3. Calculate the A B C D constants for a 275 kV overhead line of length 83 km. The parameters per kilometre are as follows: Resistance 0.078 2 Reactance 0.33 2 Admittance (shunt capacitative) 9.53 x 10-6 siemens. The shunt conductance is zero. (Answer: [A = 0.98917+ j0.00256; B = 6.474 + j27.39; C = (-1.0126 × 10-6+j 7.8671 × 10-¹)]
Short Transmission Line
A short transmission line is a transmission line that has a length less than 80 kilometers, an operating voltage level of less than 20 kV, and zero capacitance effect.
Power Flow Analysis
Power flow analysis is a topic in power engineering. It is the flow of electric power in a system. The power flow analysis is preliminary used for the various components of Alternating Current (AC) power, such as the voltage, current, real power, reactive power, and voltage angles under given load conditions and is often known as a load flow study or load flow analysis.
Complex Form
A power system is defined as the connection or network of the various components that convert the non-electrical energy into the electric form and supply the electric form of energy from the source to the load. The power system is an important parameter in power engineering and the electrical engineering profession. The powers in the power system are primarily categorized into two types- active power and reactive power.
![1. A 275 kV three-phase transmission line of length 96 km is rated at 800 A. The values of
resistance, inductance and capacitance per phase per kilometre are 0.078 V, 1.056 mH
and 0.029 mF, respectively. The receiving-end voltage is 275 kV when full load is
transmitted at 0.9 power factor lagging. Calculate the sending-end voltage and current,
and the transmission efficiency, and compare with the answer obtained by the short-line
representation. Use the nominal pi and T methods of solution. The frequency is 60 Hz.
(Answer: V 179 kV per phase)
2. A 220 kV, 60 Hz three-phase transmission line is 320 km long and has the following
constants per phase per km: Inductance 0.81 mH Capacitance 12.8 mF Resistance 0.038
V Ignore leakage conductance. If the line delivers a load of 300 A, 0.8 power factor
lagging, at a voltage of 220 kV, calculate the sending-end voltage. Determine the p
circuit which will represent the line. (Answer: Vs = 241 kV)
3. Calculate the A B C D constants for a 275 kV overhead line of length 83 km. The
parameters per kilometre are as follows: Resistance 0.078 2 Reactance 0.33 2
Admittance (shunt capacitative) 9.53 × 10-6 siemens. The shunt conductance is zero.
(Answer: [A = 0.98917 + j0.00256; B = 6.474 + j27.39; C = (-1.0126 ×
10-6 + j 7.8671 × 10-¹)]
4. A 132 kV, 60 Hz transmission line has the following generalized constants: A =
0.969620.49, B = 52.88274.79 , C = 0.001177/90.15° S If the receiving-end
voltage is to be 132 kV when supplying a load of 125 MVA 0.9 p.f. lagging, calculate
the sending-end voltage and current. (Answer: 165 kV, 498 A)
5. A 500-km, 500-kV, 60-Hz uncompensated three-phase line has a positive-sequence
series impedance z = 0.03 + j0.35 N/km and a positive-sequence shunt admittance
y = j4.4 x 10-6 S/km. Calculate: a) Zc, b) (yl), c) The exact ABCD
parameters for this line.
NB cosh(a + jb) = cosha.cosb + sinha. sinb
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