JPS63197201A - Cascade controller - Google Patents

Abstract

PURPOSE:To perform the three-element control with use of two controllers by supplying the process value or the set value of a secondary controller and carrying out an adverse arithmetic operation so that the output of a primary controller follows said process value or set value. CONSTITUTION:A forward arithmetic means 31 of an inter-loop arithmetic unit LPU performs a prescribed arithmetic operation where the process value PV3 is applied to the output MVI received from the primary controller CNT1 in a cascade control state and gives this arithmetic output as the set value SV2 of the secondary controller CNT2. An adverse arithmetic means 32 carries out an arithmetic operation in a single control state set by the controller CNT2 so that the output of the controller CNT1 follows the value SV2 or the value PV2. In such a way, a single control state is switched to a cascade control state with no bump.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a cascade control device consisting of a primary controller and a secondary controller.
The present invention relates to a cascade adjustment device that can perform cascade calculations by interposing a calculation unit between it and a next controller.

(Prior Art) FIG. 4 is a conceptual diagram of the configuration of a conventional cascade adjustment device. In FIG. 0, CNTl is a primary controller, CNT2 is a secondary
In the secondary controller, the output signal MVI of the primary controller CNTl is given as its set value signal SV2.

A cascade regulating device with such a configuration is used, for example, in a process such as controlling the water level of a boiler drum.
The boiler drum water level signal is given as an input signal to the secondary controller CNTl, and the feed water flow rate signal is given as an input signal to the secondary controller CNT2. Applicable to cases where control is required.

(Problem to be Solved by the Invention) By the way, in the process of controlling the water level of the boiler drum, in addition to the cascade control of the drum water level and the amount of water supply, it is necessary to detect the amount of steam and control the amount of steam and water supply. If the water supply volume is unbalanced, controlling the water supply volume immediately before the drum water level fluctuates will result in better mv.
s result is obtained. However, with the conventional cascade control device as shown in FIG. 4, it is not possible to control the three elements of feed water flow rate, boiler drum water level, and steam amount as described above.

The present invention was made in view of these problems, and
Its purpose is to be able to perform three-element M control using two controllers, as well as perform cascade (mwc, cascade close) control using two controllers, and independent lI control (cascade oven, cascade close) using one controller. ) The object of the present invention is to realize a cascade adjustment device that allows a pan press to perform switching between

(Means for Solving the Problems) FIG. 1 is a basic configuration block diagram of the device of the present invention. In FIG. 0, CNTl is a set value SV1. Process amount P
Primary controller that inputs VI, CNT2 is process amount PV
2 is input to the secondary controller, LPυ is the primary controller CNTl.
This is an inter-loop calculation unit installed between the controller CNT2 and the secondary controller CNT2.
The output signal MVI of the next controller CNTl and the process amount PV3
forward calculation means 3 which performs a predetermined calculation using
1, and an inverse calculation means 32 that inputs the set value SV2 or process amount PV2 of the secondary controller CNT2 and performs an inverse calculation such that the output MVI of the primary controller CNT1 follows these values. .

(Function) The 1llil calculation means 31 in the inter-loop arithmetic unit calculates the primary controller CNTl in the cascade lli control state.
A predetermined calculation is performed using the process amount PV3 on the output MVI from the
Give as V2. The inverse calculation means 32 is a secondary controller CN.
In the independent control state by T2, the primary controller CNTl
Calculation is performed so that the output follows the set value SV2 or the process amount PV2. This makes it possible to switch from the single @ control state to the cascade control state in a pan press.

(Actual jtI91) In FIG. 2, which is a block diagram of an embodiment of the apparatus of the present invention, parts corresponding to those in FIG. 1 are denoted by the same reference numerals. Here, boiler drum water supply U
This is an example of a case where S is performed.

10 is a boiler drum, 11 is a water supply channel for supplying water to the boiler drum 10, and 12 is a flow meter that detects the flow rate QV of water flowing through the water supply channel 11, and the process corresponding to the flow fullQV is secondary. Output to controller CNT2.

Reference numeral 13 denotes a valve for controlling the water supply flow rate, which is controlled 1ti101 by the output MV2 of the secondary controller CNT2. 14 is a water level meter that detects the water level LV in the boiler drum 10, and outputs the process flPVI corresponding to the water levels ① and ② to the primary controller CNTl.

15 is a steam amount detection means for detecting the steam ff1BV in the boiler drum 10, and outputs the process m PV3 corresponding to the steam amount (BV) to the inter-loop calculation unit LPLI.

MAN is a manual a node, Svl is a manual regulator) Manual control by IAN, and controller CNT1. A/M changeover switch for switching between automatic control by CNT2, and cascade open switch for 3v2 for switching between cascade control and independent control.
Close changeover switch (abbreviated as 0/C changeover switch)
, 51113 are each switch SV1. ! This is a C10/M changeover switch that is switched according to the operation of jW2.

In the inter-loop calculation unit LPU, 33 is 11 calculation means 31. A forward/reverse operation detection means 34 detects the presence or absence of an operation to be performed by the inverse operation means 32, and inputs a status signal from the A/H changeover switch SWl to determine whether the loop is in a manual control state or an automatic control state. The A/M detection means 35 is an 0/C detection means that manually inputs the status signal from the 0/C changeover switch SW2 and detects whether it is in a cascade control state or an independent control state.

Next, the operation of the device configured in this way is controlled by cascade control, single control, two manual operation modes (or output racking).
I will explain it separately.

