Integration of conventional and unconventional Instrument Transformers in Smart Grids

In this thesis the reader will be guided towards the role of Instrument Transformers inside the always evolving Smart Grid scenario. In particular, even non-experts or non-metrologists will have the chance to follow the main concepts presented; this, because the basic principles are always presented before moving to in-deep discussions. The chapter including the results of the work is preceded by three introductive chapters. These, contain the basic principles and the state of the art necessary to provide the reader the tools to approach the results chapter. The first three chapters describe: Instrument Transformers, Standards, and Metrology. In the first chapter, the studied Instrument Transformers are described and compared with particular attention to their accuracy parameters. In the second chapter instead, two fundamental international documents, concerning Instrument Transformers, are analysed: the IEC 61869 series and the EN 50160. This has been done to be completely aware of how transformers are standardized and regulated. Finally, the last introductive chapter presents one of the pillars of this work: metrology and the role of uncertainty. In the core of the work Instrument Transformers integration in Smart Grid is distinguished in two main topics. The first assesses the transformers behaviour, in terms of accuracy, when their normal operation is affected by external quantities. The second exploits the current and voltage measurements obtained from the transformers to develop new algorithm and techniques to face typical and new issue affecting Smart Grids. In the overall, this thesis has a bifold aim. On one hand it provides a quite-detailed overview on Instrument Transformers technology and state of the art. On the other hand, it describes issues and novelties concerning the use of the transformers among Smart Grids, focusing on the role of uncertainty when their measurements are used for common and critical applications.