JPS60163101A - Process controller - Google Patents

Abstract

PURPOSE:To decrease the energy loss and to improve the control efficiency by adding a mutual control function between two PID operations. CONSTITUTION:A deviation (e) is obtained from a room temperature PV and a setting temperature SP, and when the (e) is positive, a forward control is dominant, a forward PID operation output MCP as a forward control output MVP is generated, and the opening of a cooling valve is controlled accordingly, a reverse output lower limit value MLM is generated so as to minimize the opening of a hot water valve. When the forward PID operation output MCP is decreased less than the forward output lower limit value MLP, the MLP is outputted as the MVP, then the opening of the cooling valve is minimized, the control master is changed over so that the reverse direction is dominant, the reverse PID operation output MCM is generated as the reverse control output MVM and the opening of the hot water valve is controlled accordingly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process control device for controlling a system that requires simultaneous positive and negative control of an interval set point and process input.

Figure 1 shows that the process control device PC outputs a positive direction control output MVP and a negative direction control output M as an opening signal based on the room temperature (process input) PV and the set temperature (set value) SP.
This shows a system that controls the room temperature by outputting VM and controlling the opening degrees of the cold water valve VC and the hot water valve VH, thereby controlling the flow rate of cold water and the flow rate of hot water to the air conditioner.

As shown in FIG. 2, the conventional process control device used in the system shown in FIG. 1 calculates the deviation e (=PV−
3P), add this deviation e to the PID calculation unit 2, and calculate the PI
The positive direction control output MVP is generated by performing the D calculation, while the polarity of the deviation e is inverted by the polarity inverting section 3.
A negative direction control output MVM is generated by performing PID calculation in addition to the D/iii calculating section 4. now,
If e>0, the cold water valve VC has a large opening, and the hot water valve VH has a small opening; if e<0, the cold water valve VC has a small opening.

If the hot water valve V H is open, the valve will be open, but even if e=o, the cold water valve V
C and hot water valve VH both have a certain degree of valve opening and are balanced.

However, in such a configuration, two PID calculation units 2.
Since there is no correction or mutual control function between the two, for example, even if it is possible to control with cold water, the hot water valve will always be open and the cold water will be controlled with cold water, excluding the compensation bone of cold and hot water.
It has the disadvantage of wasting energy.

Therefore, an object of the present invention is to provide a process control device that can reduce energy loss and increase control 9) J rate.

A process control device according to an embodiment of the present invention will be explained based on FIGS. 3 to 5. This process control device is
As shown in Figure 3, the deviation e between the room temperature PV and the set temperature SP
There is a demand for a deviation calculation unit 1 that calculates the deviation e, a polarity reversal unit 3 that inverts the polarity of the deviation e calculated by the deviation calculation unit 1, and integral term complementary one-unit calculation for positive direction control and negative direction control. When the positive direction compensation calculation request determination section 5A and the negative direction compensation calculation request determination section 5B determine whether the positive direction compensation calculation request determination section 5A is positive, the deviation calculation section 1 calculates An integral term compensation calculation and a PID calculation are performed based on the deviation e, and when the judgment result of the positive direction compensation calculation request judgment unit 5A is negative, the deviation? Based on the deviation e calculated by Mn section 1, P
Integration is performed based on the deviation e inverted by the polarity reversing unit 3 when the determination result of the positive direction PID calculation unit 2' that performs only ID calculation and the negative direction compensation calculation request determination unit 5B is positive. Negative direction compensation calculation and PID calculation are performed, and when the judgment result of the negative direction compensation calculation request judgment unit 5B is negative, only the PID calculation is performed based on the deviation e inverted by the polarity inversion unit 3. PID calculation unit 4';
The output limit lower limit value MLP is generated as the positive direction control output Mvp in response to the output restriction command, and the positive direction P is generated from the positive direction PID calculation section 2' in response to the release of the output restriction command.
A positive direction output limiting section 6 generates the ID calculation output MCP as the positive direction control output MVP, and generates an output limit lower limit value MLM as the negative direction control output MVM in response to an output limit command, and responds to cancellation of the output limit command. and the negative direction PID
The negative direction output limiting section 7 generates the negative direction PID calculation output MCM generated from the calculation section 4' as the negative direction control output MVM, and determines the master-slave relationship between the positive direction control and the negative direction control, and determines that they are slave. Output limiter 6 or 7 in the direction
A master/slave determination unit 5C gives an output restriction command to the PI in the direction determined to be the master by this master/slave determination unit 5C.
D calculation output MCP or MCM is output limit lower limit value MLP
or a PIDID calculation output level unit 5D that determines whether or not it is equal to or higher than MLM and cancels the output restriction in that direction when the determination result is positive; When , the master-slave relationship of positive direction control and negative direction control is reversed to output a compensation calculation request for the dominant direction and to issue an output limiting command to the output limiting section 6 or 7 for the subordinate direction. This configuration includes a master-slave switching section 5E that provides a master-slave switching section 5E. In this case, the positive direction compensation calculation request determination section 5A, the negative direction compensation calculation request determination section 5B, the master/slave determination section 5C, the PID calculation output level determination section 5D, and the master/slave switching section 5E constitute the mutual control section 5.

