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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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  • Former Community Member
    0 Former Community Member
    The generator is a 3phase AC Permanent Magnet Synchronous motor. We have compared the electrical output (kW) at the generator terminals and we are comparing this to the electrical power output (kW) on the meter. The difference is about 2kW (10-15%). As part of the troubleshooting this generator was connected to a pure resistive load; the output measured at the terminals was the same as we are getting when the VSD is in circuit. 


    I have been looking through the export meter datasheet and it states that it does measure true rms at 64 samples per second.


    From what I have seen, only ABB specifically mention their drives operate at high efficiency in regenerative operation. The Siemens G120 drive states that regenerative operation is possible but no further elaboration to suggest high efficiency, so I agree that it seems this is a nice to have rather than the main focus.
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  • Former Community Member
    0 Former Community Member
    The generator is a 3phase AC Permanent Magnet Synchronous motor. We have compared the electrical output (kW) at the generator terminals and we are comparing this to the electrical power output (kW) on the meter. The difference is about 2kW (10-15%). As part of the troubleshooting this generator was connected to a pure resistive load; the output measured at the terminals was the same as we are getting when the VSD is in circuit. 


    I have been looking through the export meter datasheet and it states that it does measure true rms at 64 samples per second.


    From what I have seen, only ABB specifically mention their drives operate at high efficiency in regenerative operation. The Siemens G120 drive states that regenerative operation is possible but no further elaboration to suggest high efficiency, so I agree that it seems this is a nice to have rather than the main focus.
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