Transient Stability of the Power System with the Exact Long Transmission Line Model

Problem statement: The exact long transmission line model consists of the lump of the series resistance, reactance and shunt capacitance. With the consideration the actual long transmission line model, it causes in the difficulty of deriving the mathematical model. Approach: This study investigates the transient stability of power system with consideration the exact long transmission line model. The concept of two-port network is applied in this study. The generator, transformer and short transmission line are represented by two-port networks. With the combination principles of the series and shunt connection, the mathematical model is achieved in a much simpler way. The proposed method is tested on the sample system and compared on various cases. Results: The first swing of rotor angle curve of the faulted system without the resistance is obviously higher than that of with the resistance whereas the second swing of the faulted system without the resistance is slightly less than that of with the resistance. The critical clearing time of the system with the resistance is better than that of with resistance. Conclusion: It was found from the simulation results that the resistance of the line provides the improvement of the first swing but not for the second swing. It was found from this study that for practical long line, the resistance is very import parameters to determine the critical clearing time of the single machine infinite system whereas shunt capacitance insignificantly affects on the critical clearing time of the single machine infinite bus system.