3.6 Setting the Configuration Chapter 3: Configuration
144 493-0736-11 (6-2)
The Feed Forward block in the figure below holds the factor Gain. This factor is
either static (does not change over time, Mode = StaticGain), or adaptive (changes
with Control Loop dynamics, Mode = AdaptiveGain). Select the desired
behaviour by setting the Mode parameter.
Figure 49 Feed Forward Signal.
Static Gain
If the parameter Mode is set to StaticGain, you can determine the value of Gain
using the procedure below:
1 Disable the Feed Forward function by setting Mode to Off.
2 Bring the system into a steady state.
3 Take note of the values of the FeedForwardSignal and ControlSignal. Call
them v
1
and u
1
respectively.
4 Introduce a process disturbance, e.g. by changing the process load, and then
wait until the system is in a steady state.
5 Take note of the values of the FeedForwardSignal and ControlSignal. Call
them v
2
and u
2
respectively.
6 Use the formula below to acquire the value of the Gain parameter:
7 Enable the Feed Forward function by setting Mode to StaticGain.
FeedForwardSignal
FeedForward
PID Algorithm
Process
SP
PV
U
PID
U
FF
U
Gain =
u
1
– u
2
v
1
– v
2
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