Priority based restoration of unbalanced electric distribution systems after multiple faults

This paper presents a heuristic optimization model to restore the electrical distribution systems (EDS) after multiple faults due to natural disasters. The algorithm finds the switching sequence to energize as many healthy zones as possible after multiple simultaneous faults in an unbalanced distribution system. To improve the grid resiliency, utilities have to quickly clear the faults and restore power to the affected customers. The proposed algorithm also gives the order in which the faults have to be cleared depending on the disconnected load and the number of customers affected. Weights can be assigned based on priority to critical loads such as hospitals, emergency call centers, fire stations etc. At each step of the switching sequence, the distribution system operating constraints such as line flows, bus voltages have to be satisfied. OpenDSS is used to perform power flow and MATLAB for optimization. Studies on IEEE-123 bus system validate the algorithm proposed.