Papers by Keyword: Improved HHT

Abstract: The randomness of wind power and the nonstationarity of gearbox vibration signals greatly increased the difficulty of wind turbine gearbox faults feature diagnosis. Studies proved that Hilbert-Huang transform (HHT) has a satisfying performance when it be used to analyze nonlinear and non-stationary signals, but two troublesome problems in application of HHT are end effect problem and false intrinsic mode functions (IMFs). An improved solution method based on adaptive waveform matching endpoint extension is proposed to solve end effect problem. Meanwhile, an improved energy conservation method is proposed to eliminate false IMFs. Tests prove that improved HHT can greatly improve the accuracy of wind turbine gearbox faults diagnosis and with a balance efficiency.

Abstract: Due to a variety of electrical equipment using, the grid power quality severely polluted. For current harmonic signal is generated in hoist converter, the methods is proposed based on Hilbert-Huang Transform (HHT) to detect current harmonic signal and improved Active Power Filter (APF). The simulation mode is established by MATLAB/Simulink software about shunt APF+SPWM inverter hybrid active filter device for harmonic motion detection and suppression simulation. The results show that the harmonic of hoist converter can be detected by this design method real-time and the harmonic can also be suppressed validly.

Abstract: A vibration-based approach to detect crack damage in a cantilever composite wingbox is studied using the improved Hilbert-Huang Transform (HHT). The improved HHT is composed of HHT with Wavelet Packet Transform (WPT) and a simple but effective method for intrinsic mode function (IMF) selection. For different damage status, in order to obtain structural dynamic responses, which imply plentiful damage information, the composite wing boxes were excited by a contrived square wave signal. Then, the dynamic responses of intact wingbox and damaged wingbox are disposed using improved HHT. Finally, a feature index vector of structural damage, i.e. the
ariation quantity of instantaneous energy, is constructed. The obtained results show that the proposed damage feature index vector is more sensitive to small damage than those in traditional signal processing.