  This research presents the mathematical model of an isolated
wind-diesel-solar PV hybrid power system with conventional
proportional-plus-integral controllers for load frequency control (LFC). In
order to enhance the reliability of the power supply, renewable sources such as
wind and solar energy are integrated with diesel electric power generation
system to supply the power for isolated loads. Isolated hybrid power system is
designed to minimize the mismatch between supply and demand. Due to the
unstable generation of power from wind, solar PV sources, and frequent change
in load, there exist fluctuations of power generation and hence fluctuations
also occur in system frequency and voltage. Conventional PI controllers are
used for the load frequency control of the system to make the frequency
deviation to an acceptable range. In this paper the complete mathematical
modeling of system consisting of a wind turbine induction generator unit, a
diesel engine synchronous alternator unit and solar photovoltaic (PV) panels
with maximum power tracking converter is presented.
