Quality of the earthing voltage for electronic device protection in power substations

The aim of this work is to study the real behavior of grounding system in a High Voltage/Medium Voltage (HVmIV) substation through the Finite Element Method (FEM) usign the Ansys Maxwell software. In particular, the aim is to Fmd possible criticalities for electronic devices that can arise in case of line-to-ground fault characterized by a huge vale of the fault current. In the first part, the earthing systems used in HVIMV substations with unusual arrangements, not considered in the traditional standards, is presented and their behavior in case of fault is discussed. The second part deals with the presentation of the results of a measurement campaign carried out in a real HV/MV substation and their comparison with those obtained from the FEM analysis. Final considerations on the impact of the grounding system on electronic devices will be discussed.