Study Of Peterson Coil Automatic Resonance Adjustment Systems And Feeder Earth Fault Selection

With the development of distribution network and the great use of cable, the network's capacitor current increased fast. Association with the situation of China, the solution is grounding the neuter point by Peterson coil which will decrease the fault current and improve the human security. But it also brings two problems: first, the improper compensation will cause over voltage; second, it's hard to fault select. In this paper, the research was made to solute these problems. The Peterson coil compensation system has been designed which can measure capacitor current and damp degree; a fault selection method of distribution network which was put forward that based on FTU.At first, this paper summarized the developing and the present state of Peterson coil automatic compensation system, and introduces the basic theory of it. As an important part, the principle of measuring capacitor current and dumping degree has been analyzed. Then, an novel method to measure the capacitor current and dumping degree which is based on the signal inject is put forward. Then, the circuits of this instrument's hardware are illustrated in this paper, such as CPLD interface, extended memory circuit, real-time clock, and touch screen interface, etc. On the software, the realization of the main program and the subprograms such as display, touch keys and interrupt, are introduced with some flow charts. Finally, system's measurement error and error compensation method are analyzed, and some measures of anti-interference are taken to improve system's reliability.The project was finished by combination the theory and the practice, and a new way on Peterson coil automatic compensation is available.