Poisson-Gumbel joint distribution model uses maximum wind speed corresponding to multiple typhoons to construct sample sequence.Thresholds are usually used to filter sample sequences to make them more consistent with ...Poisson-Gumbel joint distribution model uses maximum wind speed corresponding to multiple typhoons to construct sample sequence.Thresholds are usually used to filter sample sequences to make them more consistent with Poisson distribution.However,few studies have discussed the threshold setting and its impact on Poisson-Gumbel joint distribution model.In this study,a sample sequence based on the data of Qinzhou meteorological station from 2005 to 2018 were constructed.We set 0%,5%,10%,20%and 30%gradient thresholds.Then,we analyzed the influence of threshold change on the calculation results of maximum wind speed in different return periods.The results showed that:(1)When the threshold increases,the maximum wind speed of each return period will decrease gradually.This indicates that the length of the sample series may have a positive effect on the return period wind speed calculation in Gumbel and Poisson-Gumbel methods.Although the augment of the threshold increases the average value of the maximum wind speed of the sample sequence,it shortens the length of the sample sequence,resulting in a lower calculated value of the maximum wind speed.However,this deviation is not large.Taking the common 10%threshold as an example,the maximum wind speed calculation deviation in the 50 a return period is about 1.9%;(2)Theoretically,the threshold is set to make the sample sequence more consistent with Poisson distribution,but this example showed that the effect is worth further discussion.Although the overall trend showed that the increase of the threshold can makeχ2 decrease,the correlation coefficient of linear fitting was only 0.182.Taking Qinzhou meteorological station data as an example,theχ2 of 20%threshold was as high as 6.35,meaning that the selected sample sequence was not ideal.展开更多
Using the data on the maximum wind speed within ten minutes every month in the period 1971-2009 in Zhucheng City of Shandong Province, we conduct statistical analysis of the maximum wind speed in Zhucheng City. The re...Using the data on the maximum wind speed within ten minutes every month in the period 1971-2009 in Zhucheng City of Shandong Province, we conduct statistical analysis of the maximum wind speed in Zhucheng City. The results show that over thirty-nine years, the annual maximum wind speed in four seasons in Zhucheng City tends to decline. The annual maximum wind speed declines at the rate of 1.45 m/s every 10 years. It falls fastest in winter, with decline rate of 1.73 m/s every 10 years; it is close to the average annual maximum wind speed in spring and autumn, with decline rate of 1.44 m/s and 14.8 m/s every 10 years, respectively; it falls slowest in summer, and the extreme value of the maximum wind speed occurs mainly in spring. The curve of changes in the monthly maximum wind speed in Zhucheng City assumes diminishing shape of "two peaks and one trough". We conduct preliminary analysis of the windy weather situation, and put forth specific defensive measures against the hazards of strong winds in the different periods.展开更多
In this study, the maximum wind speed （WSmax） changes across China from 1956 to 2004 were analyzed based on observed station data, and the changes of WSmax for 2046-2065 and 2080-2099 are projected using three globa...In this study, the maximum wind speed （WSmax） changes across China from 1956 to 2004 were analyzed based on observed station data, and the changes of WSmax for 2046-2065 and 2080-2099 are projected using three global climate models （GFDL_CM2_0, CCCMA_CGCM3, and MRI_CGCM2） that have participated in the IPCC Fourth Assessment Report （AR4）. The observed annual and seasonal WSmax and the frequency of gale days showed obvious declining trends. The annual WSmax decreased by approximately 1.46 m s^-i per decade, and the number of gale days decreased by 3.0 days per decade from 1956 to 2004. The amplitudes of the annual and seasonal WSmax decreases are larger than those of the annual and seasonal average wind speeds （WSavg）. The