Substation grounding
your question is not very precise. However, I will try to give it a direction by following points.

Different types of failuers can occur in a substation. Therefore the fault circuit depends on the kind of failure and the neutral point treatment.

Failure types:


three phase short circuit
two phase short circuit without earth contact
two phase short circuit with earth contact
one phase short circuit against earth
earth fault (only for nets with isolated neutral or resonant earth system)
double earth fault (only in nets with isolated neutral or resonant earth system)


Types of neutral point treatment


isolated neutral
resonance earthing
low impedance earthing