Recently, a robust nonlinear coordinated generator excitation and Thyristor-Controlled Series Capacitor (TCSC) controller has been proposed to enhance the transient stability of a single-machine, infinite-bus (SMIB) power system 111. The extension of this work to the multimachine setting is presented in this paper whereby the TCSC is located at the midpoint of transmission lines in a power system. In order to design a feedback controller to guarantee the overall stability of the multimachine power system, several practical factors are taken into consideration. These factors include the variation of network parameters, the presence of parameter uncertainities and the need to achieve a coordinated control with the use of a TCSC. Simulation results are presented to show the effectiveness of the proposed controller in stability enhancement.