ABSTRACT
This chapter examines models of transmission lines. In many power system analysis problems, the model of transmission lines is of fundamental importance. Some of the most important analysis problems are: power flow analysis, short-circuit analysis, harmonic analysis, and electrical transient analysis. The chapter considers the transmission line equations that form the basis for all subsequent models of power lines. Most of the time, power system operates under sinusoidal steady-state conditions. In this case the imposed voltages and currents on the transmission line vary sinusoidally with frequency f. Since the transmission line is a linear system, the currents and voltages at any point in the transmission line will vary sinusoidally with time. The same analysis can be applied to three-phase transmission lines. A special case of the modal decomposition results in what is known as the sequence models of a three-phase line. The chapter then presents the computation of equivalent circuits from the transmission line parameters.
