Due to high penetration of renewable energy sources, inter-area oscillations (IAOs) have become serious concern for power system stability. Hence, a wide-area damping controller (WADC) strategy is proposed for thyristor-controlled series compensator (TCSC) device to effectively damp IAOs. The feedback signals for the WADC design are selected by the modal sparse linear quadratic regulator (MSLQR) method, which are sole signals that modulate simple gains to achieve the desired damping performance. Moreover, the multi-model framework approach is adopted to ensure optimal damping corresponding to any uncertainties such as changing operating scenarios and time latency in feedback signals. However, the proposed primary control does not provide frequency regulation; hence, a secondary control based on the switched integral controller is applied in addition to primary damping control to further maintain the frequency at the steady-state level. Performance of suggested strategy is evaluated and verified on IEEE 4-machine, 11-bus system and 16-machine, 68-bus system. A comprehensive analysis shows significant improvement in the damping performance of concerned modes, leaving the local modes almost unaffected while maintaining the frequency at the prescribed steady-state level.