JPH06259105A - Automatic controller - Google Patents

Abstract

PURPOSE:To improve the process controllability by setting an optimum PI or PID control constant in response to the operating speed of an operating terminal. CONSTITUTION:An automatic controller carries out a PI or PID control operation based on the deviation between a controlled variable an the target value and operates an operating terminal by the operating signal of the control operation result. Then a deviation polarity deciding means 11 is added to the controller to decide the polarity of the preceding deviation, a target value change detector means 16 which detects the presence of absence of change of the target value, a coefficient selector means 12 which selects a multiplication coefficient in response to the polarity of deviation decided by the means 11 when a multiplication coefficient is previously set based on the opening and closing speeds of the operating terminal and the change of the target value is detected by the means 16, and a PID constant variable setting means 14 which multiplies the selected coefficient by a PI or PID control constant and sets a new control constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic controller used in a plant instrumentation system for steel, petrochemicals, foods, etc., and in particular, an appropriate PI or PID control constant is set according to the operating speed of the operating end. The present invention relates to an automatic controller with a setting technology.

[0002]

2. Description of the Related Art In a plant instrumentation system of this type, a large number of automatic controllers having a structure as shown in FIG. 2 are installed for each control target at a required location of the system. These automatic controllers are provided with a PI or PID adjustment calculation unit 1 and execute an analog or digital PI or PID adjustment calculation based on the deviation between the feedback control amount PV from the detection end 2 and the target value SV. Then, the operation signal MV, which is the obtained adjustment calculation output, is applied to the operation end 3 to control the flow rate, the temperature, the pressure, etc., which are the control targets.

By the way, conventionally, in an automatic controller using such feedback control, a fixed constant which is empirically or simulatedly obtained from a controlled object and a plant state is used as a PID control constant used when performing a PID adjustment calculation. Therefore, the required operation is performed while performing the PID adjustment calculation under this fixed constant.

[0004]

However, the automatic controller using the feedback control as described above is used for various control objects and plants, and one example thereof is, for example, a combustion furnace and its exhaust port. A damper is installed between the two, and the damper is opened or closed depending on the deviation between the furnace pressure and the target pressure. At this time, the damper, which is the operating end, is opened or closed as shown in FIG. It often operates at different operation speeds. This means that the operating speed of the operating end is different between open and closed, so the PID control constant should be changed accordingly, but the PID control constant is originally a fixed constant. Therefore, the fixed constant of the compromise between the opening direction and the closing direction is found and used. As a result, for example, opening and closing of the damper is quick with respect to changes in the target value,
Alternatively, it may be slow, which causes a hunting phenomenon, which makes it difficult to quickly attain the optimum pressure inside the furnace, and in the case of a furnace involved in combustion, causes pollution.

The present invention has been made in view of the above-mentioned circumstances, and it is an optimum PI or PID according to the operating speed of the operating end.
It is an object of the present invention to provide an automatic controller that variably sets a control constant and operates an operating end, thereby improving controllability.

[0006]

In order to solve the above-mentioned problems, the invention corresponding to claim 1 is a deviation polarity judging means for judging the polarity of the deviation between the control amount and the target value, and the operation end of the operation end in advance. Coefficient or PI depending on the operating speed at opening and closing
Control means (or PID is included) is set, and selecting means for selecting and outputting a coefficient or PI control constant according to the polarity of the deviation judged by the deviation polarity judging means;
It is an automatic controller provided with PID constant variable setting means for variably setting the PI or PID control constant of the adjustment calculation unit based on the coefficient or PI control constant selected by the selecting means.

Next, the invention corresponding to claim 2 is a deviation polarity judging means for judging the polarity of the deviation between the control amount and the target value, and a target value change detecting means for detecting the presence or absence of a change in the target value. When a coefficient or PI (or PID is included) control constant is set in advance according to the operating speed of the operating end when the operating end is open and when the operating end is detected by the target value change detecting means, Selection means for selecting and outputting a coefficient or PI control constant in accordance with the polarity of the deviation judged by the deviation polarity judging means, and PI of the adjustment calculation section based on the coefficient or PI control constant selected by this selecting means. PID for variably setting PID control constants
It is an automatic controller provided with constant variable setting means.

