Rockwell Automation 1407-CGCM Combination Generator Control Module - Manual (Page 188)

188 Rockwell Automation Publication 1407-UM001G-EN-P - April 2013
Appendix B CGCM Unit Math Models
The operating characteristics are designed to mimic the characteristics of the
limiter on the P-Q plane. The desired UEL curve is generated based on the user
input points.
Typical UEL reference is illustrated in Under-excitation Limiter Reference .
Figure 63 - Per-unit Block Diagram for Under-excitation Limiter
Figure 64 - Under-excitation Limiter Reference
Per-unit Block Diagram for Over-excitation Limiter shows the model of the
CGCM over-excitation limiter (OEL). The OEL makes up the inner loop of the
voltage regulator and uses a PI type controller. In this control scheme the actual
field current is compared with a reference field current. The operating
characteristics are designed to mimic the field current short-time overload
capability given in ANSI standard C50.13-1977. The reference field current is
calculated based on the user input parameters as shown in
Over-excitation
Limiter Reference .