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Please use this identifier to cite or link to this item: https://dspace.lboro.ac.uk/2134/16252

Title: Phase unbalance on low-voltage electricity networks and its mitigation using static balancers
Authors: Beharrysingh, Shiva
Keywords: Current unbalance
Voltage unbalance
Forward-backward sweep method
Static balancer
Low-voltage electricity networks
Low-carbon technologies
Issue Date: 2014
Publisher: © Shiva Beharrysingh
Abstract: Existing low-voltage networks may not accommodate high penetrations of low-carbon technologies. The topic of this thesis is unbalance, which if minimised can delay or avoid the constraining of these technologies or the replacing of still-useful network assets. Most of the discussion on unbalance, as seen in the standards and the literature, centres on the effects of voltage unbalance on consumer equipment. Its effects on the network are not equally reported. This thesis recognises fundamental differences between the consumer and network perspectives. It can inform distribution network operators on the interpretation of measurements taken on low-voltage networks and guide research on unbalance due to high penetrations of low-carbon technologies. Much of the work involved simulations of LV networks. Initially, existing 3 x 3 or 5 x 5 approaches to the forward-backward sweep method were thought suitable. After a review of these approaches however, there were doubts as to how accurately they accounted for the shared neutral-earth return path on which the out-of-balance current flows. This led to the derivation of a new 5 x 5 approach using only Kirchhoff s voltage (KVL) and current laws (KCL). Its results are validated thoroughly in the thesis. In addition to satisfying KVL and KCL, they match Matlab SimPowerSystems exactly and are in close agreement with measurements taken on a very unbalanced rural feeder. This thesis also investigates the mitigation of unbalance using the static balancer. This is a transformer with a single interconnected-star winding. It was used in 1930-1950s to correct unbalance. Contributions are made for its possible re-introduction as a retrofit option. They include a model for use in the forward-backward sweep method, validated by laboratory and field measurements, and the quantification of the static balancer s strengths and weaknesses as this can help identify when it should be used.
Description: A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.
Sponsor: This work was financially supported by Western Power Distribution, E.ON Engineering Ltd and the Engineering and Physical Sciences Research Council, UK, within the SUPERGEN Highly Distributed Energy Futures (HiDEF) project (EP/G031681/1).
URI: https://dspace.lboro.ac.uk/2134/16252
Appears in Collections:PhD Theses (Mechanical, Electrical and Manufacturing Engineering)

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