A.1 Level Control with Feed Forward and Gain Scheduling Appendix A: Application Examples
210 493-0736-11 (6-2)
4 Inspect the default parameter settings of each block, and determine what
changes need to be made.
5 Write down all parameter changes on paper.
6 Configure the controller using your filled out Configuration Work Sheet and
parameter changes sheet. These two papers will be a useful record of your
solution to the control problem.
A.1 Level Control with Feed Forward and Gain
Scheduling
Description
This example describes level control of a tank with two inlets and one outlet with
pump. One of the inlets is controlled by a control valve from the process
controller, while the other inlet is not controlled but measured by an analogue
transmitter.
An uncontrolled but measurable disturbance is thus affecting the level in the tank.
If the disturbance is constant, it can be compensated for without any special
functions. But if it is a varying disturbance as in this case, the feed forward
function can be utilized.
The control valve is non-linear which means it will give different gain at different
flow rates. To optimize the controller parameters to the different flow rates, gain
scheduling based on the output signal is used.
Mechanical Installation
Please refer to chapter 2 of this manual for details of the mechanical installation.
Definition of Control Problem
The object is to control a fluid flow according to the diagram below. The flow is
measured with a differential pressure transmitter using an orifice flange and
regulated by a control valve.
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