reactive power calculation

[Cazza]

Dear Experts,
                    I have a simple question that I hope to have solved as im pretty new to the Labview.  The problem is that I can measure the three phases voltages and currents and I hope to use it to measure reactive power.  Is there any vi that can help me to achieve this??  I understand that I can phase shift my voltage or current by 90 degrees, then multiply with my voltage measurements in order to obtain the reactive power.  But how can I do the phase shift and is this sugeest method correct?  i just want confirmation before implying it.  Thank your for your time.

Best Regards,
Cazza

[RER]

Dear Cazza,

Although I do not know a great deal about power engineering, I am aware of a simple and effective method of shifting the phase of a waveform.

Please find the attached VI which shows how to use the Hibert FFT functions in labview to provide a 90 degree phase shift.

Use the Hibert function to provide a 90degree lead, and the Inverse Hibert to provide a 90degree lag.

I hope this will be useful to you.

Best wishes

[Cazza]

Hi Rich,
             Thanks for the heads up, could you convert them to labview 8.0 please as i'm developing in Labview 8.0.  Do you think im approaching the correct way in calculating the reactive power?  Thank you for your time.

Best Wishes,
Cazza

[RER]

Dear  Cazza,

Not a problemo! Please find the attached VI, which you should be able to view in LV 8.0.

But, as always, please don’t hesitate to get back in touch if you hit any problems with the code.

Unfortunately, I do not think I will be able to help you any further concerning the reactive power calculations. I am merely an electronic engineer by education, and have very little experience of power engineering. I understand that you can calculate reactive and actual powers from the apparent power by looking at the phase difference between waveforms.

But that is as far as my understanding goes. Hopefully another bright, helpful poster will be able to help you further.

However, I have also attached a VI which shows how to use the tone measurement express functions to determine phase information. It mightn’t be directly relevant, but it may inspire you!

Best of luck with your project Cazza.

Best wishes,

[Cazza]

Hi Rich,
             Could you please check the phase shift by 90 degrees vi again cause im still getting the error of that it's a 8.5 version file.  Thanks for your time.

Best Wished
Cazza

[RER]

I am terribly sorry Cazza. Please find the attached LV8.0 VI.

3rd time lucky... 

[RER]

Hi Cazza, was the Hibert FFT functions any use to you?

Best wishes,