EEL 5250 Power Systems Analysis, Homework #4, Fall 2017
1. For the following radial system, assuming that the complex power consumed by the load is 1 + j0:5 pu,
z = j0:2 pu. Bus 1 connects to the substation and its voltage phasor is V1 = 16 0 . The online load tap
changing transformer can be treated as an ideal transformer to ne tune secondary side voltage. In this case,
the voltage ratio from left to the right is 1 : 1:05. Find V2 and 2 using sweeping method or Newton-Raphson
method.
SL= 1+ j0.5
zOLTC tap at 1.05 position
Bus 1
Bus 2
Figure 1: Problem 1
2. (Example 10.8) A ve-bus system is shown in Fig. 2. Its admittance matrix in per unit values Y is given.
Please ll in the blanks in the following table. An example is shown for Bus 1. Identify the unknown voltage
phasors and setup power injection equations in terms of these voltage phasors.
Table 1: Input data and unknowns
Bus Known (Power Injection and/or Voltage) Unknowns (Power Injection and/or Voltage)
1 V1 = 1:0, 1 = 0 P1, Q1
3. Choose one of the methods: Newton-Raphson method or fast decouple method to solve the power ow
problem. Please copy paste your codes in your HW report. Put a box for the iteration procedure.
4. Please present the following:
Plot the error versus iteration (use semilogy function).
Present a table of voltage phasors at each bus.
Compute the total power loss in the system.
5. Please adjust the generator dispatch pattern and recompute the system power loss. Show that the power loss
can be reduced. Present a table to compare the original case and your constructed case in terms of generator
dispatch pattern and power loss.
Table 2: Case study comparison
case 1 case 2