Short transmission lines phaser diagrams

Here sending current is equal to receiving current .But sending & receiving voltages are not equal to due to impedance voltage drop in the transmission line.

Vs=Vr+IZ

Receiving end voltage lag by  angle with respect to sending end voltage. In practical situation step-up and step –down transformer is used at sending end and receiving end of the transmission line as below.

Therefore total impedance can be implemented as Z=Z_T1+Z_L+Z_T2

This can be equivalent to single phase circuit as below and transformer impedance can be assumed as series impedance.