weakening of the East Asian winter and summer monsoons is the cause for the distinct decreases of both WSmax and WSavg over the whole China. The decrease of WSmax in the southeast coastal areas of China is related to the reduced intensity of cold waves in China and the decreasing number （and decreasing intensity） of land-falling typhoons originated in the Northwest Pacific Ocean. The global climate models GFDL_CM2_0, MRI_CGCM2, and EBGCM （the ensemble of above men-tioned three global climate models） consistently suggest that the annual and seasonal WSmax values will decrease during 2046-2065 and 2080 2099 relative to 1981 2000. The models also suggest that decreases in WSmax for whole China during 2046-2065 and 2080 2099 are related to both the reduced intensity of cold waves and the reduced intensity of the winter monsoon, and the decrease in WSmax in the southeast coastal areas of China is corresponding to the decreasing number of tropical cyclones over the Northwest Pacific Ocean in the summer during the same periods.展开更多
When the wind speed changes significantly in a permanent magnet synchronous wind power generation system,the maximum power point cannot be easily determined in a timely manner.This study proposes a maximum power refer...When the wind speed changes significantly in a permanent magnet synchronous wind power generation system,the maximum power point cannot be easily determined in a timely manner.This study proposes a maximum power reference signal search method based on fuzzy control,which is an improvement to the climbing search method.A neural network-based parameter regulator is proposed to address external wind speed fluctuations,where the parameters of a proportional-integral controller is adjusted to accurately monitor the maximum power point under different wind speed conditions.Finally,the effectiveness of this method is verified via Simulink simulation.展开更多
This paper presents a scalar volt per hertz(V/f)control technique for maximum power tracking of a grid-connected wind-driven brushless doubly fed reluctance generator(BDFRG).The proposed generator has two stator windi...This paper presents a scalar volt per hertz(V/f)control technique for maximum power tracking of a grid-connected wind-driven brushless doubly fed reluctance generator(BDFRG).The proposed generator has two stator windings namely;power winding,directly connected to the grid and control winding,connected to the grid through a bi-directional converter.In order to enhance the performance of the proposed scalar-control strategy,a soft starting method is suggested to avoid the over-current of the bi-directional converter.Moreover,the capability of generator speed estimation for sensorless control is also studied.The capability of the proposed scalar-control technique is validated using a sample of simulation results.In addition,the presented simulation results ensure the effectiveness of the proposed control strategy for maximum wind-power extraction under windspeed variations.Furthermore,the results show that the estimated generator speed is in a good accordance with the actual generator speed which supports sensorless control capability.展开更多
In this study,the movement of the maximum wind of Typhoon Rammasun(2014)was measured by the radial movement of the maximum symmetric rotational kinetic energy.The weather research and forecasting(WRF)model was used to...In this study,the movement of the maximum wind of Typhoon Rammasun(2014)was measured by the radial movement of the maximum symmetric rotational kinetic energy.The weather research and forecasting(WRF)model was used to simulate Typhoon Rammasun,and validated simulation data for the lower troposphere were analyzed to examine the physical processes responsible for the radial movement of the maximum wind.The radii,where maximum symmetric rotational kinetic energy and its maximum tendency were located,were compared to explain radial movement.The tendency in the lower troposphere is controlled by the flux convergence of symmetric rotational kinetic energy and the conversion from symmetric divergent kinetic energy to symmetric rotational kinetic energy,as well as frictional dissipation in the symmetric rotational kinetic energy budget.The inward movement before rapid intensification(RI)resulted from radial flux convergence;cyclonic circulation develops while moving inward.Stationary maximum symmetric rotational kinetic energy and RI were caused by the conversion,which was observed to be proportional to the symmetric rotational kinetic energy.Landfall increased terrain-induced friction dissipation,which led to outward movement and ended the RI.展开更多
