Measuring three phase frequency using sbrio 9642

[kprabaka]

Hi , 

    I am a power systems engineer and I am new to Labview and Labview FPGA. The hardware that I am using is an sbrio 9642. I am using Labview 2013. The following is my application

 

I have a three phase measurement of a substation. The three phase voltages are stepped down to +/- 2.7 v (270 volts actual). I am using the built in analog inputs to take these voltages. I have six inputs, two three phase voltages line to neutral. I want to measure the three phase frequency of these signals (Two frequency measurements in total).

 

I want to use the built in three phase pll in the FPGA math and analysis palette. It is ideally built for such application. But, for some reason I am not able to get the right frequency (Which should be 60 HZ).

 

I have also opened a discussion in the "Power electronics development community". I have all my files in this community. I recently found about "LAVA". So, I am posting this discussion again to get some help. I specifically want to use this method because in this way all the calculation will be done in the FPGA level and I can have the real time processor in the SBRIO for communication pruposes.

 

For more information about this please check this link

 

https://decibel.ni.com/content/message/63258#63258

 

 

Frequency_calculation.zip

[hooovahh]

Looking at your other post I'm not sure why it isn't working and I hope you can solve it.  The only thing I wanted to add was that in the past when I needed to measure 3 phase high voltage I used the cDAQ platform because it was cheaper.  But don't let me change your plans your hardware should work just fine.

 

I used a cDAQ-9174 4 slot USB chassis, a 9225 to measure three phase differential voltage simultaneously, and a 9227 to measure three phase differential current simultaneously.  This meant the measurement could be done in Windows then calculate things like power factor and phase offset and the voltage and current wouldn't need to be scaled down as long as voltage is 300VRMS or less and current was 5ARMS or less.

 

Here is the white paper on it.  NI did have a "Electrical Power Measurement" package which was a set of free VIs that took voltage and current and returned things like phase and power but have rolled it into the "Electrical Power Suite" which is no longer free but added a bunch of functionality.

[kprabaka]

Thank you for your comment and the white paper. It was really useful. 

 

The electrical power suite that was used in the white paper is in the real time layer. Frequency measurement is only 30 percent of what the sbrio have to perform. There is a lot of other communication and control programming that needs to be performed in the real time layer.

 

I want to avoid calculating the frequency in the real time layer and calculate the frequency in the FPGA layer. This is why I am particularly interested in the three phase pll block in the FPGA pallette. 

 

In the worst case, I might have to use the blocks given in the white paper.