Mechanical Properties Research Of The Multi-Rotor Wind Turbine System

Multi-rotor wind energy turbine could solve a lot of problems of the large windenergy system, such as installation, transport and so on, especially reduced the load’svariation in the wind shear. In this paper, the multi-rotor wind power system wasproposed and built, which includes ten horizontal axis wind turbines with50W each.Compared with single-rotor wind power turbine, the advantage of the multi-rotorwind power turbine is found in the wind shear.The studies mainly also include: simplified formula of blade load is establishedbased on the BEM, The effects of blade azimuth, blade length, installation height ofwind turbine, wind shear coefficient and wind speed on blade load were discussed.3Rotor wind power turbine with2kW is designed. mechanical properties are studiedby ANSYS software, including static of the tower，modal analysis of tower, therelationship between tower’s natural frequency and geometric parameter of thetower, vibration property and the seismic response of the tower.The results indicated that the load during the turbine rotating changes morewith the longer blade, the lower installation height of the wind turbine, the largerwind shear coefficient. The effect of the wind shear on blade load can be reducedsubstantially with many small wind turbines instead of the large wind turbine. Thetower’s stress nephograms where the dangerous area is easy to find in storm windcondition and working condition are plotted. The first nine natural frequencies andmode shapes are obtained. The results shows that the first two natural frequencieschange more with the larger and thicker outer diameter of the main tower, the lowerinstallation of the horizontal tower, the smaller turbine mass. The Campbell diagramshowed that the turbine would not induce the tower resonance when it operated atthe rated condition. Also, the turbine frequency that could induce tower resonancewas achieved from the Campbell diagram. The structural damping ratio wascalculated based on Indrajit Chowdhury’s method. Then, the transient analysis of thetower was made when it was applied constant gravitational load and wind load, andcentrifugal alternating load, as well as considering its calculated structural dampingratio. Finally, the dynamic response characteristics and the seismic response in ELCentro seismic wave of the tower were achieved. The results shows the tower couldbe save in those work condition.