GE C30 Instruction Manual page 232

5.6 CONTROL ELEMENTS
A general form of a PID regulator in the s domain is shown below.
y
r
w
The following terms apply to the block diagram:
• y is the process signal
• r is the setpoint signal
• w is the tracking signal
5
• u is the regulator output
• K is the proportional gain
• b is the setpoint weighting
• Td is the derivative time constant
• N is the derivative limit
• Ti is the integral time constant
• Tt is the anti-windup time constant
In discrete form, the equations for the regulator are:
Where T is the sampling time and AW is a flag which enables anti-windup. The incremental form of the above equation is:
S
Where:
5-116
b
-1
-
e
+
K

Ti
Figure 5–43: PID BLOCK DIAGRAM
e k   r k   y k  
= –
p k   K br k   y k    
= –
T
 
d
d k   ----------------------- -  
d k 1
= –
 
T NT
+
d S
u k   p k   i k   d k  
= + +
e k  
KT
S
  i k  
i k 1 ---------------------- -
+ = +
T
i
Du k   u k   u k 1
=
Dp k  
=
C30 Controller System
+

K
+
sKTd
1+sTd/N
+
1

s
+
1
Tt
+ -

kT N
 
d
 ----------------------- -   y k   y k 1 
– –
 
T NT
+
d S
T
 
S
  w k   u k    
------
AW
+ –
 
T
t
 
– –
Di k   Dd k  
+ +
5 SETTINGS
p
+
d +

u
+
i
 
–
(EQ 5.1)
(EQ 5.2)
GE Multilin