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A reliable estimate of the wind potential in the marine atmospheric boundary layer (MABL) is of great importance to justify the energetic viability of new offshore wind farms. The purpose of the study is to provide an additional tool for the prediction of the energy that a wind turbine would produces in the open sea from the usual way of measurements at sea, that is, when they are carried out with measuring masts, where the meteorological data are obtained at levels much lower than those of a wind turbine hub. For this, the variation in the wind speed with the height in the MABL is determined, based on the Monin–Obukhov similarity theory, according to the boundary conditions of the air–sea interface, where the input data for the Validation of the results are extracted from the German FINO 3 research platform during the years 2016, 2017, and 2018. It is applied to the production of electrical energy from a 6.0 MW commercial wind turbine, with the hub at 100 m above the sea surface. As a more prominent result, the deviations from the proposed method do not exceed 2.5% in the energy calculation, To the Bundesministerium für Wirtschaft und Energie (BMWi) and Projektträger Jülich (PTJ), both of the Government of Germany, for facilitating the use of data of the FINO Project. To Siemens Gamesa Renewable Energy, for the use of the characteristic curves of the SWT-6.0-154 wind turbine

The promotion of the distributed generation and the photovoltaic (PV) energy great potential put this technology in the spotlight of investors. Thus, the optimization of its efficiency is made a priority. In this paper, a complete and versatile remote controller (C&VRC) for PV systems is presented, scalable to any kind and size of installations (with or without partial shading, with or without connection to the grid, housing, small plants or even large-scale solar plants) and valid for any weather conditions. The C&VRC involves the controller itself, which is constituted by a set of sensors and actuators connected to the converters Direct Current (DC)/DC and DC/Alternating Current (AC), if necessary, and a control unit communicated with them through the third-generation mobile telecommunications technology (3G) network. The control strategies can be changed according to the different weather conditions and installations characteristics, which guaranties the optimum performance of the system. The use of the 3G network as communication platform makes the C&VRC useful in remote and low accessibility places, because it is the most extended worldwide. The C&VRC is also based on free software, open hardware and low-cost electronic devices. Experimental results are presented in this paper to show the C&VRC optimum usability., This paper is framed in the project “Integral control system to optimize the microgrids energy demand” funded by the Spanish Ministry of Science and Innovation, call for Scientific and Technical Research and Innovation 2020-2023. Funding for open access charge: Universidad de Huelva / CBUA.This paper is framed in the project “Integral control system to optimize the microgrids energy demand” funded by the Spanish Ministry of Science and Innovation, call for Scientific and Technical Research and Innovation 2020-2023. Funding for open access charge: Universidad de Huelva / CBUA.

Turbulence of the atmospheric flow in the boundary layer depends on different factors, such as: the roughness of the ground, the orography, the sea surface state and atmospheric stability conditions. In open sea conditions, the transfer of momentum from the atmosphere to the ocean is very important, since part of it contributes to the generation of waves, while the rest influences the turbulence and currents convective generation. In the offshore wind turbines wakes, the level of turbulence is greater than the wind without obstacles, causing transient loads to occur in other wind turbines located downstream, which has a structural stress effect on its components. Another effect of the wakes is the lack of uniformity of the vertical flows of the wind, that is to say, of shear, thereby increasing cyclic loads on wind turbine rotors. Therefore, in the of offshore wind farms implementation it is necessary to evaluate the turbulence in the site, since this will generate dynamic structural loads on the wind turbines, as well as variations of their electrical production.

Along the last years, the practical use of active filters to mitigate harmonics has been extended in electric power systems. Different configurations of series active filters versus shunt active filters have been proposed, among them, hybrid topologies which combine active and passive filters. Nevertheless, there is not any clear accordance about the most suitable configuration for each type of harmonic sources. In this paper, four different topologies of active power filters to eliminate harmonics have been analyzed. An experimental prototype has been implemented to each configuration and have been submitted to different performance tests. With this objective, a test bank has been developed, which includes nonlinear loads kind harmonic current source, ahrmonic voltage source, and other whose behavior is between they both. The analysis of experimental results obtained allows the most suitable active filter power topology to be determined for each type of load.

The objective of this paper is the identification of the variables which affect the acceptation by the students of two kinds of remote laboratories (photovoltaic panels and electric machines) in Higher Education. To achieve it, the Technology Acceptation Model is used and usability and usefulness are the considered factors. Two pilot experiences are carried out over a sample of 86 students which are studying the Energy Engineering Degree. 45 of them (52.3%) carry out the electric machines lab class and 41 (47.7%) the photovoltaic one. After a descriptive analysis, an exploratory and multivariate analysis is carried out. It allows the identification of relations between several variables which affect to the acceptation of both remote labs.

Distorted voltage and current waveforms is one of the problems associated to electric power quality. Continuous use of non-linear loads provokes the existence of voltage waveforms with a high distortion. Thus, it is necessary to know the responsible of this problem by means of the commonly named distortion sources identification. In this paper, the problem is analyzed through the harmonic power sign, with the objective of knowing the sense of harmonic power flow between source and one load in distorted systems. Nowadays, it has already been established in the Literature that an analysis of this kind does not solve the problem. Recently, new indices have been introduced to evaluate a specific consumer distortion level. In this paper, a comparative analysis of these indices is carried out, having as reference a practical case. The results obtained show that, in fact, these indices can help to valuate the harmonic distortion, although none of them solve the question definitively.

A control algorithm is proposed for a three-phase hybrid power filter constituted by a series active filter and a shunt passive filter. The control strategy is based on the dual formulation of the vectorial theory of electrical power, so that the voltage waveform injected by the active filter is able to compensate the reactive power, to eliminate harmonics of the load current and to balance asymmetrical loads. An experimental prototype was developed and experimental results presented.

The control strategy derived from the instantaneous reactive power theory is one of the most commonly used in the Active Power Filters (APFs). For the last decades other formulations have been developed in order to achieve compensation objectives different to the proposed in the original one. Nevertheless, all of them can be only applied to three-phase systems, i. e.: in those formulations frameworks, they can not be used to obtain the control strategy for a polyphase system. This paper presents a new approach which can be applied to n wire systems. The powers and currents expressions derived from the formulations presented up now can be obtain applying this new approach. In this paper, the original p-q and the modified p-q formulation expressions are obtain in the new approach framework.