The Digital Simulation Of Ferroresonance In Power System And Wavelet Analysis

In the neutral ungrounded power system, ferroresonance over- voltage due to electromagnetic transformer takes place frequently. Under different parameters, high harmonic, subharmonic or harmonic ferroresonance maybe happen. The ferroresonance can result in over-voltage and over-current. This would not only affect supplying power to customer, but also damage the main equipment. Firstly, this paper studies ferroresonance with computer simulation technology. The mathematical model of resonance circuit is represented by ordinary differential equation set. The numerical method is Runge-Kutta. The computer imitation of the ferroresonance which is caused by direct single phase grounded fault in the 10kV neutral ungrounded electric power system is emphatically researched. Wavelet analysis, also called wavelet transform, is a set of new and promising theories in mathematics, and has proved to be efficient for transient signal analysis. It has already been used in many fields. Because the feature of wavelet is of great benefit to fault analysis in power system, it's applied to detect the occurrence of resonance and judge the frequency of resonance in this paper. After simulating the wave shape of neutral voltage and analyzing it's feature carefully, we deal with some problems about ferroresonance detection using wavelet from many aspects, such as choosing mother wavelet and the scale parameter of wavelet transform: Furthermore, wavelet is successfully applied to the detection of ferroresonance.