11-kV Connection to 11-kV Grid

I suggest you check the utility grid connect requirements. There also may be issues related to fault levels that need to be taken care of.

Amit.

It probably is not possible to hook directly to the grid. I have no idea what the Utility requirements are in Switzerland, but I am sure you will want some sort of synchronizer and protective relays to prevent backflow or other problems which will immediately take you off the grid for the grids protection as well as your own.

Also they would should want some sort of agreement signed as to how and when you can send power. Since it is still their responsibility to maintain the grid.

Thanks for the reply,

The proper synchronisation is provided. Also the protection and the intertripping will be achieved between the network operator and the utility. Also the Generator circuit breaker is provided ( to tackle the fault current).

Definately the utility have to give the permission for this type of arrangement.

However, therotically,the galvonic separation is required or not?

Anant,

I have several generators connected directly to the 13.8KV distribution grid here. In theory and practice, it is readily achievable. My units vary in size from 1.2 MVA up to 28 MVA. Both the generators and the grid are owned by the utility (me), so getting permission is not a problem.

Assuming your generator is a grounded star connection, there is more risk to your equipment than to the utility. In a phase to ground fault, not only will your generation supply the fault, but there will be additional fault current coming through your neutral ground connection to feed the fault. All of my generators have large current-limiting reactors in the neutral leg between the wye and ground to prevent damage.

Thanks to pwr2thepeople for your response & valuable suggestion.

We had considered the Generator with isolated star point and an Neutral grounding Resistor is used of suitable rating ( for 10 sec).Also the resistor switched on to generator neutral point in case of isle mode.