EEL303: Power Engineering I - Tutorial 5
1. A single circuit 50 Hz, 3-phase transmission line has the following parameters per km:
R=0.2 ohm, L=1.3mH and C=0.01
µ F. The voltage at the receiving end is 132 KV. If the line is open at the receiving end, find the rms value and phase angle of the following:
(a) The incident voltage to neutral at the receiving end (reference).
(b) The reflected voltage to neutral at the receiving end.
(c) The incident and reflected voltages to neutral at 120 km from the receiving end.
2. Determine the efficiency of the line in the above problem if the line is 120 km long and delivers 40 MW at 132 KV and 0.8 p.f. lagging.
3. Determine the ABCD parameters of the line of above problem and verify the sending end quantities found in the above problem.
4. A three phase 50 Hz transmission line is 400 km long. The voltage at the sending end is 220 KV. The line parameters are r=0.0125 ohm/km, x=0.4 ohm/km and y = 2.8
×
10
−
6 mho/km. Find the following:
(a) The maximum permissible line length if the receiving end no-load voltage is not to exceed 235 KV.
(b) For part (a), the maximum permissible line frequency, if the no-load voltage is not to exceed 250 KV.
5. A 275 KV transmission line has the following line constraints: A=0.85
5; B=200 75
(a) Determine the power at unity power factor that can be received if the voltage profile at each end is to be maintained at 275 KV.
(b) What type and rating of compensation equipment would be required if the load is
150 MW at unity power factor with the same voltage profile as in part (a).
(c) With the load as in part (b), what would be the receiving end voltage if the compensation equipment is not installed.
6. Input to a single-phase short line shown in below Figure is 2000 KW at 0.8 lagging power factor. The line has a series impedance of (0.4+j0.4) ohms. If the load voltage is 3KV, find the load and receiving end power factor. Also find the supply voltage.
Figure 1:
Electrical Engineering Dept - IIT Delhi