Application of Genetic Algorithms to the Optimal Design of Power Distribution Systems. (Abstract) This PhD thesis presents the application of an evolutionary algorithm (genetic algorithm), for finding out the best power distribution network reliability while simultaneously minimizing the system expansion costs. A non-linear mixed integer optimization model, achieving the optimal sizing and location of future feeders (reserve feeders and operation feeders) and substations, has been used. The proposed methodology has been tested for distribution systems with dimensions that are significantly larger than the ones frequently found in the papers about this issue. The suitable curve of nondominated solutions, composed of a high number of solutions, allows the planner to select a solution of the multiobjective optimal design. Furthermore, this methodology is general since it is suitable for the multiobjective optimization of n objectives simultaneously. The model and the algorithm have been applied intensively to real life power systems showing its potential of applicability to large power distribution networks in practice.