The Effect of Thyristor Controlled Series Capacitor on Transient Stability of Single Machine Infinite Bus System with the Exact Short Transmission Line Model

Problem statement: It is becoming increasingly important to fully utilize the existing transmission system assets due to environmental legislation, rights-of-way issues, costs of construction and deregulation policies that were introduced in recent years. The Thyristor Controlled Series Capacitor (TCSC) has been proposed for better control power flow and dynamic performance. The exact short transmission line model consists of the resistance and reactance. Most of previous researches studies transient stability performance of TCSC in SMIB System while neglecting the resistance of the line. Thus the full capability of the TCSC on transient stability improvement of power system may not be applied. The consideration of the resistance causes difficulty of deriving the mathematical model. Approach: This study investigates the effect of the TCSC on transient stability of the power system with consideration the exact short transmission line mode. The concept of two-port network is applied to simplify the mathematical model of the power system. The proposed method is tested on sample system and compared on various cases. Results: The first swing of rotor angle curve of the faulted system without resistance is obviously higher than that of with resistance whereas the second swing of the faulted system without resistance is slightly less than that of with resistance. The system with a TCSC can improve transient stability of power system. Conclusion: It was found from this study that the TCSC and resistance of the line can improve first swing of rotor angle. However, the resistance of the line provides the negative effect on second swing of rotor angle. The simulation results indicate that for practical short line, the resistance is a very important parameter for evaluating transient stability of power system.