But if the disturbance affects a large area, as a great earthquake can, the resulting seismic sea waves nay behave as if they had been generated along a line rather than at a point.

But most attention should be put on the PCB design, elements position and line connection, which can suppress the source of the common mode disturbance.

On the basis of the trajectory on the phase plane and Lyapunov' s direct method, switching line is introduced for controlling static compensator under large disturbance.