scholarly journals Minimizing the Energy Cost of Offshore Wind Farms by Simultaneously Optimizing Wind Turbines and Their Layout

2019 ◽  
Vol 9 (5) ◽  
pp. 835 ◽  
Author(s):  
Longfu Luo ◽  
Xiaofeng Zhang ◽  
Dongran Song ◽  
Weiyi Tang ◽  
Li Li ◽  
...  

The construction and gradual installation of turbines on wind farms has been hindered by the high cost of the energy production. An effective way to minimize energy costs is via the optimal design of wind turbines and their layout, but relevant and synthetic studies are lacking. This paper proposes a method to minimize the energy cost of offshore wind farms by simultaneously optimizing the rated wind speed, the rotor radius of wind turbines and their layout. Firstly, a new, mixed mathematical formulation of the energy cost is presented, considering the Weibull distribution for wind, the characterizing parameters of wind turbines and the distance between two turbines. Secondly, to obtain the minimum energy cost, a composite optimization algorithm was developed, which consists of an iterative method and an improved particle swarm optimization algorithm. The former was used to search the minimal energy costs that relate to the design parameters of a single wind turbine, while the latter was adopted for optimizing the layout of the wind turbines iteratively. Finally, the proposed method was applied to three case studies with variable wind speed and constant wind direction. Results of the case studies show that the reduced energy cost after optimization has a range of 0–0.001 $/kWh, which confirms the effectiveness of the proposed approach. Meanwhile, the layout of the wind turbines after optimization tends to locate the two wind turbines with the biggest spacing in the wind direction, which justifies the utilization of layout optimization. Furthermore, exploring the optimally designed parameters of wind turbines revealed that the wind farms with a high mean wind speed can have a wider range of turbine capacity than those with a low wind speed, which offers more freedom for the designers when constructing offshore wind farms at wind sites with rich wind resources.

Formulation of the problem. Ukraine's energy sector is import-dependent, and one of the country’s sustainable development goals until 2030 is to ensure access to affordable, reliable, sustainable and modern energy sources. The wind potential of the mainland of our country has been thoroughly studied, so the focus of our interest is water areas, which are promising for the development of offshore wind energy. Offshore wind farms in Ukraine could improve the environmental situation and considerably contribute to the decarbonization of domestic energy. That is why the study considers the opportunity of offshore wind farms installation in the Sea of Azov. Methods. The analysis of literary and cartographic sources has been carried out. Mathematical methods have been used to calculate energy indicators. Using geoinformation modeling, taking into account limiting factors, suitable for the installation of offshore wind farms areas have been identified in the Sea of Azov. The purpose of the article is to geographically analyze the wind energy potential of the Sea of Azov with further assessment of the suitability of areas for the offshore wind farms location. Results. Our research has shown that the installation of offshore wind farms is appropriate in the Sea of Azov, because many areas are characterized by average annual wind speed above 6 meters per second. The most promising areas are the northern and northeastern coasts, where wind speed at different altitudes ranges from 8 to 9.3 meters per second. At altitudes of 50, 100 and 200 m, under the action of limiting factors, the most promising for offshore wind turbines areas are reduced by 8–22%. As considered limiting factors (territorial waters, nature protection objects, settlements and airports) have identical influence regardless of height, it is more effective to install wind turbines with a tower height of more than 100 m in the waters of the Sea of Azov. Interdisciplinary research is needed for the final answer on the effectiveness of offshore wind turbines in the Sea of Azov. Scientific novelty and practical significance. The results of the analysis of the wind energy potential of the Sea of Azov have been given, the tendency of its growth from the west to the east has been revealed. Attention has been paid to the method of geoinformation modeling of the location of offshore wind farms taking into account limiting factors. Maps of wind speed, potential of electricity generated by a single wind turbine and suitability of areas of the Sea of Azov for the location of offshore wind farms at an altitude of 200 m above sea level have been presented. These data can be used by designers of wind energy facilities as a basis for determining the optimal power of wind turbines and the type of energy for a particular area of the Sea of Azov.


2021 ◽  
Author(s):  
Marcus Klose ◽  
Junkan Wang ◽  
Albert Ku

Abstract In the past, most of the offshore wind farms have been installed in European countries. In contrast to offshore wind projects in European waters, it became clear that the impact from earthquakes is expected to be one of the major design drivers for the wind turbines and their support structures in other areas of the world. This topic is of high importance in offshore markets in the Asian Pacific region like China, Taiwan, Japan, Korea as well as parts of the United States. So far, seismic design for wind turbines is not described in large details in existing wind energy standards while local as well as international offshore oil & gas standards do not consider the specifics of modern wind turbines. In 2019, DNV GL started a Joint Industry Project (JIP) called “ACE -Alleviating Cyclone and Earthquake challenges for wind farms”. Based on the project results, a Recommended Practice (RP) for seismic design of wind turbines and their support structures will be developed. It will supplement existing standards like DNVGL-ST-0126, DNVGL-ST-0437 and the IEC 61400 series. This paper addresses the area of seismic load calculation and the details of combining earthquake impact with other environmental loads. Different options of analysis, particularly time-domain simulations with integrated models or submodelling techniques using superelements will be presented. Seismic ground motions using a uniform profile or depth-varying input profile are discussed. Finally, the seismic load design return period is addressed.


Author(s):  
Christine A. Mecklenborg ◽  
Philipp Rouenhoff ◽  
Dongmei Chen

Offshore wind farms in deep water are becoming an attractive prospect for harnessing renewable energy and reducing dependence on fossil fuels. One area of major concern with offshore wind turbines is stability control. The same strong winds that give deep water turbines great potential for energy capture also pose a threat to stability, along with potentially strong wave forces. We examine development of state space controllers for active stabilization of a spar-buoy floating turbine. We investigate linear state feedback with a state observer and evaluate response time and disturbance rejection of decoupled SISO controllers.


Author(s):  
Simeng Li ◽  
J. Iwan D. Alexander

In this paper, a Genetic Algorithm is used to find optimized spatial configurations of wind turbines in offshore or flat terrain wind farms. The optimization is made by obtaining maximizing power output per unit cost. A wake model which permits the calculation of single wakes, multiple wakes and wake interactions is employed to estimate wind speeds at each turbine for a given external wind distribution function and a given spatial configuration. The optimization is applied to cases of unidirectional wind, variable direction winds and variable wind speed. The placement of a turbine can be set at any location following the approach of Mittal et al. Results are obtained for different spacing limits between turbines and wind farms of different sizes. The results for some patterns of optimized placements of wind turbines are discussed in the context of the wind distributions and the wake model employed.


2002 ◽  
Vol 26 (6) ◽  
pp. 383-395 ◽  
Author(s):  
Vassilios G. Agelidis ◽  
Christos Mademlis

The technology associated with offshore wind farms is discussed in detail. First, the various offshore wind turbines are reviewed and the factors influencing their characteristics are outlined in comparison with their onshore counterparts. This overview serves as a basis for the discussion that follows regarding the possible electrical connection within the farm, and between the farm and the grid. Voltage-source converter-based HV DC connection is compared with HVAC connection. Finally, a novel multilevel converter-based HVDC system, based on flying capacitor multilevel converters is proposed, as a possible interface between the farm and the grid.


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