Experimental results indicate that the perturbation frequency exerts significant effects on the dynamic stiffness and dynamic damping coefficients of gas-lubricated bearings.

Finite element method is adopted to simulate the dynamic stiffness and damping coefficients of a typical tilting-pad gas bearing when the journal and the pads are disturbed with the same frequency,and the special interest is put in investigating the effects of the disturbance frequency .

In order to eliminate NDZ and alleviate its impact on power quality as possible,a positive feedback islanding detection method based on intermittent frequency disturbance is proposed,that is,every other one second a tiny frequency disturbance whose lasting time equals to one period of power frequency is led in to break down probable power balance under islanding state.