OVERVIEW

The course is poposed at the 1st cycle of the 1st year of the Master Degree in Electrical Engineering. Contents are placed in the framework of the electromechanic energy conversion, fundamental topic of the curriculum in Electrical Engineering for power system analysis and energy conversion modeling and control.

AIMS AND CONTENT

LEARNING OUTCOMES

The course proposed 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 previously focused 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 magnetici 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 systems;
• deduce the dynamic models of DC, asynchronous and synchronous electric machines for studies of the perturbed behavior due to fault and 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

Course 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 course content involving student partecipation.

In the 2021-2022 academic year, due to the pandemic, the course will be carried out in mixed mode with lessons held partly remotely and partly in the classroom in order to coordinate and improve learning  of the teaching contents.

SYLLABUS/CONTENT

Summary

Course 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.

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

Course lecture notes are collected and made available on the web site of the University of Genova.Furthermore, some references dealing with course 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.

TEACHERS AND EXAM BOARD

Exam Board

GIO BATTISTA DENEGRI (President)

ANDREA BONFIGLIO

RENATO PROCOPIO (President Substitute)

LESSONS

LESSONS START

https://corsi.unige.it/8731/p/studenti-orario

Class schedule

DYNAMICS OF ELECTRICAL MACHINES

EXAMS

EXAM DESCRIPTION

Examination approach

Check of student preparation level is performed by an oral test aimed at highlighting both the acquisition of fundamental contents in the more conceptual aspects, and the ability to use operational methodologies for applications of interest.

The test, lasting about an hour, is based on three questions related to:

• discussion of fundamental aspects of the electromechanical energy conversion and reference frame transformations;
• modeling, setting up and discussion of transients of DC machines under motor operations and of saturated transformers;
• modeling, setting up and discussion of fault transients and speed regulation dynamic behaviors of synchronous and asynchronous machines used both as generators and motors.

ASSESSMENT METHODS

The methods of assessing the preparation level aim to highlight the reasoning skills avoiding mnemonic repetitions of course contents.

Specifically, the student must show:

• the ability to discuss hypothesis, fundamental properties and application limits of dynamic models of electrical machines;
• the ability to set up and solve simple application examples slightly modified compared to those proposed in the course;
• the ability to validate the results obtained fron detailed modeling also on the basis of those expected from simplified engineering approaches.

Exam schedule