Wind Engineering

We describe briefly some of the challenges met by the designers of the foundation systems for offshore wind energy developments. Although some experience from the offshore oil and gas industry proves valuable, the size and nature of typical wind turbines means that the loadings on the foundations are quite different from those encountered previously offshore. The most economical solutions are also likely to differ from those conventionally used offshore. We highlight the possibilities of a novel form of foundation: the suction caisson.

A boundary-layer meso-γ-model was used for calculation of wind and turbulence characteristics inside a wind farm. The study demonstrates the ability of the model to describe wind and turbulence fields in more detail than climatological analysis only. Velocity deficit at the hub height of the wind turbine and standard deviation components inside the wind farm were calculated for various environmental situations which are constructed as combinations of the large scale input parameters of the model with surface and landscape characteristics. The load effects on the wind turbine were parameterised, and the calculated wind profiles inside the wind farm were compared with measurements. The results of 3-dimensional and 2-dimensional versions of the model were compared.

By the end of June 1999, 250 MW of wind generation had been dedicated in the State of Iowa. This represents the beginning of what is likely to be significant wind capacity development during the next 20 years in the State as a result of possible governmental mandates and consumers' desire for sustainable sources of energy. After accounting for predicted load growth over the next 15 years, we estimate Iowa's potential wind energy portfolio through to the year 2015. Winds in the Midwest are primarily generated by fronts moving through the region. The purpose of this study is to find the best way to distribute wind-generating capacity among several sites by using an electricity-production, cost and reliability model. We calculate this benefit in terms of reduction in the fuel cost of conventional generators. We also consider system reliability in terms of energy not served (ENS). Our findings indicate that it is beneficial to develop wind power plants at several sites, and that there are many possible combinations of wind locations that can be chosen to obtain diversity benefits. We also calculate capacity credit for the composite wind power plants using two different methods, and calculate a trade-off curve between the economically optimal and the most reliable solutions. The methods we use to find the best geographical locations and sizes of wind power plant are based on a dynamic fuzzy search algorithm and a genetic algorithm. Each procedure produces a solution set that can be analyzed further in other contexts, such as voltage and land use constraints. We illustrate the sensitivity of the fuzzy economic benefit solutions to small perturbations of the capacity selections at each wind site. We find that small changes in site capacity and/or location have small effects on the economic benefit provided by wind power plants.

The integration of renewable energy sources, e. g. wind energy in weak or isolated power systems produces disturbances. Such disturbances are due to the power fluctuations caused by the stochastic fluctuating wind energy, current harmonics in the power system, switching operations, tower effects and reactive power consumption of the wind energy installations. These decrease the power quality at the point of common coupling (PCC). This paper introduces a concept to compensate the disturbances by the use of a static synchronous converter with an active damping circuit. This new concept is based on the principle of the static reactive power converter, and was extended by means of system integration of largely standardized components of the drive-converter technology.

In combination with an active intervention in the pulse-pattern generator of the main converter, it is possible to balance asymmetrical loads and compensate the harmonics. The pulse pattern generator was realized through an assembler-programmed PC.

This paper considers community funded wind power development, contrasting the position in the UK with other countries. It makes the point that in countries where wind energy is booming, local people are actively involved. Local opposition to wind farms threatens the UK wind industry and may be a result of limited public consultation and participation. Using as a case study a community wind power project in South Wales, the paper argues that greater emphasis should be placed on involving local people and communities in developing the UK wind industry.

The Rayleigh-Ritz method of calculating the natural vibration frequency of a structure in the second or further order is very complicated. This paper describes a simplified method of calculating the first and second order natural vibrational frequencies of wind turbine towers.

The AWEA announced several Award winners at the ‘Windpower 2000’ conference in Palm Springs, California. The winners received their awards from outgoing AWEA President Robert Gates.

Walt Musial and Sandy Butterfield, both of the National Wind Technology Center, jointly won the Technical Achievement Award. Musial and the National Wind Technology Center test team were honored “for developing a capability at the National Wind Technology Center to provide blade and drive train structural component testing to the U.S. wind industry”. Butterfield was recognized “for successfully overseeing development of a U.S.-based certification program.”

The National Wind Technology Center (NWTC) is situated in a spectacular setting at the foot of the Rocky Mountains, in the Rocky Flats Environmental Technology Site buffer zone in Golden, Colorado. A few turbines of varying sizes and models can be glimpsed on the open plateau from Route 128 out of Golden. However the small number of turbines belies the importance of this center for the wind power industry. Most of the NWTC's work is carried out indoors, in hangars and computer labs which make it one of the world's unique testing centers.