Choice of Reference Conductor in Three Phase Systems - A Paradigm Shift

The values of non-active (reactive) and total (apparent) power for three-phase systems change with choice of reference conductor. Presently, the neutral in a four-wire system and virtual neutral in three wire systems is the commonly used reference in definitions. In this paper, it is shown that this is not necessarily the optimal choice of reference. Thus, there is a need to define an optimal reference that has practical value. As a solution to this problem, a new approach to determine the optimal reference is proposed. The approach is simple but effective. It allows extension of single-phase power definitions to 3-phase systems to produce unique values without the need to address balanced and unbalanced cases separately. The resulting definitions can be used to provide optimal non-active power compensation. The performance of this approach is illustrated with a case study. The case study uses three-phase three and four wire systems with different resistive, inductive and capacitive load combinations. The results of case study demonstrate good performance of the new approach.