Research on Interferences of VFTO to Irregular Distributions of Secondary Side Cables

Abstract

In the digital era, the secondary equipment of power system is becoming more and more sensitive to electromagnetic interference. Gas insulated switchgear (GIS) in substations will generate very fast transient overvoltage (VFTO) after switching action. The VFTO will generate transient electromagnetic fields and cause interferences to the secondary side cables. In recent years, the anti-interference measures for cable protection have been greatly improved. However, in the current cable trenches of some substations, there are still many irregular cable arrangements. It may have some influences on the electromagnetic interference to the cable generated by VFTO. This paper expresses a method for finding the exact interference areas of the cable and standardizing the wiring standard of the cable. Firstly, the relationship between the cable position variation and parameters is analyzed. Then, simulation experiments based on speculation are conducted to observe the effect of irregular cable arrangement on port voltage, and computer software simulation is performed for comparison. After that, an irregular cable is simulated and an interval type Ⅱ fuzzy neural network is used to predict the parameters of the shielding layer of the cable at each irregularly arranged point. Finally, the voltage and current at each point of the cable shield are calculated through the finite-difference time-domain (FDTD) algorithm. In this manner, the actual position of the higher interference voltage can be determined, which can provide a reference standard for cable arrangement.