The introduction of flexible AC transmission system (FACTS) has added a new dimension in power system operation and planning. Various types of FACTS controllers such as static compensator (STATCOM), static synchronous series compensator (SSSC), thyristor control series compensator (TCSC), thyristor control phase shifter (TCPS), unified power flow controller (UPFC), etc. are successfully used by various researchers in order to get optimal performance of power system. In this chapter, the various population-based nature-inspired techniques such as grey wolf optimization (GWO), teaching-learning-based optimization (TLBO), biogeography-based optimization (BBO), krill herd algorithm (KHA), chemical reaction optimization (CRO), and hybrid CRO (HCRO) are used to find the optimal size of TCSC and TCPS devices in order to find the optimum performance of IEEE 30-bus power system. The simulation results of various cases demonstrate the effectiveness and robustness of the proposed techniques to solve TCSC-TCPS-based OPF and ORPD problems.