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Fundamentals of Electrical Engineering III - Power Engineering

Electrical power engineering comprises the generation, transmission (over long distances), distribution (over short distances) and application of electrical energy.
At first, the lecture briefly repeats the most important principles of the lectures "Basics of Electrical Engineering 1 and 2", then defines in detail the terms energy and efficiency. The chapter on electrical energy supply explains differences in various power station types on the basis of their primary energy sources (coal, gas, oil, nuclear power, water wind, sun, ...). The operation behaviour of the most important types of power stations are explained. Basic principles of transmission and distribution of electrical energy by means of three-wired systems (three-phase currents) as well as vital mathematic concepts (e.g. symmetrical components) are explained. Then the lecture discusses electrical and electro-mechanical machines which are vital for power generation, transmission, distribution and applications. At first, the principle of their modes of operation is explained followed by a description of the DC machine which is particularly suitable to explain the functioning of electrical machines. In this context, the generation of DC voltages from AC or three-phase AC voltages is also explained, for which power electronics components are used. A detailed description of the transformer and the synchronous generator follows - the most important operating means for modeling energy supply nets.
Finally, the induction machine and its operating behavior at continuous and variable input frequencies is defined.

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Calculation of Electric Power Distribution Networks

The lecture explains net structures and voltage levels of energy transmission and distribution networks. The scope ranges from the European integrated network as a large-scale energy transmission net up to smaller network structures in districts or bigger industrial enterprises. Demands from the supply quality in such networks are learnt. Based on networks and demands from the networks, tasks and scope of net calculations are explained, analogue and mathematic net models presented as well as the properties of single and three-phase net models. Important mathematic means, particularly the transformation of voltages and currents in symmetrical components – are presented – supported by operating examples. The lecture outlines power and frequency controls in the network and explains in principle the control behavior of primary and secondary controls. Necessary characteristics of multi-conductor systems – particularly capacity and inductance per unit length of high-power cables – are calculated, bearing in mind bundle conductors and ground-return paths. Equivalent circuits for transformers and generators are explained and parametrised. With these details, power flow and short-circuit calculations for a network can be realized; this becomes visible at the end of the lecture.

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Dynamic processes in electric power distribution systems

Electric power distribution systems are the largest man-made technical systems. Their technical challenges are determined by international physical linkages. An additional special feature is that electric energy cannot be stored in sufficient quantities so that exactly the quantity of electrical energy must be generated at a moment which is to be consumed. The European electrical power distribution system is used as an example to explain the physical effects which lead to dynamic compensation processes for frequency and voltage at different points of the net. The lecture describes power stations, network and consumer as an automatic control engineering system and shows how they can be modeled and simulated dynamically. Second and minute reserves which are necessary at sudden large-scale generation drops, the reactive power balancing, the static stability of standard operation and the transient stability which is important at net faults are discussed.
The lecture gives information about net demands from power generating units, the so called “transmission code” and discusses the influence of increasing regenerative generation on future demands from the electrical power distribution system. Both standard operation and endangered and interrupted operating states are described. Based on these analyses, the reason and progression of blackouts – how they happened in Italy some years ago and more frequently in the United States – are discussed.

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Introduction to Electric Mobility

Within the effort to achieve a global reduction in CO2 emissions, the electric mobility will be given an expansive role. Starting with an overview of the technology and historical development of the electric mobility, the lecture considers with the operating principle and performance of electro-mechanical drive systems, energy storage and loading device. The grid integration of electric vehicles and pay-off-models are as basic prerequisites for a broad use of electric vehicles an additional focus of the course. In addition, the integration of the subsystems in the overall system of a electric vehicle and their interactions with each other are dealt with.

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Introduction to Power Systems Technology

The efficient use of fossil fuels, and expanding the use of renewable energy sources is a major challenge and also a key technology of our time. Starting from an overview of the available energy carrier, the lecture 'Introduction to Power Systems Technology' deals with to their use in thermal, chemical, mechanical, solar and electrical energy systems, with a detailed view on the structure and function of the energy systems. The highly complex overall systems, are fragmented through well-defined system boundaries into more manageable units (subsystems). Based on that, the performance of subsystems and their interactions with each other is analyzed and described mathematically.

