I work in the area of electric power measurement standards. Historically testing has been done with sinusoidal waveforms only, with stable loads and at stable frequencies.
I am interested in "real world" testing conditions where there is significant harmonic content with time varying loads. Active, reactive, and apparent power calculations to be done in the time domain and frequency domain. I have attached a short paper on definitions for these quantities. The follow the generally accepted approach in non-electric power applications. I welcome comment and discussion.
I also solicit discussion of detailed methods for practical calculation of the quantities discussed under stress conditions such as when the digital sampling frequency is not a binary multiple ( like 256 times) the fundamental frequency.
Dear William, thank you for your definitions. They are very helpful. The last proceeding in RG to your question you can find under
Data Lastgang mit dezentraler Stromerzeugung und Transformator-Erwärmung
In usual tarification based on integrated real power, if someone injects harmonic power in the grid it lowers his bill. This is not fair.
One can also present another view: "Fundamental tarification of electricity" EPE 2009 E-ISBN :978-90-75815-13-9 You take the fundamental of the voltage and multiply with the actual current. It is a much better tarification, as you get the harmonic power you damp for free. And some user who converts fundamental into harmonics devivers the harmonic power to the grid without being paid for it.
For power measurement, mainly no phase shift between current and voltage is needed.
(quasi-simultaneous sampling)
For power measurement, it is not required to have a very high sampling frequency, is sufficient that the sampling frequency and the frequencies in the signals are not correlated.
I want to thank everyone for the responses and documents that have risen to enrich this debate, in my case I read each of these contributions and I increased my culture on these issues.
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