Dynamic simulation studies for restoration planning of island power systems

Power system restoration following a system collapse, is a difficult and multi-faceted problem. A wide variety of control actions has to be performed on time, while constraints such as power balance and system stability have to be carefully respected. The application of dynamic simulation software in studying various transients during the restoration phase of Crete, the largest island of Greece, is presented. Simulation results covering distinct steps of the restoration procedures are displayed. Further, the presence of negative sequence currents due to transmission line asymmetry is investigated. These currents under light-load conditions and during restoration have been suspected of preventing synchronisation of start-up generators.