# Dynamic Thermal Rating and Development of Renewable Energy Zones in Sicily
## 1 Introduction  
As the analyses in this study show, the Sicilian electricity network is characterized by an uneven distribution of electrical loads and energy production. This imbalance results in a significant flow of electricity from the western to the eastern part of the region. This is the main challenge that is addressed in this paper. The current transmission network often struggles to cope with these power flows, resulting in frequent congestion. In this study, areas with a high concentration of renewable energy installations have been identified and designated as \"Renewable Energy Zones (REZs)\". The main contribution of this paper is the first identification of REZs using a simple and direct method. The application of Dynamic Thermal Rating (DTR) technology was then evaluated for the transmission lines within each REZ in order to solve the main challenge for the Sicilian electrical network, which is grid congestion. The use of Dynamic Thermal Rating in the analysis of Renewable Energy Zones is also an innovative technical contribution. The results are significant; the proper implementation of DTR technology would reduce grid congestion by increasing the capacity (ampacity) of critical transmission lines. Furthermore, the required interventions were found to be economically viable. In summary, there are several general aspects of this paper that are in line with the objectives of the special issue entitled \"Design, Optimization and Control Strategy of Smart Grids\". The following topics are covered in detail: power quality and grid reliability with high penetration of renewable energy sources, grid flexibility optimization, and energy curtailment management. In order to facilitate the understanding of the work carried out, it is necessary to present the current state of the Sicilian electricity grid, integrated into a broader context such as the Italian and international ones. The Sicilian transmission system is currently characterized by three voltage levels: 380 kV (Figure 1, red lines), 220 kV (green lines), and 150 kV (pink lines). The first two voltage levels are designated for transmission, while the 150 kV grid is used for the sub-transmission of electrical energy. The 150 kV voltage grid is the largest in the area and constitutes an energy connection between eastern and western Sicily [1]. The traditional paradigm, in which power flows were predominantly stable and unidirectional--originating from conventional power plants to consumers--has been largely disrupted. The electricity transmission network now operates under the need to manage bidirectional power flows, characterized by significant temporal variability [1]. The exponential increase in energy production from photovoltaic and wind power plants, together with the natural aging of some transmission lines, has necessitated a rethink of the management strategies for the Sicilian electricity system. Six of the nine provinces of the Sicily region are prone to high congestion or overload in the presence of high renewable energy generation [1]. In this context, some areas have been identified and classified as critical, two others as medium critical (Catania and Palermo), and only one province (Messina) as low critical [1]. It is useful to analyze the distribution of energy production from renewable and traditional sources throughout the territory, as well as the electricity loads that characterize the region. Electricity is mainly produced by traditional thermoelectric power plants concentrated in the south-eastern area and by numerous RES plants, mainly wind farms, located in the western area [1]. Figure 1: Electrical transmission system of Sicily, Italy (Sisnet (version 4.01), software owned by Terna). It should be noted that the distribution of installed wind power over the territory is not homogeneous, as 50% is located only in the provinces of Trapani and Palermo, in the western part of Sicily. This heterogeneity is mainly due to the different wind conditions on the western and eastern slopes of the region [2].