From measurements by a circular array consisting of 18 wave gauges in a large wave tank, directional spectra of wind-generated waves in deep water are systematically determined by using maximum likehood method.The inv...From measurements by a circular array consisting of 18 wave gauges in a large wave tank, directional spectra of wind-generated waves in deep water are systematically determined by using maximum likehood method.The investigations reveal that the angular spreading of the wave energy is consistent with cos2s(θ/2) proposed by Longuet-Higgins et al. (1963, Ocean Wad Spectra,11~136), if the bimodal distributions of wave energy are not taken into account. Bimodality occurring on higher frequency than peak frequency is too rare to affect our whole results. Surprisingly, a much broader directional spreading than that of the field, which is interpreted by the strongly nonlinear energy transfer because of the very young waves in laboratory, is found. The parameter s depends on frequency in the same way as observed by Mitsuyasu et al. (1975, Journal of Physical Oceanography, 5, 750~760)and Hasselmann et al. (1980, Journal of physical Oceanography, 10, 1264~1280) in the field, and the relationship between the four nondimensional parameters sm, fo, b1 and b2, determining the directional width, and (corresponding to the inverse of wave age) are given respectively. The observed distributions are found to agree well with the suggestion of Donelan et al. (1985, Philosophical Transaction of Royal Society of London, A315, 509~562) when applied to field waves.展开更多
Based on gradient wind equations, including frictional force, and considering the effect of the movement of a tropical cyclone on wind speed, the Fujita Formula is improved and further simplified, and the numerical sc...Based on gradient wind equations, including frictional force, and considering the effect of the movement of a tropical cyclone on wind speed, the Fujita Formula is improved and further simplified, and the numerical scheme for calculating the maximum wind speed radius and wind velocity distribution of a moving tropical cyclone is derived. In addition, the effect of frictional force on the internal structure of the tropical cyclone is discussed. By comparison with observational data, this numerical scheme demonstrates great advantages, i.e. it can not only describe the asymmetrical wind speed distribution of a tropical cyclone reasonably, but can also calculate the maximum wind speed in each direction within the typhoon domain much more accurately. Furthermore, the combination of calculated and analyzed wind speed distributions by the scheme is perfectly consistent with observations.展开更多
中国气象局陆面数据同化系统(CLDAS)和高分辨率CLDAS(HRCLDAS)实况格点分析资料弥补了海面风观测稀疏的不足,然而其风速极大值与实际存在偏差,例如在狭管效应显著的台湾海峡区域普遍存在低估现象,其中CLDAS低估更严重,不能满足气象服务...中国气象局陆面数据同化系统(CLDAS)和高分辨率CLDAS(HRCLDAS)实况格点分析资料弥补了海面风观测稀疏的不足,然而其风速极大值与实际存在偏差,例如在狭管效应显著的台湾海峡区域普遍存在低估现象,其中CLDAS低估更严重,不能满足气象服务需求。因此本文提出一种基于地面站点观测风速二次融合的格点风场极大值订正技术,即采用反距离权重法将站点风速极大值观测周围一定影响半径区域内的站点风速观测插值到区域内的风场格点上,并综合考虑区域内风场误差和空间平滑程度以确定最优影响半径。利用2021~2023年CLDAS和HRCLDAS数据开展台湾海峡区域分区域(闽东、闽中及闽南渔场)风场极大值订正试验,结果表明:风场极大值订正技术能有效改进CLDAS和HRCLDAS对台湾海峡区域格点风速极大值低估情况,且HRCLDAS改进效果更优。HRCLDAS相较CLDAS出现小值最优影响半径频率增加。极值订正后,CLDAS和HRCLDAS逐小时平均绝对误差(MAE)降低率大多达到70%~85%和90%~95%;不同月份MAE降低率均超过60%,其中10月至次年1月订正效果最优,MAE降低率分别超过85%和90%;订正后误差空间分布与海岸线平行,自西向东减少,位于福建沿海及台湾海峡区域浮标站点区域MAE极值订正后降低至1 m s^(-1)以下。2305号台风“杜苏芮”和2023年1月23~25日典型冷空气大风过程的评估结果进一步表明,风场极大值订正技术对不同类别的大风过程均有效。展开更多
一类改进的最优转矩(optimal torque, OT)法通过扩大风力机最大功率点跟踪(maximum power point tracking, MPPT)过程中的不平衡转矩来提升转速跟踪能力,进而捕获更多风能。然而,此类方法在提高风能捕获效率的同时会造成电磁转矩的频繁...一类改进的最优转矩(optimal torque, OT)法通过扩大风力机最大功率点跟踪(maximum power point tracking, MPPT)过程中的不平衡转矩来提升转速跟踪能力,进而捕获更多风能。然而,此类方法在提高风能捕获效率的同时会造成电磁转矩的频繁波动,导致风力机传动链载荷显著提升。针对这一问题,文中研究发现在风速变化下补偿转矩引起的额外电磁转矩波动是产生上述现象的主要原因。为此,文中提出一种考虑载荷影响的风力机加速OT法,在风速变化时通过利用恒转矩过渡阶段抑制额外的电磁转矩波动,提升MPPT过程中的转速跟踪能力,从而实现在提升风力机风能捕获效率的同时尽可能避免载荷增大。最后,仿真结果验证表明,文中所提加速OT法不仅可以提升不同风况下的风能捕获效率,而且能够有效抑制传动链载荷的上升。展开更多