(Cascade control) In this state, the A/M changeover switch SWI is set to contact A,
C10 changeover switch Sw2 is connected to contact C, changeover switch S
V3 is connected to contact C, respectively.

In such a connected layer, the inter-loop arithmetic unit LPU
The forward calculation means 31 in
Input , perform inter-loop calculations using a predetermined calculation formula,
The calculation result is given as the setting (msV2) of the secondary controller CNT2.

The secondary controller CNT2 is a process 51 from the flowmeter 12.
PV2. Set value Sv from inter-loop calculation unit LPU
2 and input the operation signal MV2 to the A/M selector switch SW.
It outputs to valve 13 via +. This allows the
Seth fi PVI, PV2. It enables three-element ff4 control by PV3.

(Independent control) The A/M changeover switch SWI is set to contact A, the C10 changeover switch S%'2 is set to contact O, and the changeover switch SV3 is set to contact 0.
are connected to each.

In such a connected state, the secondary controller CNT2 outputs the operation output signal MV2 to the valve 13 so that the process amount PV2 from the flowmeter 12 matches the setting mSV2. Further, the inverse calculation means 32 calculates a set value SV2 given to the secondary controller CNT2 via the changeover switch SW3.
is input, and a calculation is performed so that the output of the primary controller CNTl follows the set value SV2.

This allows bumpless switching from the independent control state to the cascade ti control state.

(Manual operation mode) The A/M changeover switch SWl is connected to the contact M, the C10 changeover switch Sw2 is connected to the contact C, and the changeover switch SW3 is connected to the contact M.

In this state, a manual operation signal from the manual adjustment II MAN is output to the valve 13. The inverse calculation means 32 inputs the process quantity PV2 and outputs the output M of the primary controller CNTl.
Compute VI.

FIG. 3 is a flowchart showing a series of operations of the inter-loop calculation unit LPU.

The 0/C detection means 35 determines whether the cascade is open or closed (1) based on the status signal from the 0/C changeover switch SV2 (step 1). If it is determined that the cascade is closed, the process moves to step 2.

The A/M detection means 34 determines whether it is in the manual control state or the automatic control state based on the status signal from the A/M changeover switch SW1 (1), and when it is in the automatic control state (auto), it moves to step 3. 1) Here, the presence/absence of forward calculation is determined by the 1-incline/inverse calculation presence/absence detection means 33. If it is determined that there is no forward calculation, the Btw calculation means 31 calculates the primary controller CNTl.
The output operation signal MVI of the secondary controller CNT2 is output as is.
The set value is set to SV2 (step 4). If it is determined in step 3 that there is a forward calculation, the forward calculation means 31 outputs the output operation signal MVI of the primary controller CNTl and the process ji.
A predetermined calculation is performed using PV3, and the calculation result f
(MV1) is set as the set value SV2 of the secondary controller CNT2 (step 5).

In step 2, manual control state! When it is determined that r4 (manual), the inverse calculation means 32 executes the process fi,
Input I'V2 and set value SV2 of secondary controller CNT2.
Tracks to PV2 (Step 6)
.

In steps 7 and 8, the I(11/inverse calculation presence/absence detection means 33 determines the presence or absence of the inverse calculation and the presence or absence of the 11m calculation, respectively. If it is determined that the inverse calculation cloth is present, the inverse calculation means 3
2, the operation output signal MVI of the primary controller CNTl
The inverse calculation means is performed so that SV2 follows the set value SV2 (
Step 9). Furthermore, if it is determined that there is heat in reverse operation and no forward operation, set value SV2 is set to MVI (step 10).
. Next, the process moves to step 11 1), where the current output operation signal MV value (output value of secondary controller CNT2 or manual controller) is determined.
The internal data of the primary controller CNTl is tracked. This allows the pan press to switch from the independent control state and manual control state to the cascade control state.

In the above embodiment, the three-element control of feed water flow rate, boiler drum water level, and steam amount is exemplified, but other process variables may be controlled. In addition, each switch SW1. SW2. Although SW3 is illustrated as a switch having contacts, these may be realized by software.

(Effects of the Invention) As described above in detail, according to the present invention, three-element M control can be performed using two controllers, and independent l! 1104 or cascade from manual control w
Cascade w4 that allows bumpless switching to 4 controls
You can save money.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration block diagram of the device of the present invention, FIG. 2 is a configuration block diagram of an embodiment of the device of the present invention, FIG. 3 is a flowchart showing a series of operations performed by the inter-loop calculation unit, and FIG. The figure is a conceptual diagram of the configuration of a conventional device. CNTl...1st order m meter, CNT2...2nd order controller, LI'U...interloop calculation unit, 31...I
n calculation means, 32...inverse calculation means. Figure 3

Claims (1)

[Claims] 1 for inputting set value (SV1) and process amount (PV1)
It consists of a secondary controller, a secondary controller that inputs the process variable (PV2), and an inter-loop calculation unit provided between the primary controller and the secondary controller, and the inter-loop calculation unit is the process variable. (PV3) is input, and the output signal (MV1) of the primary controller is input.
) and the process variable (PV3), and a forward calculation means that performs a predetermined calculation and provides the calculation result as the setting value (SV2) of the secondary controller;
V2) or process quantity (PV2) and performs an inverse calculation such that the output (MV1) of the primary controller follows the set value (SV2) or process quantity (PV2). Cascade regulator.