|
INFORMATION |
The
Ninth IASTED International Conference on
POWER AND ENERGY SYSTEMS
~ PES 2007 ~
January 3 – 5, 2007
Clearwater, Florida, USA
Tutorial
Session
Power
Quality of Electrical Machines, Transformers, and Capacitors
Ewald
F. Fuchs
Department of Electrical and Computer Engineering
University of Colorado, USA
ewald.fuchs@colorado.edu
Abstract
With distributed generation (DG), many more power producers
using renewable energy and cogeneration will be operating
at relatively low-voltage levels and with very limited short-circuit
power. Power system impedance as seen by an individual DG
power producer is relatively large, resulting in weak system
characteristics, and power-quality problems become exacerbated
as compared with very strong systems served by a few large
power stations with large short-circuit capabilities. Power
quality problems with respect to machines, transformers,
and capacitors include:
- Increase of
hot-spot temperatures due to power system harmonics voltage,
abnormal terminal voltages, increase of ambient temperatures
above 40°C due to global warming, the effect of DC
within the AC system caused by asymmetric gating of inverters,
and geomagnetically induced currents.
- Renewable
sources have intermittent power generation and conventional
power generators must take up the slack, resulting in
cyclic operation. Changing machine temperature reduces
the lifetime of insulation material.
- Greater probability
for faults and transient disturbances such as short-circuits,
reclosing, out-of-phase synchronization, and DC currents
within AC system, resulting in extreme winding and iron-core
forces, and vibrations.
- Inter- and
sub-harmonic torques in inverter-fed machines; that is,
in variable-speed drive motors and in generators (e.g.,
wind, hydro) supplying rectifiers; harmonic torques due
to time-dependent loads.
The tutorial
will discuss an overview of the physical concepts and computational
methods required to prevent or mitigate above-mentioned
power quality problems, and several case studies with respect
to induction and synchronous machines, transformers, and
capacitors will be presented.
Background
Knowledge Expected of Participants
A basic understanding of power engineering is required.
No prior knowledge of power quality with respect to machines,
transformers and power capacitor is needed.
Biography
Ewald F. Fuchs is a Full Professor in the
Department of Electrical and Computer Engineering at the
University of Colorado, Boulder, CO, USA. He has been involved
in the design, implementation, and evaluation of conventional
and renewable energy power plants for over 35 years, including
8 years at Siemens AG power plant design. He has published
more than 150 research articles on power quality, rotating
machines and transformers in IEEE, international journals,
and conferences. Recent research focuses on problems related
to renewable energy (e.g., large-scale energy storage) caused
by the intermittent operation of power plants. Currently
he is co-writing with a colleague from Australia the book,
Power Quality of Systems and Machines, to be published
by Elsevier.
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