Inrush Current Reduction Strategy for a Three-Phase Dy Transformer Based on Pre-Magnetization of the Columns and Controlled Switching

The methodology and test results of a three-phase three-column transformer with Dy connection group are presented in this paper. This study covers the dynamics events that took place first period transient state caused by energizing under no-load conditions. origin inrush currents was analyzed. influence factors accompanying switch-on impact model parameters on distribution maximum values these studied. In particular, computational methods taking into account residual magnetism different columns core, as well time instant determined voltage waveform at which indicated is supplied to given winding, were examined. carried out using nonlinear constructed basis classical modeling, hysteresis not taken account. Such formulated requires simplification, discussed described system stiff ordinary differential equations. order solve equations set for states condition, Runge–Kutta method, namely Radau IIA ninth-order quadrature formulas applied. All calculations authors’ own software, written C#. A ready-made strategy suitable pre-magnetization its given.