This paper presents a comprehensive study on the state-of-the-art and emerging wind energy technologies from the electrical engineering perspective. In an attempt to decrease cost of energy, increase the wind energy conversion efficiency, reliability, power density, and comply with the stringent grid codes, the electric generators and power electronic converters have emerged in a rigorous manner. From the market based survey, the most successful generator-converter configurations are addressed along with few promising topologies available in the literature. The back-to-back connected converters, passive generator-side converters, converters for multiphase generators, and converters without intermediate dc-link are investigated for high-power wind energy conversion systems (WECS), and presented in low and medium voltage category. The onshore and offshore wind farm configurations are analyzed with respect to the series/parallel connection of wind turbine ac/dc output terminals, and high voltage ac/dc transmission. The fault-ride through compliance methods used in the induction and synchronous generator based WECS are also discussed. The past, present and future trends in megawatt WECS are reviewed in terms of mechanical and electrical technologies, integration to power systems, and control theory. The important survey results, and technical merits and demerits of various WECS electrical systems are summarized by tables. The list of current and future wind turbines are also provided along with technical details.

High-Power Wind Energy Conversion Systems: State-of-the-Art and Emerging Technologies

In this paper, along with the progress of modern wind energy technology, the trends of wind energy technology and potential challenges have been studied thoroughly. It is estimated that within the next 2–3 decades, the Vertical Axis Wind Turbine (VAWT) can dominate the wind-energy technology. The VAWT requires less land space and using the same space; it is capable of producing more wind energy than that of its counterpart. By implying the Fish Schooling Concept effectively and successfully, it is possible to advance the wind-energy technology more. In the last 3–4 decades, the wind turbine capacity has been increased around 30–40 times. With the increase of wind energy capacity, the demand of the energy storage system has been increased significantly. Along with the many energy storage systems, fuel cells and batteries are the two most promising devices to meet the demand in RE systems. The wind-energy technology is established itself but not yet fully mature and hence there are many areas where improvements are required to reduce the cost of wind energy.

http://iran-tarjome.persiangig.com/other/1-s2.0-S1364032113000312-main.pdf

Progress and recent trends of wind energy technology

Wind energy is one of the most rapidly growing renewable sources of energy due to the fact that it has little negative impact on environment. To meet the growing demand, wind turbines are being scaled up both in size and power rating. However, as the size increases, the structural loads of the turbine become more dominant, causing increased fatigue stress on the turbine components which can lead to early failure. Another area of focus in wind energy is lowering production cost to give it a competitive edge over other alternative power sources. From the control point of view, low production cost of wind energy can be achieved by operating the wind turbine at/or near the optimum power efficiency during partial load regime, guaranteeing reliability by reducing fatigue loads, and regulating generated power to its rated value in the high wind regime. Often, it is difficult to realize a control algorithm that can guarantee both efficiency and reliability because these two aspects involve conflicting objectives. This paper reviews various control strategies that are used in wind turbine systems, both in low and high wind speed regions focusing primarily on multi-objective control schemes. Emerging trends that are likely to influence the current or future wind energy production, either positively or negatively, are also discussed.

State-of-the-art in wind turbine control: Trends and challenges

Offshore wind power provides a valuable source of renewable energy that can help reduce carbon emissions. Technological advances are allowing higher capacity turbines to be installed and in deeper water, but there is still much that is unknown about the effects on the environment. Here we describe the lessons learned based on the recent literature and our experience with assessing impacts of offshore wind developments on marine mammals and seabirds, and make recommendations for future monitoring and assessment as interest in offshore wind energy grows around the world. The four key lessons learned that we discuss are: 1) Identifying the area over which biological effects may occur to inform baseline data collection and determining the connectivity between key populations and proposed wind energy sites, 2) The need to put impacts into a population level context to determine whether they are biologically significant, 3) Measuring responses to wind farm construction and operation to determine disturbance effects and avoidance responses, and 4) Learn from other industries to inform risk assessments and the effectiveness of mitigation measures. As the number and size of offshore wind developments increases, there will be a growing need to consider the population level consequences and cumulative impacts of these activities on marine species. Strategically targeted data collection and modeling aimed at answering questions for the consenting process will also allow regulators to make decisions based on the best available information, and achieve a balance between climate change targets and environmental legislation.

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Assessing environmental impacts of offshore wind farms: lessons learned and recommendations for the future

The aim of this paper is to present the current status of the offshore wind industry and to identify trends in Offshore Wind Projects (OWPs) This was accomplished via a thorough analysis of the key characteristics – commissioning country, installed capacity, number of turbines, water depth, project area, distance to shore, transmission technology and investment cost – of the commissioned and under construction European OWPs Furthermore, the current status of the several countries outside of Europe was also investigated The analysis revealed that the European offshore wind power grew on average 361% yearly since 2001 Currently, there are 7748 MW installed and 3198 MW under construction distributed among 76 OWPs situated in European waters These projects are spread among ten countries, with the highest share of offshore projects belonging to the northern European countries The UK has 46% of the total installed European offshore wind capacity with 26 projects, Germany ranks second with 16, while Denmark is third with 13 projects These countries constitute 88% of the European offshore capacity The analysis also showed that, although the installed capacity of the OWPs is growing, the projects׳ area is not increasing at the same pace due to the release of turbines with higher rated capacities which allow projects to increase their power nameplate without proportionally increasing the number of turbines The average distance to shore and the water depth are both increasing throughout the years Although the average investment cost per project is rising with the higher distances to shore and water depths, the multi-GW plans of the northern European and Asian countries indicate that the industry will continue to grow The European Union targets of having 40 GW of offshore wind capacity deployed by 2020 in Europe and 150 GW by 2030 may represent plausible scenarios since the required growth is below the European

Trends of offshore wind projects

http://iran-tarjome.persiangig.com/other/The%20current%20state%20of%20offshore%20wind%20energy%20technology%20development.pdf

The current state of offshore wind energy technology development

Numerical investigation on aerodynamic performance of a novel vertical axis wind turbine with adaptive blades

A Savonius rotor can be used as a wind or water current energy conversion device that produces electricity. In spite of their simple structure and assembly, Savonius turbines have less commercial appeal than other types of turbines due to their relatively low energy conversion efficiency. In order to increase the output power of a Savonius turbine, most studies have only focused on optimization of the rotor configuration or installation of ancillary equipment around the rotor. However, previous research has found that a beneficial interaction that existed between two parallel Savonius turbines can also augment the power output of each rotor if they are rotating side by side. This paper numerically examines the interactions among multiple Savonius turbines with the help of the commercial computational fluid dynamics software fluent and finds that these coupling effects can effectively increase the overall power output of a Savonius turbine farm, especially when Savonius turbines are arranged relatively clo...

Xiaojing Sun

Papers

The current state of offshore wind energy technology development

Numerical investigation on aerodynamic performance of a novel vertical axis wind turbine with adaptive blades

Numerical study on coupling effects among multiple Savonius turbines

Numerical investigation on energy extraction of flapping hydrofoils with different series foil shapes

Performance characteristics of a horizontal axis turbine with fusion winglet