Transmission System Expansion Planning Considering Expected Stand-by Cost Based on Probabilistic Approach

This paper proposes a methodology for choosing the best transmission system expansion plan considering expected stand-by cost based on probabilistic approach under security criterion constraint. Long-term grid expansion planning problem includes many uncertainties of network. The method in this paper describes a model of security probability considered stand-by cost of generators in objective function. Security probability is defined as level of uncertainties of contingency elements. Furthermore, the proposed method minimizes total cost including the investment cost as well as operating cost and probabilistic stand-by cost of generators for constructing new transmission lines subject to (N-alpha) contingency security criteria, which are essentially extended types of (N-1) contingency. It models the transmission system expansion problem as an integer programming one. The method solves for the optimal strategy using a branch and bound method that utilizes a network flow approach and the maximum flow-minimum cut set theorem. The fine characteristics are shown by the proposed method applied to the 5-bus system. It demonstrates that the proposed method may become practical tool for solving the power system expansion planning problem