Transformers intended to be connected directly to generators in such a way that they may be subjected to load rejection conditions shall be able to withstand 1,4 times rated voltage for 5 s at the transformer terminals to which the generator is to be connected.
May you grow up to be righteous...
Based on the size and the current contribution,I'll take it this is a type 3 DFIG and the 9.5kA would be the initial symmetrical short circuit current for a fault applied on the HV side of the transformer. The DFIG behaviour depends very much on the converter, the control system will react...
Hi
I got a bit confused with your example above and I thought you're talking about distribution, feeding demand.
I looked at two offshore windfarms just now and one of them has 240 MVA transformer offshore 132/33 kV with 2 breakers in parallel, Siemens 8DA10 2500 A and the other one 150/33 kV...
200 MVA is a big beast for a distribution transformer, most of them are 100 MVA 400/33 kV, I've seen a few 150 MVA with 2500A breakers. Never heard of paralleling breakers, is it possible to get a transformer with two LV windings 200/100/100 MVA to get around the issue? Alternatively you should...
What would you expect to happen for a bar fault on the LV side? With 1 and 1/2 arrangement is it OK to assume you won't lose any demand or infeed from 380 kV and post fault you'll continue feeding the same demand via the two transformers all selected to the remaining busbar?
Is the...
@cranky108
If you're talking about 275 or 400 kV cables, SIL is so high that it makes almost no difference if the cable is lightly or highly loaded, still generates roughly the same amount of MVArs.
May you grow up to be righteous, may you grow up to be true...
@NewGrid,
Looks like you're talking about the UK, to get an idea, National Grid is paying power stations £3 per MVArh. In some other parts of ENTSO-E you don't have to pay for MVArs as it's part of the grid code connection agreement for power station to provide it for free, unless you're...
Agreed, smallgreek!
There are several ways to end up with a stuck breaker, loss of operating mechanism could cause it, if nitrogen and oil for instance.
For a mechanical problem you don't get any alarm and you don't know you have a stuck breaker until you have a breaker fail. For loss of...
ScottyUK,
In the UK, i heard 'stuck breaker' term being used when you really have a stuck breaker, like 'trip circuit 1 and 2 faulty' and you know whatever happens that CB is not going to trip/open, with only options left to open the breaker locally from the trip coil (if it works) or take it...
@cranky108
In India, they thought that you need a fault to operate a distance protection as well and it ended up in tears:)
May you grow up to be righteous, may you grow up to be true...
@cranky108
In the UK the electromechanical distance relays will trip the circuit for a blown fuse, instead of locking up. In some other European countries there's a different approach and the protection will lock up for blown VT fuse, hence relying on the protection ‘to know’ if it's a genuine...
Maybe if you still have old distance protection in the system, that will trip on VT blown fuse, VT supervision might be considered to give a hint on the maloperation
May you grow up to be righteous, may you grow up to be true...
REPORT OF THE ENQUIRY COMMITTEE ON GRID DISTURBANCE IN NORTHERN REGION ON 30th July 2012
AND IN NORTHERN, EASTERN & NORTH-EASTERN REGION
ON 31st JULY 2012
16th AUGUST 2012
NEW DELHI
http://www.powermin.nic.in/pdf/GRID_ENQ_REP_16_8_12.pdf
May you grow up to be righteous, may you grow up to be...
@cranky108
It's safe to say that resistive load (non-motor load) doesn't depend on frequency deviation
Without a control system the generator should trip, unless you want to see the rotor running around the power station if overspeeding or lose the blades on the turbine if running well below...
