This activity was aimed at reviewing the sleeve thickness and mass values provided for by the standard CEI EN 50341-2-13:2017: Part 2-13 National regulatory aspects (NNA) for Italy with reference to wet snow. The methodology allowed for the reconstruction of snow events over the last 20 years with a spatial resolution of 4km*4km and hourly temporal resolution. Subsequently, a probabilistic estimate of the expected values of sleeve mass for a return time of 50 years was obtained through the statistics of the extremes known as Generalized Extreme Value Analysis. The activity was divided into three years of research, and saw the development and creation of the MERIDA reanalysis dataset first, and then the calibration of the cylindrical accretion model on conductors, also known as the Makkonen model. The tuning of the model was made possible thanks to both the experimental measurements collected at the WILD station in Vinadio, and the fault data provided by electricity utilities regarding significant wet snow events. The research product consists in a new mapping of the thicknesses and mass of the sleeve on overhead power line conductors which takes into account the intense events that have occurred in the last twenty years, as requested by ARERA [Italian regulatory authority for energy networks and environment] and shared by the CT [Technical Committees] 11/7 of the CEI [Italian Electrotechnical Committee]. Such processing and data are fundamental for the planning of network infrastructures, in order to implement all the appropriate measures aimed at strengthening the network and increasing the resilience of the electricity system.
Furthermore, as far as summer weather conditions are concerned, a study was conducted on the intensity, duration and frequency of heat waves associated with the detection of faults on underground distribution cables. The calculations based on the reanalysis highlight a clear and widespread increase in intensity and persistence of the most critical heat waves over a vast area of Italy. Regarding the soil part, an analysis of the physics of the processes in the MERIDA products was conducted with particular focus on the analyses of the components of the hydrological balance in the land surface model.
Finally, a new dataset – MERIDA HRES – has been completed to better describe the meteorological variables most used in applications related to renewable energy, especially solar radiation in its direct and diffuse components, and wind.