Desing analysis and development of a nacelle main load frame for a 500 kW wind turbine

Official URL: http://192.168.1.20/record=b1499077 (Table of Contents)

Wind energy is gaining increasing momentum over the last two decades. Wind energy business is one of the most attractive in renewable energy sectors. While several wind turbine designs are available in the industry, developing a wind turbine for continuous commercial electricity production is one of the challenging engineering problems in todays world. This work involves design, analysis and development of a nacelle main load frame for a 500kw wind turbine as part of the national wind turbine development project (MILRES) of Turkey. Starting from conceptual design stage complete static and dynamic analyses were conducted including the crane loads on the nacelle bedplate. Conceptual and detail design work were conducted using commercially available 3D solid modeling code SOLIDWORKS. Structural analyses such as stress and strain calculations and modal analyses of the main load frame were performed using the finite element method. A hybrid (cast iron main base and weld formed steel extension) structure has been developed to improve stiffness while controlling overall weight. A bolted joint assembly was designed for cast base and steel extension interface. Analytical joint and bolting calculations were confirmed by finite element simulations of the assembled bedplate structure. An iterative design approach has been used. Design and analysis iterations were carried out to improve functionality, weight, and stress levels. For an optimum stress and weight design solution, topology optimization methods were applied to the structure in order to minimize weight while maintaining design safety limits and stiffness of the structure. Topology optimization stage was conducted by commercially available codes OPTISTRUCT and ANSYS shape optimization module. The optimization work resulted in 30% reduction of weight. The analysis results for optimized geometry indicated sufficiently high design safety margins for all design load combinations. Overall, an optimum Nacelle bedplate design has been developed achieving high safety factors with minimum weight.