Investigation of Asymetric Modes of Three-phase Three - legs Phase-shifting Transformer with “Inverse Double Zigzag” Scheme of Windings Connections and Commutation in Neutral Point

Abstract

The model for power three-phase three limbs phase-shifting transformer with “inverse double zig-zag connection” was investigated. Calculations and research of steady state asymmetric modes of transformer with such windings connection were fulfilled, taking into account the electromagnetic coupling of the windings, located on different legs. The analysis was made for the most specific steady state asymmetric modes, that occur during different short circuits and asymmetric no load regimes, associated with the appearance of zero sequence magnetic flux. Vector diagrams for windings currents and voltages were constructed, as well as for the relative values of magnetic fluxes in legs, which in ensemble give a clear idea about their particularities.

Keywords

• model of power three legs transformer
• asymmetric modes
• zero-sequence magnetic flux.