Study On Wind-Induced Vibration Of Large-Span Flexible Support Structures In Photovoltaic Power Plants

In 2021,a wind-induced damage event occurred in a photovoltaic project in Xinjiang,China,where a wind gust lifted the entire megawattscale photovoltaic array.More and more scholars have focused their research on the safety of photovoltaic panels.In order to accurately investigate the wind resistance performance of photovoltaic arrays,this paper takes a flexible supported photovoltaic panel in a specific project as the research object.Numerical wind tunnel simulations,fluid-structure interaction vibration simulations,and wind-induced response analyses are conducted to study the vibration characteristics of the panel under natural wind action in Class B terrain,providing practical engineering guidance for the design of flexible supports.Fifteen(3×5)local photovoltaic panels of the entire array were selected to analyze the distribution pattern of the wind pressure coefficient on the panel surface under natural wind action.The results indicate that the wind load distribution on the surface of the photovoltaic panel is nonuniform,resulting in different wind pressures on different parts of the panel,which is the main cause of torsional vibration.The wind pressure coefficient is highest at the leading edge of each panel and gradually decreases along the length,exhibiting a distinct gradient distribution.This leads to different wind pressures on different parts of the panel and consequently results in different forces applied to the upper and lower supporting cables(main cables).In addition,flow separation occurs at the top and bottom of the photovoltaic panel,creating vortices on the leeward side and forming negative pressure regions.The intensity,size,and influence of the vortices gradually decrease downstream,and the peripheral photovoltaic modules of the array are most affected by the wind field,posing the greatest risk.Sufficient attention should be given to this aspect during the design process.Flexible cables experience significant displacements under wind action,resulting in an aerodynamic interaction effect.The study focuses on a partial(3×5)photovoltaic array and reveals that there is a noticeable shadowing effect of the front row panels on the rear row panels.When the front row panels are dynamically stable,their displacements reach 6.8 cm,while the displacements of the two rear rows are only 0.4 cm.This is because the incoming flow creates vortices after passing through the front row panels,leading to negative pressure regions behind the panels and significantly reducing the wind pressure on the rear row panels.Therefore,when designing photovoltaic panels,using static pressure calculations would result in a conservative safety margin for the rear row panels.The findings of this study are of great significance for the design and optimization of photovoltaic panels and provide practical guidance and references for related engineering projects in the field of photovoltaics.Based on the array model used in the proj ect,a finite element model of the "mooring-dragging structure" flexible support system employed in the project is established for wind-induced response simulations,and a comparison is made with the traditional rigid support system.The results show that:(1)Under the flexible support system,the photovoltaic panels mainly exhibit vertical vibration as the primary mode,with a secondary vibration in the along-wind direction,while under the rigid support system,the main mode is lateral oscillation.(2)The amplitude of wind-induced response under the flexible support system(around 13 cm)is larger than that under the rigid support system(0.5 cm),but it still maintains reliable safety.In some areas with unfavorable terrain conditions,the flexible support system can be considered as an alternative to rigid support structures,and the wind-induced response coefficient is recommended to be set at 1.8.(3)The anchoring-dragging structure in the flexible system significantly constrains the vertical displacement of the photovoltaic panels.Ground anchor cables can be applied to areas with excessive displacement in the array to increase safety.(4)Under the flexible support system,the axial force distribution of the main supporting cables throughout the array remains approximately the same.The maximum axial force in each main supporting cable is around 60 kN,indicating a certain level of stiffness distribution in the flexible support cable system.This research provides practical and theoretical foundations for the design of flexible photovoltaic arrays,including the incorporation of ground anchor design into project practices.In conclusion,this study investigates the wind resistance and dynamic characteristics of a flexible supported photovoltaic panel through numerical simulations and analyses.The uneven distribution of wind pressure on the panel surface and the shadowing effect between rows of panels are identified.The study also compares the wind-induced response of flexible and rigid support systems,highlighting the advantages of the flexible support system.The findings contribute to the design,optimization,and practical implementation of photovoltaic panels,particularly those employing flexible support structures.