topic Re: Measuring power at two different point (three phase) in LabVIEW Electrical Power Toolkit

electrical power suite zero crossing

m2b — Mon, 02 Nov 2015 13:11:11 GMT

Hi,

I am usign zero crossing.vi to measure 1/2 RMS and frequency,

besides that, i need an extra output that provides a logical output for every zero crossings.

maybe this is quite easy but i am not good at labview.

waiting for your help. 🙂

thanks.

Re: electrical power suite zero crossing

James_McN — Fri, 27 Nov 2015 23:50:41 GMT

What do you need to do with it?

If you look at the output odd the zero crossing you will see that it actually interpolate where it is between samples do there is no one samples that it can flag. You could round this up or down get this though

Re: electrical power suite zero crossing

m2b — Wed, 02 Mar 2016 17:58:17 GMT

Thank you
and i am sorry...
It has been long time since my last post. I could not study becouse of my health problems.
The attached file is my sample project and it includes the zerocrossing.vi
My teacher have asked me to built a vi which shows every zero crossing as a digital 1/0 output. Also the number of the crossings per one second.
How can i do that.
output of the "Zero crossing.vi" is a sawtooth wave which enters to "Frequency.vi".
how this block calculates the frequency?

thaks for your help

best regards

Measuring power at two different point (three phase)

m2b — Wed, 02 Mar 2016 18:51:25 GMT

Hi
I have two 9225 and two 9227. I can measure three phase the voltage and the current of one point with one 9225-9227 pair by using labview sample project.

I have attached the project file. However, I need a second 3 phase measeure point in order to improve my project for my thesis.
How can I modify the FPGA VI and Realtime.VI?

Also, do you have an idea about 180 degree phase shifted pwm?

best regards

My hardware:

cRIO-9024 and cRIO-9118 chassis

ni-9223, ni-9263, ni-9401, ni-9474

two ni-9225 and ni-9227

Re: electrical power suite zero crossing

Yifan.Liu — Thu, 03 Mar 2016 02:32:51 GMT

The zero crossings output by Zero Crossing.vi are the zero crossing positions as the index of the samples in the input waveforms block. You can convert the zero crossing index to zero crossing time by multiplying the dt of the waveform. Then you could generate the digital 1/0 output based on the zero crossing time and calculate the number of crossings per second.

The frequency is calculated based on the zero crossings because the period (1/frequency) of a sinusoidal signal could be determined from every two zero crossings time.

Re: Measuring power at two different point (three phase)

Yifan.Liu — Thu, 03 Mar 2016 02:36:05 GMT

Please refer to the Multiple Line Power Quality Applications example if you need to perform PQ analysis on power system of multiple bus/line.

You can find the example project at:

C:\Program Files (x86)\National Instruments\LabVIEW 2015\examples\Electrical Power\Power Quality\Multiple Line Applications (cRIO) (Delta-Sigma)

Re: Measuring power at two different point (three phase)

m2b — Wed, 16 Mar 2016 16:03:04 GMT

thank you for your help.
the multipoint sample is working. I have changed the frequency from 60 hz to 50hz but the measured the voltage level is twiced when compared with the real.
The origal version of the sample is for 110 volt 60Hz. I have divided the voltage wave value in two. how can I get rid of this wrong values?

after I have asked of you the question, I have found this.

http://forums.ni.com/t5/LabVIEW-Electrical-Power-Suite/Wrong-Voltage-Values-using-NI-9225-and-ELectrical-Power-Suite/td-p/3028881

best regards;