In this paper, to introduce the frequency control by the PV
generator, a new control method based on simple fuzzy logic
is proposed for the PV–diesel hybrid system. This method uses
fuzzy control to produce the output power command. Three inputs
are considered for fuzzy control: frequency deviation of
the isolated utility; average insolation; and change of insolation.
The output power command of the system is decreased to response to a low frequency and is increased to response to a
high frequency. First, the proposed method is compared with the
conventional maximum power point (MPP) control considering
two cases: with and without an ESS. Then, the proposed method
is compared with the control method described in [30]. From
the numerical results, it is found that the proposed method is
effective in achieving the following key features: frequency regulation
by the PV generator as it controls the PV power according
to the frequency deviation; supplying the possible maximum
amount of PV power to the isolated utility without reducing the
reliability of the utility; and reduction of the capacity of the
ESS.