Tinh123
Electrical
- Nov 16, 2006
- 27
Hi, I'm very new at this and need your advises. I was recently asked to determine the fault current contribution of a group of generators locates at a bus within our system. This group of generators was represented as a single equivalent source in Aspen software and connected to a 345 kV system through the 13.8/345 kV Y-Delta (Delta lags) transformer. The issue is that how can i represent this same equivalent generator and transformer if it was connected to a completely different voltage levels (i.e. The original generator would be connected to 145 kV system through a 18/145 kV transformer). I was able to represent the generator equivalent impedance at 18 kV through the use of this equation Z2 = Z1*(V1/V2)^2 (assumed same MVA base), but have much difficult in represent the 345/13.8 kV transformer impedances in the 145/18 kV transformer scheme. Below are some of the data:
Original Data: (13.8 - 345 kV network)
Generators Equivalent Impedances (connected at 13.8 kV bus)
Subtransient = Transient = Ps = .001 + j.200
ns = .003 + j.2005
zs = .004 + j.2007
Transformer Impedances (13.8/345 kV Xfmr)
Zero Seq = Pos Seq = .0005 + j.0300
How can i correctly translate the transformer impedances to 145/18 kV system, assume that MVA bases are the same.
Thanks for any advice. I have been struggling with this for couple of days. Even without the translation of impedance process, is there any other way that I can calculate fault current contribution of the 345/13.8 kV system at 145/18 kV one. Thanks for all the help.
Original Data: (13.8 - 345 kV network)
Generators Equivalent Impedances (connected at 13.8 kV bus)
Subtransient = Transient = Ps = .001 + j.200
ns = .003 + j.2005
zs = .004 + j.2007
Transformer Impedances (13.8/345 kV Xfmr)
Zero Seq = Pos Seq = .0005 + j.0300
How can i correctly translate the transformer impedances to 145/18 kV system, assume that MVA bases are the same.
Thanks for any advice. I have been struggling with this for couple of days. Even without the translation of impedance process, is there any other way that I can calculate fault current contribution of the 345/13.8 kV system at 145/18 kV one. Thanks for all the help.