Define the Surge Impedance

The surge impedance $Z_0$ is defined as the square root of the ratio of inductance $L$ to capacitance $C$ of the line.

$Z_0 = \sqrt{\frac{L}{C}}$

Calculate SIL for 132 kV line

Using $V = 132 \times 10³$ V and $Z_0 = \sqrt{160 \times 10³} \approx 400 \Omega$, we find $P_{SIL} = \frac{(132 \times 10³)^2}{400} = 43560 \text{ kW} \approx 44 \text{ MW}$.

$P_{SIL1} = \frac{(132)^2}{\sqrt{160 \times 10³}} \approx 44 \text{ MW}$

Calculate SIL for 400 kV line

Using $V = 400 \times 10³$ V and $Z_0 = \sqrt{62.5 \times 10³} \approx 250 \Omega$, we find $P_{SIL} = \frac{(400 \times 10³)^2}{250} = 640000 \text{ kW} = 640 \text{ MW}$.

$P_{SIL2} = \frac{(400)^2}{\sqrt{62.5 \times 10³}} = 640 \text{ MW}$