Modal Parameter Identification And Inverse Analysis Research Of Dynamic Loads On Offshore Wind Power Structures

With the growing energy crisis of the world, all of the countries are strengthening the development on the wind power which has the characteristics of large storage, renewable and clean.However, because of the complex environment,the offshore wind power structure is always suffered from much influences such as the joint effect of exterrial loads, the effect turbine rotor running and impeller rotation and forced to vibrate. These external incentive is likely to cause structure vibration and their own damage, and then create the corresponding engineering problem.Taking the offshore wind power prototype in Rudong as the research object and the vibration signal from the different measured points as research data, This article aims to explore the vibration features of the offshore wind power and achieve the accurate identification of structure modal parameter under the normal working state with the method of EEMD and identification methods resulted from the ambient excitation.While using the measured data after filtering and denoising,we made a preliminary analysis and discussion on the multiple environmental loads and structural vibration source based on the theory of modal analysis.The main research contents are as follows:1)The analysis on the vibration signal characteristics of offshore wind power structure.According to the measured data collected from the offshore wind power structure, this paper analyze the statistical envevalue,correlation and power spectrum density which are used to reflect the vibration characteristics of the structure.It is the first time that we introduce the theory of self-adaptive filter and use the self-adaptive notch filter and self-adaptive noise canceller in signal filtering,and prove these filters applicability in the example analysis and the de-noiseing process of the measured signal.2) The modal parameter identification of offshore wind power structure.This part introduces the method of EEMD and makes a application both on the decomposition and analysis of the measured signal and signal de-noising.In view of the vibration characteristics of the structure, we put forward that we can use the way combined EEMD with self adaptive filter together to complete the reduction of the noise.based on the vibration signal after filtering, we can get the preliminary result on the modal parameter identification of the offshore wind power structure with both the “NExT+ERA” and the method of HHT transform.3) The identification on dynamic loads and the analysis on vibration sources of the offshore wind power structure.In this part, we make a numerical model calculation on the self-vibration characteristics of the sea fan structure by seting up the complete model and explain the resonant characteristics between the impeller and support structure. Based on this result and the measured data, the dynamic loads which the structure suffers, the result on the analysis of the vibration source and the whole dynamic response filed can be obtained with the method about the modal analysis.