A linearized formulation of AC multi-year transmission expansion planning: A mixed-integer linear programming approach

• We propose a linearized formulation for transmission expansion planning (TEP) problem.
• The nonlinear model is transformed into a mixed-integer linear programming (MILP).
• The proposed LACTEP (linearized AC-TEP) will lead to more precise and optimal plan in a power system.

This paper presents a method in expansion planning of transmission systems using the AC optimal power flow (AC-OPF). The AC-OPF provides a more accurate picture of power flow in the network compared to the DC optimal power flow (DC-OPF) that is usually considered in the literature for transmission expansion planning (TEP). While the AC-OPF-based TEP is a mixed-integer nonlinear programming problem, this paper transforms it into a mixed-integer linear programming environment. This transformation guarantees achievement of a global optimal solution by the existing algorithms and software. The proposed model has been successfully applied to a simple 3-bus power system, Garver's 6-bus test system, 24-bus IEEE reliability test system (RTS) as well as a realistic power system. Detailed case studies are presented and thoroughly analyzed. Simulations show the effectiveness of the proposed method on the TEP.