Development and metrological characterization of measuring instruments for low-voltage networks monitoring

This thesis collects the main results about my research and the work related to the designing of monitoring systems of LV distribution networks. The first three chapters are introductive; the first one describes the main concepts contained in the guide for the evaluation of measurement uncertainty (also called GUM), since some of them are recalled in the next sections. Chapter 2 provides the main notions on the smart grid concept, the new generation of distribution networks characterized by a high degree of automation, and on the main power quality problems affecting the grids. Therefore, the following standard, connected to the above topics, are presented: (i) EN 50160. (ii) IEEE 519. (iii) IEC 61000-4-7. Finally, chapter 3 presents a general description of the main sensors suitable for the LV monitoring systems for the acquisition of voltage and current waveforms, providing information on the working principles, the metrological performances and recalling the related standards (as the IEC 61869). Chapter 4 gets to the heart of the work done in my PhD course; in fact, the two monitoring devices specifically developed to meet the needs of the future smart grids are presented: the Guardian Meter and the Network Monitoring Unit. Hence, information is provided on the purposes of each device, on their technical characteristics, on the tests conducted for the metrological characterization and on the results related to measurement performance. It is noteworthy that the testing activity has led to the development of procedures, some of which innovative, for the metrological evaluation of monitoring devices. In fact, the last chapter collects the scientific outcomes deriving from the R&D activity, which can be the starting points for the updating of current standards related to monitoring systems and for the development of new procedures to evaluate the metrological performance of the energy meters.