Research On The Method Of Constructing Artificial Seismic Wave In The Seismic Analysis Of Converter Valve

The issue of safe and efficient operation of the power grid has attracted close attention from many engineer in recent years,with the increasing scale of China’s power grid.The converter valve,as a key facility,is essential to ensure its safety and stability when an earthquake comes.The fitting constructing method of its artificial seismic waves will be studied based on the special structure of the suspension type in this thesis.The main research contents are as follows,(1)The three-dimensional finite element model of the suspended converter valve is established,the special structure and characteristics of the suspended converter valve are analyzed employing ANSYS simulation software;its natural frequencies are analyzed,the expression between the seismic amplification factor and the ratio of input load and natural frequency of the structure is derived and the dynamic characteristics of the suspension converter valve are obtained using simulation method.The results show that the natural frequency of the suspended converter valve is extremely low,the first-order vibration mode is only 0.1790 Hz,the response in the spectrum analysis is mainly horizontal rotation,and the vertical direction response direction is single and the insulator,the hinge and other connecting parts make the converter valve have high flexibility and seismic characteristics.(2)The white noise random signal is compared and analyzed based on the mathematical principles of the trigonometric series method and the wavelet transform method respectively,The results show that: the wavelet packet transform method not only meets the requirements of adjusting specific bands,but also the precision is higher and the time is shorter,compared with the trigonometric series method.Db4 wavelet function is selected to fit the seismic wave while five common wavelet functions are listed and compared.Db4 wavelet function is used to fit the artificial seismic wave and the original El wave is decomposed by wavelet packet to get the wavelet node.The low-frequency wavelet node which coincides with the natural frequency of the converter valve is identified,and the node is adjusted and reconstructed to fit the suitable for the suspended converter valve Artificial seismic wave the results show that the low-frequency component of the seismic wave fitted by the wavelet packet transform method is raised from 63.44% to 67.36%,which proves that the use of the wavelet packet transform method to fit the seismic wave can meet the analysis of the seismic characteristics of the converter valve.(3)The geological conditions of Luopu County in southern Xinjiang is taken as an example,the artificial seismic waves are fitted using the triangle series method and the wavelet packet method respectively,and the frequency distribution and simulation results of the artificial seismic waves fitted by the two methods are calculated and compared;The results show that the seismic wave and converter valve fitted by the wavelet packet transform method have higher low-frequency content,lower peak frequency of lower frequency,shorter calculation time,and greater maximum stress and maximum displacement compared with the triangular series method.Therefore,the seismic wave fitted by the wavelet packet transform method is more suitable for the seismic analysis of the suspended converter valve.