A Study On The Theory Of Wave Energy Converter Array Layout And Its Application

As a strategic resource,ocean renewable energy has been internationally recognized,and ocean energy development and utilization technology has gained a rapid development in recent years.Among various ocean energies,wave energy development technology is increasingly mature,but due to the constraint of such factors as ocean engineering technology,construction cost and wave energy resources,the single-machine power of wave energy device can't be increased infinitely.So we propose wave energy array which means laying out a plurality of wave energy devices in the sea according to a certain rule,when the single device reaches a certain scale,wave energy development and utilization technology can satisfy total installed power by increasing the number of modules in the array.Wave energy array is an effective way to improve the reliability of wave energy technology,reduce its cost and drive its breakthrough in technology bottleneck to achieve industrialization.This technology is not only expected to improve the array's capture efficiency of wave energy,reduce the adverse effect between devices but also control the distance between devices to save array's sea occupying area,meanwhile reducing their maintenance cost and the layout of required cable and other supporting facilities.In this paper,the research is carried out to seek out relevant theoretical methods and solutions to application in the process of designing wave energy device array layout with the point absorber selected as the research object,The following are the main research results.Firstly,the motion equation of wave energy capture device in wave field is derived systematically on the basis of the fundamental theory of hydromechanics,furthermore,in line with the technological features of wave energy devices,the conditions of solving the equation are reasonably set,with the solution to the equation,the mathematical expressions in response to the amplitude of the single device in the wave field and the devices in the array layout are derived,thus realizing the theoretical description of the motion characteristics of wave energy capture devices array in wave field under complicated surroundings,and laying a theoretical base for the implementation of this research.Secondly,refined observation methods of wave elements in small areas are studied and worked out.In combination with historical data and hydrodynamic theory analysis,a refined exploration plan is drawn up,and revised through representative verification test,and then it is applied to conduct long-term observation of the targeted sea area.In the process of the research,the northern sea area of Weihaichu Island is selected for the application and practice of the method.Under the premise of ensuring observation quality,this method has effectively reduced observation cost.On the other hand,through combination of statistical method with numerical simulation,it can accurately calculate and analyze the wave height,wave period and the distribution characteristics of wave energy of each wave direction in the targeted sea area.In the process of setting up numerical models,the characteristics of surrounding sea area featured by deep water and complex topography was fully taken into account,and targeted model settings were carried out.Thirdly,an optimal design method of the structure of point absorber is figured out.Based on the characteristics of wave energy resource in the targeted sea area,the installed power of point absorber is set reasonably,and the diameter of point absorber is analysed and calculated;then calculation software is used to calculate the corresponding correlation between the draught depth and the inherent period of point absorber under multiple working conditions,and through analysis,the change regularity of the inherent period of point absorber with the change of its draught depth is derived,finally,based on the observational statistics of the wave period of the sea area where point absorbers are laid out,the optimal draught depth of point absorber in this sea area is analysed,calculated and figured out.Finally,the mathematical expression of array energy acquisition coefficient is derrived by applying this theorectical research results.On this basis,two new effect evaluation indexes of wave energy array layout-array energy gain coefficient and and array energy capture density are proposed,and their mathematical expressions are also deduced,realizing the quantitative evaluation of the overall energy capture effect and sea using efficiency of array layout;moreover,the practicality of the research results has been verified through examples.In addition,the new indexes can also be applied to the evaluation of optimization effect of the device array layout of tidal energy and offshore wind energy,thus enriching the evaluation index system of of ocean energy array layout effect.