Author Topic: Wind Turbine Performance Testing  (Read 3366 times)

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faqmar

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Wind Turbine Performance Testing
« on: July 08, 2016, 11:07:13 AM »
I am doing a wind turbine performance test and I have read several references in doing such test but I still could not find any clear procedure for it, especially in how do they load the turbine to get the power recorded. The basic standard I am refering to is the IEC 61400-12-1: Power performance measurements of electricity producing wind turbines.

Some performance tests that I am refering to aswell are the tests done by NREL. One of the test equipment they mentioned is power transducer and by definition a power transducer is a device that measures true electrical power delivered to a load, and converts that measurement to a DC voltage or current signal proportional to the power measured (source: ohiosemitronics.com). But then there is no explanation on what kind of load do the NREL use in the performance tests.

Can anyone please explain about how do the standard, official and certified performance test on wind turbine picked the load for the test?

Thanks a bunch!
faqamar

stofanel

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Re: Wind Turbine Performance Testing
« Reply #1 on: July 08, 2016, 04:59:36 PM »
A power transducer is basically an engine dynamometer. First, you need a mechanism to dissipate the power produced, and then measure it. Depending on the size of the wind turbine, one can modify an automotive alternator, or even an electrical generator head to do the job.

faqmar

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Re: Wind Turbine Performance Testing
« Reply #2 on: July 08, 2016, 10:58:42 PM »
thank you stofanel for the input. I actually had managed to do a test by myself by using a rectifier circuit and some automotive DC light to dissipate the power produced. I managed to get a power curve aswell as the result of the performance test, but I don't think that my testing configuration is in accordance with the international standard 100%.

So I was wondering more about how do the experts, such as NREL (National Renewable Energy Laboratory-US), do this kind of test?
here the some of the performance test done by NREL I am refering to:
http://www.nrel.gov/docs/fy13osti/56499.pdf
http://www.nrel.gov/wind/pdfs/34305.pdf

Cheers

stofanel

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Re: Wind Turbine Performance Testing
« Reply #3 on: July 09, 2016, 07:02:40 PM »
First of all, the experts use certified testing equipment. But the actual tests consists of nothing more than data logging: wind speed vs mechanical power vs electrical power (if they are testing the generators also). It sounds complicated, but it's not.

Adriaan Kragten

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Re: Wind Turbine Performance Testing
« Reply #4 on: July 10, 2016, 04:25:20 AM »
I can't answer your question about the standards but we have performed field measurements about 35 years ago when I was working for the wind energy group of the University of Technology Eindhoven. The biggest problem isn't measuring of the supplied electrical power for the normal load for which the windmill is designed but measuring of the correct wind speed. The wind speed and the wind direction vary continuesly. If the cup anemometer is placed that far in front of the windmill rotor that it is not in the expanding wake, there is a time delay in between the measured wind speed and the wind speed at the rotor plane. So if you measure a certain wind speed, the power belonging to this wind speed will be measured some seconds later. How much later depends on the wind speed and the distance. If you measure the wind speed in the rotor plane, you must be that far outside the blade tip that you feel no influence of the wind speed reduction which is caused by a power generating rotor. Finally we placed a long pole on the head with the cup anemometer on top of it and such that the cup anemometer is in the rotor plane. Wind tunnel measurements in the open wind tunnel of the University of Delft have shown that a distance of 1/4 R in between the cup anemometer and the blade tip of a blade with radius R is large enough to be in the undisturbed wind speed. For this position there is no time delay and this has as result that all measured points of the Pel-V curve are lying closer to each other than for a cup anemometer in front of the rotor.

SparWeb

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Re: Wind Turbine Performance Testing
« Reply #5 on: July 21, 2016, 01:11:17 AM »
Hi Faqmar,
The performance tests you linked to are the right kind of testing for certification of wind turbines.
There is also the SWCC (Small Wind Certification Council) that oversees the certification in the USA.  The NREL is involved only because they have the expertise and equipment to do some of the testing.

If you want to carry out the kinds of tests used in these reports, you will need to consider the whole field around the turbine, the system that collects and stores the energy it produces, all parameters measured in that production, and simultaneously monitor the wind speed approaching the turbine in a way that allows estimating the wind speed from most directions (which may require multiple meteorology towers and anemometers at more than one elevation).

Do you want to certify a wind turbine for commercial sale, or are you simply interested in measuring the performance of a WT you built for yourself?
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
System spec: 135w BP multicrystalline panels, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
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faqmar

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Re: Wind Turbine Performance Testing
« Reply #6 on: July 24, 2016, 03:40:28 PM »
Thank you for the reply SparWeb and Adriaan Kragten
I may say that I have understood about the complexity of that kind of certified test that I am not referring to it precisely. What I am more interested in is the system that collects and stores the energy it produces that these kind of test are using, and that aspect is  what I want to imitate in doing a performance test.

I am doing a research in modifying the shape of the blade and comparing its energy production characteristic to the comercial-usual blade, and this research might be written into a journal/paper in the future so that I am looking for a good-reliable way to do a performance test on wind turbine.

SparWeb

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Re: Wind Turbine Performance Testing
« Reply #7 on: July 27, 2016, 12:19:00 AM »
Hello,
I agree that you can do without the "certification" aspects of the testing in your case, but the data you need to prove that one blade profile is better than another is still pretty high, and all of the data mentioned above will be necessary, in practice.  In fact, you may be asking for even more data - such as blade pitching and flapping moments relative to RPM, wind speed, temperature, pressure, density, etc.  Probably even a gradient of wind speed from the tip of the top blade to the tip of the bottom blade (where the wind speed is slower) so that 1/REV oscillations in your data can be distinguished from other sources of error such as yaw error.  Collecting that data in-situ on the rotor as the turbine is turning is difficult but it has been done.

Here is an example: NREL/TP-500-38550 (October 2005) Small Wind Research report (Bergey Excel 10kW)
There is a lot of airfoil comparison testing on the NREL/Sandia labs websites, all of which can be found with some google searching.

You may prefer to investigate wind turbine performance analysis codes which can solve these problems numerically.  I would suggest WTPerf from the NREL or something similar as your starting point.
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
System spec: 135w BP multicrystalline panels, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
www.sparweb.ca