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Electric Drives

The lecture explains vital aspects which are necessary for planning an electrical drive, starting with the energy supply via power-electronic control elements up to the driving machine and its operating and protection classes. A description of the mechanical properties of the drive follows, for example the gearbox, and of the behavior of the load. The lecture ends with monitoring and control concepts for different driving systems. The control of driving machines is explained on the basis of two very different examples. DC machines are explained at first: the detailed modeling of the DC machine using clearly defined approaches allows for a simple, safe and quick control. Afterwards the operating behavior of the induction machine is discussed in detail. Various control methods are presented which partly take into account the properties of the power-electronic control element directly. The lecture lays the foundation that the drive engineer is able to choose and plan the most suitable drive for a certain driving task. By active participation in exercises, bonus points can be collected.

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Electric Railways

Electric railways make particularly high demands from power electronics and have always been the first area of application for high tech in power-electronics. On the one hand, this is due to difficult environment conditions by an energy supply via only two conductors and the limitation in construction space and weight for drives and their power electronics, on the other hand, the already high costs in traction technology in the railway field allow indeed for complex solutions. The lecture gives detailed information about the complex interaction between energy supply, electric drive and mechanical components to transmit the traction power to the railway. At first, the different traction power systems and traction types as well as mechanical basics like traction mechanics, tracking, adhesion and anti-slip devices are discussed. Afterwards, the respective components of traction vehicles are described, i.e. the drive motors with their control and energy supply and the power transmission from the motor to the wheel set. The different types of current supply in the range of electric railways are presented in detail. Particularly rigid regulations regarding mains pollutions and signal interference are also explained. Finally, the lecture gives an overview about different control methods for traction converter drives.

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Energy Storage Systems

The lecture "Energy Storage Systems' deals with different types of storage for chemical, potential, kinetic and thermal energy and its use in energyrelated systems. Based on the physical basics of the storage types, their operation principles will be discussed. To shape the different types of storage types, the perfomance will be derived, based on the characteristic curves. For storage of electrochemical energy, different types of accumulators are treated. Therefor the different types of electrochemical processes in the accumulators will be discussed. Pumped storage systems act as a storage of potential energy and are very different, depending on the morphological conditions of the location. In addition to the electrical subsystems, such as generators and motors, also parts of the hydraulic systems, such as piping and pumps will be discussed. Finally the regulation of turbines, generators and motors will be treated. Flywheel storage systems are used to store kinetic energy. Starting from the physical coherences, the dynamic performance of the electrical and mechanical subsystems, and finally the entire system, will be discussed. In addition, special technologies for manufacturing high-revving flywheels are presented. When storing thermal energy, different principles of the memory process, such as sensitive, latent and chemical storage will be presented. Furthermore, a subdivision in low and high temperature storage, with examples of their different application areas, takes place.

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Electrical Power Economics

A high quality, low-price energy supply at every desired place is the basis for the successful functioning of our society. To meet this demand, a close cooperation of the technology with other areas like economy, ecology, law and politics is necessary. The lecture “Electrical Power Economics” is intended to emphasize the narrow interlacing between technical and economic aspects of generation, conversion and application of energy and explains the modus operandi for the layout and operation of energy supply units and systems based on economical aspects.
The major part of the lecture deals with the electric power industry bearing in mind the a.m. aspects, other aspects are only touched as far as they are necessary to understand the global correlations.

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Power Electronic Control Elements

Main subject of the lecture are self-commutated power converters and their application for the control of electrical power. At first, an overview of standard circuits of self-commutated power converters is given, followed by information about available power electronic components and their properties to realize these circuits. Particular emphasis is given to the losses during the switching operations and their limitations. Harmonic components induced by the rapid switching of the semi-conductor valves must be limited. Common input and output filters used for this purpose are presented. One important task of power converters is the provision of direct voltage from alternating and three-phase voltages. For this purpose, self-commutated converters offer distinct advantages against conventional rectifier circuits; they are, however, considerably more complex and expensive. The most important concepts und properties are explained. The last chapter provides information about current control and improves the knowledge imparted in the lecture “Basics of power electronics”. For the layout of the control particular care must be taken that the power semiconductors are switched basically so that no continuous output signal is generated. Special control structures take this property into account.