The process control device shown in the above functional block diagram can actually be realized using a microprocessor. The operation of this microprocessor will be explained below with reference to FIGS. 4 and 5.

■ Forward processing First, deviation e (=PV
-3P), and then it is determined whether there is a request for integral term compensation calculation for forward direction processing, and the determination result is YE.
When S, an integral term compensation calculation is performed based on the deviation e, and then a PID calculation is performed, and when the determination result is NO, a PID calculation is immediately performed based on the deviation e.

Next, it is determined whether the forward direction control is the main control, and when the determination result is YES, the positive direction PID calculation output MCP obtained by the PID calculation is the positive direction output limit lower limit value ML.
Determine whether it is greater than or equal to P. This judgment result is YES
When S, the positive direction PID calculation output MCP is generated as the positive direction control output MVP, and the process moves on to the next process, and when the judgment result is No, switching between master and slave (positive direction control is made secondary, negative direction control is made main) ), then requests integral term compensation calculation for negative direction processing, and further sets positive direction output limit lower limit value ML.
P is generated as the forward direction control output MVP, and the process moves to the next step.

On the other hand, when the above-mentioned master/slave determination result is No, the forward direction output limit lower limit value MLP is generated as the forward direction control output MVP, and the process moves to the next process.

■ Negative direction processing First, deviation e (=PI
-3P), then performs a calculation to invert the polarity of the deviation e, then determines whether there is a request for integral compensation calculation for negative direction processing, and if the determination result is YES, calculates the polarity of the deviation e. After performing integral term compensation calculation with PID
The calculation is performed, and when the determination result is No, the PID calculation is immediately performed based on the deviation e.

Next, it is determined whether the negative direction control is the main control, and when the determination result is YES, the negative direction PID calculation output MCM obtained by the PID calculation is the negative direction output limit lower limit value ML.
Determine whether it is greater than or equal to M. This judgment result is YF
, S, the negative direction PID calculation output MCM is generated as the negative direction control output MVM, and the process moves on to the next process. When the judgment result is No, the master/slave switching is performed (the positive direction control is the main one, and the negative direction control is the subordinate one). ), then perform the integral term compensation calculation for the positive direction processing, and then calculate the negative direction output limit lower limit M
LM is generated as the negative direction control output MVP, and the process moves to the next step.

On the other hand, when the above-mentioned master/slave determination result is NO, the negative direction output limit lower limit value MLM is generated as the negative direction control output MVM, and the process moves to the next process.

In this case, the positive direction processing and the negative direction processing may be performed either serially or in parallel. Moreover, the master and slave of the positive direction control and the negative direction control are initialized at the time of initialization, for example, such that the positive direction control is the main and the negative direction control is the slave.

