Power Quality Factor for Networks Supplying Unbalanced Nonlinear Loads

Abstract

A single indicator [i.e., the power quality factor (PQF)] in the range between 0 and 1 is suggested in this paper to integrally reflect the power transfer quality of a general three-phase network feeding unbalanced nonlinear loads. The prominent power quality aspects considered in the paper are the following: 1) the voltage and current harmonic levels; 2) the degree of unbalance; and 3) the phase displacement factor in the different phases at the fundamental frequency. A network that supplies balanced sinusoidal currents at balanced sinusoidal voltages with zero phase displacement between the corresponding currents and voltages yields a PQF of unity. The measurement of the PQF is discussed. Practical examples illustrate the use and relevance of the new quality factor.