Study On Cross-interface Semi-submersible Ocean Current Power Generation Method And Device

As one of the ocean energy,ocean current energy has strong regularity and predictability due to its density and distribution.Ocean current energy is large and stable,more convenient for development and utilization.The ocean current energy is mainly used for power generation.At present,the method of ocean current power generation is generally to fix the turbine to the seabed or to be installed below the sea level,and pushes the turbine to rotate to drive the generator to product electricity.Different from the existing ocean current power generation method,this paper proposes a new method of semi-submersible ocean current energy generation,that is,a part of the turbine impeller is placed below the sea surface,and part of it is exposed to the air.According to the semi-submersible ocean current power generation method,the design of water turbine blade structure was carried out and a semi-submersible ocean current power generation device was developed.Finally,the performance of the semi-submersible ocean current power generation system was studied experimentally.The main work and conclusions of this paper are as follows:1.A new experimental scheme of semi-submersible ocean current power generation and traditional full-immersion ocean current power generation was designed,and a sea current energy power generation experimental platform was built.The experimental platform was stable.2.Under the equal circulation area,the power generation,system conversion efficiency and power generation of the trans-interface semi-submersible ocean current power generation system were higher than those of the fully immersed turbine-type ocean current power generation system.3.The designed semi-submersible curved blade structure was reasonable,and the optimization design of blade improved the power generation and conversion efficiency of the ocean current energy.4.Experimental research found that the power generation and conversion efficiency of the semi-submersible ocean current power generation device were directly related to the structure of the blade(curveness,quantity)and the depth of the blade axis.Firstly,the power generated by the curved blade impeller was more powerful than that of the straight blade impeller.Secondly,from the curved blade structure,the impeller with the arc of 70°,the arc length/chord length ratio of 1.16 and the number of blades was 8(hereinafter referred to as Ben5).The impeller had a higher arc conversion efficiency of 125°,an arc length/chord length ratio of 1.58,and a blade number of 6.Finally,from the depth of the impeller diving,the depth of the impeller is 40-60 % of the impeller diameter,and the power generation performance of the system is better.5.The performance of the semi-submersible ocean current power generation system was analyzed by using the power characteristics of ocean current power generation as an evaluation index.In terms of power characteristics,the system power generation increases with the increase of the water flow rate.When the Ben5 impeller operates at a flow rate of 1.3 m/s,the system obtains the maximum power which is about 1.7 W.In terms of system conversion efficiency,the maximum conversion efficiency of the system is 34.3% when the Ben6 impeller is at a flow rate of 0.9 m/s.6.Compared with the performance of the traditional full-immersion ocean current power generation system,the power generation of the semi-submersible curved blade power generation system is significantly larger than that of the full-immersion twisted blade power generation system.In the flow velocity of 0.5-1.3 m/s,the power of semi-submersible water impeller is more than 33.7% of the total immersed turbine power;compared with the conversion efficiency,the average of semi-submersible system is within the experimental flow rate range.The conversion efficiency is higher than 7% of the full immersion power generation system;compared with the annual power generation,the annual power generation of semi-submersible ocean current power generation device is 27.3% higher than the annual power generation capacity of the full immersion ocean current power generation device.7.Compared with the performance of the traditional full-immersion ocean current power generation system,the output torque and system mechanical power are used as evaluation indexes.In the flow rate range,the output torque of the semi-submersible curved blade is larger than the output torque of the fully immersed torsion blade 0.36 N·m;in output mechanical power,the output mechanical power of the semi-submersible power generation system is greater than the output mechanical power of the fully immersed power generation system,which exceeds 3.8 W.8.In order to make the semi-submersible curved blade ocean current power generation device practical,on the basis of laboratory research,the power generation system is optimized and improved,and a set of trans-interface semi-submersible current energy power generation adapted to the sea was preliminarily designed.The system included the design of the floating system,the fixed system,and the protection system of the power generating device.The research results propose a new method for the ocean current energy generation technology.Compared with the traditional full-immersion turbine ocean current energy generation method,the trans-interface semi-submersible ocean current energy generation technology has improved power generation and system conversion efficiency.The system has good performance and has practical engineering application value.