Study On The Application Of Spectrum Correction In The Run-up And Shutdown Analysis For Rotary Machinery

It is a special process that rotary machinery run up and run down. Because of the big change of the unit status, especially when rotor speed increase or decrease, dynamical characteristic and fault symptom of the rotor is very useful information, which plays a guidance role to make equipment run safely and scientifically. Therefore, analyzing the process is very important to monitor condition and diagnose fault for rotary machinery.Firstly, the paper introduces the feature and purpose of several diagram analysis ways containing Bode plot, Nyquist plot, Waterfall plot and Cascade plot. Secondly, spectrum correction technology is expatiated in the thesis, which is used to correct frequency, amplitude and phase so that can improve spectrum analysis precision. In view of the demand of the actual application, mathematical derivation of the basic principle of three discrete spectrum correction methods is proposed emphatically in the paper, too. With the help of the virtual testing software LabVIEW, the detailed course of the correction algorithm is carried out. The analysis and comparison of the simulating results verifies the precision and the application occasion of these spectrum correction ways.During developing the management system of the startup and shutdown process, some items must be satisfied including how to choose exploitation tool and key technique. In the module of signal acquisition, a pulse signal is built to calculate rotor speed, and then pulse trigger sampling is realized by PCI-6143 and DAQ driver, which can remove the initial phase error and improve the veracity of data acquisition. Besides, the real-time transmission protocol DataSocket is chosen to exchange data among acquisition machine, server and client, and the reliable database system Oracle8i is used for data storage, maintenance and backup. Both the convenient accessing database technique LabSQL and perfect table structure design are a guarantee of keeping system efficient.In the end, two vibration signals from X and Y direction are acquired in the test-bed of the rotor, which are saved into database from server. In the analysis module, the fundamental amplitude and phase are corrected by using these correction methods, and then the formative graphs are used to identify system parameters and judge fault type of the rotor. The test result shows the validity and advantage of spectrum correction technology in the run-up and shutdown analysis. It can enormously reduce phase error and will have a big foreground in the industrial application.