Fault Current Contribution - HV transmission
Fault Current Contribution - HV transmission
(OP)
Thanks Dandel, davidbeach, and others who gave me very beneficial suggestions. I have recently worked on a problem of fault current contribution from the surrounding elements on a high voltage bus 138 kV. What I noticed is that when i changed one set of generation and transformer using completely different impedance values for both the transformer and generator- the value of the fault current contribution of the new set of generator and transformer to the bus fault is significantly less. As anticipated, If the fault contribution from one element is less then the overall bus fault should be decreased. The results I got indicated differently. The fault current contribution of the new element to the bus fault is less, however, the fault contribution from other circuits are increased significantly; hence, it increases the overall bus fault. Why would this be?






RE: Fault Current Contribution - HV transmission
RE: Fault Current Contribution - HV transmission
RE: Fault Current Contribution - HV transmission
This would indicate that the new transformer has less impedance, is that true?
RE: Fault Current Contribution - HV transmission
RE: Fault Current Contribution - HV transmission
The combined fault current contribution from the new set of generator and transformer is lower, given the transformer has less impedance than the original configuration. However, I don't understand why the impedance of the new transformer would affect the fault current contribution to the bus from other elements, as i observed the fault current contribution from other attached generators are increased compare with the original configuration.
RE: Fault Current Contribution - HV transmission
I'm now assuming that you have two or more generators connected to the primary of a transformer, and are looking at faults and contributions on the transformer secondary, primary, and generator connection buses.
You say that changing the transformer impedance only changes the fault current from the generators? Or are you changing the bus voltages at, and the impedances of, the generators also?
RE: Fault Current Contribution - HV transmission
Given a 138 kV bus with step up transformers A, B, C, & D associate with Gen_A, ...Gen_D. If i were to increase the zero sequence impedance of transformer A, then i noticed a decrease in fault current contribution from Gen_A and A transformer to the 138 kV bus, which is understandable, but why would the increase in transformer A zero sequence impedance results in an increase in fault current contribution from B, C, D equipments ? I also tried to see what is the overall effect if i were to increase transformer A positive sequence impedance. The result is that fault current contribution from element A decreases, but fault current contribution from B, C, D are also decrease. Any thought on this ? Note: All these are with respect to Single Line to Ground fault. Thanks.
RE: Fault Current Contribution - HV transmission
RE: Fault Current Contribution - HV transmission