Rockwell Automation 1407-CGCM Combination Generator Control Module - Manual (Page 45)

Rockwell Automation Publication 1407-UM001G-EN-P - April 2013 45
CGCM Unit Operation Chapter 3
Field Current Regulation Mode (FCR)
FCR mode provides manual control of the excitation current. In FCR mode, the
CGCM unit measures and controls its field excitation current output to maintain
the commanded field current setpoint. The FCR feedback loop includes
adjustable proportional, integral, and derivative gains. In FCR mode, automatic
voltage control, reactive power control, power factor control, over-excitation
limiting, and under-excitation limiting are disabled. To activate FCR mode:
• the gains must be set.
• FCR mode must be selected (tag AVR_FCR_Select = 1).
• the desired setpoint must be written to the FCRSetpt tag.
• excitation enabled (tag SoftwareExcEn = 1).
• remote Excitation Enable On (discrete input).
Automatic Voltage Regulation Mode (AVR)
AVR mode provides automatic control of the excitation current. In AVR mode,
the CGCM unit controls field excitation current output to maintain the
commanded generator voltage setpoint. The AVR feedback loop includes
adjustable proportional, integral, and derivative gains. To activate AVR mode:
• the metering VTs must be properly connected and configured.
• the AVR gains must be set.
• AVR mode must be selected (tag AVR_FCR_Select = 0).
• the desired setpoint must be written to the AVRSetpt tag.
• excitation enabled (tag SoftwareExcEn = 1).
• remote Excitation Enable On (discrete input).
• for constant voltage control, droop must be disabled
(tag V_DroopEn = 0).
Droop (reactive current compensation)
Droop (reactive current compensation) is a method of controlling reactive
current when a generator is connected in parallel with another energy source.
Droop adjusts the generator voltage in proportion to the measured generator
reactive power. The CGCM unit calculates reactive power by using the 3-phase
generator voltage and current sensing inputs. The droop adjustment represents
the percent reduction from the generator voltage setpoint when the generator
produces reactive power corresponding to rated generator kVA.