Unification and evaluation of the instantaneous reactive power theories

The instantaneous reactive power theory proposed by Akagi and his coauthors is widespread. However, this theory contains ambiguities when applied to a three-phase four-wire system. In this paper, a unified instantaneous reactive power theory is proposed, in which unequal resistances of transmission lines are taken into account and those ambiguities are clarified. It is also shown that the proposed unified instantaneous reactive power theory provides the spatial optimal solution, whereas the generalized power theory recently proposed provides the spatial-temporal optimal solution.