Rockwell Automation Publication 1407-UM002B-EN-P - February 2019
201
CGCM-DLR Unit Math Models
Appendix
B
Figure 65 - Per-unit Block Diagram for Over-excitation Limiter
Figure 66 - Over-excitation Limiter Reference
V/Hz Limiter
V/Hz limiter is designed to help protect the generator and step-up transformer
from damage due to excessive magnetic flux that results from low frequency
operation and/or overvoltage.
V/Hz limiter has been designed with an adjustable slope (K
V/HZ
) from flat to
3 pu V/Hz. When the system is in an under-frequency condition, the voltage
reference is adjusted by the amount calculated based on two programmable
parameters, the corner frequency and the V/Hz slope. Its mathematical model is
shown in V/Hz Limiter.
Figure 67 - V/Hz Limiter
Reference Field Current (I
OEL_REF
)
Count Down For Reset
Time (s)