How to modify the filter to match the power output of the wind turbine with the wind speed?

hello,

I have the wind turbine power results on the left and the wind speed on the right, both varying over a 24-hour period. From three different scenarios, it's clear that the power output doesn't align with the wind speed. Could this be due to the filter I uploaded? If so, how can I modify it?

thank you in advance

Answer 1

[William Rose]

@jana nassereddine,

The horizontal axis labels and values are partly cut off, or absent, on the three images you uploaded which contain two plots each. It appears that the horizontal axis labels for the left side plots are "Load (kW)". If that is correct, then the plots are not power versus time. Do the right side plots (with black background) show wind speed versus time? Please plot power versus time and wind speed versus time, with visible labels and units and values, for both axes. Then we will know what is being compared.

The system diagram shows a sampling rate of 1e-6, but the right side plots appear to be sampled much more slowly. Please figure out why this is so, and why the sampling rate appears different for the right and left side plots.

I don't think the lowpass filter is the cause of the mismatch between wind speed and power output, because the power waveform in the plots does not appear to be a lowpassed version of the speed waveform. I suspect the difference is due to the inner workings of the wind turbine power system box, or the difference is because you are not plotting what you mean to be plotting.

[William Rose]

@jana nassereddine,

Thank you for the additional plots.

Did you edit your original post? I am asking because I can no longer see the system diagram, which you had attache as a figure in your original post.

I agree that a sampling time of 1e-3 versus 1e-6 does not make a difference. But I am still puzzled by the fact that the wind speed scope signal seems to be peicewise linear with corners about every 0.08 seconds. It looks like a signal that is sampled at about 12 Hz. But let's ignore that for now. Let's focus on the plots in your two most recent comments.

I am not a simulink person. Therefore I don't understand the difference between the white background plot labelled "Wind Power (kW)" and the black background plot labelled "Wind Power AC (Watts)". The former is > 10 kW and the later is <3 kW. Why? It's not due to a lowpass filter.

In your two most recent comments, the first order lowpass filter time constant is 0.015 s. The difference between the wind power waveforms and the windspeed waveform , in the two most recent comments, is not due to the first order lowpass filter. Wind power is roughly proportional to velocity squared, i.e. a nonlinear relationship. A real wind turbine has complicated dynamics and nonlinearities. I don't know what lives inside your wind turbine block, but I assume it has some of the complictaed dynamics and nonlinearities of a real wind turbine. Therefore it is likely that you should not be surprsed that the wind power waveforms do not have a simple relationship to the wind speed. There is probably no simple linear filter that could make the wind power waveform look like a scaled version of the wind speed waveform.

A person who is competent in Simulink could provide better advice than me.

[jana nassereddine]

thank you for your reply;

Now, about the data sampling. You've got 24 data points over 2 seconds, which means each data point represents a time interval of 0.083 seconds.

I used an AC/DC converter to turn the wind's AC power into DC power. That's why I have two power sources – one AC and one DC. The former is <3 kW and the later is > 10 kW. I also added a boost converter.

[jana nassereddine]

this filter is for the first plot

this second filter for for AC power the second plot;

[William Rose]

@jana nassereddine,

You said above that you use an AC-DC ocnverter to convert the turbine's AC power to DC, and you said the former is <3 kW and the later is >10 kW. That is odd, since you get more power out of the converter than you put in. I would investigate that if it were my work.

In the most recent plots, the initial delay in turbine power, relative to initial wind speed, is probably due to initial condition of the system and the inertia and inductance of the rotor and generator. After that, I am not exactly sure which aspects of which waveforms you are referring to.

You say in your recent comment that the sampling rate is 12 Hz. Are you referring to the wind speed? Is the wind speed signal, sampled at 12 Hz, the input to the rest of the system? If so, then I am surprised by the small rapid fluctuations in power from 0.5 to 0.8 seconds. These fluctuations occur faster than the wind speed sampling interval. If it were my project, I woudl want to udnerstand that. I can't help you understand it because I don't know what lives inside the wind turbine block, and I don't know for sure what signals are inputs and outputs from what. (You included a figure showing the system block diagram in an early post, and it seems that you have deleted it since then.)

[jana nassereddine]

Thank you very much for your responses.

This is because I added a boost converter, which I will show you in this figure. I am trying to understand what you mean by the speed of the wind and the speed of the wind turbine's power output.

[William Rose]

@jana nassereddine,

Thank you for tthe additional diagrams.

I see that you have deleted some of your earlier comments in our exchanges above. You are welcome to do this, but it does make it harder for anyone, including me, to understand my comments above, which refer to now-deleted posts. I also think you edited your remaining comments above. Such edits can make subsequent comments by others (such as me) seem misguided or odd, so please be careful with such after the fact edits.

You say in your most recent comment: "I am trying to understand what you mean by the speed of the wind and the speed of the wind turbine's power output." When I refer to wind speed I am referring to your plot labelled "wind speed (m/s)". This plot has the title "Scope" at top left. I do not think I ever refer to "speed of the wind turbine's power output". When I referred once to "turbine power", I was referring to your plots "Wind Power (kW)" and "Wind Power AC (Watts)", which has the title "Scope 2" at top left.

You say you converted AC power to DC power and you added a boost converter. You say the boost converter explains why the DC power is >10 kW and the AC power is <3 kW. I do not think this is a correct use of the boost converter. The boost conevrter is designed to boost voltage but not power. The boosted voltage from a boost converter has, or should have, less current-driving capability than the input, and thus it should conserve energy. See the boost converter help here (1) and here (2). It appears to me that you are using boost converter (1), of the two listed above.

You need assistance from someone who knows more about simulink than me.

[jana nassereddine]

Thank you for your help! It seems I made a mistake in calculating the power of DC and AC. I’ve fixed it now and deleted the comments because I want to ask a new question about this. Apologies for that!

[William Rose]

@jana nassereddine, you're welcome. I encourage leaving old comments even if they reveal mstakes along the way, because everyone makes mstakes, and we can learn form them. Also, it makes the other people's comments (which you can't delete) seem weird and misguided.

Good luck with your project.