Question

#2. A 3-phase, 60-Hz transmission line is 140 miles long and has r :0.30 Ohms/mile, x =1.5 Ohms/mile, and the shunt admittance is 7.8 x 100900 mho /mile. The load at the receiving end of the line is 36 MVA at 220 kV and a power factor of 0.90 lagging (i)Find the ABCD parameters of the line. (i)Find the sending end phasor voltage, Vs and phasor current, Is iv)What is the real power, P and the reactive power Q at the sending end? (v) Calculate the the voltage regulation, V.R., of the line. (vi)What is the efficiency, n, of the transmission line?

Answer 1

Consider medium �T� Network Transmission line Impedance/mile = (0.3 + j 1.5) ohm for 140 miles, Total impedance z^bar = 140(0.3 + j 1.5) z^bar = 42 + j 210 ohm Admittance/mile = 7.8 times 10^6 angle 90 degree for 140 miles, Total admittance Y^bar = 140 times 7.8 times 10^-6 angle 90 degree = 1.092 times 10^-3 angle 90 degree ABCD parameters A = D = (1 + Y^bar z^bar/2) = 1 + (1.092 times 10^-3 angle 90 degree)(42 + j 210)/2 = 0.8856 angle 1.4837 degree C = Y^bar = 1.092 times 10^-3 angle 90 degree B^bar = z^bar(1 + y^bar z^bar/4) = (42 + j 210)(0.9427 + j 0.01147) = 201.902 angle 79. 387 degree A = 0.8856 angle 1.4837 degree C = 1.092 times 10^-3 angle 90 degree B = 201.902 angle 79.387 degree D = 0.8856 angle 1.4837 degree. \r\n Receiving end current I_R = SR/squareroot 3 times V_1 I_R = 36 times 10^6/squareroot 3