9492600990 5-5
DECS-150 Regulation
The LD
Value
is the per-unit value seen down the line from the generator. Equation 5-2 is used to determine
the voltage needed to adjust for line drop.
,
=
,
Equation 5-2. Voltage Needed to Adjust for Line Drop
Equation 5-3 is used to obtain primary units.
=
,
×
Equation 5-3. Obtain Primary Units
The new line drop adjusted setpoint is calculated using Equation 5-4.
=
+
Equation 5-4. Line Drop Adjusted Setpoint
Cross-Current Compensation
Cross-current compensation (reactive differential) mode serves as a method of connecting multiple
generators in parallel to share reactive load. When reactive load is shared properly, no current is fed into
the DECS-150 cross-current compensation input (terminals IB+ and IB–). Improper sharing of reactive
load causes a differential current to be fed into the cross-current compensation input. When cross-current
compensation is enabled, this input causes the DECS-150 to respond with the proper level of regulation.
The response of the DECS-150 is controlled by the cross-current compensation gain setting which is
expressed as a percentage of the system nominal CT setting.
Application information about cross-current compensation is available in the Voltage and Current section
of this manual.
Network Load Sharing
In a multiple-generator application, the load sharing function ensures equal generator reactive-power
sharing. It operates in a similar manner to cross-current compensation but without the external hardware
requirements and distance limitations. Instead of sharing load based on the CT ratio, load is shared on a
per-unit basis calculated from the generator rated data. Sharing of load information between DECS-150
controllers is accomplished through the Ethernet port of each DECS-150 communicating over a peer-to-
peer network dedicated for the load sharing function. Each DECS-150 measures the reactive current of
its associated generator and broadcasts its measurement to all other DECS-150 controllers on the
network. Each DECS-150 compares its level of reactive current to the sum of all measured currents and
adjusts its excitation level accordingly.
When the unit’s configuration does not match the configuration of the other units with load sharing
enabled, the Network Load Share Config Mismatch logic element becomes true. The Configuration
Mismatch Delay setting adds a delay before the element becomes true.
A Load Share ID setting identifies the DECS-150 as a load sharing unit in the network. Checking a Load
Sharing Unit number box allows any DECS-150 load sharing units on the network with that Load Share ID
number to share load with the currently connected DECS-150. It is not necessary for the Load Share ID
to be unique for each unit. This allows for load sharing units to be grouped.
Load sharing settings consist of an Enable checkbox and Droop, Kg, Ki, Max Vc, Configuration Mismatch
Delay, and Load Share ID settings.
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