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distribution during load steps. It also enables bump less loading or unloading of the SFC, so
that parallel generators are not exposed to large load steps.
It also enables fixed real power and Var sourcing for advanced uses.
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SureWave SFC performance
11.5.1 Step load capability
The step load capability of a power converter or generator is a measure of how much load can
be applied to the converter or generator, without output voltage or frequency deviating from
specification.
The step load capability of a generator is typically between 10% and 75% of its capacity, de-
pending on the generator and type of prime mover. In contrast, the step load capacity of the
SureWave SFC is 100% of its capacity.
Thus, depending on the parametrization of the SureWave SFC, if it is used in parallel with one or
more generators, the step load capability of the overall system is substantially improved. Imme-
diately on load application, the SureWave SFC typically will take on all the additional load, and
then the load increase is gradually passed over to the generator(s).
11.5.2 Load rejection capability
A load rejection is a decrease in load. Load rejection capability is a measure of how much load
can be removed from the output of a converter or generator while still providing output voltage
and frequency within specifications.
The load rejection capability of a generator set is very dependent on its prime mover. Typical
figures may be:
Steam turbine: 10 to 30% of its present loading.
Gas reciprocating: 50 to 100% of its present loading.
Diesel reciprocating: 90 to 100% of its present loading.
The SureWave SFC has a load rejection capability in excess of its present loading – that is, the
SFC output power can briefly go negative by regenerating power into the source grid.
Thus, if the SureWave SFC is used in parallel with one or more energy sources, it can assist in
handling load rejection by absorbing any energy transients and dissipating them by regenerat-
ing back into the grid. This can prevent the generator(s) from going into “reverse power” and
tripping off. The decrease in load is then passed over to the other generator(s).
Note, for load rejection capability of the SureWave SFC, the real power (P) limits need to be con-
sidered.
