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When synchronizing a system between systems with differing metering
configurations, the synchronization configuration must account for any phase
shift or voltage differences between the two systems. For example, when
synchronizing a three-wire (delta) generator to four-wire (Wye) bus system, the
synchronization configuration must account for the 30° phase shift between
line-to-line and line-to-neutral voltage.
Synchronizing Connection Schemes
The CGCM-DLR unit provides information that its host Logix controller uses
to synchronize the generator output voltage, frequency, and phase to a reference
power system, or bus. 3-phase, dual bus, and single-phase connection schemes are
described in the following section:
• 3-phase
In this scheme, the 3-phase output of the generator and all three phases of
the reference system are connected to the CGCM-DLR unit. This
connection lets the CGCM-DLR unit match voltage, frequency, phase,
and phase rotation of the generator to the reference system. The 3-phase
scheme provides the CGCM-DLR unit with the most power system data,
which lets it perform the most thorough synchronization.
To enable a 3-phase connection, select the Generator and Bus VT
Configurations as two-transformer open-delta, three-wire Wye, or
four-wire Wye.
When delta systems, are synchronized, the CGCM-DLR unit uses
line-to-line voltage for voltage, frequency, and phase matching. When
synchronizing Wye systems, the CGCM-DLR unit uses line-to-line
voltage for voltage and frequency matching, and line-to-neutral voltage for
phase matching.
• Dual Bus
The CGCM-DLR unit can synchronize a generator to either one of two
reference busses. The CGCM-DLR unit supports this synchronization by
monitoring one line-to-line phase of the two reference busses. You must
select the appropriate bus for synchronization. It is not possible to
synchronize to two different busses simultaneously. For dual-bus
synchronization, the 3-phase output of the generator and one phase from
each reference bus are connected to the CGCM-DLR unit. This scheme
lets the CGCM-DLR unit match voltage, frequency, and phase, but not
phase rotation of the generator to the reference system.
However, the CGCM-DLR unit verifies that the generator output phase
rotation matches the user-configured selection of ABC or ACB.
To enable the dual-bus mode, select the Bus VT Configuration as Dual
Breaker.
Rockwell Automation Publication 1407-UM002B-EN-P - February 2019
CGCM-DLR Unit Operation
Chapter 3
65
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