Optimised Reactive Power Supports using Transformer Tap Stagger in Distribution Networks

Linwei Chen, Haiyu Li

    Research output: Contribution to journalArticlepeer-review


    In distribution networks, the operation of two parallel transformers in small different tap positions, i.e. known as tap stagger, can provide a means of absorbing reactive power. The aggregated VAr absorption from many pairs of parallel transformers could help mitigate the high voltages in the upstream transmission system during periods of low demand. Considering distribution networks as reactive power support providers, this paper presents an optimal control strategy for the tap stagger to minimise the introduced network losses as well as the tap switching operations. A genetic algorithm based solution procedure is developed to find the optimal dispatch for the transformer tap positions, in order to achieve the VAr absorption required by the transmission system. The proposed method is compared with two alternative control approaches based on the rule-based method and the branch-and-bound algorithm, respectively. Two practical UK distribution networks are modelled from real data and used to demonstrate the effectiveness of the proposed control strategy under different operating conditions.
    Original languageEnglish
    Pages (from-to)1987-1996
    Number of pages10
    JournalI E E E Transactions on Smart Grid
    Volumevol. 8
    Issue number4
    Publication statusPublished - Jul 2017


    • Genetic algorithm
    • Parallel transformers
    • Reactive power absorption
    • Tap stagger
    • VAr optimisation.


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