Wind Turbines

[tom baker]

I got a tour of the puget sound energy wild horse wind and solar facility. 149 turbines, 2 MW each. They had a static display of the gearbox, generator and a blade.
I was able to go in the base of one tower and look way up. The output speed of the gearbox to generator is 1800 RPM.
Question. When the wind turbine is connected to the grid, does the grid hold the generator speed to 1800 rpm/60 hz?

 

[Hv&Lv]

I got a tour of the puget sound energy wild horse wind and solar facility. 149 turbines, 2 MW each. They had a static display of the gearbox, generator and a blade.
I was able to go in the base of one tower and look way up. The output speed of the gearbox to generator is 1800 RPM.
Question. When the wind turbine is connected to the grid, does the grid hold the generator speed to 1800 rpm/60 hz?

That was my thinking..
once the synchronous speed gets too slow the grid supplies energy turning the alternator into a motor.

 

[tom baker]

I asked the tour guide but she didn’t understand
Next question
The HV cables obviously came down the inside of the tower. I think the voltage was 34k, is there any hazard to be close to the cable when it’s energized? The turbine tower base I went in was shut down.

 

[Hv&Lv]

I asked the tour guide but she didn’t understand
Next question
The HV cables obviously came down the inside of the tower. I think the voltage was 34k, is there any hazard to be close to the cable when it’s energized? The turbine tower base I went in was shut down.

They are probably just MV cables that have a jacketed CN wrapped around the insulation.
same as any other MV cable in the ground.

Ive told people before you have to really try hard to hurt these cable or get hurt around them.

 

[tom baker]

I got a picture of a sample section I can post later
The cable hangs from the nacelle, the nacelle can rotate 3 1/2 turns before it has to untwist the cable

 

[synchro]

I got a tour of the puget sound energy wild horse wind and solar facility. 149 turbines, 2 MW each. They had a static display of the gearbox, generator and a blade.
I was able to go in the base of one tower and look way up. The output speed of the gearbox to generator is 1800 RPM.
Question. When the wind turbine is connected to the grid, does the grid hold the generator speed to 1800 rpm/60 hz?

This a a quick summary of wind turbine electrical technology:

 

[LarryFine]

I got a picture of a sample section I can post later
The cable hangs from the nacelle, the nacelle can rotate 3 1/2 turns before it has to untwist the cable

Is that done automatically? I had envisioned slip-rings.

 

[MattG0311]

I thought they all fed to a common DC bus and then rectified to AC?

 

[kwired]

They use a wound rotor design, I don't understand well enough to describe how it actually works, but speed of the rotor is not a critical factor, grid frequency is still the output frequency, and there is some grid current flowing through the thing in the process.

I learned about it somewhere on this site, if I find that thread I will post link to it.

 

[kwired]

They use a wound rotor design, I don't understand well enough to describe how it actually works, but speed of the rotor is not a critical factor, grid frequency is still the output frequency, and there is some grid current flowing through the thing in the process.

I learned about it somewhere on this site, if I find that thread I will post link to it.

edit time expired:
Didn't find it yet, but from recollection: think of it as a wound rotor motor, grid is powering that motor if there is no wind at all, if wind is fast enough it will turn the rotor faster than it was being powered for and therefore will create back EMF. Wound rotor was more common for speed control before variable frequency drives for three phase motors, same thing happens with a wound rotor three phase motor that has high inertia load that is trying to run faster than the base speed of the motor.

That is what I recall and if you understand what is going on here you probably have an idea of the basics of how these turbines can put out grid frequency even though speed will vary as the wind varies.

 

[kwired]

Still not finding the thread on MH, seem to recall it was a slightly off topic discussion within another thread, was maybe a topic on speed control and wound rotor motors were brought up.

Here is a link that has information on it though

Is basically a wound rotor motor with the load overhauling the motor and the grid volts/frequency is the excitation source. It says in there that most won't be able to black start on a dead grid, it needs grid power for excitation.

 

[electrofelon]

I got a tour of the puget sound energy wild horse wind and solar facility. 149 turbines, 2 MW each. They had a static display of the gearbox, generator and a blade.
I was able to go in the base of one tower and look way up. The output speed of the gearbox to generator is 1800 RPM.
Question. When the wind turbine is connected to the grid, does the grid hold the generator speed to 1800 rpm/60 hz?

Is that the one you see on the left when heading east on 90, before and as you go down into the Columbia gorge?

 

[synchro]

Still not finding the thread on MH, seem to recall it was a slightly off topic discussion within another thread, was maybe a topic on speed control and wound rotor motors were brought up.

Here is a link that has information on it though

Is basically a wound rotor motor with the load overhauling the motor and the grid volts/frequency is the excitation source. It says in there that most won't be able to black start on a dead grid, it needs grid power for excitation.

See the article at the link below:
https://en.wikipedia.org/wiki/Doubly-fed_electric_machine

Basically, a doubly-fed induction generator or motor commonly has rotor windings that are fed by a VFD. As a result, the rotor creates its own rotating magnetic field that interacts with the rotating magnetic field of the stator. The AC currents in the rotor windings sourced from the VFD can therefore either speed up or slow down the rotation of the magnetic field of the rotor relative to that of the stator, depending on the phase sequence of the VFD output. In this manner, an appropriate amount of "slip" above synchronous speed can be maintained to achieve effective induction generator operation even when the rotor mechanical speed is not ideal. The VFD often has an active front end with a switching supply that is bidirectional, and it is therefore able to supply power generated by the rotor windings to the grid under appropriate conditions.
I'm sure our motor experts on the forum could provide further insights.

 

[tom baker]

Is that done automatically? I had envisioned slip-rings.

No slip rings. The nacell keeps track of turns and will unwind

 

[tom baker]

Is that the one you see on the left when heading east on 90, before and as you go down into the Columbia gorge?

It’s in that area, there are many turbines there and they all look the same. Tours are 10 and 2 pm. When you cross the Columbia River, if you stop at the wild horse monument rest stop, and scramble to the top, you can see the PSE visitor center. The tour is one of the few where you can go in the base of a tower

 

[tom baker]

I thought they all fed to a common DC bus and then rectified to AC?

No it’s AC on these