negative and zero sequence question
negative and zero sequence question
(OP)
would the negative and zero sequence components on the generation side be affected by the grid's negative and zero sequence components when there is a fault, let's say on the common point of coupling? i thought they wont but perhaps i'm wrong. just hope someone could clarify for me.
thanks.
thanks.






RE: negative and zero sequence question
RE: negative and zero sequence question
Presume you are talking of a case where there is YNd connected Generator step-up trafo between generator and the PCC.
If true, the zero sequence currents from faults in the grid cannot be seen by the protective relays at generator terminals. Positive and negative sequence currents ofcourse can be.
Thus, an earth fault in the grid can cause operation of negative sequence protection at generator terminals (earth faults have negative phase sequence currents in addition to zero sequence ones).
Hope the explanation is relevant.
RE: negative and zero sequence question
Thanks.
RE: negative and zero sequence question
It is a objective different from short circuits unbalanced!.
RE: negative and zero sequence question
"Theory is when you know all and nothing works. Practice is when all works and nobody knows why. In this case we have put together theory and practice: nothing works... and nobody knows why! (Albert Einstein)
RE: negative and zero sequence question
It is like the impedance of the G+GT circuit is in parallel with that of grid at the fault point. Thus, lower the grid impedance, lower is going to be the contribution to the fault from the generator (higher fault contribution from the grid, in other words). This is generally speaking.
If you have a specific query or looking for more specific details, you need to share more information / draw sequence diagrams as dpc suggested.
RE: negative and zero sequence question
Hope this will answer part of your question.
RE: negative and zero sequence question
A fault-to-ground in Yn side of 1pu , will result in contribution current of 1/V3 pu of 2 phases from d side.
RE: negative and zero sequence question
Assume the grid impedance increases when one transformer in parallel is out of service, does the wind farm still contribute the SAME magnitude of zero and negative sequence components to the common coupling point? Sorry, I dont know about the configuration of the transformer on the grid side connected to the common coupling point.
thanks,
RE: negative and zero sequence question
But, I do not understand nothing abou your system. Youneed to show an unifilar diagram with the information about grounding generators and type of conexion of power transformers
RE: negative and zero sequence question