  The rapid integration of Renewable Energy Sources (RESs) strengthens the need
for a power network that can robustly handle the system's uncertain scenarios.
Thus, this paper proposes the first nonlinear novel dual based bi-level
approach for robust AC Transmission Expansion Planning (TEP) plans with
uncertainties in RES generations and loads. It utilizes a convex relaxation and
is solved by Benders Decomposition (BD), where the master determines the robust
AC TEP plan. The novel dual slave model for the second level of BD circumvents
the issues in using the conventional conic dual theory and aids in the
worst-case realization of uncertainties using additional novel constraints. The
novel dual slave is solved using Interior Point Method (IPM), as it is not a
mixed-integer problem. The proposed work also includes additional linear
constraints to reduce the BD's slow convergence and direct the master towards
optimality. The robustness of the AC TEP plans is verified by Monte-Carlo
Simulation (MCS) of the actual nonlinear and non-convex AC Optimal Power Flow
(OPF). The effect of the budget of uncertainty on the AC TEP plans is also
investigated. A comparison with the results of a previous work reveals the
superiority of the proposed work.
