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Sending end active power from ABCD, 132/130.5 kV

Short answer

Sending end active power is −27.63 MW, meaning 27.63 MW flows into the sending-end bus. Result from power-circle equation with VS=132 kV, VR=130.5∠10° kV, A=0.97∠0.5°, B=100∠75° Ω.

A 3-phase overhead line has the following parameters: VS = 132∠0° kV, VR = 130.5∠10° kV, A = 0.97∠0.5°, B = 100∠75° ohms/ph. Determine the sending end active power.

Use the sending-end power-circle equation (taking D=AD = A). With line voltages in kV, the result is in three-phase MW:

PS=∣A∣∣VS∣2∣B∣cos⁡(β−α)−∣VS∣∣VR∣∣B∣cos⁡(β+δ)P_S = \frac{|A||V_S|^2}{|B|}\cos(\beta-\alpha) - \frac{|V_S||V_R|}{|B|}\cos(\beta+\delta)

Here δ\delta is the angle by which VSV_S leads VRV_R. Since VS=132∠0∘V_S = 132\angle0^\circ and VR=130.5∠10∘V_R = 130.5\angle10^\circ,

δ=0∘−10∘=−10∘\delta = 0^\circ - 10^\circ = -10^\circ

Data: ∣A∣=0.97|A| = 0.97, α=0.5∘\alpha = 0.5^\circ, ∣B∣=100 Ω|B| = 100\ \Omega, β=75∘\beta = 75^\circ.

Substitution

∣A∣∣VS∣2∣B∣=0.97×1322100=169.01∣VS∣∣VR∣∣B∣=132×130.5100=172.26β−α=74.5∘,β+δ=65∘\begin{aligned} \frac{|A||V_S|^2}{|B|} &= \frac{0.97\times132^2}{100} = 169.01 \\ \frac{|V_S||V_R|}{|B|} &= \frac{132\times130.5}{100} = 172.26 \\ \beta-\alpha &= 74.5^\circ,\quad \beta+\delta = 65^\circ \end{aligned} PS=169.01cos⁡74.5∘−172.26cos⁡65∘=169.01(0.2672)−172.26(0.4226)=45.17−72.80=−27.63 MW\begin{aligned} P_S &= 169.01\cos74.5^\circ - 172.26\cos65^\circ \\ &= 169.01(0.2672) - 172.26(0.4226) \\ &= 45.17 - 72.80 = -27.63\ \text{MW} \end{aligned}

Meaning

PSP_S is negative because the receiving-end voltage leads the sending-end voltage by 10∘10^\circ. Active power flows from the leading to the lagging end, so about 27.6 MW actually flows out of the line at the sending end (from the "receiving" bus towards the "sending" bus).

Answer: PSP_S ≈ −27.63 MW (27.63 MW flows into the sending-end bus).

✓ Answer checked by Claude Opus 5.5 (high effort)

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