Budeanu and Fryze: Two frameworks for interpreting power properties of circuits with nonsinusoidal voltages and currents

Contents The development of power theory of circuits with nonsinusoidal voltages and currents was shaped for several decades by two different approaches introduced, separately, by Budeanu and Fryze in the nineteen thirties. This paper investigates these two power theories from the present perspective and up to date comprehension of power phenomena in circuits with distorted voltages and currents. It shows the reasons for which Budeanu's power theory misinterprets power phenomena and why it does not provide fundamentals for the power factor improvement. This paper shows that a number of concepts introduced to power theory by Fryze are still alive and are very important for developing that theory, but it also has a number of serious limitations. Because of that, some issues, important theoretically, and a number of practical problems in systems with distorted waveforms were not solved within Fryze's power theory. This was the reason for further developing the power theory of systems with nonsinusoidal voltages and currents. This process is not completed yet and a lot can be learned from the history of this theory's development.