Optimal construction method and demonstration application of multi-in-one station grounding system

Mutual influence may be driven by different models and operating mechanisms of grounding systems in multi-in -one substations. Even equipment damage and personal injury will occur in the event of a short-circuit or lightning strike. To meet the construction requirements of different multi-in-one substations, two typical application modes of grounding systems in multi-in-one substations are analyzed in this paper: plane and longitudinal layout schemes. First, the safety index and withstand voltage of secondary equipment in multi-in-one substations are introduced. Second, the plane layout scheme of grounding grids is examined. Based on a 35-kV multi-in-one substations in Shanghai, it was verified that the overall grounding grid needs to be laid to meet the safety of secondary equipment in the station. Finally, considering that it is feasible to rebuild the upper layer of a substation, the longitudinal layout scheme of the grounding grid in multi-in-one substations is also examined. Safety assessment is carried out in terms of aspects such as short-circuits and lightning strikes, and relevant optimization construction methods are analyzed. In this study, a real 35-kV substation in Shanghai was selected as an example. Simulation and field tests based on Current Distribution, Electromagnetic Fields, Grounding and Soil Structure Analysis (CDEGS) software verified that the proposed construction scheme can achieve safe operation of multi-in-one substations. This construction idea can also serve as a reference for the future construction of multi-in-one substations.