Where does synchronising usually takes place on solar farms?

[electrical429]

Talking about UK by the way, but the question is not country specific. It is my understating that the usual practice is to have final synchronising at the inverter level. So assuming for example 132 kV connected solar farm - 132 kV breaker at 275/132 kV substation, 132 kV cable, 132/33 kV transformer, G99 (sync relay in UK) at 33 kV incomer breaker, 33 kV feeders, 33/0.4 kV transformers and then inverters. If the solar farm gets disconnected from the network G99 relay will trip 33 kV incomer on the loss of mains. Inverters would then also disconnect on the loss of mains. Once 132 kV and then 33 kV volts appear on 33 kV incomer G99 relay would close 33 kV incomer providing volts to downstream inverters, which would then synchronise. I always assumed that this is the only way.

On a project I am working on people were asking where the synchronising would take place and one of the potential options was at 132 kV breaker at the 275/132 kV substation. Can this be done? Can inverters back energize the network up until 132 kV breaker. And if they can then how would it be possible to synchronise? Wouldn't you would need a comms link from 132 kV breaker up to the inverters to adjust voltage and phase angle in order to match with the grid?

 

[waross]

Foe distributed generation the inverter will trip off when the grid goes down.
When the grid comes back up, the inverter will self synchronize as it starts up.
If the solar system continues to run islanded when the grid goes down, the a breaker must trip out somewhere to avoid back feeding.
This breaker must have reverse current protection.
This breaker may be the first choice as it will already have CTs and PTs installed which may be used for the synchronizing gear.
This would be my first choice but not my only choice.
There may be factors which suggest that another choice may be preferred.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!