Abstract-Series FACTS devices are capable of relieving congestion and reducing generation costs in the power system. This paper proposes a planning model to optimally allocate TCSCs in the transmission network considering the base case and N − 1 contingencies. We consider a single target year and select three distinct load patterns to accommodate the yearly load profile. A reformulation technique is utilized to linearize the nonlinear power flow constraint introduced by a TCSC. Numerical case studies based on the IEEE 118-bus system demonstrate the high performance of the proposed planning model.