Model-based control design of a TCSC-compensated power system

The characteristic of a thyristor-controlled series compensator (TCSC) is usually defined by the overall reactance of the device versus the firing angle of the TCR that is connected in parallel with a fixed capacitor. This characteristic is nonlinear in nature. Most of the TCSC control systems employed in practice use a conventional type controller to obtain the reactance order. This reactance order is converted into the corresponding firing angle of the TCR through a look-up table. However, in most cases, this controller is designed heuristically and there is no guarantee that such a control law will provide a global stability. In this paper, the characteristic of this device is used to obtain a linear, discrete-time state space model of a TCSC-compensated transmission line. This model is derived in the d–q axis domain. Three different controllers are designed based on this model, two of which are used for regulation and one for power tracking. The model and the controllers are validated through digital computer simulation studies.