Transmission Line Parameter Calculation

Transmission line length formula:


Length=\frac{\sqrt{XB}}{2\Pi f }\times the velocity of light in km/s

Now suppose  a transmission line parameter data is as follows

R= 0.010 pu, X= 0.085 pu, B=0.176 pu.

The base value of power and voltage is given as

Vb=230 kV , Sb= 100 MVA

Then the length is

Length=\frac{\sqrt{0.085\times0.176}}{2\times3.1416 \times 60} \times(3\times 10^5 km/s)

Length = 97.33 km


Now we will calculate the resistance value:

\mathbf{R_{actual}= R_{base}\times R_{pu}}

R_{base}= X_{base}= \frac{V_{b}^{2}}{S_{b}} = \frac{(230\times 10^3)^{2}}{100\times 10^6} = 529

R_{actual}= 529\times 0.01 = 5.29 \Omega

R_{\Omega /km} = R_{actual}/Line Length = 5.29/97.33= 0.0543 \Omega /km

Zero Sequence Resistance R_{0}= 0.0543 \times 3 = 0.0163 \Omega / km

Inductance Value Calculation:

X= 0.085 pu

Xbase= RbaseXbase =529Xactual= 529×0.085             = 44.965Lactual= Xactual2πf           =44.9652×3.1416×60           = 0.1192

X_{base}= R_{base} = 529

X_{actual}= 529\times 0.085 = 44.965



So L actual is 0.1192 Henry

Want to get the value in per kilometer, so we will divide this value by the total length of the transmission  line(97.33 km)

LH/km= 0.119297.33             = 1.225×103 H/km

Zero sequence Inductance will be

L0= 1.225×103×3     =3.676×103 H/km

Capacitor Value Calculation:

In order to find the value of capacitance, first, we have to calculate the value of susceptance which is the reciprocal of

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