Short Transmission Line

Transmission lines can be broken down to four basic parameters:
R - Resistance in Transmission Line
L - Inductance in Transmission Line
G - Shunt Conductance
C/2 - Half Capacitance (ignored in short transmission lines)

For now, I am just going to cover 3-phase short transmission lines, which are defined as less than 50 miles or 80 km. There are two primary equations.

Igen = Iload = I
The current is same through both ends of the transmission line.

Vgen/√(3) = Vload/√(3) + I * (R + jL)

V/√(3) is the voltage conversion from a 3-phase to a single phase.
R+L is the impedance equivalent in the transmission line.

Bonus information:

Percent Voltage Regulation: %regulation = 100% * (Vgen - Vload) / Vload

Percent Voltage Regulation is used to measure the change of terminal voltage when there is a change in the load current. A good generator regulation is when there is no change terminal voltage if there are changes between a no load and full load. If the terminal votlage change is high, then you have poor voltage regulation.

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