In this paper we apply the singular perturbation based nonlinear control redesign of to guarantee a desired transient performance of single machine infinite bus (SMIB) electric power systems with dynamic flexible AC transmission system (FACTS) control. We illustrate the design by two different case studies, namely, a SMIB system with a thyristor controlled series compensator (TCSC) installed on the transmission line, and a system feeding an induction motor load controlled by a static VAr compensator (SVC). For both of these plants, we redesign the mechanical power input to the main generator to guarantee a desired closed loop transient performance even in the presence of the FACTS dynamics. The effectiveness of the redesigns in recovering desired system trajectories is then illustrated through simulations.