Transformerless series dip/sag compensation with ultracapacitors

[摘要] ENGLISH ABSTRACT: This thesis covers the development of a transformerless series dip compensator. Of all known powerquality problems, voltage dips are the greatest reason for concern. Series injection dip compensatorsoffer the advantage of only having to compensate for the decrease in supply voltage during a dip.This results in significant reduction in converter ratings and energy storage requirements. The aim ofthis thesis was to take up previous developments and combine them with new technologies tomaximize their functionality. The new design was implemented with ultracapacitors to offer amaintenance-free device lifespan of 20 years. As they are very expensive, a new topology wasintroduced in this thesis to maximize their use so that they become viable for industry. Furthermore,a new method of daisy chaining switches was introduced to minimize costs involved in controllingthem. A single-phase compensator, with this new topology and the new way of controlling switches,was designed and built according to specifications stated by Eskom. This ultracapacitor-based dipcompensator was tested with a dip generator, developed by the University of Stellenbosch fordifferent load currents. The experimental results confirmed simulations made with identicalparameters. This thesis presents a reliable and cost effective solution for dip compensation.

[发布机构] Stellenbosch University