WRIM Induction Motor working like a Wind generator 1

[pirulo]

Hello

I am new at this forum and I want to know how works one WRIM like wind generator.

Thanks and best regards

Pirulo

 

[LionelHutz]

With any induction motor, connect the leads to line power and drive the shaft above the synchronous speed and it will become a generator. Often, capacitor are used to correct the power factor.

A WRIM can be used with a 4-quadrant VFD connected to it's rotor which allows the synchronous speed to be varied.

The question is too vague to get into much more detail.

 

[electricuwe]

Search for publications on DFIG or doubly fed induction generator. This setup has been the most popular in windpower for at least the last ten years.

 

[edison123]

Goodt tip electricuwe.

Muthu

http://www.edison.co.in

 

[davidbeach]

DFIG is patented and only available from one, or a limited number of, vendors. Induction generator -> power electronics -> dc bus -> inverter -> ac system seems to be another common approach that doesn't involve the GE patents.

 

[jraef]

First decide what you want to do. If you want a GRID CONNECTED induction generator, that's a good way to go. But induction generators are difficult to make work as stand-alone generators (also known as Island Mode) because they need excitation. When connected to the grid, that is where the excitation comes from but without it, they never begin generating on their own. There are tricks using residual magnetism and capacitors to make them self-excited induction generators that may work, but it is highly subjective to the amount of residual magnetism in the motor.

Decent web page on the subject of "doubly fed induction generators" and wound rotor motors.

http://www.allaboutcircuits.com/vol_2/chpt_13/8.html

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[electricuwe]

Davidbeach,

there are no patents that limit the use of the basic setup of DFIG wind turbine. DFIG designs in fact currently have the largest market share on the world market.

If you disagree, please post the relevant patent number.

To be avoid being red-flagged I refrain from commenting on US patent policy in comparison to rest of world.

 

[davidbeach]

All I see is that there is only one manufacturer in the North American market that I am aware of using the DFIG configuration. Everybody else that I am aware of uses some other system. But then I'm only a lowly protection guy and don't see all the wheeling and dealing that goes on in selecting the machines.

 

[jpts]

DFIG is quite old invention, and definitely is not patented. In wind business it is at the moment the most common solution, and there are several big players (GE, Vestas, Siemens..) which are using this technology. With DFIG, stator is directly connected to grid, and the rotor is connected to converter. Typically only max 20...30% of the power goes through the converter, while biggest part goes directly to grid. Therefore the converter is much smaller compared to e.g. synchronous wind generators, where 100% of the power must go through converter. Biggest drawback of DFIG is the need for slip-ring unit (needs regular maintenance) and poor operation during grid-faults. Tightening grid-codes are the biggest reason, why wind industry is moving towards synchronous machines, especially permant magnet synchronous machines.

At the moment GE has patent in US for using full-power conversion in wind business (synchronous machines), and that's the main reason why DFIG is commonly used instead in US. That patent should expire next year, though.

Hope this helps.