The awareness of electric power quality has increased over the past decade as electronic equipment
has become more susceptible to power disturbances. The most disruptive power disturbances are voltage
sags and momentary interruptions and their effect on adjustable speed drives (ASDs) is studied in this
thesis.
Several solutions have been suggested to provide only voltage sag ride-through to ASDs, but most
solutions focus on ASDs with passive rectifiers since they hold the largest share of the market. This thesis
focuses on ASDs with active rectifiers, which is an emerging and growing market due to the advantages
of four quadrant operation and reduced harmonics offered. A solution is presented which provides an
ASD with an active rectifier with the capability to ride through the most common sags in order to reduce
the frequency at which the ASD trips and thereby increase its reliability.
In order to provide ASDs with the capability to ride through momentary interruptions, it is
necessary to interface an energy storage system to the ASD. Flywheels, ultra-capacitors and batteries are
evaluated for use in an energy storage system to provide voltage sag and momentary interruption ride-through
and a detailed comparison of six systems based on these technologies is presented. The interface
circuit between the energy storage system and ASD has a significant influence on the performance of the
energy storage system and therefore interface circuits to ASDs with passive and active rectifiers are
studied.
The addition of an ultra-capacitor energy storage system to an ASD with an active rectifier in order
to provide ride-through of deeper sags and momentary interruptions is studied and a fuzzy logic controller
is designed to enhance system performance. Initially, no communication between the ASD and the ultra-capacitor
system is assumed and the ultra-capacitor system can therefore be added as a retro-fit to an
existing ASD. It is, however, foreseen that the market for ASDs with ride-through capability of voltage
sags and momentary interruptions will grow and the concepts for an integrated design of an ASD and an
energy storage system are presented. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33345 |
| Date | 15 December 1998 |
| Creators | van Zyl, Annabelle |
| Contributors | Spee, Rene |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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