Optimal Restoration of Electrical Distribution Systems Considering Switching Sequence

Abstract

A short literature review on optimal restoration methods applied to electrical distribution systems (EDS) was presented in chapter one. On that context, this chapter presents a mixed-integer linear programming (MILP) model for the optimal restoration of electrical distribution systems, considering switching sequence. After a permanent fault has been identified, the optimal service restoration determines the status of the remote-controlled switches and the operation of the dispatchable distributed generation (DG) units, in order to isolate the faulty zone and supply as many customers as possible. The proposed mathematical approach considers the switching sequence over a horizon of S discrete steps, guaranteeing that the operational constraints of the system are not violated in every step. By considering the switching sequence in the optimization model, the restoration time and the number of switching operations can be controlled. Thus, the reliability and the power quality of the system are enhanced. The use of a MILP model guarantees convergence to the optimal solution by applying convex optimization techniques. Tests are run using a 136-node distribution system with 28 remote controlled switches, and dispatchable DG. Finally, a comparative analysis is used to establish the relationship between the total un-supplied demand and the number of switching actions along the sequence horizon.