Wind turbines are very vulnerable to lightning because of their height, sharp edges and remote locations often with low soil conductivity. In this paper we present numerical simulations of the impedance of a typical wind turbine grounding geometry. We analyze the effect of interconnecting grounding systems of different wind turbines. IEC TR61400-24 suggests interconnection of grounding electrodes of wind turbines through horizontal electrodes (in the form of insulated or bare conductors) to achieve low steady-state grounding resistance. The analysis takes into account frequency dependent soil parameters. It is shown that the low frequency grounding impedance is reduced by a factor of two or more. However, the reduction is lower at higher frequencies because of the interconnection wire's inductance.
The life style of building occupants is continuously arising towards conditions that are more comfortable involving, on turn, the growing of the electric energy consumptions for climatization purposes. This calls for the improvement of the efficiencies of equipment along with environmental performance of building materials. Laboratory analyses of samples of mixed materials, utilizing tomato stems harvested in Sicily and Cataluna, have been conducted Thermal conductance and mechanical properties have been detected for different rates of bio-component and inert materials. First results of the thermal properties seem to situate such bio-composites among the insulating building materials, for all the analyzed percentages of the presence of tomato stems. On the other hand, measurements regarding mechanical properties of the same samples suggest that further analyses are certainly required in order of getting definitive judgments concerning the optimal rate of tomato fibers.
emission trading system is one of the recent controlling tools for the greenhouse gases (GHG) emission. This policy was made in order to decrease the amount of emission from pollutant industries. One of the most challenging subject in this criteria is the mechanism of allowance allocation. The grandfathering and the allowance auction are two common approaches to allocate allowances to generation companies in electricity market. . In this paper, the emission market is modeled to investigate the interaction of the two market simultaneously. To model the behavior of the generation units in the presence of emission market, the Cournot model for electricity market and the allowance supply function for emission market is utilized. Furthermore, the impact of emission allowance auction, the approaches of allocating emission allowances to power plants and allowance trading in emission market on the profitability of production units in the electricity market is investigated.
The present work aims at analyzing the use of the wave resource together with solar and wind resources to supply energy to the Pantelleria public bus system, by substituting the existing Diesel buses with electric buses. Wave resource is exploited by means of the ISWEC (Inertial Sea Wave Energy Converter), a floating, all-enclosed, gyroscopic wave energy converter, deployed at full scale prototype in Pantelleria in 2015. In this paper, the efficiency of an optimal control designed earlier is studied in numerical environment, using a Matlab model and results compared with a Droop Control Method for DC Microgrids Based on Low Bandwidth Communication.