With this configuration, when the room temperature PV is higher than the set temperature SP, the positive direction control becomes the main control, and the negative direction control becomes the subordinate control.On the other hand, when the room temperature PV is lower than the set temperature SP, the negative direction control becomes the main control. Therefore, the forward direction control becomes the slave. In any case, the PID calculation output is generated as the control output when it is the main, and the output limit lower limit value is generated as the control output when it is the slave.

Now, for example, if the positive direction control is the main direction control and the negative direction control is the secondary direction control, the positive direction PID calculation output MCP is generated as the positive direction control output MVP, and the chilled water valve VC is controlled in opening accordingly, and the A negative direction output limit lower limit value MLM is generated as the direction control output MVM, and thereby the opening degree of the hot water valve VH becomes the minimum.

Here, when the positive direction PID calculation output MCP decreases and becomes smaller than the positive direction output limit lower limit value MLP, the forward direction output limit lower limit value MLP is output as the positive direction control output MVP, and thereby the opening degree of the chilled water valve VC is Minimum. Also, at this time, the main/slave mode is switched so that the positive direction control is the slave and the negative direction control is the main, and for the negative direction control, a compensation calculation of the integral term of the PID is performed to prevent sudden changes. , the negative direction PID calculation output MCM is the negative direction control output MVM
The opening of the hot water valve VH is controlled accordingly.

After this, when the negative direction PID calculation output MCM decreases and becomes smaller than the negative direction output limit lower limit value MLM, the negative direction output limit lower limit value MLM is set as the negative direction control output M'VM.
is output, and as a result, the opening degree of the hot water valve VH becomes the minimum. Also, at this time, the master and slave are switched so that the positive direction control is the main and the negative direction control is the slave, and for the positive direction control, P
After compensating the integral term of ID to prevent sudden changes, a positive direction PID calculation output MCP is generated as a positive direction control output MVP, and the opening degree of the cold water valve VC is controlled accordingly.

Thereafter, the same operation is repeated to control the room temperature PV to the set temperature SP.

As a result of this configuration, the positive direction and negative direction control outputs M
Both VP and MVM are not PID calculation outputs MCP and MCM, and either one is PID calculation output MCP.
Also, in MCM, one of the other is output limit lower limit value MLM
Alternatively, since it is an MLP, the control outputs in the positive direction and the negative direction are not canceled out, and control efficiency can be improved. Moreover, since the integral term compensation calculation is performed at this time for switching between the positive direction and the negative direction control output, the switching is continuous and no sudden change occurs.

In other words, by adding a mutual control function between the two PID calculations, when controlling the room temperature using cold water, when there is waste such as in the summer, room temperature control is performed only by controlling the cold water, and as in the winter. When it's cold, room temperature is controlled only by controlling hot water, which can save energy compared to controlling both cold and hot water.

Also, compared to the method of manually setting only cold water in the summer and only hot water in the winter, if this is done automatically as in the example, it is possible to control parts that cannot be controlled manually in spring and autumn, etc. It's also effective.

As described above, according to the process control device of the first invention, the control outputs in the positive direction and the negative direction are not canceled out,
It has the effect of increasing the control effect, and the second
In addition to the effects of the first invention, the invention has the effect of preventing sudden changes when switching control in the positive direction and the negative direction.

