This model demonstrates the dissipation of active power of a purely resistive transmission line, connected to two infinite buses, one with a phase-to-phase voltage U = 10 kV, one with a phase-to-phase voltage U = 9 kV, both with a 30 deg phase. The resistance of each conductor is 1 Ohm.
As a consequence, the current flowing in each conductor is
I = (VA - VB)/R = ((UA-UB)/sqrt3)/R = 577.35 A.
The reactive power flow in the line is zero. The active power entering the line from portA is
3*VA*I = UA*(UA - UB)/R = 10 MW
while the active power dissipated by the transmission line is
portA.P + portB.P = 3*(VA - VB)*I = (UA - UB)^2/R = 1 kW
By choosing a base power of 10 MW and a base voltage of 10 kV, the current flowing through the line is 1 p.u., the active power entering portA of the line is 1 p.u. and the active power leaving portB of the line is 0.9 p.u. All currents and voltages have 30 deg phase.