Coordination of phase-shifting transformers to improve transmission network utilisation

The location and variability of wind generation along with the difficulty of gaining permits for the construction of new overhead lines are placing increasing pressure on transmission system operators to increase utilisation of existing transmission capacity in as flexible a way as possible. Phase sifting transformers (PSTs) can contribute to this. However, to gain maximum benefit, the settings of a number of PSTs should be coordinated in a `smart´ way. This paper presents an overview of PSTs, their technical characteristics and their current use on GB Transmission Network. Issues and challenges for their effective and coordinated operation are raised and discussed with examples from a test network.