Hi,

I want to design a 3 phase meter which provides following basic functions:

- Harmonic calculation
- Voltage dip monitoring
- Voltage swell monitoring

….

As I know, if the device needs harmonic calculation, the metering library with FFT should be used.

But to implement the voltage dip monitoring and swell monitoring function, the meter has to calculate the Urms

every 1/2 period, for 50 Hz grid, every 10 ms the Urms must be calculated. If I choose metering library with FFT, it must call METERLIBFFT_CalcMain first and this function take much time. If I call it every 10 ms, I am afraid the meter performance will reduce a lot.

Or I can use two metering library FFT and Filter at the same time, using Filter library to calculate Urms every 10 ms and FFT library to calculate harmonic every 20 ms (50 Hz).

Is there someone can tell me how I can solve this problem?

Martin

Hi, Martin,

I do not think there is good idea to handle your case. I suppose you have to use two library, you can use meter library to calculate the RMS of both voltage and current, in other words, you calculate the Rms of voltage/current in time domian with 10ms period. You can use FFT library in 20ms period to calculate the other parameters.

Hope it can help you.

BR

XiangJun Rong