Coordination of smart hybrid transformers in distribution networks

A hybrid transformer is a combination of a conventional transformer and power electronics, which can be used to help alleviate power quality issues in distribution networks at lower costs than solid-state transformers. This paper proposes a novel method of coordinating multiple hybrid transformers in 3-phase distribution networks in order to reduce the curtailment of distributed generators. This is accomplished through the use of sequential linear programming, key features of which include accounting for the nonlinear voltage control capabilities of hybrid transformers, and managing the nonlinear constraints of hybrid transformer power electronics. Test cases were carried out in a modified unbalanced version of the IEEE 69-Bus network and a reduced version of the European Low Voltage test feeder. Test case results demonstrate that hybrid transformers can substantially increase the utilisation of distributed generators.