LEARNING OUTCOMES

The teaching proposes a dynamic modelling oriented approach of electrical machines for transient, dynamic and harmonic application studies. Suitable analytical and numerical tools are provided to face with analisys and control problems and defined proper proteciton systems.

AIMS AND LEARNING OUTCOMES

Aims focused in the teaching are related to analysis and management of production, conversion and utilization of electric energy systems, fundamental topics in Electrical Engineering. Dynamic modelling of electric machines together with analytical and numerical tools are provided in order to face with control, protection and harmonic problems in power system, drives and industrial network including renewable electric energy sources.

Specifically, the student will be able to:

• know the effects of magnetic saturation on transformer transients;
• acquire the principles and application methodologies of electromechanical energy conversion;
• apply the variable transformations for the transient analysis of three-phase electrical machines;
• deduce the dynamic models of DC, asynchronous and synchronous electric machines for studies of the perturbed behavior due to fault and/or regulation effects;
• solve problems of dynamic behavior of electrical machines in real applications using simplified dynamic models and critically discussing the results.

TEACHING METHODS

Teaching approach

Teaching couples theoretical lessons (about 50 hours) with practical applications (abuot 10 hours) including model set-up, exercises and numerical computations, sometime using computer aided dynamic simulation programs. Exercises concern with solution of simple problems on content involving student partecipation.

In the 2022-2023 academic year, the teaching will be again carried in the classroom supported by lecture notes in order to improve learning  of the teaching contents. Lecture notes are more extensive with respect contents discussed during the lessons. Additional topics may be useful for individual study without impact on the examination.

SYLLABUS/CONTENT

Summary

Teaching contents concern transient and dynamic modelling of electric machines. Transformer saturated models are derived and used for investigating inrush current, ferroresonance, short circuit and overvoltages phenomena. Modelling of rotating machines are developed based on the generalized theory of electromechanic energy conversion according to the coupled circuit in relative motion approach and related reference frame transformations. Vector models are deduced, actually applied to a large extent in on-line industrial applications.

Contents

1. Transient phenomena in electric machines. Time-frame classification. Analysis approaches.

2. Transformers. Non-linear transient model including saturation effects. No-load current waveform distortion. In-rush and short circuit currents. Ferroresonance. Overvoltages distribution and dielectric strength.

3. Electromechanic energy conversion. Coupled circuit theory of electromechanic systems. Energy balance. Electromagnetic forces and torques from magnetic energy and co-energy. Permanent magnet systems. Step motor applications

4. Studio di transitori elettrici e/o elettromeccanici significativi nell'esercizio delle macchine elettriche rotanti.

4. Introduction to modelling and dynamic of rotating electric machines. Coupled circuit description of DC, induction and synchronous machines. Dynamic equations. Reference frame transformation. Dynamic equivalent circuits. State space equations. Reduced order models for special purpose applications. Operational and vector approaches. Block diagrams. Dynamic model initialization from steady-state analysis. Parameter identification.  Modelling application to the study of relevent dynamic behaviour in management and control of rotating electric machines (DC motor start-up, AC supply of series-excited DC motor, induction motor short circuit, direct on line and variable frequency induction motor start-up, induction motor flux oriented control, syncronous machine short circuit, synchronous machine transient stability).

RECOMMENDED READING/BIBLIOGRAPHY

Recommended Reading

Yeaching lecture notes are collected and made available on the web site of the University of Genova. Furthermore, some references dealing with teaching content are given. Students are non required using them to prepare examination but only to improve their ability level.

References

1. Fitzgerald, Kingsley, Kusko - Electric Machinery, The Processes, Devices and Systems of Electromechanical Energy Conservation, 3rd Edition, Mc Graw Hill.

2. Krause, Wasynczuk, Sudhoff - Analysis of Electric Machinery and Drive Systems, 2nd Edition, Mc Graw Hill.