Variable speed induction generator

[PaulCurrie]

Hi guys,

We have a generator project that requires the induction generator to operate at a variable speed. We are hoping that by using an ABB ACS800-11 drive that we can generate into the local system. This drive has an "active front end" so that regenerated energy is transferred back into the system.

I am not too familiar with drives so can anyone offer any advice? Specifically, if we start the motor and run to say 2 hz, in order to excite the motor, does the drive then need to be changed into regenerative mode? Or do we just open the valves and set the required generator speed and the regeneration take care of itself? Presumably this is often done for cranes, however, these wouldn't be continuously regenerating. Would there be any issue with continuous regeneration?

Thanks in advance.
Paul

 

[Skogsgurra]

A drive with genuine four-quadrant properties, which the ACS 800 with AFE is, adjusts itself to energy flow. No need to switch between different modes.

The "constant rectified voltage" property of a symmetrical three-phase system makes operation over a wide range of speeds possible. But not from superlow speeds like the 2 Hz you mention. The generator voltage is usually too low to produce any power into the grid at that speed. I guess you will be running at that speed only to start the system and then take it up in speed.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[waross]

Hi Gunnar;
Considering the volts/hertz ratio, how low can the speed/voltage go and still regenerate? What happens to the power factor?
Thanks
Bill

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

I couldn't say. Depends a lot on the machine, I think.



Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...