This paper presents a method for determination of breakdown voltage characteristics (BDV) of a gas-insulated switchgear (GIS) disconnector. The method is applicable for modeling very fast transient overvoltages that are generated during the disconnector opening and closing operations. The method is based on full-scale measurements, as typically performed during the disconnector development and/or type tests. The method is first presented in a simplified, illustrative setting, and then applied for the full-scale measurement results obtained for an 1'100 kV disconnector design. The BDV determined is then applied for two 1'100 kV test setups as recently reported for the Wuhan (China) station. Selected test cases are simulated, analyzed, and validated with the use of the multispark modeling approach, with two BDV characteristics implemented: the nonlinear BDV obtained with the method presented here applied for the measurement results on the example 1'100 kV disconnector, and the linear BDV reported in the literature for the 1'100 kV disconnector used in the Wuhan GIS station.

This paper investigates on a new concept for very-fast transient overvoltages (VFTOs) attenuation in gas-insulated switchgear (GIS). The concept, first introduced by the authors in this paper, involves modification of the GIS disconnector contact system in order to dissipate the VFTO energy in damping elements placed inside the GIS busbar conductor. The concept is an alternative to the state-of-the-art method where magnetic rings are placed in the space between the GIS conductor and the enclosure. The proposed arrangement has no impact on the damping element on the dielectric design of the GIS busbar, and it highly reduces the impact on the GIS thermal design. This paper presents analyses which show feasibility of the concept, through 1) principles which govern voltage conditions inside the GIS busbar and 2) full-Maxwell finite-element method electromagnetic simulations of VFTO attenuated with the use of the proposed concept.

In development of electric power products, aspects related to thermal phenomena are becoming very important due to the fact that they guarantee the correct operation of product. The temperature limits specified by the standards cannot be exceeded which makes the knowledge of the temperature behaviour an important factor in order to predict reliability and performance of the product component in its working environment. In this study, thermal network method (TNM) is used for modelling of temperature conditions in typical geographical information system (GIS) compartment arrangements. Models implemented in ATP–EMTP software were validated with OrCAD Capture simulation environment and with high‐current measurement results. On the bases of the TNM presented as the network approach composed of heat sources, thermal resistances and capacitances which can be easily represented and calculated by means of ATP–EMTP simulation software and also with the OrCAD Capture environment. This study addresses the thermal behaviour of a standard ELK‐3 GIS compartment. Modelling in application to design rating calculations of the typical GIS compartment arrangements are presented and analysed. These analyses can serve as a base for development of more advanced ATP–EMTP models using the TNM approach.

Development and type testing of gas-insulated switchgear (GIS) disconnectors are supported with the simulation-based analyses of very fast transients (VFTs) that are associated with the disconnector switching operations. In order to analyze local field values in the entire GIS geometry, the full-Maxwell approach needs to be involved for simulating the VFT generation process. According to power substation layout studies, 90°-angled GIS disconnectors are often used in GIS projects, since they offer most layout options and, at the same time, require the lowest number of GIS components. This implies that the test setups are asymmetric, thus the direct use of the full-Maxwell approach requires 3-D models, the application of which is considered to be highly demanding from a numerical point of view. The paper shows a comparison of the results obtained from full-Maxwell numerical simulations for a development test setup of 1100 kV GIS. The analyses are conducted for full 3-D geometry and for the corresponding 2-Daxisymmetric geometry. Example simulations of the VFT overvoltage (VFTO) waveforms are presented for both geometries, together with a comparison of the numerical effort needed for solving the associated field equations. The presented approach based on the 2-D-axisymmetric GIS model allows one to significantly reduce the numerical effort involved to support design work and development tests.

This paper presents a novel approach to modeling magnetic cores for high-frequency transient analyses in power system applications. A method is presented to obtain a frequency-dependent, nonlinear equivalent circuit model of magnetic cores, suitable for simulations of transients in high-frequency and high-current conditions. The model can be used in any Electromagnetic Transients Program (EMTP)-like simulation software for power system transient analyses and hardware design of transient mitigation solutions. The model has been developed based on the frequency characteristics of the complex impedance of a magnetic core, measured for different operating points on the magnetization curve. Based on the measured characteristics and on some basic material properties, a nonlinear equivalent model composed of a set of lumped elements was established. The presented method is generic; however, the results are presented for a magnetic core of nanocrystalline type and the model implementation is shown in EMTP simulation software. The exemplary model is dedicated for the frequency range f = 1 kHz ÷100 MHz, and for the current range I = 0 ÷ 10 kA. The model accuracy was validated with selected measurement results, and the accuracy of the method is thoroughly discussed.

Nanocrystalline magnetic rings have been experimentally proven for effective damping of very fast transient overvoltages (VFTOs) in gas-insulated switchgear (GIS). The application of any damping solution in a specific GIS setup (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 the saturation effect of the material magnetization characteristics. The saturation effect is modeled by a bypassing branch, activated at a certain saturation current value calculated according to the specific magnetic material properties and for the VFTO main frequency component. The model was implemented in Electromagnetic Transients Program simulation software and validated experimentally in a full-scale 550-kV GIS test setup. The validation proved the applicability of the model for the assessment of VFTO damping effectiveness with the use of nanocrystalline magnetic rings and, thus, for the design of a particular magnetic-based damping solution in a specific GIS setting.