An Improved Method for Estimating the Wind Power Density Distribution Function

Abstract

The wind power density (WPD) distribution curve is essential for wind power assessment and wind turbine engineering. The usual practice of estimating this curve from wind speed data is to first estimate the wind speed probability density function (PDF) using a nonparametric or parametric method. The density function is then multiplied by one-half the wind speed cubed times the air density. Unfortunately, this means that minor errors in the estimation of the wind speed PDF can result in large errors in the WPD distribution curve because the cubic term in the WPD function magnifies the error. To avoid this problem, this paper presents a new method of estimating the WPD distribution curve through a direct estimation of the curve using a Gauss-Hermite expansion. It is demonstrated that the proposed method provides a much more reliable estimate of the WPD distribution curve.

Characterization of wind power resource in the United States

“…Jaramillo and Borja (2004) found that the two-parameter Weibull distribution can not be generalized since it is not accurate in the case of some wind regimes. Morrissey et al (2010) give an example of wind speed distribution for Boise City, Oklahoma and point out that the two-parameter Weibull distribution does not fit the wind speed distribution well. When the Weibull distribution is used for that wind speed data, the frequencies of lower speeds are underestimated and those of the higher speeds are overestimated which results in an overestimation of the resource.…”

“…Thus the use of Weibull distribution underestimates the frequencies of the higher wind speeds. As argued by Morrissey et al (2010), the first step in computing a WPD distribution is to study the WPD distribution rather than the wind speed distribution. Jaramillo and Borja (2004) found that the two-parameter Weibull distribution can not be generalized since it is not accurate in the case of some wind regimes.…”

Estimated Pollution Reduction from Wind Farms in Oklahoma and Associated Economic and Human Health Benefits

“…However, the wind does not blow all the time, so an estimate of the percent of total capacity generated by the wind must be estimated. Previous research [9,10,27] has examined the Oklahoma wind resource. Using this analysis of the typical wind speeds in the state their overall distribution, as well as analysis of more recent research by the US DOE [1], a "capacity factor" value of 0.37 was used to produce the estimates of emissions reduction.…”

“…us, with the world becoming ever more aware of the effects of carbon and other pollution emissions on our planet, the matter of whether or not wind will be able to supply the country with clean electricity is at the forefront of many minds. Much of the research in the area of wind power generation tends to focus on issues such as the examination of the wind resource, [9,10] cost of production, the maximum amount of electricity that wind power may be able to provide, and the potential environmental impact to wildlife, and so forth [2]. However, less has been written about the environmental savings associated with the pollution reduction associated with the switch from "grey" fossil energy to "green" energy such as wind energy (although there have been studies by Denny and O'Malley [11] and others).…”

Advanced Wind Resource Characterization and Stationarity analysis for Improved Wind Farm Siting

“…Thus, the kernel method is not an optimal method for estimating the wind speed PDF, since if a PDF estimator is to be used in further mathematical computations a tractable function with a limited number of terms is required (Hall 1980). There has also been recent research to utilize concepts from the field of geostatistics to develop a transform function of the wind speed PDF as a function of scale (Morrissey, et al, 2010a(Morrissey, et al, , 2010b. If knowledge of the variance of the wind speed at a given scale is known (or can be estimated) then the probability density function representing the required scale may be estimated.…”