The Influence of a Transformer with “Double Zigzag with Zero Output” Windings on the Level of Asymmetry and Nonsinusoidal Currents in a 0.38-kV Network

Abstract

The results of laboratory studies of the transverse inclusion of a transformer with a circuit for connecting “double zigzag with zero output” windings to a 0.38-kV network model in order to increase the capacity of the electrical network by reducing the operating current in the zero working conductor of a three-phase four-wire electrical network are presented. The analysis of currents creating a load of the zero working wire of the network with a voltage of 0.38 kV is performed. For the load side of the power transformer, the equations of the instantaneous values of the most significant harmonic components of the currents are presented, which are obtained from experimental studies with different load coefficients of the power transformer. The shunting effect of a transformer with a “double zigzag with zero output” winding connection scheme on the asymmetry coefficients of currents and voltages of the reverse and zero sequence, as well as on the distortion coefficients of the sinusoidal curves of currents and voltages and the coefficients of the third harmonic component of current and voltage, is estimated. The revealed patterns of changes in the current load of the zero working wire make it possible to improve the efficiency of electricity transmission in the electrical network, extend the service life of cable lines, and reduce the fire hazard of electrical installations.