In-deep First Assessment of the Influence of Nonlinear Elements in Three-Phase Networks with Neutral

Harmful effects introduced by nonlinear single-phase elements present in three-phase power distribution networks are assessed from the perspective opened by Professor Ţugulea’s theory. The unwanted parasitic active and reactive power flows leading to additional losses and power quality deterioration are investigated utilizing the non-symmetry and residual (distorting) active and reactive powers introduced by this theory in a three-phase network with zero impedance. A brief description of the original theory is presented followed by recent advances trying to generalize the initially obtained results. Due to the vast complexity of real-life network configurations, the problem is tackled in a simplified circuit structure, where a three-phase balanced linear line supplies two nonlinear three-phase loads present at the same connection point. These two loads have both a single-phase nonlinear resistor, whose ampere-volt characteristics are significantly different being provided analytically. Even simplified, the investigated circuits analyze and power flow determination present difficulties in what the big amount of data management and computation effort are concerned. Four test-circuits are investigated, and the obtained results are interpreted and discussed.