A 220-kV, 60-Hz, three-phase transmission line is 120 km long. The transmission line parameters are: R = 0.15 ohms/km, X = 0.9 ohms/km, Y = j5.8 x 10^-6 Siemens/km, where R is the resistance per km, X is the reactance per km, and Y is the shunt admittance per km. The voltage at the receiving end of the transmission line is 220 kV line-to-line. The load at the receiving end is 100 MVA at 0.9 power factor lagging. Determine: 1. the sending end voltage VS (line-to-line) in kV [15 marks] 2. the voltage regulation [5 marks] 3. the power factor at the sending end [5 marks] 4. the efficiency of the transmission line [5 marks]