Application of hardening strategies and DG placement to improve distribution network resilience against earthquakes

During natural disasters, distribution systems operation is severely affected by facing many failures. In this regard, it is crucial to enhance the resilience of the distribution systems (DSs) against these disasters. However, nowadays, due to limitation of resources for investment in these networks, only the most efficient measures should be implemented. In this paper, a new tri-level optimization model based on the min-max-min model is presented to improve the distribution system resilience. In this method, reviewing the past earthquakes' consequences in Iran and some parts of the world, three strategies are taken into account: 1- hardening distribution poles 2- hardening the connection of distribution transformers on their supporting poles 3- allocating distributed generator (DG) units in candidate nodes. In this model, the system planner determines which lines and nodes to be hardened in the upper level. In the middle level, the most vulnerable lines and nodes under occurrence of natural disasters are identified. In the lower-level, the system operator decides how to reconfigure the grid by a set of switching operations to minimize the load-shedding. The proposed method is implemented on a real 48-bus distribution network in Tehran. The results verify the effectiveness of the proposed method.