Research On Technologies Of Faulty Line Selection In Resonance Grounding Power Systems

The majority of distribution networks are resonance grounding systems in China. When a resonance grounding system meets a permanent single line-to-ground fault, due to the compensation of the Petersen coils the arc ground overvoltage can be reduced effectively and the fault current can be limited in a very low value. But how to select the faulty line quickly and accurately is difficult and it is a key problem to safety of power system. The scale of power networks have been expanding and cables are increasingly used so that capacitance currents are much greater. And the installation of Petersen coils is more and more. Although the fault line selection method is numerous, the practical application is not satisfied.This thesis relies on the subject cooperated with enterprises. The existing methods of faulty line selection are researched specifically. According to various forms of Petersen coils, the deficiency and problem of various line selection methods in theory and actual application are studied. With analysis on the reason why existing line selection methods are not accurate both in theory and practice, it is pointed out that the line selection should cooperate with form, tuning and control of Petersen coils. On the basis of this, faulty line selection technology cooperated with style and control of Petersen coils is put forward. Besides, the content of power system analysis and the knowledge of signal analysis and processing is combined, and technology coping with weak signals is applied for line selection. The useless signal is effectively suppressed and the useful signal is enlarged by this technology which can increase the accuracy of faulty line selection. Later on through the computer simulation, this thesis makes further analysis on characteristics of line-to-ground fault, and improved technology is verified. Finally taking Visual Basic6.0as the development platform, and combining hardware controller with the form and control of Petersen coils, the improved technology of faulty line selection is achieved on an industrial computer.This study proceeds with theory analysis, computer simulation, hardware research and so on. It would be beneficial for design and development of Petersen coils and its control system in the future, which possesses practical value.