In working with electrical power production and
distribution, a key problem faced is being able
to see the unseen - in other words, how does one
view invisible electrical and magnetic forces
Hydro-Québec needed to be able to see magnetic
flux density near a distribution power line, which
is essentially understanding the power flow in
the power lines. The physical problem, having
no rotational symmetry or linear periodicity,
had to be solved completely in 3D.
Hydro-Québec is the provincial government-owned
electrical power utility in Québec, Canada. The
Institute of Research (IREQ) is the research facility
of Hydro-Québec and one of the world's largest
laboratories studying techniques and equipment
used in electrical power production, transmission,
distribution, and use.
Hydro-Québec's high-voltage Transmission and Distribution
divisions as well as external partners and clients
are the main beneficiaries of the research conducted
Sylvain Gravel is a research scientist at IREQ.
Gravel, a theoretical physicist, has worked at
IREQ since 1980, first as a graduate student and
later as a full-time researcher. Over the years
Gravel has been involved in modeling and simulation
of physical phenomena related to lightning, electric
fields in dielectrics, thermonuclear fusion (tokamak),
hybrid vehicle dynamics, high-efficiency in-wheel
motors, astrodynamics, HV lines de-icing and computational
Gravel used Tecplot 360 software to create these
plots illustrating the magnetic flux density isosurfaces
near a dual-circuit distribution power line with
two lateral secondary branching circuits.
Figure 1 (above) shows a few isosurfaces of magnetic
flux density (Bm), also sometimes called magnetic
induction, near a complex configuration of 3-phase
distribution power lines. This equally loaded
dual-circuit, 3-phase 60Hz power line has two
lateral branching circuits. Each 3-phase secondary
branching circuit carries 20% of the main current.
The main conductors and the corresponding branching
conductors are connected by jumper cables. The
lines were assumed balanced (no neutral currents).
Gravel explains how the data was generated: Because
this is an open boundary problem, using a boundary
element method (BEM) instead of finite elements
eliminated the need to mesh a large volume of
space far from the region of interest." He adds
that "BEM software solves Maxwell's equations
in integral form using an equivalent source Green's
function approach so computational elements need
only to be defined on the surfaces of interest
and not inside of them."
Gravel computed the magnetic flux density values
in 3D using Faraday, a 3D magnetic induction BEM
simulation program developed by Integrated Engineering
| Figure 2: This plot
represents the same physical situation
seen from below. To show Bm around
jumper cables and secondary conductors,
the beige (41,5µT) isosurface was
a larger image .
The fields (Bx, By, Bz and Bm and corresponding
phase angles) were computed using Faraday for
the given currents. A cubic region of interest
(3m x 3m x 3m) was defined, field values were
computed in this region on a 101 x 101 x 101 regular
grid and results were exported to a 200+ MB text
This data was then imported into Tecplot 360.
Another small input file with simple Tecplot primitives
was used to create zones for the rectilinear conductors
with proper phase color coding.
Then a set (C1) of contours levels for some Bm
values of interest (41,5µT, 83,0µT and 420,0µT)
were defined to be used for plotting the isosurfaces
(respectively shown in beige, blue and red). Transparency
was added to the blue one and Value Blanking was
defined above a certain value of Z for the beige
isosurface to create the "open box" look and enable
a view of the inner structure.
Another more complete set of contour levels (C2)
between 83µT and 420µT was defined with a Cutoff
Color Below value of 83µT. These levels were used
to create the contour plots with flooding and
lines. These were plotted on Slices parallel to
the YZ and XZ planes defined at specific values
of X and Y respectively, making use of the slices
grouping options. Transparency was added to all
the contour plots.
Titles, legend, company logo and other elements
were added on the same frame and the final output
was saved to a compact PNG file, which can be
easily integrated in publications and presentations.
The features of interest are the isosurfaces at
83µT (blue, transparent) and 420µT (red, solid)
and, more specifically, their shape and exact
position and extent in space in relation to the
conductors. The contours plotted on the slices
give a general idea of the magnetic flux density
At the current level used, the surfaces at Bm=420µT
around each conductor can be considered independent
from each other. This is not the case at 83µT
where isosurfaces overlap and merge. This would
also not be the case if the main currents were
Gravel explains, "Due to the reverse phasing (ABCCBA)
of the main conductors, we have a low-field region
between the two central conductors as expected.
This region is the hollow cylindrical surface
running between the phase C main conductors (shown
in blue). This is useful as a quick check of the
proper phasing of the input data."
According to Gravel, another easily predictable
but nevertheless interesting effect well shown
here is the narrowing of the 420µT (red) iso-surfaces
around each main conductor after each branching
circuit. "The current source (100%) is assumed
to be located near the observer so as each secondary
circuit carries 20% of the main current, the smaller remaining current in the main conductors makes the Bm iso-surfaces shrink around them. No surprise here,
of course, but it's another good verification
that nothing is seriously wrong with the results"
Gravel uses Tecplot 360 almost exclusively for
its 3D capabilities, iso-surfaces, 3D contouring,
slicing planes and 3D arrow plots on zone geometries
and mainly for electric, magnetic and thermal
simulations. He also uses the software to create
animations of certain physical parameters to get
a better understanding of their dynamics.
Gravel adds, "These 3D views and animations can
also now be incorporated in 3D PDF documents and
be interactively manipulated by the final reader
of the document. This adds tremendous power and
versatility to Tecplot outputs."
Researchers at IREQ use Tecplot at the research
stage to explore data and reveal relations between
parameters. Gravel clarifies, "About 80% of all
the plots generated-although of publication quality-don't
end up in final documents but are used during
this analysis phase."
The final plots are incorporated in internal and
external technical publications and reports. "Because
of their powerful 3D visualization qualities,"
Gravel adds, "they are also very useful for presentations
to less technical audiences."
Gravel, who has used Tecplot for 10 years, believes
that Tecplot would have helped him during his
days as a student. "I wish I could have had access
to a 3D tool such as Tecplot when I was a student.
Powerful 3D visualization can greatly enhance
one's understanding of complex physical phenomena
and Tecplot is a fantastic tool for intricate
what-if data exploratory work."
Today, Tecplot facilitates Gravel's research efforts
by helping him explore data dependencies and visualize
complex interactions between parameters in 3D.
"Newer and better simulation and visualization
tools such as Tecplot assist us with the periodic
reassessment and refinement of our equipment and
practices and help us remain an environment-friendly
utility company," says Gravel.
Gravel adds that it is also very useful for rapidly
spotting input data errors and is also very useful
for dissemination of 3D results in internal and
external publications, reports and presentations.
Gravel, who has used many other technical plotting
and visualization packages in the past, believes
that Tecplot distinguishes itself in many ways.
"Tecplot gives me more control over the details
of my plots and allows me to combine several types
of data representation in the same multi-variable
3D plot," says Gravel. "Tecplot 360 doesn't try
to substitute itself for more sophisticated data
analysis or simulation software; it stays focused
on its primary purpose: generating advanced 3D
plots, and it does it better than the other packages
I have used in the past."
3D views and animations can also now be
incorporated in 3D PDF documents and be
interactively manipulated by the final reader
of the document. This adds tremendous power
and versatility to Tecplot outputs.”
- Sylvain Gravel, Hydro-Québec
360 stays focused on its primary purpose:
generating advanced 3D plots, and it does
it better than the other packages I have
used in the past.”
- Sylvain Gravel, Hydro-Québec