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3-Phase Voltage Waveform to Complex Numbers

I read this topic and and I do not think it worksfor my case. http://forums.ni.com/t5/LabVIEW/How-to-convert-waveform-into-complex-number/m-p/808360/highlight/tru...

 

I would like to simulate 3-Phase voltage Waveform at the sample rate of 1000 sample/s and get their numberic values as complex numbers. I could only get the Y-value but not the phase.

 

Could someone points out how to get the complex values (1000 values) in the attched example for VA, VB, and VC?

 

 

 

 

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Message 1 of 5
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Hi muahang1234,

 

You could try something like the image I've attached. Basically, you generate the waveform and create another waveform that is 90 degrees out of phase. That way, you can track the Y position of each of the waveforms. The first waveform will be the real position while the other waveform's Y will be the imaginary position, or phase, of the waveform. You may have to convert this into polar form if you want it in that format, but that shouldn't be too hard.

 

It may be a little inconvenient to do this for 3 waveforms, but that should at least give you an idea of what to do about the issue.3-Phase Answer.jpg

 

Regards,

 

Andy F.

Applications Engineering

National Instruments

Andy F.
Applications Engineering
National Instruments
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Message 2 of 5
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I tried but the values bettween one of the three-phase and the 90o phase are switching between 90 and -90 (The first value for Phase A vs 90o is 0).

 

 

 

 

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Message 3 of 5
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What do you think the results should be?  The image below shows the amplitudes (Y) for each of the three phases.

 

Please post what the complex values correlated with these real values are.

 

Three phase.png

 

If you represent the data as r*exp(i*theta), then you must express theta as a function of time and frequency as well as the phase angle between signals.

 

Lynn

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Message 4 of 5
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Let me try again and let you know soon. 

 

Bascially, I will need to do 3-phase power measurement from a cDAQ system and I will set the sample rate to be 1000 Samples/s but I need a way to extract each individual value for further analysis.

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