Detection of Partial Discharge in High Voltage Systems using Optical Fibre Bragg Gratings

Abstract: For electricity suppliers, a very important goal is to have a stable operation and to
consistently and reliably deliver electricity. A big threat to that operation is obviously
equipment breakdown that could cause downtime. In high voltage equipment, its insulation
could arguably be considered one of the most important component. When electrical
insulation deteriorates, small cracks and voids will start to appear within the material.
These voids have less insulating ability and will eventually not be able to withstand the
high voltage and become conductive and cause equipment breakdown. Before this critical
situation occurs, when the deterioration is not enough for the voids and voltage to cause
a full arc, there will be small sparks or partial discharges occurring. There are already
methods for sensing these partial discharges but this thesis focuses on a new promising
method utilizing optical fiber Bragg Gratings as sensors. An advantage with optical sensor
being their immunity to electromagnetic interference, making it theoretically possible
for them to be placed in harsh environments where conventional methods could not be
used.
The project started with researching previously written material on this relatively
uncharted area of application and continued on to successfully constructing an optical
sensor for ultrasound. The techniques used for that sensor could then be brought into
a high voltage lab to conduct testing on generated partial discharges. A new method of
mounting the fiber Bragg grating inside an insulation material for testing with partial
discharges was created. The results were not final but showed promising potential in this
kind of application for optical fiber Bragg gratings to exist.