ABB COMMANDER C355 - Single Loop with Feedforward Operations

21
350.0
351.5
70
PV – CSPt
Deviation
OP1
•1
70
FF
2 OPERATOR LEVEL…
2.6 Single Loop with Feedforward (Templates 9 and 10)
These templates provide three-term PID control with feedforward. The disturbance variable is
weighted by the feedforward gain (FFGn) and the feedforward bias (FFbS) values and added to the
controller output value.
•1 With the Ramping Set Point function enabled (see Section 4.3, Set Points/ Ramp Rate), the
bargraph shows the actual deviation (PV/Ramping Set Point value) The digital display shows the
target set point value.
Process Variable
Control Set Point
['SPLO' to 'SPHI' – see Section 5.5]
Adjustable in Local control only.
Control Output
[0 to 100%]
Adjustable in Manual control only.
Feedforward
Note. To disable feedforward action (e.g.
during system tuning), set the Feedforward Gain
parameter to 0FF – see Section 4.2, Level 2/ Tune.
[0 to 100%]
Feedforward disturbance variable signal.
Continued…
CSPt
I/P3
I/P1
I/P2
OP1
Local Set Point
Remote Set Point input
PV input
Feedforward Disturbance Variable
MPV
PID
Control Loop
•1
•1 Template 10 Only
Manual Output
LSPt
L
LR
rSPt x rAtO + bIAS
DV x FFGn + FFbS
∑
PID O/P +
(DV x FFGn + FFbS)
FFGN = 0
Profile Set Point
Fig. 2.5 Single Loop Controller with Feedforward