Development of network dimensioning guidelines for Renewable Island

Advancement in renewable energy sources (RES) such as photovoltaic (PV) and wind turbine generators (WTG) create the possibility of a transition from conventional diesel powered islands towards a “Renewable Island”. This transition comes with challenges, as PV and WTGs are equipped with converters and so naturally they do not contribute to the system inertia and have a small amount of short circuit (SC) power in comparison to classical voltage controlled synchronous generators. Thus, the focus of this work is to develop network dimensioning guidelines for a Renewable Island with low inertia and less short circuit power, in such a way that the system will remain stable in frequency and voltage when facing transient disturbances. Initially, the number and size of power generating units are analytically determined in order to achieve steady state stability of an island in presence of RES. Then, guidelines are given in order to calculate droop settings of the primary frequency controllers for frequency stability and minimum SC power required for voltage stability. Simulation of an off-grid Renewable Island in the simulation program PSS®SINCAL is provided to validate the correctness of the dimensioning guidelines.