This paper presents the methodology followed for sizing a flywheel energy storage system (FESS), in order to prevent frequency stability problems in an isolated network with an increased production of renewable generation. The analyzed case study is a real isolated power system that includes diesel, wind and photovoltaic solar generation. In the proposed methodology, the flywheel sizing is obtained from performing dynamic simulations of the power system, considering foreseen wind and photovoltaic power variations, namely a severe major power loss or frequent and short-term typical fluctuations. The obtained results demonstrate that the dimensioned FESS, with a proper choice of the control parameter values, provides the necessary control action to avoid security problems in the analyzed power system. They also reveal that in order to obtain an efficient FESS operation, for different types or severity level of expected renewable disturbances, the amount of FESS stored energy and the values of the FESS control parameter must be adapted on line, by following the suggestions of intelligent control algorithms
