Automatic Selection Method for Candidate Lines in Transmission Expansion Planning

How to select candidate lines to improve the quality and to reduce the computation burden of the transmission expansion planning is an important issue, considering the trend of multi-regional transmission network interconnection. In this paper, a method consisting of five stages to select candidate corridors is proposed, which can provide an optimal candidate set for system planners. In the first and second stage, existing corridors are reinforced to eliminate congestion and to satisfy N-k security criteria. In the third stage, candidate buses are identified to specify the scope of new possible corridors. In the fourth stage, the difference of local marginal price is applied to select new corridors. In the fifth stage, residual possible corridors are checked by using a linear relaxation technique to enhance the performance of the candidate set, and to reduce the required computation time. The proposed method is verified on the revised IEEE 24-bus test system and revised IEEE RTS-96-bus test system.