ECE 466 Power Systems I
Intro to PowerWorld Simulator
Submission Deadline: 02/15/2019
This assignment introduces PowerWorld version 20, and shows how shunt capacitors
can be used for reactive compensation. There is a free educational version of
PowerWorld software, which solves power systems with up to 42 buses that can be
Power system analysis requires a model of the power system. With PowerWorld, you
can either build a new case (model) from scratch or start from an existing case. Most
of the time, including here, we'll start from an existing case. In ECE 466 using
PowerWorld we’ll be assuming a balanced three-phase, 60 Hz ac system. The model
of the system can be shown using a oneline diagram. As the name implies, on a
oneline the actual three phase conductors are shown using a single line. The initial
oneline used here is shown in Figure 1.
Figure 1: Initial Case Oneline Diagram
In the onelines generators are shown as a circle with a "dog-bone" rotor, large arrows
represent loads, and transmission lines are simply drawn as lines. In power system
terminology, the nodes at which two or more devices join are called buses. Hence this
is a three bus system, though initially Bus 3 is not connected. In PowerWorld thicker
lines usually represent buses; the bus voltages are shown in kilovolts (kV) in the fields
immediately next to the buses. In addition to voltages, power engineers are also
concerned with how power flows through the system (the solution of the power flow
problem will be discussed later in the semester). In PowerWorld, power flows can be
visualized with arrows superimposed on the generators, loads, and transmission
lines. The size and speed of the arrows indicates the direction of flow. Here the green
arrows show the flow of real power and the blue arrows the flow of reactive power.
1. Download the Lab2 case files (zip format) uploaded on canvas.
2. Start PowerWorld. To open the initial case click File, then select Open Case.
This displays the Open Dialog. Select the Lab2_Start case, and then click
Open. The display should look similar to Figure 1.
3. PowerWorld has two major modes of operation. The Run Mode is used for
running simulations and performing analysis. The Edit Mode is used for
modifying existing cases and building new cases. Like many programs,
PowerWorld uses a ribbon interface. To change modes, make sure the ribbon
is visible, and then click on either the Edit Mode or Run Mode buttons; both
are located in the upper left portion of the display immediately below the
PowerWorld icon. For the next steps few steps select the Run Mode.
4. One of the unique aspects of PowerWorld is its ability to animate power
systems. To start the animation, select the Tools tab on the Ribbon and then
click on the green and black arrow button above Solve (i.e., the "Play" button).
The simulation is now running, and the oneline should come to life!
5. Here the amount of nominal reactive power supplied by the capacitor is
assumed to be controllable in discrete, 1.0 Mvar increments between 0 and 10
Mvars. Note, the nominal reactive power assumes a rated voltage (here 16.0
kV) while the reactive power shown for the capacitor is the actual reactive
power supplied, which varies with the square of the bus voltage. When the
simulation is running to change the amount of reactive power click on the up
or down arrows next to the capacitor. Record the system losses and the load
bus voltage as the reactive power is varied between 0 and 10 Mvars in the 1.0
Mvar increments. What value of nominal capacitance minimizes the losses?
6. In the simulation the assumed real and reactive load can also be varied by
clicking on the up or down arrows next to the load fields. Change the load to
12.0 MW and 3.0 Mvar. Then repeat the step 5 analysis.
7. Next, we will add load at bus 3 and then connect it to the other buses by
distribution lines. First switch to Edit Mode. Load can be inserted graphically
by selecting Network, Load, and then clicking on bus 3. The Load Options
dialog appears, allowing you to set the load parameters. Note that the load was
automatically assigned to bus 3. Leave all the fields at their default values,
except set the orientation to "Down," and enter 10.0 in the Constant Power
column MW Value field. As the name implies, a constant power load treats the
load power as being independent of bus voltage; constant power load models
are commonly used in power system analysis. By default PowerWorld
"anchors" each load symbol to its bus. This is a handy feature when changing
a drawing since when you drag the bus the load and all associated fields move
as well. Note that two fields showing the load's real (MW) and reactive (Mvar)
power were also auto-inserted with the load. You should resize the fields using
the Draw, Format, Font command.
8. As you make changes to the model be sure to be saving the cases. You can do
this by selecting, File, Save Case As.
9. Now we need to join the bus 3 load to the rest of the system. We'll do this by
adding a line from bus 2 to bus 3. Select Draw, Network, Transmission Line
and then click on bus 2. This begins the line drawing. During line drawing
PowerWorld adds a new line segment for each mouse click. After adding
several segments place the cursor on bus 3 and double-click. The Transmission
Line/Transformer Options dialog appears allowing you to set the line’s
parameters. Note that PowerWorld should have automatically set the "from"
and "to" bus numbers based upon the starting and ending buses (buses 2 and
3). If these values have not been set automatically then you probably did not
click exactly on bus 2 or bus 3; manually enter the values. Next, set the line's
Series Resistance (R) field to 0.3, the Series Reactance (X) field to 0.6, and the
MVA Limits Limit (A) field to 20 (transformer and transmission line modeling
will be covered in future lectures). Select OK to close the dialog. Note that
PowerWorld also auto-inserted two circuit breakers and a round "pie chart"
symbol. The pie charts are used to show the percentage loading of the line. You
can change the display size for these objects by right-clicking on them to
display their option dialogs.
10. Repeat this process, by adding a line between bus 3 and 1 with the same
impedance and limit values.
11. Switch back to Run Mode, start the simulation, make sure the Bus 2 load is
again 10.0 MW and 5.0 Mvar. At the end of this step your oneline should be
similar to what is shown in Figure 2.
Figure 2: Oneline Diagram after Line Addition
12. Repeat the step 5 analysis.
13. Save an image of your final oneline as a *.jpg file for your report. To save an
image, right-click on a black portion of the oneline. This will display a local
menu. Select Export Image to File and save it in one of your directories.
Provide a step by step account of the procedure you followed and the results you have
obtained. Answer all questions appearing in any of the steps of the procedure. Also
include the final image from step 12. As always list all of the references you use in
preparing the report. If you use any references, number them and refer to them
within your report.
Upload the pdf/word copy of the solution on canvas by 12:00 AM, 02/15/2019.
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