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Dissertation angenommen durch: Universität Duisburg-Essen, Campus
Duisburg, FB für Ingenieurwissenschaften, Abteilung Elektrotechnik und
Informationstechnik, 2005-01-14
BetreuerIn: Prof. Dr.-Ing. Istvan Erlich ,
Universität Duisburg-Essen, Campus Duisburg, FB für
Ingenieurwissenschaften, Abt. Elektrotechnik und Informationstechnik,
Institut für Elektrische Energie- und Automatisierungstechnik
GutachterIn: Prof. Dr.-Ing. Istvan Erlich , Universität
Duisburg-Essen, Campus Duisburg, FB für Ingenieurwissenschaften,
Abteilung Elektrotechnik und Informationstechnik GutachterIn: Prof. Dr.-Ing. Peter Schegner , Technische Universität Dresden, Institut für Elektroenergieversorgung und Hochspannungstechnik
Schlüsselwörter in Englisch: Micro-turbines, fuel cell,
distributed generation, stability analysis, dynamic simulation, optimal
management, dynamic equivalents
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Abstrakt in Englisch
Distributed generation is attracting more attention as a viable
alternative to large centralized generation plants, driven by the
rapidly evolving liberalization and deregulation environments. This
interest is also motivated by the need for eliminating the unnecessary
transmission and distribution costs, reducing the greenhouse gas
emissions, deferring capital costs and improving the availability and
reliability of electrical networks. Therefore, distributed generation
is expected to play an increasingly important role in meeting future
power generation requirements and to provide consumers with flexible
and cost effective solutions for many of their energy needs. However,
the integration of these sources into the electrical networks can cause
some challenges regarding their expected impacts on the security and
the dynamic behaviour of the entire network. It is essential to study
these issues and to analyze the performance of the expected future
systems to ensure satisfactory operation and to maximize the benefits
of utilizing the distributed resources.
The thesis focuses on some topics related to the dynamic simulation and
operation of distributed generating units, specifically fuel cells and
micro-turbines. The objective of this dissertation is to put emphasis
on the following aspects:
Dynamic modelling of fuel cells: Analyzing electrical power systems
requires suitable dynamic models for all components forming the system.
Since fuel cell units represent new promising sources, the research
ascribes special consideration to developing models that describe their
dynamic behaviour. It is envisaged to develop a simple and flexible
model for stability studies and controller-design purposes in addition
to an exhaustive nonparametric model for detailed analysis of the fuel
cells.
Simulation of a large number of DG units incorporated into a
multi-machine network: With large numbers of distributed sources, it is
expected that decentralized generation impacts the dynamic behaviour of
the high voltage network. Therefore, it is intended to investigate the
case, where several fuel cells and micro-turbines are integrated into
the distribution system of a multi-machine network. This can help in
studying the operation of the entire network and highlighting the
mutual impact of the high-voltage and low-voltage networks on each
other.
Dynamic modelling and simulation of hybrid fuel cell/micro-turbine
units: The hybrid configuration of fuel cells and micro-turbines
exhibits many advantages enabling this technology to represent a
considerable percentage of the next advanced power generation systems.
The dynamic performance of such units, however, is still not fully
understood. Hence, it is desirable for understanding their behaviour to
highlight the dynamic interdependencies between the fuel cell and the
micro-turbine, the overall system transient performance, and the
dynamic control requirements.
Dynamic equivalents of distribution power networks: The need for fast
and simplified analysis of interconnected power networks obligates
developing robust dynamic equivalents for certain electrical power
subsystems. Nonparametric dynamic equivalents will avoid the
identification of complicated mathematical models, which would
adequately reflect the performance of the replaced network under
various operating conditions. For distribution systems, the equivalent
model has to take into consideration the characteristics of distributed
generating units which are mostly connected to the network through
inverters and in some cases their operating principles are not based on
the electromechanical energy conversion mechanism.
Impact of distributed generation on the stability of power systems: The
existence of distributed sources with large numbers can impact the
stability of the power system considerably. Angle-stability, frequency
stability as well as voltage stability can be affected when the power
from these units increases. It is essential to study this impact to
ensure secure operation of the power system. Therefore, it is envisaged
to study the performance of a hypothetical network and to demonstrate
different stability classes at different penetration levels of the
distributed generating units.
Online management of fuel cells and micro-turbines for residential
applications: The optimal management of the power in distributed
generation for residential applications can significantly reduce the
operating cost and contribute towards improving their economic
feasibility. The management process, however, has to be accomplished in
the online mode and to account for all decision variables that affect
the setting values. Therefore, it is aimed to develop an online
intelligent strategy to manage the power generated in fuel cells and
micro-turbines when used to supply residential loads in order to
minimize the daily operating cost and achieve an overall reduction in
the electricity price.
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