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I'm currently working on a power meter device based on simultaneous sampling of current and voltage values, I intend to use this system to measure the active, reactive and apparent power on a non-linear load. I am currently able to sample the current and voltage values periodicaly and to estimate the RMS value of the those by calculating the power of 2 of each sample, averaging them out and taking the square root afterwards. However I don't know how to estimate the active power value.

How can I estimate the active power value on my system? Please cite a paper for reference if possible, I have to put this in my monography.

Thanks to whoever answers. Tchau

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  • \$\begingroup\$ Can you measure phase of current? Do you know p.f.? What is the bandwidth of current? This must be filtered to avoid aliasing errors when using > 2x f-max. for sampling rate. \$\endgroup\$ – Tony Stewart EE75 Nov 4 '17 at 13:38
  • \$\begingroup\$ I'm looking forward to answers, I think it shall involve detecting how much power was delivered from load to supply per cycle. What is your sampling rate and supply frequency? Can we multiply instantaneous voltage and current to get instantaneous power and then add all such power ratings over a cycle time? Would this represent average power? And would apparent power be integration of absolute magnitudes of v & i? I have more questions than answers ^^" \$\endgroup\$ – Deep Nov 4 '17 at 13:50
  • \$\begingroup\$ See OpenEnergyMonitor where all this work is already done. \$\endgroup\$ – Transistor Nov 4 '17 at 15:01
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With a non-linear load, to calculate the real power, multiply instantaneous current and voltage samples. Average the positive and negative values and divide by the number of samples to determine the real power. You could work with the fundamental components of the waveform, but it might be difficult to get the phase information.

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