Optimal Design, Based On The Uncertainty Of The Evidence Theory Megawatt-class Wind Power Growth

The speed increaser is one of the most important parts in wind turbine generator systems (WTGS), and its basic function is to transfer torque to electric generator and then to the related parts. In the design and manufacturing process of the speed increaser there are many uncertainties which may ultermately impact the reliability and safty of the product. Without carefully quantifing such uncertainties, the WTGS may suffer a great risk and bring about a catactrophic consequence.For the uncertainty in the design of the speed increaser, a reliability-based optimization design method is proposed in this thesis to deal with the protential uncertainty during the design of the speed inceraser with capacity up to MW. The main contributions of this thesis are summarized as follows:(1) An improved evidence-based design optimization method (EBDO) is developed to consider the interval variables and random variables simultaneously. The main steps are: 1) Estimate the extreme value of the limit state function within the intervals via vertex method; 2) Use the first order reliability method (FORM) to estimate the reliability at the extreme value point of the limit state function; 3) Ues EBDO to optimize the objective function.(2) The uncertainties in the design of speed increaser are quantified. Because both epistemic uncertainty and aleatory uncertainty exist, interval variables and random variables are adopted in proposed method to quantify the uncertainties.(3) A design optimization formulation for the speed increaser is developed. The proposed EBDO method is used to the optimazition problem via Matlab program.(4) The results using EBDO are compared with those of the conventional methods in which all the parameters are treated as determistic parameters. The solution shows that the proposed method is more reliable.