A Hybrid Transformer Topology for Distribution Network Voltage Regulation

Abstract

Worldwide, distributed generation sources are being installed in increasing numbers within distribution networks. This poses new challenges for distribution network operators, including voltage fluctuations beyond permissible limits that can differ in different parts of the same distribution network. The Hybrid Transformer (HT) is an effective solution that can mitigate voltage fluctuations continuously, dynamically and in a local manner, through combining a standard distribution transformer with a power electronic converter. In this paper a retrofittable HT topology is proposed. It utilises a second, fractionally-rated line frequency transformer (LFT) to enable the use of low-voltage power electronics with low power ratings for reduced costs and complexity. The proposed topology is modelled and a scaled hardware prototype is used to verify theory and simulation results. The simulation and experimental results show the efficacy of the proposed topology, its applicability to mitigate voltage fluctuations, and its benefits over alternative approaches.