Accurate wind and turbulence information are essential to wind energy research and utilization, among which wind shear and turbulence intensity/scale have seldom been investigated. In this paper, the observational dat...Accurate wind and turbulence information are essential to wind energy research and utilization, among which wind shear and turbulence intensity/scale have seldom been investigated. In this paper, the observational data from the100-m high wind towers in Xilinhot in Inner Mongolia(2009–10; grassland region), Huanghua in Hebei Province(2009–10; coastal flat region), and Xingzi County in Jiangxi Province(2010–11; mountain–lake region) are used to study the variations in near surface winds and turbulence characteristics related to the development of local wind energy over different underlying surfaces. The results indicate that(1) the percentage of the observed wind shear exponents exceeding 0.3 for the grassland region is 6%, while the percentage is 13% for the coastal flat region and 10%for the mountain–lake region. In other words, if the wind speed at 10 m is 10 ms^(–1), the percentage of the wind speed at 100 m exceeding 20 ms^(–1) for the grassland region is 6%, while the percentage is 13% for the coastal flat region and 10% for the mountain–lake region.(2) In terms of the turbulent intensity in the zonal, meridional, and vertical directions(I_u, I_v, and I_w, respectively), the frequencies of I_v/I_u < 0.8 in the grassland, coastal flat, and mountain–lake regions are 23%–29%, 32%–38%, and 30%–37%, respectively. Additionally, the frequencies of I_w/I_u < 0.5 in the grassland, coastal flat, and mountain–lake regions are 45%–75%, 52%–70%, and 43%–53%, respectively. The frequencies of I_v/I_u < 0.8 and Iw/I_u < 0.5 in each region mean that I_u is large and the air flow is unstable and fluctuating,which will damage the wind turbines. Therefore, these conditions do not meet the wind turbine design requirements,which must be considered separately.(3) At 50-and 70-m heights, the value of the turbulence scale parameter Λ in the grassland region is greater than that in the coastal flat region, and the latter is greater than that in the mountain–lake region. Therefore, under the same cond展开更多
1-year hourly wind speed data from two Burundian stations, namely Bujumbura and Muyinga, have been processed in this work to bring an efficient help for the planning and installation of wind energy conversion systems ...1-year hourly wind speed data from two Burundian stations, namely Bujumbura and Muyinga, have been processed in this work to bring an efficient help for the planning and installation of wind energy conversion systems (WECS) at those localities. Mean seasonal and diurnal variations of wind direction and wind shear exponent have been derived. Two-parameter Weibull probability density functions (PDFs) fitting the observed monthly and annual wind speed relative frequency distributions have been implemented. As shown through three complementary statistical tests, the fitting technique was very satisfactory. A wind resource analysis at 10 m above ground level (AGL) has led to a mean power density at Bujumbura which is almost thirteen fold higher than at Muyinga. The use of the empirical power law to extrapolate wind characteristics at heights from 150 to 350 m AGL has shown that energy potential of hilltops around Muyinga was only suitable for small, individual scale wind energy applications. At the opposite, wind energy potential of ridge-tops and hilltops around Bujumbura has been found suitable for medium and large scale electricity production. For that locality and at those heights, energy outputs and capacity factors (CF or C<sub>f</sub>) have been computed for ten selected wind turbines (WTs), together with costs of electricity (COE) using the present value of cost (PVC) method. Amongst those WTs, YDF-1500-87 and S95-2.1 MW have emerged as the best options for installation owing to their highest CF and lowest COE. Moreover, an analysis of those two quantities at monthly basis for YDF-1500-87 WT has led to its best performance in the dry season. Compared to the average present COE of household hydroelectricity consumption, results of this study have evidenced economical feasibility and benefit of WECS setting in selected Burundian sites in order to supplement traditional electricity sources.展开更多
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund(GYHY20120626)
文摘Accurate wind and turbulence information are essential to wind energy research and utilization, among which wind shear and turbulence intensity/scale have seldom been investigated. In this paper, the observational data from the100-m high wind towers in Xilinhot in Inner Mongolia(2009–10; grassland region), Huanghua in Hebei Province(2009–10; coastal flat region), and Xingzi County in Jiangxi Province(2010–11; mountain–lake region) are used to study the variations in near surface winds and turbulence characteristics related to the development of local wind energy over different underlying surfaces. The results indicate that(1) the percentage of the observed wind shear exponents exceeding 0.3 for the grassland region is 6%, while the percentage is 13% for the coastal flat region and 10%for the mountain–lake region. In other words, if the wind speed at 10 m is 10 ms^(–1), the percentage of the wind speed at 100 m exceeding 20 ms^(–1) for the grassland region is 6%, while the percentage is 13% for the coastal flat region and 10% for the mountain–lake region.(2) In terms of the turbulent intensity in the zonal, meridional, and vertical directions(I_u, I_v, and I_w, respectively), the frequencies of I_v/I_u < 0.8 in the grassland, coastal flat, and mountain–lake regions are 23%–29%, 32%–38%, and 30%–37%, respectively. Additionally, the frequencies of I_w/I_u < 0.5 in the grassland, coastal flat, and mountain–lake regions are 45%–75%, 52%–70%, and 43%–53%, respectively. The frequencies of I_v/I_u < 0.8 and Iw/I_u < 0.5 in each region mean that I_u is large and the air flow is unstable and fluctuating,which will damage the wind turbines. Therefore, these conditions do not meet the wind turbine design requirements,which must be considered separately.(3) At 50-and 70-m heights, the value of the turbulence scale parameter Λ in the grassland region is greater than that in the coastal flat region, and the latter is greater than that in the mountain–lake region. Therefore, under the same cond
文摘1-year hourly wind speed data from two Burundian stations, namely Bujumbura and Muyinga, have been processed in this work to bring an efficient help for the planning and installation of wind energy conversion systems (WECS) at those localities. Mean seasonal and diurnal variations of wind direction and wind shear exponent have been derived. Two-parameter Weibull probability density functions (PDFs) fitting the observed monthly and annual wind speed relative frequency distributions have been implemented. As shown through three complementary statistical tests, the fitting technique was very satisfactory. A wind resource analysis at 10 m above ground level (AGL) has led to a mean power density at Bujumbura which is almost thirteen fold higher than at Muyinga. The use of the empirical power law to extrapolate wind characteristics at heights from 150 to 350 m AGL has shown that energy potential of hilltops around Muyinga was only suitable for small, individual scale wind energy applications. At the opposite, wind energy potential of ridge-tops and hilltops around Bujumbura has been found suitable for medium and large scale electricity production. For that locality and at those heights, energy outputs and capacity factors (CF or C<sub>f</sub>) have been computed for ten selected wind turbines (WTs), together with costs of electricity (COE) using the present value of cost (PVC) method. Amongst those WTs, YDF-1500-87 and S95-2.1 MW have emerged as the best options for installation owing to their highest CF and lowest COE. Moreover, an analysis of those two quantities at monthly basis for YDF-1500-87 WT has led to its best performance in the dry season. Compared to the average present COE of household hydroelectricity consumption, results of this study have evidenced economical feasibility and benefit of WECS setting in selected Burundian sites in order to supplement traditional electricity sources.