[0008]

Therefore, according to the invention corresponding to claim 1, the deviation polarity judgment means judges the polarity of the deviation between the control amount and the target value, or the deviation polarity and its When it is judged that the deviation exceeds the predetermined value,
The selecting means selects and outputs a coefficient or a PID control constant which is set in advance in accordance with the operating speed of the operating end when the operating end is open and when the operating end is closed. Then, by multiplying the PI or PID control constant by using the selected coefficient to variably set the PI or PID control constant, or by selecting and setting a new PID control constant, the operating speed at the time of opening and closing Accordingly, the operating end can be appropriately operated, and the controllability can be improved.

Next, the invention according to claim 2 has means for determining the polarity of the deviation between the control amount and the target value, and means for detecting whether or not the target value has changed, and the target value has changed. Only at this time, a coefficient or PID control constant that is set in advance according to the operating speed of the operating end when the operating end is opened and closed is selected and output according to the polarity of the deviation. Then, by multiplying the PI or PID control constant by using the selected coefficient to variably set the PI or PID control constant, or by selecting and setting a new PID control constant, it is possible to ensure that the target value changes. In addition, it is possible to determine whether the operating end is in the opening direction or the closing direction based on the polarity of the deviation, and appropriately operate the operating end according to the operating speed during opening and closing, thereby improving controllability.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an automatic controller according to the present invention. The same parts as those of a conventional automatic controller are designated by the same reference numerals, and detailed description thereof will be omitted.

Hereinafter, a part that is particularly different from the conventional one will be described. That is, this automatic controller takes in the control amount PV and the target value SV from the detection end 2 at all times or at regular intervals, and judges whether the deviation between these signals is positive or negative and outputs the deviation polarity. A judging means 11 is provided. The deviation polarity determination means 11 compares not only the polarity of the deviation but also the magnitude of the deviation with a predetermined threshold value set in advance if necessary, and only when the deviation exceeds the predetermined threshold value, the deviation The signal relating to the polarity of
It may be configured so that the data is sent to No. 2.

Reference numeral 13 denotes a memory table, which has a PI or PID depending on the operating state when the operating speed of the operating end 2 is different between open and closed as shown in FIG.
A multiplication coefficient for changing the control constant is stored.
At this time, there are cases where the operation speed has linearity and cases where it has nonlinearity. For example, when it has linearity, two multiplication coefficients should be stored in consideration of the open time and the closed time. However, in the case of having non-linearity, a large number of multiplication coefficients are stored in advance so that they can be selectively taken out in accordance with the passage of time.

In the coefficient selecting means 12, when a signal relating to the polarity of deviation arrives from the deviation polarity judging means 11, the memory table 1 is sent according to the signal relating to the polarity.
The required multiplication coefficient is selectively read from the memory table 3 or the required multiplication coefficient is sequentially read from the memory table 13 with the lapse of time and sent to the PID constant variable setting means 14.

The PID constant variable setting means 14 has a function of taking in the multiplication coefficient selected by the coefficient selecting means 12, multiplying it by the PI or PID control constant of the adjustment calculation section 15, and varying the PI or PID control constant. There is.

Further, the automatic controller is provided with a target value change detecting means 16 for detecting a change in the target value SV. The target value change detecting means 16 is set with a predetermined threshold value capable of reliably judging the change of the target value, and when the target value SV exceeds the threshold value, the coefficient selecting means 12
To select the coefficient of the memory table 13.

The reason why the coefficient is selected only when the target value SV changes by providing the target value change detecting means 16 in this way is that the adjustment calculator 15 usually obtains a deviation every predetermined sampling cycle and PI Alternatively, since the operating end 3 is operated while executing the PID adjustment calculation, the range of the deviation is relatively small and has little influence on the controllability, but when the target value changes, the range of the deviation is large and the change is small. This is because the controllability needs to be improved by following the above and promptly settling. Next, among the controllers as described above, the operation of the controller including the target value change detecting means 16 will be described.

The adjustment calculator 15 controls the control amount PV and the target value S.
After obtaining the deviation from V, PI or PID adjustment calculation is executed based on this deviation, and the control signal is controlled by applying the operation signal MV which is the obtained adjustment calculation output to the operation end 3. . In this state, it is assumed that the deviation polarity judging means 11 and the target value change detecting means 16 respectively make necessary judgments or detections by fetching required signals constantly or at a predetermined cycle.

