Abstract
Green energy has become a media issue due to climate changes, and consequently, the population has become more aware of pollution. Wind farms are an essential energy production alternative to fossil energy. The incentive to produce wind energy was a government policy some decades ago to decrease carbon emissions. In recent decades, wind farms were formed by a substation and a couple of turbines. Nowadays, wind farms are designed with hundreds of turbines requiring more than one substation. This paper formulates an integer linear programming model to design wind farms' cable layout with several turbines. The proposed model obtains the optimal solution considering different cable types, infrastructure costs, and energy losses. An additional constraint was considered to limit the number of cables that cross a walkway, i.e., the number of connections between a set of wind turbines and the remaining wind farm. Furthermore, considering a discrete set of possible turbine locations, the model allows identifying those that should be present in the optimal solution, thereby addressing the optimal location of the substation(s) in the wind farm. The paper illustrates solutions and the associated costs of two wind farms, with up to 102 turbines and three substations in the optimal solution, selected among sixteen possible places. The optimal solutions are obtained in a short time.

Abstract
The buildings' energy consumption increasing requires solutions to improve their energy efficiency, thus reducing the electricity bill's associated costs. This paper aims to study the load profiles of a service building and its optimization to reduce the costs related to electricity consumption. The electrical load profiles are analyzed, and the electrical equipment and its consumption are characterized. Moreover, to increase energy efficiency and reduce energy costs, a renewable energy system based on photovoltaic panels is sized and integrated into the building. The analysis of the building's consumption profiles allowed the PV system's dimensioning to eliminate power peaks, enabling a reduction in the contracted power. The results demonstrate the effectiveness of the proposed solution, resulting in a reduction of the electricity bill.

Abstract
In the coming years, many countries are going to bet on the exploitation of offshore wind energy. This is the case of southern European countries, where there is great wind potential for offshore exploitation. Although the conditions for energy production are more advantageous, all the costs involved are substantially higher when compared to onshore. It is, therefore, crucial to maximize system efficiency. In this paper, an optimization model based on a Mixed-Integer Linear Programming model is proposed to find the best wind turbines location in offshore wind farms taking into account the wake effect. A case study, concerning the design of an offshore wind farm, were carried out and several performance indicators were calculated and compared. The results show that the placement of the wind turbines diagonally presents better results for all performance indicators and corresponds to a lower percentage of energy production losses.

Abstract
Bidirectional electric vehicle charging stations (EVSE) offer new business models to users and can provide ancillary services to the electrical grid. During charging operation EMC standards and during discharging grid codes are applicable. In this study the harmonic emissions including the total harmonic distortion (THD) and total distortion demand factor (TDD) together with the grid impedance up to 2 kHz of a 10 kW bidirectional charging station are analyzed. While harmonic emission measurements of EVSE at laboratory conditions gives results for idealized conditions and field tests strongly depend on local grid conditions, the real-life operation of an EVSE at a well-known reconstructed grid gives valuable information about the harmonic behavior and impact to the grid impedance. The results show that the bidirectional EVSE can be a main pollutant of harmonic emissions at low power set-points, harmonic phase angle can change from inductive to capacitive behavior and the first resonance frequency of the grid impedance is moved to lower frequencies.

Abstract
Bidirectional electric vehicle charging stations (EVSE) offer new business models like Demand Response to users or can provide ancillary services to support the electrical grid (V2G and G2V). This type of charging station represents a novelty in the electrical grid, as it is considered as load and as power generation unit at the same time. In this study the supraharmonic emissions of a bidirectional EVSE are analyzed at a reconstructed electrical distribution grid. The emissions are determined according to existing standards (IEC61000-4-7 and IEC61000-4-30) for different grid conditions and operating points. Influence factors for supraharmonic emissions are identified as well as narrowband and wideband emissions of the EVSE. Time-domain analysis of the high-frequency signals which can lead to equipment malfunction concludes this work and emphasizes the need of regulations in this frequency range.

Abstract
The increase in the world's population combined with the development of new economies has led to a large scale increase in the demand for energy resources. New technologies have emerged that allow for the maintenance of the energy supply. Renewable sources and energy storage systems (ESS) are emerging as a crucial option for the development of Smart Grids. Using a Mixed Integer Linear Programming (MILP) optimization model, the effects of renewable production sources and storage systems on an electrical grid were studied, in order to maximize the profit of a Virtual Power Plant (VPP). The obtained results allowed us to verify the efficiency of the proposed method. The placement of renewable producers and the ESS, as well as the management optimization of the purchase and transfer process of the stored energy definitely increased the profit of VPP. The use of these technologies also improves the voltage profile and decreased the active power losses by 84% along with the network.