I'm looking at wind turbine current - power trends, and there is a phenomenon I need help to explain!

The data I'm analysing is from a 3-phase generator. Below is a scatter plot of current (x axis) against power (y axis).

enter image description here

Can someone help explain or suggest reasons for the 'tail' at the bottom of the graph? I don't understand how there can be significant current output, but no power.

Many thanks for any help!

  • 2
    \$\begingroup\$ What are the axes - are you sure it is not Voltage across the X-axis? \$\endgroup\$ Commented Apr 13, 2017 at 19:29
  • \$\begingroup\$ You'd see something like this if you applied a short circuit to provide dynamic braking. I'm not saying that's what is happening here, you haven't really told us anything about the wind turbine. If you know anything about its braking systems, add that info to the question. \$\endgroup\$
    – user16324
    Commented Apr 13, 2017 at 19:45
  • \$\begingroup\$ Phase issues? Is the power "real power"? \$\endgroup\$
    – pjc50
    Commented Apr 13, 2017 at 20:02
  • \$\begingroup\$ It may have something to do with the fact that at low wind speeds you still get gusts as opposed to a driving wind. It depends on how they define power and measure the current though. \$\endgroup\$
    – Trevor_G
    Commented Apr 13, 2017 at 20:19
  • \$\begingroup\$ Definitely current across the x-axis! The wind turbine uses a hydraulic mechanical brake if that helps? The power is active power for the whole wind turbine, but the current is from one phase of the three-phase output, the other two phases look exactly the same when plotted against power output! Many thanks for the suggestions so far, it's a bit puzzling \$\endgroup\$
    – Archie
    Commented Apr 13, 2017 at 20:26

1 Answer 1


If the data is from a Siemens turbine, it seems likely that a "reactive power at no wind" control scheme is responsible for high current with low or zero power. Even if it is not a Siemens system, some similar scheme is likely responsible assuming there is no problem with the presentation of the data.

However, it is difficult to understand how plotting current vs. power reveals anything useful about the performance of the system.


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