Study On Main Coolant Pump Flywheel Vibration Monitoring System Based On HHT

Vibration Monitoring plays a vital role in Nuclear Power Plant maintenance and security.The flywheel is the most important part for the main coolant pump rotor energy storage.It can guarantee safe operation when power outage occurs.Operation data shows that the flywheel is most prone to fault in actual operation.The flywheel failure will affect the normal operation of the reactor and result in the high cost of maintenance.Therefore,the main pump flywheel vibration status monitoring is necessary.This study was based on the design principles of main pump flywheel vibration monitoring system.The Hilbert-Huang transform theory for signal analysis and state recognition method are studied,in addition,the flywheel monitoring system is developed on LabVIEW platform.In order to extract the flywheel vibration signal characteristics,the finite element analysis was applied for flywheel solid model.Firstly,a three-dimensional solid model of the flywheel was established by Pro/E.Secondly,the static structure analysis for the model provides stress& strain distribution cloud charts.Then modal analysis results show the first six natural frequencies and mode shapes.Lastly,the harmonic response simulation was performed to gain the vibration response of the flywheel under operation which can clearly reflect the response of vibration acceleration.In this paper,we attempt to present a Hilbert-Huang transform(HHT)algorithm for flywheel vibration analysis.Empirical mode decomposition(EMD)of HHT is a new time-frequency analysis methods.HHT has the good partial time-frequency performance,which is suitable for nonlinear and non-stationary rotating machinery vibration signal analysis.But noise has a great impact on EMD method.So the wavelet noise reduction preprocessing would come to the first.It can improve EMD accuracy.This study using MATLAB programming of the HHT and get a clear Hilbert marginal spectrum.Results of calculation show that this method can effectively flywheel vibration signal analysis.LabVIEW virtual instrument is used to design the flywheel monitoring system.Simulation analysis shows that the system can realize online monitoring of the flywheel vibration signals.It can provide an intuitive and accurate display as well as status analysis functions of the reactor internals for the operators.This thesis indicated that the proposed flywheel vibration signal analysis method performs well and provides a new insight for nuclear devices modeling analysis,it brings meaningful exploration of HHT,enriches the methods of vibration analysis.It laid the foundation for flywheel fault diagnosis and put forward a new way to the safety of reactor operation.