Manual 02007
DSLC Digital Synchronizer and Load Control
Woodward
69
Figure 5-2. Isochronous Mode
Droop/Isochronous Load Sharing on an Isolated Bus
Droop/Isochronous combines the first two modes. All generator sets in the
system except one are operated in the droop mode. The one unit not in droop is
operated in the isochronous mode. It is known as the swing machine. In this
mode, the droop machines will run at the frequency of the isochronous unit. The
droop and speed settings of each droop unit are adjusted so that each generates
a fixed amount of power as illustrated in Figure 5-3. The output power of the
swing machine will change to follow changes in the load demand.
Maximum load for this type of system is limited to the combined output of the
swing machine the total set power of the droop machines. The minimum system
load cannot be allowed to decrease below the output set for the droop machines.
If it does, the system frequency will change, and the swing machine can be
motorized.
The machine with the highest output capacity should be operated as the swing
machine, so that the system will accept the largest load changes within its
capacity.