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Regenerative Drives - Effect of Power Factor

Former Community Member
Former Community Member

I am working on a small 16kW hydro system which is experiencing about 15% loss in the Regenerative VSD. To maximise efficiency the turbine operates at variable speed. The VSD controls a synchronous generator and supplies the grid.

The VSD is a Siemens G120. The datasheet states that the efficiency should be around 96%, whilst also stating that the Power Factor is 0.9. I am looking to replace this drive for an ABB ACS 880-11 which has similar efficiency but a unity power factor.

Firstly can I trust these datasheets since, I assume, they relate to the VSD delivering electrical energy to a motor rather receiving it from a generator? Is there an efficiency penalty for regenerative generation?

Secondly, with all else being equal, will the drive with a unity power factor equate to more electrical energy on the meter than the drive with a 0.9 power factor? 

Thanks

 

 

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    I am actually a mechanical engineer so I look at power in from the generator and the power out on the meter and consider everything else a loss, I appreciate this isn't technically correct since the energy still exists but it is not useful (at least in this application).
     

    It's probably easier to think of ‘reactive power’ as not being real power at all - it exists as current that's repeatedly exchanged between source and load (and back again), but the actual power (in Watts) is always zero (excepting minor cable losses etc).  The old school approach of calling the reactive current ‘wattless current’ was perhaps clearer.

       - Andy.

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  • 0

    I am actually a mechanical engineer so I look at power in from the generator and the power out on the meter and consider everything else a loss, I appreciate this isn't technically correct since the energy still exists but it is not useful (at least in this application).
     

    It's probably easier to think of ‘reactive power’ as not being real power at all - it exists as current that's repeatedly exchanged between source and load (and back again), but the actual power (in Watts) is always zero (excepting minor cable losses etc).  The old school approach of calling the reactive current ‘wattless current’ was perhaps clearer.

       - Andy.

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