Research On A New Ground Fault Protection Method Based On Fast Adjustable Perterson Coil

In recent years, with the large-scale reconstruction of city power system, the scale of power system is continuously expanding, and the power supply network is becoming larger and larger. In addition, the enormous use of cables in city power system increases the current through the grounded capacitor. These lead to more and more instantaneously grounding faults unable to eliminate naturally. To solve these problems, the compensating method of neutral point grounding through Perterson coil is commonly used in our country.After the neutral point is grounded through Perterson coil, it can decrease the capacitor current through fault point and the over-voltage caused by the grounding fault, which is advantage for the extinguishments of electric arc. But there are some disadvantages in this system, especially it is difficult to select the exact line with fault. In this system, once the method of selecting line with fault is perfected, the method of neutral point grounding through Perterson coil will be the preferred method of neutral grounding in power supply networks without doubt. The traditional method of selecting the line with fault is not very exact, and the problems of unselecting the line with fault or selecting the line without fault are serious. In order to settle this problem, basing on a power electronic controlled fast adjustable Perterson coil, this paper provide a new principle of selecting the line with the fault, which make use of the dynamic changes in the current through the zero order line. This method bases on the relativity of the current through zero order line and the sensible current through the Perterson coil. This scheme has certain innovation and high-applied value. It provides a quite perfect method of selecting the line with fault for the system of grounding through Perterson coil. So it theoretically solves the problem of low precision of in traditional method of selecting the line with fault. This paper proves this criterion in theory and proves the correctness of this criterion with Saber simulation. This paper mainly discusses the new theory of selecting the line with fault in the system of nuclear grounding through Perterson coil. It makes some valuable researches for the selecting line with fault protecting theory in fast adjustable Perterson coil.