| Wind turbines use wind blades to convert the mechanical energy of airflow into electrical energy,which is an essential equipment for wind power generation.As one of the important components,wind turbine blades are affected by alternating loads for a long time,and the main failure mode is fatigue failure.Full-scale fatigue loading test is the most effective and convenient method to test the fatigue resistance of blades.Pendulum resonance loading method is basically adopted by domestic blade manufacturers and testing institutions.Among them,the resonant loading scheme of centrifugal pendulum uses the motor mounted on the blade to drive the eccentric mass to make circular motion in the vertical plane,which is the mainstream method for fatigue loading test of blades in China.The experimental device is relatively simple in structure and low in test cost,but the self-weight of excitation equipment affects the test accuracy.Therefore,this paper proposes a new fatigue loading method for wind turbine blades driven by electromagnetic force,which can effectively improve the testing accuracy because the excitation device does not need to be fixed on the blades.Specific research contents are as follows:Firstly,in order to verify the feasibility of the new method of electromagnetic excitation fatigue loading of wind power blades,the wind power blades are simplified as linear elastic bodies after the static equilibrium position is determined from the theoretical research,and the system differential equation is established for the simplified dynamic model by using Lagrange equation.The bi-directional pulse signal is decomposed into several harmonic forms by Fourier series,and the electromagnetic excitation response is obtained,and the electromagnetic pulse force needed to be input by a specific blade excitation system is obtained by energy analysis method MATLAB software is used to verify that the blade can obtain stable amplitude output and realize sinusoidal loading when subjected to bidirectional electromagnetic pulse force.Secondly,the solenoid electromagnet is designed as the power source of the fatigue loading device of wind turbine blades,which provides periodic bidirectional pulse force for the vibration of the blades.The whole structure of wind turbine blade fatigue loading device is designed and the structural design scheme of electromagnetic excitation device is expounded in detail The calculation method and influencing factors of electromagnetic force in solenoid electromagnet are studied theoretically It is verified by ANSYS Maxwell electromagnetic simulation software that solenoid electromagnet can be used as power source to provide pulse force for blade loading system,and the action range of electromagnetic force in blade loading process is designed.Then,according to the given blade specifications and electromagnetic loading parameters,the influence of structural parameters of blade electromagnetic device on loading force and speed is analyzed.In order to get the blade stiffness,the parameters of the blade model are set and meshed in ANSYS software,and the deflection value of the blade is obtained by static analysis Maxwell was used to analyze the coil turns,shape parameters,core length and core outer diameter in transition zone,and the solenoid parameter range of electromagnetic force and speed needed to reach the core was given.Finally,based on the complete design of the electromagnetic excitation system structure of wind turbine blades,the fatigue loading control system of the system is studied.In this paper,a closed-loop feedback control system is proposed,which uses adaptive filtering of improved RLS to process noise signals,and uses closed-loop feedback PID control algorithm combining RLS with single neuron to improve the accuracy of closed-loop control The sine pulse width modulation is realized by equivalent area method,and the pulse amplitude of electromagnetic exciting force is analyzed The feasibility of electromagnetic excitation fatigue loading method for wind turbine blades is verified by experiments. |
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