The A, B, C, D constant of a 220 kV line are : A = D = 0.94 ∠1°, B = 130 ∠73°, C = 0.001 ∠90°. If the sending end voltage of the line for a given load delivered at nominal voltage is 240 kV, the % voltage regulation of the line is

Concept:

Voltage regulation of the transmission line is defined as the ratio of the difference between sending and receiving end voltage to receiving end voltage of a transmission line between conditions of no-load and full load.

It can be expressed in percentage as

\(V.R = \frac{{{V_{RN}} - {V_{RF}}}}{{{V_{RF}}}} \times 100\)

Sending end voltage for the transmission line is given as,

V_S =AV_r + BI_r

Under no-load condition, Ir = 0

Calculation:

Voltage at sending-end,

V_s = AV_R + BI_R

At no-load, I_R = 0

From the given data,

V_RF = 220 kV

From the above concept,

\(\begin{array}{l} \Rightarrow {V_{RN}} = \frac{{{V_S}}}{A} = \frac{{240 \times {{10}^3}}}{{0.94}} = 255.3kV\\ \% \ V.R = \frac{{255.3 - 220}}{{220}} \times 100 = 16\% \end{array}\)