 2,

5. A control system configured to be able to execute the control method according to any one of claims 1 to 4.

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