Small current grounding system is the system that the neutral point doesn't ground or grounds across the arc suppressing coils, which has been applied commonly in distribution system of many countries. As the grounding fault occurs, current is the one caused by capacity of circuit to ground only and it is rather small. The status of fault is complexity, e.g., the electromagnet interferes together with the amplified impact of zero-order loops to high-order singularity waves and various temporary variables. All these result in the lower ratio of the fault element signal to noise caused by zero-order current.
In this paper, the position of signal singularity and the magnitude of the singularity degree are analyzed based on the variable focus character of wavelet, and the time fault occurs is then determined. The series db wavelet with close sustain is adopted, and the line selection is according to the zero-order voltage of the generatrix and the current of various outlet line. It is proved by the experiment that the fault circuit diagnosis method based on wavelet analysis to the character of temporary status of single-phase grounding fault plays an important role to a finer line selection.
The on-line float glass thickness measurement system is based on digital image technology. LCCD is employed to
capture a set of images of the delivering glass ribbon in real-time, and accordingly the measured thickness computation
is carried out through the center orientated images. A new method for extracting the central line of the glass thickness
image has been put forward for the blurring edge and distortion of noise problems occurred in the thickness image.
Firstly, Canny algorithm is employed to detect the light-stripe edge precisely. Secondly, an improved barycenter method
is employed to acquire each stripe image center accurately within the edge region. Comparing to other center orientation
algorithms, the improved barycenter method can remove the image noise more effectively. The experiment results
indicate that the extraction precision can be improved to 0.1% and the relative error of the thin glass plates is less than
0.14%, therefore it provides a thickness measurement system in high precision and high stability.