|MTT035 - High voltage engineering
| Syllabus adopted 2012-02-21 by Head of Programme (or corresponding)
|Grading: TH - Five, Four, Three, Not passed
|Education cycle: Second-cycle
Major subject: Electrical Engineering
Department: 43 - MATERIALS AND MANUFACTURING TECHNOLOGY
Teaching language: English
Open for exchange students
20 Dec 2012 pm M,
05 Apr 2013 pm V,
21 Aug 2013 pm V
TIELL ELECTRICAL ENGINEERING - Electrical Engineering, Year 3 (compulsory)
MPEPO ELECTRIC POWER ENGINEERING, MSC PROGR, Year 1 (compulsory)
Docent Jörgen Blennow
High voltage engineering
Course evaluation: http://document.chalmers.se/doc/596a4bc1-f2d1-4cdf-8d09-9a86b6470c4e
Eligibility:For single subject courses within Chalmers programmes the same eligibility requirements apply, as to the programme(s) that the course is part of.
Course specific prerequisites
For the student this course represents the first contact with the diverse subject of high voltage engineering. It mainly aims at: i) introducing fundamental concepts and providing basic understanding within the area of classical experimental high voltage engineering; ii) familiarising the student with the electric power system on a component level and iii) preparing the student for the second course High Voltage Technology which is essential for the student wishing to achieve a broader and deeper understanding of the subject. After successful completion of the two courses in high voltage engineering as a part of the electric power programme the student is well prepared for a carrier e.g. as a R&D-engineer of high voltage design and laboratory activities or as a qualified engineer dealing with various aspects of the components in the power system. In addition, the two courses together constitute a solid base for post-graduate studies in electric power engineering.
Learning outcomes (after completion of the course the student should be able to)
- perform analytical calculations of the electric field distribution in insulation systems having plane-parallel, coaxial and spherical geometries.
- point out un-suitable geometries where the field locally will be very high and suggest improvements of design.
- explain the mechanism of electric breakdown in gases under low pressures by using a simple ballistic collision model (Townsends breakdown mechanism).
- define mean free path, Townsends first and second ionization coefficients and the breakdown criteria.
- explain, from an engineering point of view, and point out parameters important for obtaining high electric withstand strength.
- apply the Paschen curve for estimating the electric strengths of short homogenous gas gaps under low pressure and varying ambient conditions.
- understand the influence of time lags on breakdown voltage and explain the implications on insulation coordination.
- demonstrate familiarity with the characteristics of laboratory equipment for generation and measurement of high voltages by making a well-motivated choice for a specific test situation or test purpose.
- plan and physically arrange a high voltage test set-up in a safe way and be able to minimize and assess risks with respect to personal safety and integrity of measuring circuits and instruments.
- demonstrate knowledge in high voltage test procedures for finding breakdown and withstand voltages.
- be able to statistically evaluate such performed test sequences and make necessary atmospheric corrections.
- identify electric power components in a substation and explain their role in the station and their characteristics.
- compare and discuss advantages/disadvantages of using equipment of different design or working principles.
- identify and explain different construction elements of overhead and cable lines.
- assist, under guidance of an experienced engineer, in planning and project management of constructing a sub-station.
- evaluate consequences of short circuit currents: mechanical- and thermal stresses.
- apply the thermal form of Ohm's law it for calculating the loadability of a cable buried in the soil.
- calculate the probable number of annual faults for an overhead line due to direct hits to the line according the Rolling sphere theory and considering the risk of back-flashovers.
- calculate overvoltages caused by travelling waves and reflections in the power system and demonstrate how surge arresters can be used to limit these.
- explain and schematically illustrate different origins of switching and temporary overvoltages and their characteristics.
- demonstrate insight in, and under guidance of an experienced engineer be able to coordinate the insulation level of specific apparatus with respect to over voltages occurring at a specific position in the system with the use and appropriate choice of protective measures in order to achieve (calculate) a technical/economical acceptable risk.
- show very rudimentary insight into power system ageing: assessment, maintenance and retirement.
- identify and discuss technologies that might have a negative impact on environment and human health. Such examples can be choice of insulation media, exposure to electromagnetic fields, acoustic noise and visual appearance.
The course starts with fundamental electric field calculations (Laplacian fields) in insulation systems of simple geometries followed by an introduction to gas discharge physics, Townsends theory of electric breakdown in air and Paschens law and its implications on gas insulation strength. A central area of the course is experimental techniques which is applied and put into practice during laborations. The concept of insulation coordination connects in a natural way the different topics and constitutes the red thread through out the course. In addition, knowledge of components in the power system and their characteristics is also of vital importance for a professional engineer and is therefore dealt with.
Lectures and tutorials cover the following topics:
- Fundamentals of electric fields: boundary conditions, meaning of Gauss- law, analytical calculations of field distribution in plane-parallel-, coaxial- and spherical geometries under ac-stress, field control.
- Electric breakdown of gases under low pressure: gas kinetics, collision ionisation, the electron avalanche, Townsend's breakdown mechanism, Paschen's law, time lag, voltage-time characteristics, influences and corrections of ambient conditions.
- Overvoltages: the lightning stroke mechanism, the Rolling sphere theory for assessing exposure for a direct hit, back-flashovers, annual probability for power line failure due to lightning, wave impedances, travelling waves, protection of power lines and sub-stations, characteristics of atmospheric overvoltages, origin and characteristics of switching and temporary overvoltages.
- Dimensioning stresses: electrical-, thermal- and mechanical stresses.
- High voltage laboratory techniques: generation and measurements of high voltages i.e. transformer-, resonance- and rectifier circuits, impulse generators (e.g. the Marx generator), voltage measurements using sphere gaps and voltage dividers, current measurements using coaxial shunts and Rogowski coil.
- Insulation co-ordination: reduction of over-voltages, travelling waves, reflections, surge arresters (SiC and ZnO), protective range for arresters, test methods including statistic evaluation of measured data (e.g. the up-and-down method), breakdown probabilities for system of objects, deterministic-, statistic- and semi-statistic insulation co-ordination.
- Components and apparatus in the power system: overhead lines, cables, cable accessories (terminations and joints) power transformers, bushings, instrument transformers including ratio and angular errors, breakers, disconnectors, fuses, capacitors, reactors, substations, gas insulated systems (GIS).
- Power system ageing: assessment, maintenance and retirement
Laboratory experiments (compulsory)
Two laboratory experiments are included in the course, which deal with:
1. Lightning impulse testing - the Marx generator, influences and correction of ambient conditions, evaluation of impulse tests, voltage-time characteristics. Resistive voltage divider: Importance of controlling the electric field in order to reducing the response time and thereby the amplitude error when measuring a chopped impulse voltage.
2. Overvoltages in cables - wave impedances, reflections, effects of surge arresters, measurements of impulse voltages and impulse currents
In order to enhance understanding short reports should be handed in after each experiment, discussing and concluding the performed laboration.
The course comprises of ca 20 lectures (2 x 45 min), 18 tutorials (2 x 45 min), two laboratory exercises (4 h).
E. Kuffel, W. S. Zaengl, J. Kuffel, High Voltage Engineering Fundamentals, Newnes 2000, 2nd ed, ISBN 0 7506 3634 3
Written examination. Grades: Fail, 3, 4 or 5. Approved laboratory exercises including short laboratory reports.