**Investigating the E** ff**ect of Several Model Configurations on the Transient Response of Gas-Insulated Substation during Fault Events Using an Electromagnetic Field Theory Approach**

#### **Muresan Alexandru 1, Levente Czumbil 1, Roberto Andolfato 2, Hassan Nouri 3 and Dan Doru Micu 1,\***


Received: 28 August 2020; Accepted: 20 November 2020; Published: 27 November 2020

**Abstract:** Assessment of very fast transient overvoltage (VFTO) requires good knowledge of the behavior of gas-insulated substation when subjected to very high frequencies. The international standards and guidelines generically present only recommendations regarding the VFTO suppression without a technical and mathematical background. Therefore, to provide an accurate image regarding the critical locations across a gas-insulated substation (GIS) from a transient response point of view, a suitable modeling technique has to be identified and developed for the substation. The paper aimed to provide an accurate assessment of the GIS holistic transient response through an electromagnetic field theory (EMF) approach. This modeling technique has always been a di fficult task when it came to gas-insulated substations. However, recent studies have shown that through suitable Computer-aided design models, representing the GIS metallic ensemble, accurate results can be obtained. The paper investigated several simplifications of the computational domain considering di fferent gas-insulated substation configurations in order to identify a suitable modeling approach without any unnecessary computational e ffort. The analysis was performed by adopting the partial equivalent element circuit (PEEC) approach embedded into XGSLab software package. Obtained results could provide useful hints for grounding grid designers regarding the proper development and implementation of transient ground potential rise (TGPR) mitigation techniques across a gas-insulated substation.

**Keywords:** gas-insulated substations; VFTO; EMF modeling; transient ground potential rise