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Control of Induction Machines

Self-commutated three-phase power converters can both be operated in an energy supply net and used to feed induction machines. Induction machines fed this way can be controlled highly dynamically and efficiently. For both applications, a control system is necessary which must comply with the properties of the self-commutated power converter. The voltages and currents to be taken into account can best be described by space vectors. This highly effective mathematic tool is explained in detail. Using it as a basis, the control methods for an induction machine are defined . Both simple and low-cost and complex and highly-dynamical extensive control methods can be described and understood by means of space vectors in an excellent manner.

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Smart Grids

Power Electronics

Power electronics enables the specific application of electric energy at a very high degree of efficiency. It contributes to improve the operating properties considerably at concurrently reduced energy consumption. Traffic systems, industry plants and current supply systems of, e.g. computers, make use of this so that power electronics is one of the most important future technologies. At first, the lecture explains the basic principles of power electronics, followed by a detailed description of the most important power-electronic components and their properties. Design and function of the most essential self-commutated and mains-commutated power converter circuits are explained in detail. Examples for such power converter circuits are three-phase bridge connections as rectifier circuits and boost resp. step-down converters for the adjustment of direct voltages. Power-electronic units itself are used as control elements, so that the control is of particular emphasis and must be tailored to the power-electronic properties. This is explained in the lecture by a current control example.

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Methodology of Scientific Publishing

The course „Methodology of scientific publishing – Learning the procedure by validation and assessment of recent research results” is divided into three progressive stages: In the first stage each student receives learning materials for self-study as well as one English-language scientific publication, which is then independently analysed. The publication is thematically limited to the following topic areas: Energy system technology, electric mobility, decentralized power systems and control engineering. To validate the research results appropriate models will be developed by use of Matlab/Simulink and simulations will be carried out. The results will be elaborated in the form of a German-language scientific publication. In the second stage the students assess three pseudonymized elaborations of other students in a double-blind review process and in accordance with a prescribed scheme – a so-called peer-review. In the third and last stage the students have the opportunity to revise their elaboration on the basis of the three assessments.

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Mechatronic Drive Systems

In the lecture 'Mechatronic Drive Systems', initially the methods of the system description are taught. Subsequently the transfer functions of the elementary system units (gearbox, torsionally elastic coupling, power electronic actuators, sensors, mechanical-electrical energy converters, electric drive motors), the discretization of the system structure and modelling with particular attention to the stationary and dynamic behavior will be extensive discussed. To model these complex systems mathematically, a reduction of the order is required, wherefore there will be presented some methods in the lecture. As part of the theoretical and experimental system analysis, finally complete drive systems with the relevant regulations (speed and torque control, as well as active torsional vibrations attenuation) are modeled and dimensioned.

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Mobile Mechatronic Drive Systems

Note: The lecture was last offered in the summer semester 2016.

The lecture Mobile Mechatronic Drive Systems is based on the fundamental principles taught in the lectures Mechatronic Drive Systems and Electrical Drives. First of all, areas of application and their specific boundary conditions in mechatronic drive systems for mobile applications are discussed. The transfer behavior of each component and subsystem is then considered using system theory and control engineering principles. Finally the complete operation of mobile mechatronic drive systems is presented and analysed.

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Charging facilities for electric mobility

In the lecture "Charging facilities for electric mobility" first, the problems and basic concepts are explained. Subsequently follows a system overview, which will look at the connection to the mains supply, DC-DC converter types, advantages respectively disadvantages and use case. DC-DC converters with and without potential isolation, their circuit topologies and applications for e-mobility will subsequently be presented in detail, followed by an overview of the rectifier and PFC whose types, functional, standard conditions, power supplies, power filter and control. Contactless power transfer and loading facilities, the construction, connection and communication with the vehicle form the end of the lecture.

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Renewable Electric Power Engineering

On the basis of overview of the available energy sources, solar, wind, geothermal heat and biomass, as well as the thermal, chemical, mechanical and electrical processes, which are needed for the energy conversion, the possibilities of anthropogenic use of renewable energies will be taught in the lecture 'Renewable Electric Power Engineering', with discussion on the usable potentials of the solar energy, wind energy, geothermal energy and biomass, as well as technologies for their usage. To assume that, their stationary and dynamic performance is presented. Particular attention is given to the usage-based description of energy sources and the selection of the most useful form of energy for this energy conversion chain.


There are no current information on the lectures.