lookKIT 02/2011 - PKM - KIT

0211
Ways 37
From today’s perspective, the solar power system
on the roof of ETI on KIT’s Campus South seems
rather modest. The 72 solar modules are distributed
over an area of 32 m 2 . With a total output of barely
four kW, they supply just enough power for a
single-person household. Nevertheless, when put
into operation in 1992, the system was the largest
solar power plant in Karlsruhe and considered
the epitome of solar progress for being the first
transformerless grid-connected system.
Twenty years ago, the system was set up to enhance
solar energy production and increase the efficiency
of electronic components. “Bruno Burger, who
was one of my Ph.D. students later on, introduced
the plant concept and first inverter in his diploma
thesis,” Professor Helmut Späth remembers. The
student developed a solar inverter for direct feed-in
that supplied solar power at high efficiency over the
entire power range and with less power electronics
effort than the best device on the market at that
time, a system designed by the Fraunhofer Institute
for Solar Energy Systems (ISE).
counseling level,” he explains. “Therefore, I have
specialized in quality and project management
already during studies.”
Power electronics continues to be one of the
institute’s key subjects. Jochen Weber, who is
Ruben’s supervisor, says that “power electronics
always means to convert electrical energy for
electrical or mechanical applications.” Emphasis
is on the low-loss transformation of direct current
into alternating current in the case of solar power
plants and on the conversion of three-phase
current with changing voltages and frequencies
into grid quality in the case of wind power plants.
High-efficiency inverters are always in demand. In
addition, ETI’s repertoire includes modern storage
media – batteries and condensers – such as those
used for electrical drives. Professor Späth outlines
the spectrum of the ETI study courses: “Diploma
and master students can choose between two
study models: Renewable energy sources or power
electronics and electrical drives. Renewable energy
sources and alternative drives are becoming more
and more popular. On the basis of the fundamentals
of our spectrum of research and teaching, our
graduates are fit for almost any career challenge.”
The pioneering collectors mounted on the almost
perfectly south-facing, 34 degree-slanted roof of
the institute continue to catch the sunlight. The
solar power generated is fed into the building’s
lighting grid to illuminate the workplaces and
drive computers. Some solar energy is in all of the
activities performed at ETI.
While modern transformerless photovoltaic systems
equipped with such inverters today ensure a lowloss
solar energy generation and meet technical
standards, Professor Bruno Burger now works
at that very Fraunhofer ISE in Freiburg. Students
have been continuing to perform research with his
collectors. 31-year-old Ruben Glatt, for example,
outlines the results of his research project entitled
“Evaluation and Representation of the Measured
Values of a Solar System:” Fifty pages of text, a new
solar power site on the institute’s homepage and,
of particular importance, a database that makes
available to researchers all operating data that have
been collected since 1994. That database already
provides the foundation for a bachelor’s thesis on
the system’s long-time development.
Ruben Glatt had quit his job to take up studies
for a better career outlook. After his intermediate
examination in electrical engineering, he changed
over to the cross-faculty mechatronics program.
His diploma thesis will again deal with renewable
energy sources. But instead of researching into
solar energy, he will dedicate himself to developing
business models for technical service providers by
the example of wind power plants. “I intend to
work at the renewable energies management or
Pioniertat und Studienobjekt: Photovoltaikanlage am KIT
Solarstrom mit
Wechselwirkung
Eine Pionierleistung erbrachte das Elektrotechnische Institut (ETI) des KIT vor nunmehr gut 20 Jahren,
als auf dem Institutsdach die mit 32 Quadratmetern Modulfläche damals größte Solarstromanlage
Karlsruhes errichtet wurde. Ein neuartiger Wechselrichter war wesentlicher Bestandteil ihrer Leistungselektronik,
die heute noch entscheidend die solare Stromerzeugung mitbestimmt. Kontinuierlich
liefert die Photovoltaikanlage elektrischen Strom und dient den Studierenden am ETI als Forschungsobjekt
für Studien-, Bachelor-, Diplom- und Masterarbeiten. Eine erst kürzlich in einer Studienarbeit
eingerichtete Datenbank macht sämtliche Betriebsdaten seit 1994 für Forschungszwecke verfügbar
und ist der Öffentlichkeit über die Homepage des Instituts zugänglich.
Leistungselektronik beherrscht auch weiterhin die laufenden Forschungs- und Entwicklungsarbeiten
am Institut. Die zunehmende Bedeutung regenerativer Energiequellen verleiht ihrer technischen Weiterentwicklung
eine zusätzliche Dynamik. Denn insbesondere die möglichst verlustarme Erzeugung
und Netzeinspeisung von elektrischer Energie aus regenerativen Quellen wie Sonne und Wind stellt
die betreffenden elektronischen Bauteile vor große Herausforderungen. Mit entsprechenden Schwerpunkten
hat sich das ETI auf das zunehmende Interesse von Studierenden an diesen Themenfeldern
eingestellt. Mit ihren breit angelegten Kenntnissen können Absolventen aber weiterhin auch alle
anderen beruflichen Herausforderungen angehen.
Joachim Zeitner