Modified Instantaneous Power Theory for Three-Phase Four-Wire Power Systems

In this paper, the instantaneous power theory of three-phase four-wire power supply systems was further developed by substantiating new determination formulas for instantaneous active current, instantaneous apparent power and instantaneous power factor, considering the dependence from the ratio of transmission line resistances. The use of matrix-vector algebra formulas allowed to obtain a new decomposition of the load current of a three-phase four-wire system for instantaneous active current and compensation current, which is the theoretical basis for the construction of an active filtration system without electric energy storage with the minimum possible power losses in transmission line. A new decomposition of the squares of the instantaneous power modules is obtained, which corresponds to the specified current decomposition, as well as to the new formulas of the instantaneous apparent and vector imaginary power. The results of the computer experiment confirm the adequacy of the proposed new formulas of the modified instantaneous power theory.