calculating or obtaining xfmr load & no load losses 1

[shocker23]

In currently creating a spread sheet to size a capacitor bank at a wind farm. Because turbine is an inductive machine cap banks are used to offset the inductive influence at the collector system. The xfmr mfg's cut sheet did not provide it. I have my collector CU losses from wind plant, the CU load & no load losses of turbine xfmr. I need to know how to obtain the transformer load (windings)loss and no-load (core)loss both expressed in vars.

shocker23

 

[magoo2]

Also are you talking about a 1000 kVA transformer? 2000 kVA? What voltage rating? Transformer losses are quite variable depending on what value the user places on them, so I don't think you'll get a good answer from what you asked.

You would be better served to monitor the output of the wind farm over several weeks to see what capacitor bank rating you need.

If this is simply a calculation procedure, you need to assign a factor accounting for the fact that one or more of the machines might not be running at all at a particular time.

 

[dpc]

Transformer losses are in watts not vars. Vars do not represent power loss. The vars consumed by a transformer are actually quite minimal - just the reactive portion of the magnetizing current.

None of these "losses" you are talking about have anything to do with power factor correction. That will be driven almost entirely by the var requirements of the induction generator and will vary with the generator output.



"The more the universe seems comprehensible, the more it also seems pointless." -- Steven Weinberg

 

[pwrtran]

shocker23
If you are indeed after the kVar losses, you may calculate the no-load and load kVar losses by using the following methods:
1) if you are given the Z%, Iex% by the manufacture, assume you already have the kWatt no-load loss and kWatt load loss, you can get Sno-load=Iex%*Srated, Sload=Z%*Srated, from there it is straight forward to get Qno-laod and Qload by having Pno-laod and Pload values known
2) if you are not given the values in 1), you can assume 0.3% for the kWatt no-load loss, 0.7% for the kWatt load loss and 1.5% for the kVar no-load loss, then use Z%*Srated=Sload to calculate kVar load loss.

 

[shocker23]

Thank you all for your input(minus one). I guess I have to apologize for being new in the industry. My knowledge and insight on some issues may be slight but very willing to learn.
That not withstanding the capacity of the xfmr=150MVA. I do have the wind plant gen information.

And yes the xfmr losses may not have anything to do w/pfc in the end however being new to the wind energy industry (4-months after graduation)I my mix in a questionable term or two. Power factor correction is the end result of my spreadsheet using goal seek to adjust the turbine pf and using the capacitor bank to maintain 0.95 pf.


PWTRAN: what does the term - I(current ) ex mean; Iex%
I=kva/sqr root3*345kW?
shocker23

 

[pwrtran]

shocker23
Iex% stands the transformer excitation current in percentage measured at 100% rated voltage. If you are given that, say, Iex=0.1% and your transformer is 100MVA at self-cool rating, then you have apparent no-load loss Sno-load=0.1%*100=150kVA. If you are also given the kW no-load loss, say Pno-load=40kW, the you have kVar no-load loss Qno-load=60kVar. Whe you do the Sload, you first use Z%*Srated to get the Sload.