High Power low voltage wind turbines

[Hanimlat]

Hi Colleagues,

Today wind turbines can go up to even 12MW at low voltage - 0.69kV.
this sounds very challenging with regards to low voltage equipment.
how would a connection of a 12MW generator look like?
at 0.69kV we are talking about 12kA current. biggest LV breaker and LV bus I know are 6300A
so how do you protect and disconnect the LV side?
Also, for this kind of current the cabling is enormous, how is it feasible?

 

[cranky108]

It is difficult to find fully rated generator breakers, and most likely for a fault here, you would need to stop the machine to clear the fault.
Remove the exciting voltage, and stop the machine.

 

[thermionic1]

I would guess placing a step up transformer in the nacelle stepping the voltage from 690/???.

Years ago when I worked for ABB they were talking about a 138kV generator, as in it generates at 138kV (or close). ABB HV Gen

 

[cranky108]

Most wind farms that I have seen are stepped up to 34.5kV. Likely reason is that 34.5 is the highest voltage you can purchase distribution gear in.

 

[LionelHutz]

Generating 12MW at 690V makes no sense. Who is doing that, post a link please.

 

[FreddyNurk]

I agree with LionelHutz.

EDMS Australia

 

[jraef]

GE has been advertising the Haliade-X 12MW wind turbine, but they are 66kV output. Methinks maybe you have a misplaced decimal point there...


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[Hanimlat]

for some reason I remember seing 12MW but I can't seem to find it now.
anyway, ABB have a converter for up to 8MW:
[URL unfurl="true"]https://library.e.abb.com/public/25e19011bbcd4f2782f4b2c8271072af/Wind_converter_catalog_3AUA0000231755_RevA_EN.pdf[/url]
this is still an enormous current.

 

[LittleInch]

The 8MW version looks like it is 2 x4MW, so not as big a current as you might think.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Hanimlat]

it's possible that the ABB 8MW unit consists of 2X4MW modules but at the end
you only have 1 generator in a wind turbine.
maybe this is only a catalog item that doesn't exist in the real world.

 

[TugboatEng]

Out of curiosity, would it be acceptable to run multiple smaller breakers in parallel shunt tripped by a single current transformer?

 

[itsmoked]

I wouldn't expect so Tug. That would lend itself to a cascading failure of epic proportions. The dimensions, mass, and design are all required to interrupt the available source.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[FacEngrPE]

This is the reference for 66kV voltage level. At the terminals of the generator voltage and frequency will be a function of shaft speed. The power needs to be conditioned before it can be made useful to customers

https://en.wind-turbine-models.com/turbines/318-vestas-v164-8.0

 

[IRstuff]

That's nearly 12 kA; lightning strike territory. How big a conductor is needed for that?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[LionelHutz]

What is 12kA? 12MVA @ 690V would be about 10kA. 4MVA converters would be about 3.4kA for each converter.

It seems 8MVA may exist but the power isn't all through one converter. I expect 12MVA if it exists would be 3 or more converters in parallel.

I just dealt with a customer running approximately 28kA @ 63V, but then that's only 3MVA.

 

[RedSnake]

What is 12kA?

k = kilo
Greek word χίλιοι (chilioi), meaning "thousand".
12000A ;-)

ABBs largest
ACS880-87LC-8000A/8268A-7
generator side current 8000 A
grid side current 8268 A
generator rating 8000 kW 8 MW
generator side 9561 kVA 9,561 MVA
grid side Grid 9881 kVA 9,88 MVA
2 units each containing 5 inverters and 6 Insulated-gate bipolar transistor.

Motors over 200kW 0,2MW
Have a lower cost for 690 V motors (from 20 to 60% less) compared to the
corresponding 6000 V motor.
Also lower for 11kW 0,011MW 380V motors and upwards.

Best Regards A


“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[LionelHutz]

I don't need basic theory explained to me.

IRstuff posted "That's nearly 12 kA" and I was asking what because nothing in this thread is 12kA. Maybe he was referring to the OP commenting on it being 12kA. Still, 12MW through a power converter would not be 12kA.

The parallel 4MW converters to get 8MW could easily be fed with parallel winding in the generator.

 

[Hanimlat]

Just to clear up things,
A 12MW generator at 0.69kV, PF of 0.9 will have a current of 11.2kA.
For 8MW it would be 7.5kA. In any case these currents are larger than the biggest LV breaker available so as I see it there is no way to protect the converter and the generator on the LV side except for the protections inside the converters itself. Also, I asked about cabling. How would you deal with such currents and what are the common practices in wind turbines?

 

[LionelHutz]

The 8MW inverters are parallel 4MW sections and have a 4kA breaker in each section.

If they are built right, the converters should run very close to unity on both sides.

It's very doubtful there would be any cables, it would be bus until the step up Transformer.

 

[FacEngrPE]

I suspect that the only to protect the generator is to feather the blades and apply the rotor brake. A breaker or fuses between the generator and the inverters could only provide fault protection for the downstream cabling and inverter, at the risk of loss of load over speed.

This is not really too different than protecting a steam plant, some types of electrical faults need to trip the turbine stop valve, in addition to anything that might be done with an electrical disconnect.