Mathematical model for describing characteristics of TCSC

The choice of the synchronizing signal has strong impacts on the transient behaviors of TCSC (thyristor controlled series compensation). When the capacitor voltage is used as the synchronizing signal, both overshoot and oscillation occur. However, when the line current is employed, TCSC acts as a first-order lag element. This paper presents a mathematical model to explain this extraordinary phenomenon. Based on the model, the factors affecting transient response of TCSC are also discussed. The model can give advice to the design of TCSC controller. Rules of controller parameters adjustment are discussed. This model is verified by digital simulation results.