In this paper, a novel non-linear thyristor controlled series compensation (TCSC) control scheme for damping power oscillations and improving transient stability of a multi-machine power system is presented. Based on the analysis of TCSCpower modulation in a two-machine system, a non-linear control law for the TCSC is established via local measurements. With the help of the feedback linearization technique, the non-linear model of a multimachine power system is transferred to an equivalent linearization model. To this equivalent linear system a welldeveloped optimal linear design methodology with integral-of-time-multiplied-absolute error criterion (ITAE) is adopted to achieve optimal control performance. The eflectiveness and robustness of the non-linear control scheme proposed are demonstrated with a three-machine system equipped with a TCSC. In comparison with a conventional control scheme, significant improvements in dynamic performance are achieved by the proposed TCSC control strategy.

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