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The wolf system: forecasting wet-snow loads on power lines in Italy

pubblicazioni - Presentazione

The wolf system: forecasting wet-snow loads on power lines in Italy

The purpose of the system named WOLF (Wet-snow Overload aLert and Forecasting) is to provide the ice load on overhead lines during wet-snow events and, sufficiently in advance, to alert the Italian TSO to take appropriate preventive measures and dispatching. The system is based on the outputs of a Numerical Weather Prediction model (NWP) with horizontal resolution of 5 x 5 km, and the forecast is valid for the next 72 hours. The outputs of the NWP feed an ice accretion model, assuming a conservative growth of the sleeve on a cylindrical conductor. The grid of meteorological model is intersected with the path of the Italian transmission lines, so as to obtain for each point of the model, the information regarding to the characteristics of power lines (type of conductor, sections and diameters). The WOLF output is presented to the user on a WEBGIS allows to display the alert points on several specific thematic layers as paths of power lines, cabins, cartography, DEM, etc. WOLF provides, for every grid-point, a chart where the time development of the principal weather forecasted variables is represented, as the air temperature, precipitation amount, wind intensity and its direction. The ice-sleeve growth on conductors, in terms of ice load and thickness, is represented too. For each lines, affected by wet-snow, the anti-icing current is computed by a literature model where the Joule power is dissipated considering the convection and radiation terms. The system also provides the possibility to send an alert message via SMS, whenever the value of ice load exceeds the alert threshold of 5 Kg/m on a specific monitored area. SMS shows the number of points in alarm for each monitored area and the altitudes where the phenomenon is expected. In order to test the WOLF forecasts, mobile field campaigns were organized and some collected data have been used to compare the outputs of ice models. An innovative prototype ice-station has been developed and tests are underway.

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