Investigating the Critical Clearing Time of Power System with the Exact Medium Transmission Line Model

Problem statement: The exact medium transmission line model consists of the resistance, series reactance and shunt capacitance. Most of previous research studies show the critical clearing time of single machine infinite bus while neglecting the resistance and capacitance of the line. Approach: This study investigates the critical clearing time of power system with consideration the exact medium 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. Conclusion: It was found from this study that the resistance of the line provides the improvement of the first swing but not for the second swing. The simulation results indicate that for practical medium line, the resistance is very import parameters to determine the critical clearing time of the single machine infinite system whereas shunt capacitance doesn’t affect on the critical clearing time of the single machine infinite bus system.