Electric Field Optimization to Reduce Corona in AAU/ET's 200 kV High Voltage Laboratory
Translated title
Electric field optimization to reduce corona in AAU/ET’s 200 kV High Voltage laboratory setup
Author
þorsteinsson, Bjarni Helgi
Term
4. term
Education
Publication year
2013
Submitted on
2013-09-12
Pages
81
Abstract
Dette speciale undersøger, om mængden af corona i AAU/ET’s 200 kV-højspændingsopstilling kan reduceres ved at optimere det elektriske felt. Arbejdet kombinerer teori om ionisering, elektronavalanche og feltfordeling med analytiske eksempler (koaksiale cylindere og stang-til-plan) og numerisk modellering i Opera3d FEM. I laboratoriet udføres partielle afladningsmålinger med en Omicron MPD-600 for at lokalisere coronakilder, vurdere deres intensitet og bestemme koronaens tændspænding. Den komponent, der identificeres med lavest tændspænding, er en forbindelsessfære mellem transformator og kapacitiv spændingsdeler, hvor skarpe kanter skaber høje feltmaksima. To afhjælpningsstrategier vurderes: en coronaafskærmning eller et redesign. FEM-resultater sammenholdes med streamer-gennembrudskriteriet for at validere målingerne og dimensionere en ny, glat sfære, designet til at være uden corona ved 200 kV. Den nye sfære fremstilles i værkstedet, og PD-målinger gentages for at vurdere effekten. Den tilgængelige tekst indeholder ikke de endelige, kvantitative resultater; disse præsenteres senere i specialet.
This thesis investigates whether corona in AAU/ET’s 200 kV high-voltage laboratory setup can be reduced by optimizing the electric field. The work combines theory on ionization, electron avalanches, and field distribution with analytical examples (coaxial cylinders and rod-to-plane gaps) and finite element modeling in the Opera3d FEM program. In the laboratory, partial discharge measurements with an Omicron MPD-600 are used to locate corona sources, assess their intensity, and determine the corona onset voltage. The component identified with the lowest onset is a connecting sphere between the transformer and a capacitive voltage divider, where sharp edges create high field concentrations. Two mitigation strategies are evaluated: a corona screen or a redesign. FEM results together with the streamer breakdown criterion are used to validate the measurements and to size a new, smooth sphere designed to be corona-free at 200 kV. The new sphere is manufactured in the workshop, and PD tests are repeated to evaluate its effect. The available text does not report the final quantitative outcomes; these are presented later in the thesis.
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