Optimization of Transmission System Security Margin under (N-1) Line Contingency Using Improved PSO Algorithm.

The abnormalities like (N-1) line contingencies are unavoidable and consequently can cause for either transmission system security margin decrement or power loss increment. Both the issues are primary objectives of the modern power system operation due to their significant effect on generation capacity and economics. This paper proposes Generalized Unified Power Flow Controller (GUPFC) for maintaining adequate security margin and performance improvement under (n-1) contingencies. At first stage, the optimal location of GUPFC device is proposed to determine based on (N-1) line contingency severity index. In second stage, the rating of the GUPFC device is optimized towards minimization of multiobjective function, which formulated using real power loss and security margin index. The parameters involved in the power injection modeling (PIM) of GUPFC and various system operational parameters are optimized using Particle Swarm Optimization (PSO) and Improved Particle Swarm Optimization (IPSO) algorithms towards minimization of multi-objective function. The case studies on IEEE 14-bus and IEEE 30-bus test system are validating the capability GUPFC device to minimize transmission loss and improve security margin significantly even under (n-1) line contingency and need of FACTS devices for real-time. [ABSTRACT FROM AUTHOR]