At this time, if the target value SV changes, the deviation polarity judgment means 11 takes in the deviation between the target value SV and the controlled variable PV and judges whether the polarity of the deviation between the two signals is positive or negative. , The coefficient selection means 12
Send to.

On the other hand, the target value change detecting means 16 compares the input target value SV with a predetermined threshold value, and when the target value SV exceeds the threshold value, there is a change in the target value SV. Therefore, a signal indicating that the target value has changed is sent to the coefficient selecting means 12.

When the coefficient selecting means 12 receives the signal indicating that the target value has changed, the coefficient selecting means 12 reads out a required multiplication coefficient from the memory table 13 in accordance with the signal relating to the polarity of the deviation and causes the PID constant variable setting means 14 to read it. send. Therefore, when the setting means 14 receives the multiplication coefficient and sends it to the adjustment calculation section 15, the adjustment calculation section 15 multiplies the PI or PID control constant by the multiplication coefficient and the PI corresponding to the operating speed of the operating end 3. Alternatively, it is set to the PID control constant.

Therefore, the adjustment calculation section 15 executes the adjustment calculation for making the deviation between the control amount PV and the target value SV zero by using the newly set PI or PID control constant, and outputs the adjustment calculation output. By applying the operation signal to the operation end 3, it is possible to secure an optimum operation for both the opening operation and the closing operation of the operation end 3, and it is possible to improve the controllability of the process when changing the target value.

In the above embodiment, the automatic controller using the feedback control system has been described, but the automatic controller using the cascade control + feedback control system is also applicable. Further, in the memory table 13, not the multiplication coefficient but the PI or PI used in the adjustment calculation unit is used.
A configuration in which the D control constant is set and the control constant is directly set by the adjustment calculation unit may be used. In addition, the present invention can be modified in various ways without departing from the scope of the invention.

[0023]

As described above, according to the present invention, when the operating end can be operated according to the polarity of the deviation or when the target value changes, the deviation of the target value depends on the polarity of the deviation. It is possible to operate the operating end by using the optimum PI or PID control constant according to the operating speed of the operating end even when the operating speed of the operating end is different between open and closed. The controllability of can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an automatic controller using a feedback control system according to the present invention.

FIG. 2 is a block diagram of an automatic controller using a conventional feedback control system.

FIG. 3 is a view for explaining that the operating speeds of the operating end are different when the operation end is opened and when the operation end is closed.

[Explanation of symbols]

1 ... Detection end, 3 ... Operation end, 11 ... Deviation polarity determination means, 1
2 ... Coefficient selecting means, 13 ... Memory table, 14 ... PI
D constant variable setting means, 15 ... Adjustment calculating part, 16 ... Target value change detecting means.

Claims (2)

[Claims] 1. An automatic controller in which an adjustment calculation unit executes PI or PID adjustment calculation based on a deviation between a control amount and a target value, and operates an operating end using an operation signal which is the obtained adjustment calculation output. A deviation polarity determining means for determining the polarity of the deviation between the controlled variable and the target value, and a coefficient or PI (or PID) control constant depending on the operating speed of the operating end when the operating end is opened and closed. And selecting means for selecting and outputting a coefficient or PI control constant in accordance with the polarity of the deviation determined by the deviation polarity determining means, and the adjustment based on the selected coefficient or PI control constant. An automatic controller characterized by variably setting a PI or PID control constant of a computing unit. 2. An automatic controller in which an adjustment calculation unit executes PI or PID adjustment calculation based on a deviation between a control amount and a target value and operates an operating end using an operation signal of the obtained adjustment calculation result. A deviation polarity determining means for determining the polarity of the deviation between the control amount and the target value, a target value change detecting means for detecting the presence or absence of a change in the target value, and when the operating end is opened and closed in advance. A coefficient or PI (or PID is included) control constant is set according to the operation speed, and when the target value change detecting means detects that the target value has changed, the polarity of the deviation determined by the deviation polarity determining means is determined. And a selecting means for selecting and outputting a coefficient or a PI control constant in accordance with the selected coefficient or PI control constant, and variably setting the PI or PID control constant of the adjustment calculation unit based on the selected coefficient or PI control constant. An automatic controller characterized in that