# HW 3 problems ```EGR 325
HW 3
due Sept 24
4pm, room 352
Using the PowerWorld Simulator, do the following three problems.
1. Open Problem 2_32 (in chapter 2 of the GSSampleCases folder, in the Simulator
folder). This system has an 8 MW/4 MVAr load that is supplied at 13.8 kV
through a feeder with an impedance of 1 + j2Ω. The load is compensated with a
capacitor whose output, Qcap, can be varied in 0.5 MVAr steps between 0 and 10.0
MVArs.
a. What value of Qcap minimizes the real power line losses?
i. Include a screen shot of the PowerWorld one-line diagram for this
value of Qcap. State/show how you determine the real power line losses.
b. What value of Qcap minimizes the MVA power flow into the feeder?
i. Include a screen shot of the PowerWorld one-line diagram for this
value of Qcap. State/show how you determine the MVA power flow into
the feeder. State what “MVA power flow into the feeder” actually is.
c. Why would a power company be interested in the results of (a) and/or (b)
above? (very brief comment)
d. Why would a consumer be interested in the results of (a) and/or (b) above?
(very brief comment)
e. Plot the real and reactive line losses as Qcap is varied between 0 and 10.0
MVArs. Briefly comment on the meaning and/or significance of these
2. Load PowerWorld Simulator case Problem 6_46. Plot the reactive power output
of the generator at Bus 2 as a function of its voltage set point value in 0.005 pu
voltage steps over the range between its lower limit of -50MVAr and its upper
limit of +50MVAr.
a. What is the significance of the reactive power output of a generator, to the
owner of the generator? … to the power system? (very brief comments)
(Note: To change the generator 2 voltage set point first select Tools, Play to
begin the power flow simulation and then click on the up/down arrows on
the bus 2 magenta voltage set point field.)
3. Open Problem 6_59. This models a seven bus system. Bus 7 is the slack bus. The
real power generation/load is shown at each bus, while the per unit reactance of
each of the lines (on a 100MVA base) is shown in yellow. Your task is an openended one. Find one (or two related) things to change on this system that lead to
unexpected, or non-intuitive results.
a. State what you did, perhaps with an annotated figure of the one-line