Simulation and experimental method for the suppressing of very fast transient over voltages in a 245kv gis using ferrite rings

Abstract

Very fast transient over voltages are generated during the switching of disconnectors in gas insulated substation (Gas Insulated Substation). Such over voltages can cause mal functioning of protection circuits and control circuits and also initiates faults and influence on other components such as transformers. The suppression of VFTO (Very fast transient over voltage) is very important in GIS systems. There are some deficiencies in the existing suppressing methods. In this paper a new idea for the suppressing VFTO by ferrite is put forward, and the computer simulations were conducted on 245kV GIS models with and without ferrite rings and the results are verified with the experimental results. The simulation test results are closely matched with the experimental results so the use of magnetic rings to suppress VFTO is distinctly efficient.

Experimental Research on Suppressing VFTO in GIS by Magnetic Rings

“…Measurements using a scale model and simple simulation calculations have been reported in [13]- [17]. Some researchers performed tests and measurements on 550-kV GIS [18], [19], but they used only six rings at the most and did not find remarkable suppressing effects.…”

New Concept for VFTO Attenuation in GIS with Modified Disconnector Contact System

“…The most up-to-date overview of main methods for VFTO attenuation in GIS is given in papers [10], [11]. They include: disconnector equipped with damping resistor [12], disconnector with reduced voltage due to the trapped charge reduction during the disconnector opening operation (the so called Trapped Charge Voltage, TCV) [3,13], application of high frequency resonators [14], and application of magnetic material of different types [15], [16], [17], [18], [19], [21].…”

“…Different types of magnetic materials are currently under investigation for application in GIS. In [16], [17] the magnetic rings of ferrite type are used in low-and medium-voltage measurement set-up, with the source voltage amplitude value of 0.4 kV in [16] and 3.3 kV in [17]. Measurement results in high voltage set-up are presented in [19] and [21].…”

“…In each previously referenced papers, when the magnetic rings are of concern [15], [16], [17], [18], [19], [21], the rings are located in the space between the GIS busbar conductor and the GIS busbar enclosure. In such case, the dielectric and thermal conditions of the GIS busbar are affected by the rings during the GIS normal operation, which has to be taken into account at the design stage of the equipment.…”

Study of very fast transient overvoltages and mitigation techniques of a gas insulated substation

“…The mitigation of these VFTOs is a very important issue of the GIS. There are some mitigation techniques developed which has been extensively used by the industries like shunt resistors [10], ferrite rings [11][12][13][14][15] and RC filters [16] etc. There is still need to be more exploration in this area of the development of more reliable and effective techniques to mitigate the VFTOs of the gas insulated substation.…”