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Modeling power grid dynamics in high school physics
Matthew W. Milligan – Physics Teacher, Farragut High School
Center for Ultra-wide-area Resilient Electrical Energy Transmission Networks
(CURENT)
Knoxville, TN
Introduction
To be an effective teacher it is essential to capture
and maintain the attention of the student. Toward this end
it is very helpful to find useful applications of physics
topics that may be brought into the classroom and used as
a source for example problems, student projects,
laboratory experiments, etc. The electric power grid
provides many interesting avenues to pursue along these
lines and also illustrates the value of physics principles in
action.
One particularly interesting phenomenon that is
here considered as a potential focal point for high school
physics students is the occurrence of frequency
disturbances that propagate as electrical-mechanical
waves through the nation’s power grid. Not only is this a
thought-provoking occurrence, a sound understanding of
it requires knowledge and experience with both power
grid concepts and also many high school physics topics.
This makes it an ideal subject to study.
Methods
A novel approach to visualizing power grid
frequency disturbances was developed using FNET1 data
from the 2008 Florida generator trip2. A Matlab script
was used to read the raw data files (.txt format), generate
3-D images, and create a video file (.avi format).
Results
A 3-D video animation of a frequency disturbance was created and
experiments with small generators were performed, yielding data that will
promote student comprehension of physics and the power grid.
Classroom Power Grid
In order to model the power grid’s network of generation facilities and
consumer loads, hand-cranked DC generators and simple “flashlight-type” lamps
were interconnected. Switches were used to vary loads and simulate faults.
Students can observe electrical energy output and mechanical work input.
A novel aspect of this activity is that students experience tactile feedback and can
actually feel the changes in the amount of power required by the grid.
Power Transmission Model
Disturbance Animation
Modeling AC Power
A 3-D animation was created in order to make
frequency disturbance more engaging and
comprehensible to students. The frequency of the power
grid is represented as a surface. The height of each node
of the surface is proportional to the frequency measured
by one of FNET’s Frequency Disturbance Recorders
(FDR’s)1. The appearance of the waves in this virtual
surface is similar to ripples in a stretched bed sheet or
table cloth.
A bicycle dynamo (AC generator) can be used to
assist student comprehension of the significance of
frequency as a characteristic of the power grid. The
output of this dynamo was measured with a computerized
data collection system (equivalent to an oscilloscope).
Students can view this animation and then be
asked to determine wave properties such as speed of
propagation, frequency, wavelength, amplitude, nodes &
antinodes, etc. Students can also be asked to hypothesize
on the cause(s) of the propagating frequency variations.
Additionally, various types of small electrical
generators were tested in terms of applicability and
practicality for use in a model of the power grid and in
experiments suitable for high school physics classrooms.
Students can determine electric power and energy
and relate these to mechanical properties of the dynamo’s
flywheel in order to draw connections between the
frequency and voltage of AC power and the rotation rate
of the generator.
Bicycle “Dynamo”
with Flywheel
A
G
G
Vin
Vout
Experimental Setup
Generators
Genecon HandCrank Generator
Transmission
Line
Load
Schematic Diagram
Experimental Setup
Conclusions
The phenomenon of a power grid
frequency disturbance can provide a
useful focal point to enhance the
teaching of physics concepts involved
in understanding waves, energy,
electricity, and circuits.
For further information
Data and Calculated Values of Power & Energy produced by LoggerPro software
Works cited
These are selected
frames from the
animation of the 2008
Florida Generator Trip
that was produced
using Matlab
Please contact [email protected]. More
on this and related projects can be found at curent.utk.edu
Acknowledgments:
1R.
M. Gardner and Y. Liu, "FNET: A Quickly Deployable and Economic System to
Monitor the Electric Grid," inTechnologies for Homeland Security, 2007 IEEE
Conference on, 2007, pp. 209-214.
2North
Data and Calculated EMF produced by LoggerPro software
American Electric Reliability Corporation (NERC) Unexpected Loss of
Generation Due to Low Voltage on the System, Advistory Background A-2008-0626-01, 2008
This material is based upon work supported by the National Science Foundation and Department of
Energy under Grant No. 1041877. Any opinions, findings, and conclusions or recommendations expressed in this material
are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.