Study On Bending Moment Matching Optimization Technology In Full-scale Loading Test Of Wind Turbine Blades

Blade is one of the key components of wind turbine system,the full-scale loading certification test is required for blades that are newly developed or are major technology changed.The degree of bending moment matching under loading is closely related to the accuracy of certification results.At present,most of domestic and foreign researchers focus on the control of loading system,and the lack of equivalent load setting of bending moment and additional masses scheme optimization method lead to long test time,high costs,and low accuracy.The purpose of this paper is to develop bending moment optimization technology for full-scale loading test of wind turbine blades by problem analysis,algorithm research,simulation and field application.(1)Based on the problem analysis of bending moment matching optimization,three global intelligent optimization algorithms are screened out: Particle Swarm Optimization,Differential Evolution and Artificial Immune Algorithm.Aiming at the shortcomings of Particle Swarm Optimization which is prone to fall into premature convergence and local extremum,the APSO algorithm with improving parameters of weight and learning factors is designed.Considering the superiority of hybrid optimization algorithm,a differential variation is introduced into APSO,and the population diversity evaluation index in AIA is used as the variation condition,two hybrid intelligent optimization algorithms DE＿APSO and AIA＿DE＿APSO are proposed.Based on the example of function minimum solution,it is verified that the designed algorithm has the advantages of high accuracy,fast search speed,and good adaptability.(2)The key factors influenced bending moment distribution of wind turbine blade’s static test are analyzed.A static test moment calculation modal that introduced weight is built by discretizing blade based on equivalent substitution principle.The mean square error as fitness function,the programming is performed by combining the calculation model and the designed algorithms.The bending moment matching optimization in flap-wise direction of LZ75.8-3 blade is carried out,and a 5-points loading scheme is determined.The DE＿APSO algorithm is the most effective in static test bending moment matching.The correctness and feasibility of designed optimization method are verified through shell modeling and simulation analysis of test blade.The optimization technique is applied to the collapse test,and the interdisciplinary and trans-dimension analysis of blade structure and material failure is performed,which lays a theoretical foundation for the strengthening of blade weak points and the improvements of blade structure design.(3)Aiming at the problems of additional masses distribution of bending moment matching in fatigue test,the parameters identification in modal test and force analysis of system are carried out.The mathematical model of bending moment calculation under single axis fatigue loading driven by rotating masses is constructed.The mean section moment error as the objective function,joint optimization of bending moment distribution and amplitude control problems are performed by setting constraints.The example analysis of optimization technology for fatigue test is performed based on LZ40.3-1.5 blade to acquire the matching accuracy and the additional masses distribution scheme in flap-wise and edge-wise direction.The equivalent fatigue damage at critical section is calculated based on strain data in field test.Finally,the sensitivity analysis of the variable parameters of the dual-axis loading is performed,the accuracy difference of bending moment matching in two directions under dual-axis excitation is balanced by combining with the rough surface and fine line search strategies.The bending moment matching optimization in full-scale loading test of wind turbine blade is a set of solutions including working condition analysis,model build of bending moment calculation,optimization algorithm design and application research,which simplifies the influences of blade materials and structural attributes,reduces the bending moment error of key sections to 5%,shortens the test period and has extensive application prospect and value.