Rockwell Automation 1407-CGCM Combination Generator Control Module - Manual (Page 63)

Rockwell Automation Publication 1407-UM001G-EN-P - April 2013 63
CGCM Unit Operation Chapter 3
Synchronizing Control Software Interface
When synchronization is active, the CGCM unit adjusts the values of the
Scheduled Read table tags as described below.
• Voltage Match Error as computed above
• Frequency Match Error as computed above
• Phase Match Error as computed above
• Voltage Raise and Lower tags, which are set when the voltage match error
is above or below, respectively, the voltage acceptance window as defined
by the configured synchronizing voltage high and low limits
• Frequency Raise and Lower tags, which are set when the frequency match
error is above or below, respectively, the frequency acceptance window as
defined by the configured synchronizing frequency high and low limits
• Phase Raise and Lower tags, which are set when the phase match error is
above or below, respectively, the phase acceptance window as defined by
the configured synchronizing phase high and low limits
• The applicable Close Breaker tag, which is set when the voltage match
error, frequency match error and phase match error have all remained
continuously within their respective acceptance windows for the
configured acceptance window delay time
Real-power Load Sharing
The real-power load sharing function lets two or more CGCM units or other
compatible generator control devices (such as the Line Synchronization Module,
bulletin number 1402-LSM) to load the generators under their control such that
the same per unit output is developed by each generator. A 0…5V DC signal is
developed proportional to the per unit kW output of the generator and fed to the
load sharing terminals through an internal resistor. The configurable full-scale
voltage corresponds to the rated generator kilowatts. The load sharing output is
updated every 50 ms.
The load sharing terminals are connected in parallel (plus to plus, minus to
minus) with other compatible devices. If the CGCM unit’s generator is more
heavily loaded than the others, its developed load share voltage is higher, and
current flows out of the CGCM unit and into other devices on the network. A
more lightly loaded generator results in a lower load share voltage and current
flowing into the CGCM unit.
The direction and magnitude of current flow is used to develop the Load Share
Error value the CGCM unit makes available to the host logic controller. The host
logic controller program can use this value to control the prime mover governor
and balance generator output with others in the system.
The CGCM unit exhibits two rate of change features, Limit and Rate, that work
together to protect against an unstable system.