A concise assessment of original and modified instantaneous power theory applied to four-wire systems

In 1962 Depenbrock published a power theory generally valid for N-wire systems. In 1983 independently Akagi, Kanazawa and Nabae introduced the original "theory of instantaneous power", valid with few restrictions for N=3. Because of more problems at N=4 Nabae and coauthors introduced a modified version of the instantaneous power theory in 1995. By a discussion of this modified power theory Akagi and coauthors in 1999 showed, that under certain conditions the modified theory leads to compensation results inferior to those resulting from the original theory. Because both theories do not present optimal compensation rules under all conditions of four-wire systems, this paper gives the compensation rules based on the older generally valid FBD power theory and analyses the differences with regard to the other theories.