Transmission Line
- Build the power system shown in Figure 1 using the data in the Bus and branch tables
which are given below. - Show on the one-line diagram all parameters: bus voltages (both magnitude in per unit
and angels), line flows (both numerical values on both ends of the line and symbolical
by means of arrows) for real and reactive power. - Simulate the circuit and observe the values on the one-line diagram and:
a. Explain whether the line flows are as you would expect them (direction and
magnitude of P & Q). Give reasons for your answer.
b. Describe the size of the arrows as they propagate from the Bus 1 to Bus 2 or vice
versa. - Graph (record the change in voltage as you vary the load from 0 to 1000 MW) the load
bus voltage magnitude and angle as a function of load real power (assuming unity power
factor at the load). Change the load in steps of 50 MW.
a. Describe the changes you observe.
b. Why does the reactive power flow in the line change despite the load being unity
power factor?
c. Why do you think the arrows that represent reactive power flow diminish as they
get closer to the load end? - Increase the load reactive power from 0 to 500 MVArs in steps of 25 MVArs (assume
the load real power remains fixed at the rated value of 500 MW) and plot graph of load
voltage and angle versus load reactive power.
a. Describe the changes you observe.
b. How does your observation differ from that in (4(a)) above?
Figure 1: Two bus power system
Table 1: Bus data
Bus
Number Name Nom kV PU Volt
Volt
(kV)
Angle
(Deg)
Load
MW
Load
Mvar
Gen
MW
Gen
Mvar
1 1 138 1 138 0 1000
2 2 138 500
Table 2: Branch Data with MVA Base of 500.
Branch Branch Device Type
From
Bus To Bus Line Xfrmr R X B
Lim
MVA
1 2 Yes NO 0.02 0.08 0.8 1000