The influence of the treatment mode of the neutral in the 6-35 kV networks on the displacement voltage in the quasi-stationary regime

Abstract

In the work are analyzed the quasi-voltage surges in the 6-35 kV networks with the neutral treatment by the electric arc compensation coil, mixed - by the compensation coil in association with the resistor, through the resistor. It determines the displacement voltage of the neutral. It is analyzed the influence of the degree of asymmetry on the displacement voltage of the neutral. There are presented the ways of connecting the neutral treatment devices: the electric arc compensation coil, the low voltage and medium voltage resistors, the low value resistor and the high value resistor. It is shown that the introduction of a resistor in neutral causes the active component to appear in the grounding current instead of the defect. This fact plays an important role in reducing the overvoltages, making selective current protections and increasing the reliability of the operation of the electrical installations. The selection of the optimum neutral grounding method is made for a long period of time, it involves a large volume of investments and a very careful technical foundation, so that the chosen solution is as best as possible for the network considered. For each grounding method, this article presents brief description and calculation of the neutral displacement voltage.