B. Diesel Generator Model
In Fig. 5, the standard model of the diesel generator and
speed governor is illustrated in block diagram form. This model
is widely used and describes well the dynamic behavior of small
diesel-generator sets, as it has been shown in [35]. The diesel
engine and the valve actuator servomechanism are represented
by first-order lags, with time constants Td and Tsm , respectively.
Parameters of the speed governor are the droop R and the integral
control gain Ki . The objective of the integral control is
to eliminate the steady-state frequency error and in many cases
(particularly in small and older units) may be absent. The actuator
position limiter is ignored in the frequency domain analysis,
where linearized models are used. Input to the model is the load
demand PL , i.e., the output power of the electrical generator.
Output is the generator speed ωd , which is equal (in per unit)
to the electrical frequency of the system ωe . The derivation of
the model equations is a straightforward and rather trivial procedure,
and for this reason it is omitted.