International Journal of Electronic and Electrical Engineering. ISSN 0974-2174 Volume 4, Number 1 (2011), pp.123-134 © International Research Publication House http://www.irphouse.com Alleviation of Line Congestion using Multiobjective Particle Swarm Optimization Sawan Sen 1 , S. Sengupta 2 and A. Chakrabarti 3 1 EE Department, Techno India, Salt Lake, Kolkata, India 2 Applied Physics Department, University of Calcutta, India 3 EE Department, Bengal Engineering and Science University, Howrah, India E-mail: 1 sen_sawan@rediffmail.com, 2 samarsgp@rediffmail.com 3 a_chakrabarti55@yahoo.com Abstract This paper presents an effective method of congestion management. Congestions or overloads in transmission network are mitigated by generation rescheduling and/or load curtailment. Here, the two conflicting objectives 1) mitigation of overload and 2) minimization of cost of operation are optimized to provide pareto-optimal solutions. A multiobjective Particle Swarm Optimization (MOPSO) method is used to solve this complex nonlinear optimization problem. The proposed congestion constrained cost optimization algorithm, is capable of limiting line congestion with a minimum management charge without any load curtailment and it also provides better operating conditions in respect of voltage profile, total line loss and security for the system during contingency. For contingency selection and ranking, a Security Sensitivity Index (SSI) has also been proposed in this paper. The main advantage of this algorithm is that, it can also confine the level of congestion at any preferred value according to the affordable congestion management cost decided by market participants in deregulated environment. Though the proposed algorithm has been shown to be tested on IEEE 30 bus test system, the same has been found to be effective with system of higher number busses. Keywords: contingency, congestion management, particle swarm optimization, generation rescheduling, security sensitivity index. Introduction The main objective of power system restructuring is to provide the customer more