Study On Wind-prevention And Sand-fixing Benefits Of Reed Sand Barrier In The Photovoltaic Plant

To clarify the benefits of wind and sand fixation after laying reed sand barriers in the Hobq Desert photovoltaic power plant,in this paper,we carried out field observations on the wind speed(20cm,50cm,100cm,200cm)and near-surface sand transport after laying the reed sand barrier.The sand fixation effect of the reed sand barrier on the periphery of the photovoltaic power plant,in the power plant and under different sand burial conditions is analyzed comparatively.The wind protection effect of reed sand barriers with separate wind coverage and different coverage is illustrated by wind speed profile,roughness,friction speed,wind speed increase rate and other indicators.The main research conclusions are as follows:(1)The wind speed of the transit wind from bare sand into the photovoltaic array declines significantly.The increased rate of wind speed in upwind and downwind is about 1-2 times of that in bare sand.The roughness and friction speeds are 79.39 times and 1.33 times,of bare sand,respectively.The amount of sand transported upwind and downwind is 65.07%and 47.79%of the exposed sand,respectively.When the wind speed decreases from 8.57m·s-1 to 7.64m·s-1,the total sand transport volume of the reed sand barrier decreases by 22.47%from 44.20g·cm-2·h-1 to 34.27g·cm2·h-1;The sand-fixing efficiency decreases from 95.5%to 45.52%,and the average saltation height increases by ten times.(2)According to the field observations of wind speed changes and sand transport conditions in photovoltaic power plants with reed sand barriers,we find that the reed sand barrier is only 6.95%of bare sand,the total sand-fixing benefit is 93.05%.The amount of bare sand is more than 90%concentrated in 0-8cm.The wind and sand flow structure of the reed sand barrier tends to move to the upper layer.The main components of the reed sand barrier are fine sand and medium sand.The content of fine sand is 71.99%?78.76%,and the content of medium sand is 15.98%?25.74%.The total sediment transport at different height of sand burial ranked from high to low is as follows:fully buried(2.9705g·cm-2·min-1),deeply buried(0.2159g·cm-2·min-1),and shallowly buried(0.1410g·cm-2·min-1).The shallow burial sediment transport is only 4.75%of the total burial,and the deep burial accounts for 7.27%of the total burial sediment transport.The jump heights of the three sand burial states are fully buried(1.97cm),deep buried(4.29cm),and shallowly buried(6.91cm).(3)The wind speed profile,aerodynamic roughness and friction velocity of reed sand barrier laid with coverage of 45%and 55%are different at distinct wind speed and wind downward.Under different wind directions,the wind protection effect of reed sand barrier with 55%coverage is better than that of 45%coverage within the height range of 0-50cm.The roughness of bare sand increases with the increase of wind speed,and the overall roughness is 55%coverage>45%coverage>bare sand.The pimpling of reed sand barrier decreases with the growth of wind speed.(4)Through the study of the surface erosion and deposition characteristics of different photovoltaic arrays,it is found that the photovoltaic array 1 is in erosion state under and in front of the plate,and the photovoltaic array 2 and 3 are in accumulation under the plate and erosion in front of the plate.The width of wind erosion gully in photovoltaic array 1 is 4.5m,The erosion intensity is-39.67cm/m2;the width of wind erosion gully of photovoltaic array 2 is 2.2m,the erosion intensity is-15.31 cm3/m2,the width of wind erosion gully of photovoltaic array 3 is 3.2m,and the erosion intensity is-9.84cm3/m2.Half a year after the reed sand barrier was laid,the reed sand barrier of photovoltaic array 1 was completely buried by sand,which lost the role of wind and sand fixation.The reed sand barriers of photovoltaic array 2 and photovoltaic array 3 were buried by sand to varying degrees,and the role of wind and sand fixation was weakened.