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.

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 .