Power system restoration with high penetration level of renewable generation — New challenges and strategies

Grid reconstruction after a blackout is a complex process mainly involving power system stability, grid observability and control. Now, with the introduction of embedded renewable generation and with the wide spread of Information and Communications Technologies (ICT), Transmission System Operators (TSO) are facing additional challenges during reconstruction due to uncontrolled generation, decrease of substation autonomy and increase of needed coordination with other actors (DSO, generation,...). In order to face these challenges, several strategies need to be developed by TSOs to speed up and increase the robustness of the system reconstruction: choice of frequency and voltage of reconstruction, determination of number of generating units regulating a network island and clearing or not of DSO substations prior to energization are strategies considered in this paper. In addition, different stages of system reconstruction are defined based on the capability of the reconstructed system to withstand unexpected events and faster reconstruction actions. This analysis leads to the elaboration of strategies and guiding criteria for the optimal design of a grid restoration process.