Winding Current Utilization Calculation of Controllable Reactor of Transformer Type Based on Equivalent Leakage Reactance

The calculation of winding current and the analysis of winding coupling effect are distinctly important to improve the efficiency of the controllable reactor of transformer type (CRT). Based on the grading principle of step-single-branch operation mode, the formulas of control winding current, equivalent leakage reactance, and rated current utilization are derived. These formulas demonstrate that the variation of current distribution and the inefficiency of rated current utilization are caused by the equivalent leakage reactance, which is constituted by the winding´s self and mutual leakage reactance, and the rated current utilization is the monotone decreasing function of equivalent leakage reactance. Thus, the quantitative relation between the current variation and the winding coupling effect is derived. Meanwhile, a criterion used to evaluate whether the winding current utilization meets the design objective is elaborated. Finally, the results of an example show that winding current utilization and work efficiency in different working conditions can be correctly and quickly obtained, which confirms the presented method and underpins the further design of a CRT.