The Research On Intelligent System Of Single-phase Grounding Fault Detecting In Peterson-coil-grounded Neutral System

After the single-phase grounding (SPG) fault occurs in Peterson-coil- grounded neutral system, the electric equipment still can work for a while. So small current neutral system is widely used in power distribution network in our country. In order to avoid enlarging the accident, the fault line should be detected as soon as possible. At the same time, because of the coil's compensation, the amplitude of fault current is small. Further more, the disturbance and the measurement error exists. So it is quite difficult to select the fault line. Since 1950s, the difficult problem has been studied. The researcher presented many methods. But none can resolve the problem well. Therefore it is necessary to study the problem further.Majority of traditional methods are based on the steady fault signal that is small and the affect is not satisfied. After the SPG fault occurs, the transient signal includes plenty of fault characteristics. In latest years, the application of wavelets empowers us to be able to study the transient process. Based on the experiences, this paper analysis extensively the transient signal with the wavelet packet improves the methods in existence and presents a novel method. This method is free from the influences of the disadvantageous factors and can improve the correctness greatly.Now we have acquired many methods based on various principles. In fact, we usually detected the fault line based on only one method. With the development of information (data) fusion, this paper adopts this technology to fuse various fault characteristics, integrate the advantages of several methods and detect the fault line. The precision and robustness of line selection can be improved with information fusion maximally.At last, the realization of these methods in project depends on the higher sampling rate and circulating complicated algorism more quickly. Traditional detecting device can't satisfy the demands. Based on DSP (data signal processor), new-fashioned fault detection hardware and software programming are researched relatively further in this paper.