A new OPF based distribution system restoration method

• The distribution restoration problem is solved using the Optimum Power Flow (77).
• Electrical constraints, radial configuration and priority consumers are considered (84).
• Discrete variables representing the switch status are modeled as sigmoid function (87).
• Provides a fast and feasible switching operation sequence to restore the system (81).

This paper presents a new methodology to solve the electrical distribution system restoration problem using the Optimum Power Flow (OPF) technique aiming to minimize consumer load shedding. This is a mixed integer nonlinear programming problem, which is difficult to solve because the real network is radial and large scale as well as current and voltage limits must be considered. The discrete variables (0 or 1) representing the open or close switching states are modeled as continuous functions, allowing the problem to be solved using both the Primal–Dual Interior Point method and sensitivity analysis. The restoration problem is solved step by step and whenever a switch closure causes the formation of a loop, the methodology indicates the switch that must be opened in order to maintain the radial network topology. Consequently, the switching sequence to restore the system is obtained. The load to be restored as well as the consideration of priority loads to be supplied is also calculated at each step of the restoration procedure, avoiding additional load shedding tasks. The proposed methodology has been validated using two test systems available in the literature and a 476-bus real distribution system. The results were compared with other methodologies.