[Brief Description of the Drawings] Fig. 1 is a system configuration diagram of a general room temperature control system, Fig. 2 is a functional block diagram of a conventional process control device used in Fig. 1, and Fig. 3 is a system configuration diagram of a general room temperature control system. The functional block diagrams of the process control apparatus of the embodiment, FIGS. 4 and 5, are flow charts for explaining its operation. ■...Deviation calculation section, 2'...PID calculation section, 3...
・Polarity inversion section, 4'... PID calculation section, 5... Mutual control section, 6... Positive direction output limiting section, 7... Negative direction output limiting section, 5A... Positive direction compensation calculation Request determination section, 5B
. . . Negative direction compensation calculation request determination section, 5C . . . Master/slave determination section, 5D . . . PID calculation output level determination section, 5E . . .
・Main-slave switching section Fig. 2 Fig. 4 Fig. 5

Claims (2)

[Claims] (1) A deviation calculation unit that calculates the deviation between the process input and the set value, a polarity inversion unit that inverts the polarity of the deviation calculated by the deviation calculation unit, and a polarity inversion unit that inverts the polarity of the deviation calculated by the deviation calculation unit. a positive direction PID calculation section that performs a PID calculation based on the deviation inverted by the polarity inversion section; a negative direction PID calculation section that performs a PID calculation based on the deviation inverted by the polarity inversion section; a positive direction output limiting section that generates, as the positive direction control output, a positive direction PID calculation output generated from the positive direction PID calculation section in response to the release of the output limitation command, which is generated as the direction control output; negative direction output limitation, which generates an output limit lower limit value as a negative direction control output, and generates a negative direction PID calculation output generated from the negative direction PID calculation section as the negative direction control output in response to release of the output restriction command; a master-slave determination unit that determines the master-slave relationship between positive direction control and negative direction control and issues an output restriction command to the output restriction unit in the direction determined to be the slave; a PID calculation output level determination unit that determines whether the PID calculation output in the determined direction is equal to or greater than the output control lower limit value and cancels the output restriction in that direction when the determination result is positive;
A master-slave switching unit that reverses the master-slave relationship of positive direction control and negative direction control and issues an output limiting command to the output limiting unit in the slave direction when the determination result of the ID calculation output level determining unit is negative. A process control device equipped with (2) A deviation calculation unit that calculates the deviation between the process input and the set value, a polarity inversion unit that inverts the polarity of the deviation calculated by the deviation calculation unit, and an integral term compensation calculation unit for positive direction control and negative direction control. a positive compensation calculation request determination unit and a negative compensation calculation request determination unit that determine whether there is a request;
When the determination result of the positive direction compensation calculation request determination unit is positive, an integral term compensation calculation and a PID calculation are performed based on the deviation calculated by the deviation calculation unit, and the positive direction compensation calculation is performed.
P based on the deviation calculated by the deviation calculation unit when the determination result of the direction compensation calculation request determination unit is negative.
A positive direction PID calculation unit that performs only ID calculation, and an integral term compensation calculation and PID calculation based on the deviation inverted by the polarity inversion unit when the determination result of the negative direction compensation calculation request determination unit is positive. a negative direction PID calculation unit that performs only a PID calculation based on the deviation reversed by the polarity reversal unit when the determination result of the negative direction compensation calculation request determination unit is negative; and an output restriction command. In response to the release of the output limit command, the output control lower limit value is generated as the positive direction control output, and in response to the release of the output limit command, the positive direction PID calculation section generates the positive direction PID calculation output. and a negative direction PID/iii generated from the negative direction PID 64 calculating section in response to the output limitation command and generating the output limitation lower limit value as a negative direction control output in response to the release of the output limitation command. A negative direction output limiting section that generates the calculated force as the negative direction control output, and a master/slave relationship between the positive direction control and the negative direction control are determined, and an output limiting command is issued to the output limiting section in the direction determined to be slave. A main () 1-judgment unit that determines whether the PID calculation output in the direction that is determined to be the main by this master/slave determination unit is greater than or equal to the output limit lower limit value, and when the determination result is affirmative, outputs in that direction. A PID calculation output level judgment unit that cancels the restriction, and when the judgment result of this PID calculation output level judgment unit is negative, the master-slave relationship of positive direction control and negative direction control is reversed to compensate for the dominant direction. A process control device comprising a master-slave switching section that outputs a calculation request and also gives an output limiting command to an output limiting section in a direction that has become a slave.