This paper presents a distribution free method for predicting the extreme wind velocity from wind monitoring data at the site of the Runyang Suspension Bridge (RSB), China using the maximum entropy theory. The maximum...This paper presents a distribution free method for predicting the extreme wind velocity from wind monitoring data at the site of the Runyang Suspension Bridge (RSB), China using the maximum entropy theory. The maximum entropy theory is a rational approach for choosing the most unbiased probability distribution from a small sample, which is consistent with available data and contains a minimum of spurious information. In this paper, the theory is used for estimating a joint probability density function considering the combined action of wind speed and direction based on statistical analysis of wind monitoring data at the site of the RSB. The joint probability distribution model is further used to estimate the extreme wind velocity at the deck level of the RSB. The results of the analysis reveal that the probability density function of the maximum entropy method achieves a result that fits well with the monitoring data. Hypothesis testing shows that the distributions of the wind velocity data collected during the past three years do not obey the Gumbel distribution. Finally, our comparison shows that the wind predictions of the maximum entropy method are higher than that of the Gumbel distribution, but much lower than the design wind speed.展开更多
Based on sorting out the data, this paper makes statistics and analysis for the basic features of sea surface wind of each season in the shore and offshore areas of Qingdao and calculates the maximum wind velocity onc...Based on sorting out the data, this paper makes statistics and analysis for the basic features of sea surface wind of each season in the shore and offshore areas of Qingdao and calculates the maximum wind velocity once in a century.展开更多
基金This work was supported by the Second Tibet Plateau Scientific Expedition and Research Program(STEP)under grant number 2019QZKK0804the National Natural Science Foundation of China“Study on the dynamic mechanism of grassland ecosystem response to climate change in Qinghai Plateau”under grant number U20A2098.
文摘Poisson-Gumbel joint distribution model uses maximum wind speed corresponding to multiple typhoons to construct sample sequence.Thresholds are usually used to filter sample sequences to make them more consistent with Poisson distribution.However,few studies have discussed the threshold setting and its impact on Poisson-Gumbel joint distribution model.In this study,a sample sequence based on the data of Qinzhou meteorological station from 2005 to 2018 were constructed.We set 0%,5%,10%,20%and 30%gradient thresholds.Then,we analyzed the influence of threshold change on the calculation results of maximum wind speed in different return periods.The results showed that:(1)When the threshold increases,the maximum wind speed of each return period will decrease gradually.This indicates that the length of the sample series may have a positive effect on the return period wind speed calculation in Gumbel and Poisson-Gumbel methods.Although the augment of the threshold increases the average value of the maximum wind speed of the sample sequence,it shortens the length of the sample sequence,resulting in a lower calculated value of the maximum wind speed.However,this deviation is not large.Taking the common 10%threshold as an example,the maximum wind speed calculation deviation in the 50 a return period is about 1.9%;(2)Theoretically,the threshold is set to make the sample sequence more consistent with Poisson distribution,but this example showed that the effect is worth further discussion.Although the overall trend showed that the increase of the threshold can makeχ2 decrease,the correlation coefficient of linear fitting was only 0.182.Taking Qinzhou meteorological station data as an example,theχ2 of 20%threshold was as high as 6.35,meaning that the selected sample sequence was not ideal.
