Effects of field forcing on fault currents
Effects of field forcing on fault currents
(OP)
Does field forcing in generators (50-100MW size) act to increase the fault currents? I have had somebody tell me that it can push the fault current contribution by a generator well above (2pu)the subtransient value. A search around the web has give me lots of interesting stuff on generator control, but not much on how the fault contribution behaviour is affected. I would be particularly interested in modelling techniques.
thanks
thanks
Bung
Life is non-linear...






RE: Effects of field forcing on fault currents
http://www.hq.usace.army.mil/cemp/e/Et/nolinear.pdf
http://www.usace.army.mil/publications/eng-tech-ltrs/etl1110-2-317/chap-6.pdf
http://www.usbr.gov/research/results/High%20Voltage.pdf
for the generator amortisseur winding, and
http://www.easypower.com/help/manual14.html
for generator modeling data
RE: Effects of field forcing on fault currents
Bung
Life is non-linear...
RE: Effects of field forcing on fault currents
ijl
RE: Effects of field forcing on fault currents
RE: Effects of field forcing on fault currents
The field forcing is a measure to ensure that sufficient curret is available to operate the protection.
As the duration of the fault progresses the sub transient reactance has less of an effect.
Eventually after sufficiect time (say in the order of 5 seconds) the fault current is IL/xd (xd=direct axis synchronous reactance of the machine).
As 1/xd is equal to the short circuit ratio of the machine the final current would be the SCR x IL.
This would result in a fault curret being half the value of the normal line current if the machine had a short circut ratio of 0.5 hence the field forcing to keep the current at a higher value.
RE: Effects of field forcing on fault currents
Bung
Life is non-linear...
RE: Effects of field forcing on fault currents