Research On Optimization And Hydraulic System Of Wave Energy Converter Arrays

Energy and environmental problems are becoming more and more serious worldwide,and vigorous development of renewable energy has become the consensus of all countries in the world,which is also a necessary condition for human society to achieve sustainable development.The ocean accounts for about 71%of the earth’s surface and contains huge reserves of renewable energy.Wave energy has become a research hotspot for renewable energy utilization because of its high energy density,concentrated distribution and high theoretical energy capture efficiency.After decades of development,wave energy utilization technology has been relatively mature,but its low energy conversion efficiency,poor reliability and high cost have restricted the application and development of wave energy utilization technology.In analogy with solar energy,wind energy and other renewable energy technologies,the establishment of wave energy converter farms and the use of wave energy converter arrays to collect the dispersed wave energy play an important role in reducing the cost of wave energy converters and improving the efficiency and stability of wave energy converters.In this thesis,an oscillating buoy type wave energy converter array was studied,a mathematical model was established,a method to optimize the array layout using genetic simulated annealing algorithm was proposed,and its buoy hydrodynamic characteristics and hydraulic system output characteristics were analyzed.This thesis firstly elaborated the research background and significance of this research,briefly described the classification and typical devices of wave energy converters,highlighted the research progress of wave energy converter arrays layout optimization and its hydraulic system,and proposed the research content of this topic in combination with the research progress.Secondly,the mathematical model of wave energy converter arrays was derived based on the linear wave theory,and the mathematical model was built in MATLAB,and the accuracy of the established mathematical model was verified by comparing with the calculation results of AQWA simulation software.Then,based on the established mathematical model,the effects of buoy radii,buoy drafts and damping coefficients on the hydrodynamic performance of the single wave energy converter and the laws of damping control and complex conjugate control,buoy spacings,wave incidence directions,number of buoys and array layout forms on the hydrodynamic performance of the wave energy converter array device were analyzed.Again,a genetic simulated annealing algorithm was proposed to optimize the arrays layout,and the influence laws of damping control and complex conjugate control,the number of buoys,the radius of buoys and the draft of buoys on the layout optimization of wave energy converter arrays are explored,and the results are also compared with the optimization effect of genetic algorithm,which shows that the optimization effect of genetic simulated annealing algorithm is better than that of genetic algorithm.In addition,based on the application requirements of wave energy converter arrays,two system forms are designed,one hydraulic power take-off(PTO)system for multiple buoys and one hydraulic PTO system for each buoy separately,and a simulation model was built in Simulink to compare the output characteristics of the two systems,and the influence of array layouts,buoy spacings,wave incidence directions,significant wave heights and spectrum peak period on the system output characteristics was investigated.Finally,the conclusions of this thesis were summarized and the prospects for future research were presented.