Power System Transients

Introductory description of high voltage equipment and substations. Analysis of overvoltages in electrical systems in addition to an overview of protective measures as design, grounding, shielding and surge protection. Overvoltages caused by lightning, circuit breaker operations, ground fault and resonances are discussed and analyzed analytically. Methods for analytical calculation of voltages and currents in circuits with physical extension is emphasized. This implies calculation and measurement of travelling waves in power systems. An overview of ligthning overvoltages in high and low voltage systems, lightning protection and lightning induced overvoltages as well as switching overvoltages and temporary overvoltages is given. Ideal computational models valid for the voltage and frequency ranges represented by the overvoltages are established. Different types of overvoltage protective devices in both high- and low-voltage systems are described with a focus on metal oxide arresters. Overview on dimensioning and location of protection in the system to avoid damage to equipment. Introduction to computer calculation of transients with EMTP.

Knowledge: After completing this course the candidate shall: - have a solid foundation in understanding the source and characteristics of lightning, switching, and temporary overvoltages. - understand travelling wave propagation on transmission lines. - understand the critical switching transient situations. - be able to set up differential equations for RLC circuits and solve it via stationary and transient solutions. - understand the mode of operation and dimentioning criteria for surge arresters. - understand the physical and electrical construction of high voltage systems.

Skills: After completing this course the candidate shall be able to: - carry out simple, analytical calculations of transient overvoltages and currents in power systems. - set up lattice diagrams and make calculation in systems with two reflection points. - utilize EMTP programs in a critical and effective way for calculation of power system transients. - dimentioning surge arresters in power systems. - contribute to a reliable operation of high voltage systems. - use high voltage instruments and equipment in the laboratory.

General competence: After completing the course, the candidate has increased: - skills in cooperation and interdisciplinary collaboration - ability to communicate effectively to professionals and non-specialists alike through reports and presentations

Lectures. Compulsory exercises, computer exercise, laboratory experiments.