Finite Element Analysis-Based Impedance Calculation of GIS Station Horizontal Pipeline Considering Magnetization Curve

During GIS (Gas Insulated Substation) operation, Very Fast Transient Overvoltages (VFTOs) are generated, resulting in transient currents flowing through the pipeline that connects the GIS station and the ground network. The impedance of the pipeline reflects the transmission characteristics of electrical signals within the pipeline system. By calculating the impedance of the pipeline, we can obtain information about the transmission mode, transmission rate, and signal amplitude of electrical signals in the pipeline system. This allows us to evaluate the impact of VFTOs on the GIS system. In this paper, a method is proposed to calculate the impedance of horizontal pipelines in GIS stations, taking into account the magnetization curves. The magnetization curves of the pipeline material are measured and used to calculate the magnetizing current in the pipeline during VFTO events. Finite element analysis is performed to calculate the impedance of the pipeline, and the results are compared with those obtained from the traditional approach. The proposed method provides a more accurate assessment of the impact of VFTOs on GIS systems.