文摘Using the data on the maximum wind speed within ten minutes every month in the period 1971-2009 in Zhucheng City of Shandong Province, we conduct statistical analysis of the maximum wind speed in Zhucheng City. The results show that over thirty-nine years, the annual maximum wind speed in four seasons in Zhucheng City tends to decline. The annual maximum wind speed declines at the rate of 1.45 m/s every 10 years. It falls fastest in winter, with decline rate of 1.73 m/s every 10 years; it is close to the average annual maximum wind speed in spring and autumn, with decline rate of 1.44 m/s and 14.8 m/s every 10 years, respectively; it falls slowest in summer, and the extreme value of the maximum wind speed occurs mainly in spring. The curve of changes in the monthly maximum wind speed in Zhucheng City assumes diminishing shape of "two peaks and one trough". We conduct preliminary analysis of the windy weather situation, and put forth specific defensive measures against the hazards of strong winds in the different periods.
基金Supported by the Open Laboratory Fund of the Institute of Plateau Meteorology of China Meteorological Administration(CMA)(LPM2012005)National Natural Science Foundation of China (41205114)CMA Special Public Welfare Research Fund(GYHY201106018 and GYHY200806009)
文摘In this study, the maximum wind speed （WSmax） changes across China from 1956 to 2004 were analyzed based on observed station data, and the changes of WSmax for 2046-2065 and 2080-2099 are projected using three global climate models （GFDL_CM2_0, CCCMA_CGCM3, and MRI_CGCM2） that have participated in the IPCC Fourth Assessment Report （AR4）. The observed annual and seasonal WSmax and the frequency of gale days showed obvious declining trends. The annual WSmax decreased by approximately 1.46 m s^-i per decade, and the number of gale days decreased by 3.0 days per decade from 1956 to 2004. The amplitudes of the annual and seasonal WSmax decreases are larger than those of the annual and seasonal average wind speeds （WSavg）. The weakening of the East Asian winter and summer monsoons is the cause for the distinct decreases of both WSmax and WSavg over the whole China. The decrease of WSmax in the southeast coastal areas of China is related to the reduced intensity of cold waves in China and the decreasing number （and decreasing intensity） of land-falling typhoons originated in the Northwest Pacific Ocean. The global climate models GFDL_CM2_0, MRI_CGCM2, and EBGCM （the ensemble of above men-tioned three global climate models） consistently suggest that the annual and seasonal WSmax values will decrease during 2046-2065 and 2080 2099 relative to 1981 2000. The models also suggest that decreases in WSmax for whole China during 2046-2065 and 2080 2099 are related to both the reduced intensity of cold waves and the reduced intensity of the winter monsoon, and the decrease in WSmax in the southeast coastal areas of China is corresponding to the decreasing number of tropical cyclones over the Northwest Pacific Ocean in the summer during the same periods.
基金supported partially by the National Natural Science Foundation of China under Grant 61503348the Hubei Provincial Natural Science Foundation of China under Grant 2015CFA010the 111 project under Grant B17040
文摘When the wind speed changes significantly in a permanent magnet synchronous wind power generation system,the maximum power point cannot be easily determined in a timely manner.This study proposes a maximum power reference signal search method based on fuzzy control,which is an improvement to the climbing search method.A neural network-based parameter regulator is proposed to address external wind speed fluctuations,where the parameters of a proportional-integral controller is adjusted to accurately monitor the maximum power point under different wind speed conditions.Finally,the effectiveness of this method is verified via Simulink simulation.
