Rockwell Automation 1407-CGCM Combination Generator Control Module - Manual (Page 187)

Rockwell Automation Publication 1407-UM001G-EN-P - April 2013 187
CGCM Unit Math Models Appendix B
VAR/Power Factor
Controller The VAR/PF controller is a summing point type controller and makes up the
outside loop of a two-loop system. This controller is implemented as a slow PI
type controller. The voltage regulator forms the inner loop and is implemented as
a fast PID controller.
The model of the CGCM VAR and power factor controller is shown in Per-unit
Block Diagram for Var Controller and Per-unit Block Diagram for PF
Controller , respectively. Non-windup limit (V
CLMT
) is used for bounding the
VAR/PF controller output voltages (V
Q
and V
PF
).
Figure 61 - Per-unit Block Diagram for Var Controller
Figure 62 - Per-unit Block Diagram for PF Controller
Limiters Both the over-excitation limiter (OEL) and the under-excitation limiter (UEL)
in this implementation are of the summed limiter type as opposed to takeover
type.
Per-unit Block Diagram for Under-excitation Limiter shows the model of the
CGCM under-excitation limiter. The UEL makes up the outer loop and the
voltage regulator makes up the inner loop. The UEL uses a PI type controller.