A nonlinear binary programming model for electric distribution systems reliability optimization

Abstract

This paper presents a new nonlinear binary programming model aiming to minimize the SAIDI and SAIFI reliability indices of a distribution feeder. Graph theory and a contingency simulation-based technique are used in the explicit formulation of the objective functions to accurately model the protection system response to faults and system reconfiguration practices. To ensure the solution’s feasibility both technical and economic constraints are considered. An alternative economic constraint is proposed, taking into account the current locations of the protective devices and sectionalizing switches, which directly affect the utility costs for reliability improvement. To solve the proposed model, an optimization technique based on the branch-and-bound algorithm is used in this paper. Hence, this technique enables deterministic optimization of distribution feeder reliability by identifying types and locations of protection devices and sectionalizing switches, so that SAIDI and SAIFI reliability indices are minimized. Test cases are presented to illustrate the reliability optimization of a test feeder considering the use of different protection schemes and cost constraints. A value-based reliability optimization formulation is derived from the proposed model and its application to the test feeder is also illustrated. Additionally, the solutions obtained from the proposed model are compared with the solutions obtained from two other state-of-the-art models found in the literature. A comparative study is also carried out to evaluate the efficiency of the genetic algorithm in solving the proposed models.