In this paper, a load frequency controller is designed for isolated wind Diesel hybrid power
systems, and its effect on the transient performance of the system is evaluated. The modelling of the system,consisting of a wind turbine induction generator unit and a Diesel engine synchronous alternator unit,is presented along with the controller, both for continuous and discrete control cases.Optimum parameter
values are obtained for different hybrid power system examples with continuous and discrete load
frequency control and with and without blade pitch controllers, using the integral square error criterion (BE).It is shown that wind Diesel or multi-wind Diesel hybrid power systems, with blade pitch control mechanism and with continuous load frequency control, have better dynamic performance than any other configuration of the isolated wind Diesel hybrid systems.Finally, some of the transient responses of the systems are shown for optimum gain settings.