Question

A 50-Hz, three-phase transmission line is 300 km long. It has a total series impedance of 23 + j75 Ohms and a shunt admittance of j500 µS. It delivers 50 MW at 220 kV, with a power factor of 0.88 lagging. Find the voltage at the sending end using:

1) the short line approximation.

2) the medium-length approximation.

3) the long line equation.

How accurate are the short- and medium-length approximations for this case?

Answer 1

491 KA

Shxt TanSmis sion Jine 15 Is 1 1925 61 64 32ot 1 1825 to 61 693 jSin 61693 225 3112 t9.9y065 225.525 2.5 Kv 5 Itrz 2. 2 2 NoDu5) (23t i 5 22023+1) 219 125tj I265 t 1:696 294.593 219.125+ il265t3:32888 213

ys2-一228:053841 9.4743. Iva l = 228,25 KV Long Line Trans mission exe Tzr-一1231,15)(ja.ono5) 0.0375 0 o115 00332237 10u _18.yy7/12.g5 0.0005し3c .Ze - 2 23t 15-ー เป็005 1--39trtg 84とか525- 391 722-58-7179

isin hal Sin h 1 9357 nh-19386 Sin -02935) -1, ol88 ±10.005785 1018 0 325 e Sinh ーSinh(0,19586)c s (-0, 0293 57)njusbla 19586)- S n (0.029351 SMg711X0.9g956-10.02.99 0299 0.1992 -63. put above values in equation (1 81 0 325) + 3-0333-529 (0:1125) (a.1992と8-63) Vs E V3.96 lo: 325 +111 -45.512 三 232-1997 trt 1,122 232.308-156 kv V5232 308 K v IVs1 232 308kV ムng line