Woodward 9907-026, Product Manual

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Load Sharing Module (Analog Output) Manual 02029
18 Woodward
Isochronous Load Sharing
The controller circuit compares the voltage on the paralleling lines to the load
signal voltage for this generator set and generates an error voltage. This error
voltage goes through the summing point and the output terminals of the Load
Sharing Module to the speed control. The Load Sharing Module output biases
the speed loop of the speed control so that the fuel is increased or decreased in
order to keep the load signal voltage of this generator set equal to the voltage on
the paralleling lines, while not changing the common frequency of the generator
sets.
Droop Operation
In droop operation, a portion of the output voltage of the Load Sharing Module is
fed back to the controller circuit. This voltage is proportional to the load sensed
and is used by the controller circuit to reduce the output voltage of the controller
circuit by a percentage determined by the DROOP potentiometer. Load Sharing
Module output is reduced, and actuator shaft position is changed, according to
the desired droop percentage.
When a generator set using the Load Sharing Module is paralleled in droop with
other generator sets, the common load signal on the paralleling lines is not used.
The frequency of the generator set could, therefore, vary with load, so it must be
determined by a different means.
In an isolated system with two or more generator sets paralleled, if isochronous
speed control is required, one of the generator sets must be running in the
isochronous mode. This generator set determines the frequency of the system. If
this generator set is in droop and is paralleled with an infinite bus, either by itself
or with other generator sets, the bus determines the frequency. The DROOP
potentiometer and the SPEED potentiometer on the speed control determine the
amount of the load that is carried by the generator (when running in droop).
If an SPM-A Synchronizer is used with the system, it biases the output of the
Load Sharing Module at the summing point, in order to synchronize the generator
set with the bus.