文摘This paper presents a scalar volt per hertz(V/f)control technique for maximum power tracking of a grid-connected wind-driven brushless doubly fed reluctance generator(BDFRG).The proposed generator has two stator windings namely;power winding,directly connected to the grid and control winding,connected to the grid through a bi-directional converter.In order to enhance the performance of the proposed scalar-control strategy,a soft starting method is suggested to avoid the over-current of the bi-directional converter.Moreover,the capability of generator speed estimation for sensorless control is also studied.The capability of the proposed scalar-control technique is validated using a sample of simulation results.In addition,the presented simulation results ensure the effectiveness of the proposed control strategy for maximum wind-power extraction under windspeed variations.Furthermore,the results show that the estimated generator speed is in a good accordance with the actual generator speed which supports sensorless control capability.
基金supported by the National Natural Science Foundation of China(Grant No.41930967).
文摘In this study,the movement of the maximum wind of Typhoon Rammasun(2014)was measured by the radial movement of the maximum symmetric rotational kinetic energy.The weather research and forecasting(WRF)model was used to simulate Typhoon Rammasun,and validated simulation data for the lower troposphere were analyzed to examine the physical processes responsible for the radial movement of the maximum wind.The radii,where maximum symmetric rotational kinetic energy and its maximum tendency were located,were compared to explain radial movement.The tendency in the lower troposphere is controlled by the flux convergence of symmetric rotational kinetic energy and the conversion from symmetric divergent kinetic energy to symmetric rotational kinetic energy,as well as frictional dissipation in the symmetric rotational kinetic energy budget.The inward movement before rapid intensification(RI)resulted from radial flux convergence;cyclonic circulation develops while moving inward.Stationary maximum symmetric rotational kinetic energy and RI were caused by the conversion,which was observed to be proportional to the symmetric rotational kinetic energy.Landfall increased terrain-induced friction dissipation,which led to outward movement and ended the RI.
文摘From measurements by a circular array consisting of 18 wave gauges in a large wave tank, directional spectra of wind-generated waves in deep water are systematically determined by using maximum likehood method.The investigations reveal that the angular spreading of the wave energy is consistent with cos2s(θ/2) proposed by Longuet-Higgins et al. (1963, Ocean Wad Spectra,11~136), if the bimodal distributions of wave energy are not taken into account. Bimodality occurring on higher frequency than peak frequency is too rare to affect our whole results. Surprisingly, a much broader directional spreading than that of the field, which is interpreted by the strongly nonlinear energy transfer because of the very young waves in laboratory, is found. The parameter s depends on frequency in the same way as observed by Mitsuyasu et al. (1975, Journal of Physical Oceanography, 5, 750~760)and Hasselmann et al. (1980, Journal of physical Oceanography, 10, 1264~1280) in the field, and the relationship between the four nondimensional parameters sm, fo, b1 and b2, determining the directional width, and (corresponding to the inverse of wave age) are given respectively. The observed distributions are found to agree well with the suggestion of Donelan et al. (1985, Philosophical Transaction of Royal Society of London, A315, 509~562) when applied to field waves.
基金supported by the National Natural Science Foundation of China (NSFC) under Grant Nos. 40425009 and 40730953
文摘Based on gradient wind equations, including frictional force, and considering the effect of the movement of a tropical cyclone on wind speed, the Fujita Formula is improved and further simplified, and the numerical scheme for calculating the maximum wind speed radius and wind velocity distribution of a moving tropical cyclone is derived. In addition, the effect of frictional force on the internal structure of the tropical cyclone is discussed. By comparison with observational data, this numerical scheme demonstrates great advantages, i.e. it can not only describe the asymmetrical wind speed distribution of a tropical cyclone reasonably, but can also calculate the maximum wind speed in each direction within the typhoon domain much more accurately. Furthermore, the combination of calculated and analyzed wind speed distributions by the scheme is perfectly consistent with observations.
