A Stage-Coupled Field–Circuit Simulation Method for GIS Multiple Restrikes Considering Time-Varying Arc Resistance

Multiple restrikes during gas-insulated switchgear (GIS) disconnector operations generate very fast transient overvoltage and associated electromagnetic disturbance. Conventional circuit-based simulations can reproduce the temporal sequence of multiple restrikes but cannot directly resolve three-dimensional electromagnetic propagation, whereas full-wave models generally rely on predefined excitation sources and have difficulty representing the complete dynamic restrike process. To address these limitations, this paper proposes a stage-coupled field–circuit simulation method for GIS multiple restrikes considering time-varying arc resistance. A logic-controlled multistage arc model is incorporated into a wideband circuit model, in which each restrike is represented by the pre-breakdown, stable-arcing, and extinction stages. The transient voltages and arc parameters generated for individual restrikes are subsequently mapped to the corresponding breakdown location in a three-dimensional full-wave model to calculate transient enclosure voltage (TEV) and spatial transient electromagnetic fields. The proposed method is applied to electromagnetic-interference analysis in high-voltage direct-current (HVDC) converter stations and is further validated against on-site measurements, with relative amplitude peak deviations of approximately 10.7% and 6.8% for the TEV and electric-field amplitudes. The main spectral characteristics exhibit generally consistent trends, while the dominant frequencies are mainly distributed within the range of 15–17 MHz. The results show that GIS opening operations generally produce stronger electromagnetic disturbances than closing operations, with a maximum TEV of 32.66 kV and a maximum spatial electric field of 13.16 kV/m in the investigated offshore converter-station case. Comparison with the onshore converter-station measurements further indicates that the compact offshore configuration exhibits substantially higher TEV levels and slower attenuation of transient disturbances along the metallic grounding path. These results demonstrate that the proposed method provides a physically consistent approach for analyzing multiple-restrike-induced electromagnetic interference in HVDC converter stations and for assessing the influence of station layout and grounding configuration on transient electromagnetic propagation.