Flexible transmission and network reinforcements planning considering congestion alleviation

Abstract

A framework for obtaining an optimal network reinforcement scheme to jointly meet both long-term transmission capacity requirements as well as the alleviation of short- or medium-term congestion in a competitive power market is presented. A value-based network expansion strategy is formulated in which long-term network investment cost is justified by the long-term congestion cost saving. Network expansions and flexible AC transmission system (FACTS) device installations are investigated as possible alternatives for network reinforcement. These alternatives are considered separately as well as in different combinations. Two types of FACTS devices namely the phase shifter and the series compensator are explored for the purpose. The solution methodology is implemented using the generalised Benders decomposition technique in which the master problem is the network investment cost minimisation and the operational subproblem is the social cost minimisation in network constrained power dispatch. Case studies have been carried out on the modified IEEE 24-bus system to illustrate the features of the proposed technique and to demonstrate the ability of the technique to produce good network reinforcement schemes under various conditions.