文摘中国气象局陆面数据同化系统(CLDAS)和高分辨率CLDAS(HRCLDAS)实况格点分析资料弥补了海面风观测稀疏的不足,然而其风速极大值与实际存在偏差,例如在狭管效应显著的台湾海峡区域普遍存在低估现象,其中CLDAS低估更严重,不能满足气象服务需求。因此本文提出一种基于地面站点观测风速二次融合的格点风场极大值订正技术,即采用反距离权重法将站点风速极大值观测周围一定影响半径区域内的站点风速观测插值到区域内的风场格点上,并综合考虑区域内风场误差和空间平滑程度以确定最优影响半径。利用2021~2023年CLDAS和HRCLDAS数据开展台湾海峡区域分区域(闽东、闽中及闽南渔场)风场极大值订正试验,结果表明:风场极大值订正技术能有效改进CLDAS和HRCLDAS对台湾海峡区域格点风速极大值低估情况,且HRCLDAS改进效果更优。HRCLDAS相较CLDAS出现小值最优影响半径频率增加。极值订正后,CLDAS和HRCLDAS逐小时平均绝对误差(MAE)降低率大多达到70%~85%和90%~95%;不同月份MAE降低率均超过60%,其中10月至次年1月订正效果最优,MAE降低率分别超过85%和90%;订正后误差空间分布与海岸线平行,自西向东减少,位于福建沿海及台湾海峡区域浮标站点区域MAE极值订正后降低至1 m s^(-1)以下。2305号台风“杜苏芮”和2023年1月23~25日典型冷空气大风过程的评估结果进一步表明,风场极大值订正技术对不同类别的大风过程均有效。
文摘一类改进的最优转矩(optimal torque, OT)法通过扩大风力机最大功率点跟踪(maximum power point tracking, MPPT)过程中的不平衡转矩来提升转速跟踪能力,进而捕获更多风能。然而,此类方法在提高风能捕获效率的同时会造成电磁转矩的频繁波动,导致风力机传动链载荷显著提升。针对这一问题,文中研究发现在风速变化下补偿转矩引起的额外电磁转矩波动是产生上述现象的主要原因。为此,文中提出一种考虑载荷影响的风力机加速OT法,在风速变化时通过利用恒转矩过渡阶段抑制额外的电磁转矩波动,提升MPPT过程中的转速跟踪能力,从而实现在提升风力机风能捕获效率的同时尽可能避免载荷增大。最后,仿真结果验证表明,文中所提加速OT法不仅可以提升不同风况下的风能捕获效率,而且能够有效抑制传动链载荷的上升。
基金Project supported by the National Natural Science Foundation of China (Nos. 50725828 and 50808041)Scientific Research Foundation of Graduate School of Southeast University (No. YBJJ0923)the Teaching and Research Foundation for Excellent Young Teacher of Southeast University,China
文摘This paper presents a distribution free method for predicting the extreme wind velocity from wind monitoring data at the site of the Runyang Suspension Bridge (RSB), China using the maximum entropy theory. The maximum entropy theory is a rational approach for choosing the most unbiased probability distribution from a small sample, which is consistent with available data and contains a minimum of spurious information. In this paper, the theory is used for estimating a joint probability density function considering the combined action of wind speed and direction based on statistical analysis of wind monitoring data at the site of the RSB. The joint probability distribution model is further used to estimate the extreme wind velocity at the deck level of the RSB. The results of the analysis reveal that the probability density function of the maximum entropy method achieves a result that fits well with the monitoring data. Hypothesis testing shows that the distributions of the wind velocity data collected during the past three years do not obey the Gumbel distribution. Finally, our comparison shows that the wind predictions of the maximum entropy method are higher than that of the Gumbel distribution, but much lower than the design wind speed.
文摘Based on sorting out the data, this paper makes statistics and analysis for the basic features of sea surface wind of each season in the shore and offshore areas of Qingdao and calculates the maximum wind velocity once in a century.
