A Bi-Level Polyhedral-Based MILP Model for Expansion Planning of Active Distribution Networks Incorporating Distributed Generation

This paper proposes a novel mixed-integer linear programming (MILP) model for the expansion planning of active distribution networks, which not only is able to accurately reflect the fundamental characteristics of the problem, but also provides the opportunity to find its optimal solution in a computationally efficient manner. This model is able to jointly expand both the network assets (feeders and substations) and distributed generators (DGs) while minimizing the investment and operation costs and taking all the necessary physical and technical constraints into account. A highly accurate linearization method based on polyhedral approximation is utilized to eliminate the nonlinearities of AC power flow equations and obtain the proposed MILP model. Furthermore, a bi-level approach is also proposed to accelerate the solution process and reduce the computation time. This solution approach is comprised of a pre-solution level in which a simplified MILP model is solved to find a near-optimal initial solution for the expansion planning problem, and a main solution level in which the proposed accurate MILP model is solved considering the already found initial solution. Finally, a 24-node distribution system is used to verify the effectiveness of the proposed planning methodology.