When solid grounding scenario is applied in power generation level, in some case the one grounding point in power generation bus is recognized enough for control of non desirable over voltage due to earth leakage faults by designer team, so in this case we can omit some earth path of grounding system for reduction of total earth fault current of system. 
Also when two or more generators are operated in parallel at generated voltage, there is the possibility of circulating harmonic currents. This is true whether the neutrals are interconnected or not. The two conditions necessary for the flow of harmonic current are: the presence of a resultant harmonic voltage, and a path for the flow of current. It is important to note the term