High-Frequency Model of Magnetic Rings for Simulation of VFTO Damping in Gas-Insulated Switchgear With Full-Scale Validation

Abstract

Nanocrystalline magnetic rings have been experimentally proven for effective damping of Very Fast Transient Overvoltages (VFTO) in Gas-Insulated Switchgear (GIS). Application of any damping solution in specific GIS set-up (rated voltage, GIS arrangement) requires simulation-based design, which in turn requires reliable models with proven accuracy in demanding high frequency and high current VFTO conditions. This paper presents a new model of a magnetic ring, employing full frequency-dependent characteristics of the ring's complex impedance, as well as the dedicated approach on modeling of the saturation effect of the material magnetization characteristics. The saturation effect is modeled by a bypassing branch, activated at certain saturation current value calculated according to the specific magnetic material properties and for the VFTO main frequency component. The model was implemented in EMTP-ATP simulation software and validated experimentally in a full scale 550 kV GIS test set-up. The validation proved applicability of the model for the assessment of VFTO damping effectiveness with the use of nanocrystalline magnetic rings, and thus for design of particular magnetic based damping solution in a specific GIS setting.

Multi-spark modeling of very fast transient overvoltages for the purposes of developing HV and UHV gas-insulated switchgear and of conducting insulation co-ordination studies

“…One branch is based on dissipation of the energy associated with the electromagnetic wave that the VFTO consist of. These methods require insertion to the GIS current path of an energy dissipating element, which can be of resistive [29], magnetic [30,31] or resistive-inductive [32] type. Also, internal resonators [33] and surge arresters [34] are being proposed to serve this purpose.…”

Numerical Analysis of a Spiral Tube Damping Busbar to Suppress VFTO in 1000 kV GIS

“…Several methods have been considered to mitigate such overvoltages [9,10]. VFT suppression has been proposed by many researchers using a disconnector equipped with a damping resistor [11], a disconnector with reduced voltage during the opening operation (the so-called trapped charge voltage (TCV)) [12], surge arresters [13,14], high-frequency resonators [15,16], magnetic rings of different types [17][18][19][20], and VFTO mitigation by controlling the voltage conditions preceding voltage breakdown in SF 6 gas [21,22]. It could be well observed from the literature that an accurate design using the specific parameters of the GIS DS (Disconnector) contact system is required for VFTO mitigation by controlling the voltage conditions preceding voltage breakdowns in the disconnector contact system.…”

Highly Sensitive Acoustic Emission Sensor Based on Polarization-maintaining and Absorption-reducing Polarization-maintaining Fiber

“…(5)(6)(7) Being one of the important performance characteristics of the GIS, the reliability of its insulation is of great importance to the safety of power systems. As insulation failure usually starts with PD activity, which is usually accompanied by secondary phenomena such as sound, light, electromagnetic waves, temperature changes, and chemical reactions, (8)(9)(10)(11) hidden internal dangers can be detected by monitoring PD so that the reliability of the equipment can be ensured.…”