Neutral grounding for Wind & Solar MV network (Reactor vs Resistor) 3

[mastergate]

For industrial and distribution MV grids, we commonly use Resistance grounding (NGR), but what I've seen in Renewable generation projects (wind & solar) is that they're using reactance grounding (neutral point coil).
Can anyone please clarify what are the reasons/advantages of reactor grounding for MV network within solar/wind plants.

thank you

 

[Gr8blu]

Renewables (wind and solar in particular) do not necessarily produce an output frequency (at the individual units) that is synchronized with the transmission portion to which they are connected. What this means is that the wind generator produces a variable frequency output (at the generator terminals) because it is dependent on the instantaneous wind speed. For solar, the output at the actual photovoltaic panel is actually DC, not AC. Both have to go through power electronics to achieve conformity with the grid frequency - which means there will be harmonic content and (high frequency) switching transients. It may also mean a common mode voltage and/or a DC offset voltage where the neutral plane is concerned. This also means that the traditional "solid" or "resistive" ground path is not going to work all that well - hence the hybrid (resistance and reactance) ground application typically in use in these facilities.

Converting energy to motion for more than half a century

 

[RRaghunath]

The MV in Renewables has long cables with substantial capacitance overall.
Probably, the reactor in the Neutral-to-ground circuit compensates some of the cable capacitance and thus reduces the ground fault current magnitude.
I t is just my guess and I could be wrong.

 

[wcaseyharman]

At the utility I work for all the MV substations, if they use a ground impedance, are reactance grounded. I’m assuming this is because it’s less expensive at the MV level versus a separate neutral grounding transformer and resistor.