JIT_V1_N1_RP2 M. Mahdavi H. Monsef A. Bagheri Journal on Information Technology 2277-5250 1 1 24 32 BPSO, Loading Optimization, STNEP, PSO Transmission network expansion planning (TNEP) is an important component of power system planning. It determines the characteristic and performance of the future electric power network and influences the power system operation directly. In this paper, expansion planning has been implemented by merging lines loading parameter in the STNEP and including investment cost into the fitness function constraints using binary particle swarm optimization (BPSO) algorithm. The particle swarm optimization is a recently developed evolutionary algorithm (EA) based on the swarm behavior in the nature and has a strong ability to find the most optimistic results. The motivation for using the BPSO technique is to reduce design effort and find an optimum planning network. Expanded network will possess a maximum adequacy to provide load demand and also the transmission lines overloaded later. The proposed idea has been tested on the Garvers network. The results evaluation shows that the network will possess maximum efficiency economically. December 2011 - February 2012 Copyright © 2012 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=1707