In China, most of the receiving systems with the UHVDC access are in the situation of "strong DC and weak AC" in present. After the DC blocking fault occurs, the system will undergo the large-scale power flow transfer, which may cause overloads in some lines. Under the circumstance, a thyristor-controlled series capacitor (TCSC) device is added to the receiving system, and a bilevel planning model is established for fixed-capacity and site selection of TCSC devices which takes N-1 security constraints into account. The upper-level planning model aims to minimize the investment cost of installing a TCSC device. The lower-level planning model aims to optimize the power flow under the constraint of N-1. Afterwards, the lower layer selects the N-1 fault that has a serious impact on the system operation through the optimal power flow solution. The lower layer results are returned to the upper layer to add a new constraint and the final solution is given by iterating. The planning model proposed in this paper are verified in the modified IEEE 39-node system.