In the power system, what is the difference between different grounding potentials when grounding?

When the power system is grounded, the following three potentials should be considered. The grounding resistance cabinet on the medium voltage side can prevent the grounding on the high voltage side from affecting the grounding on the medium voltage side transformer
The steady-state potential at the high voltage side of the grounding grid is the product of the short circuit current and the grounding resistance: U=IR. The grounding resistance does not consider the excessive resistance and the grounding resistance, but is considered as the metal grounding short circuit. The attenuation of short circuit current in transient period is not considered.
The temporary potential of the grounding grid refers to the power frequency temporary potential rise of the grounding grid to U=1.8IR, taking into account the influence of the non periodic component of the current.

Instantaneous potential refers to the instant when a short circuit occurs. It means that the voltage of a phase has just reached its peak value, while the system is just grounded, which means that the instantaneous potential reaches a high value. If the grounding grid has more grounding points and more input and output circuits, the grounding instantaneous potential will be larger. For the conventional grounding consideration, the instantaneous potential of the 110 kV system grounding grid can reach 6.2-29 kV, the instantaneous potential of the 220 kV system grounding grid can reach 12.4-58 kV, and the instantaneous potential of the 330 kV system grounding grid can reach 17.8 kV - 82.5 kV. Such high potential may cause damage to electronic components, and serious flashover events may cause harm to personnel and equipment.
For the low voltage side and medium voltage side of the substation, when the system is grounded, the grounding resistance cabinet shall be installed to prevent the neutral point current from being too large, burning the transformer and alternator System.