GE UR F35 Series, Instruction Manual

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GE Multilin F35 Multiple Feeder Protection System 5-209
5 SETTINGS 5.7 CONTROL ELEMENTS
5
A general form of a PID regulator in the s domain is shown below.
Figure 5–94: PID BLOCK DIAGRAM
The following terms apply to the block diagram:
• y is the process signal
• r is the setpoint signal
• w is the tracking signal
• u is the regulator output
• K is the proportional gain
• b is the setpoint weighting
• T
d
is the derivative time constant
• N is the derivative limit
• T
i
is the integral time constant
• T
t
is the anti-windup time constant
• s is the domain
In discrete form, the equations for the regulator are:
(EQ 5.27)
Where T
S
is the sampling time and AW is a flag which enables anti-windup. The incremental form of the above equation is:
(EQ 5.28)
Where:
y
r
w
+
-
e
K
T
i
+
+
1
s
1
T
t
+ -
i
+
+
+
d
u
sKT
d
1+sT /N
d
+
-1
b
+ p
K
832031A1.cdr
e k
( )
r k
( )
y k
( )
– =
p k ( ) K br k ( ) y k ( )
–
( )
=
d k ( )
T
d
T
d
NT
S
+
------------------------
 
 
d k 1
–
( ) ×
kT
d
N
T
d
NT
S
+
------------------------
 
 
y k ( ) y k 1
–
( )
–
( ) ×
– =
u k ( ) p k ( ) i k ( ) d k ( )
+ + =
i k 1
+
( )
i k
( )
KT
S
e k
( )
T
i
-----------------------
T
S
T
t
------
w k
( )
u k
( )
–
( )
AW
× ×
 
 
+ + =
Du k
( )
u k
( )
u k 1
–
( )
– =
Dp k
( )
Di k
( )
Dd k
( )
+ + =