Modified Bat Algorithm for transmission network expansion planning considering active power losses

Abstract

This paper presents a metaheuristic algorithm, called BATp optimizer, to solve the combinatorial problem of static transmission networks expansion planning (STNEP) considering the effect of active power losses in the circuits. The optimizer is composed of two modules. One module generates candidate solutions, using the modified Bat Algorithm (BA), and the other that makes solutions with over costs or infeasibilities competitive. The modification made to the original BA consists in the inclusion of a local search intensification operator that acts on the elements of the current global optimal solution to improve the convergence rate and hinder stagnation in a suboptimal solution. The number of elements modified in the current global optimal solution is defined as a function of the number of buses and branches in the analyzed system. The size of the initial population is also defined as a function of the number of buses and branches. The active power losses are represented in the equality constraints of the mixed-integer nonlinear programming (MINLP) problem. The performance evaluation of the transmission network of the analyzed system is done by a linear power flow. The performance of the BATp optimizer was tested in three systems well known in the literature: the IEEE 24-bus and the South Brazilian -SB 46-bus. In each of the analyzed systems, situations were simulated with and without the possibility of generation redispatch. The BATp optimizer was able to find good results compared to those published in the literature, with relatively low computational effort.