Point on Wave Energization Strategy and Sequential Phase Shifting for Sympathetic Inrush Current Mitigation in Three-Phase Transformer - Measurement

Abstract

Inrush currents generated when an electrical transformer is energized can achieve great values and cause abnormal difficulties in the power grid. The sympathetic inrush current phenomenon is resulted in the power system when a transformer is energized with the existence of other transformer already energized. The main objective of this article is the attenuation of sympathetic inrush current in a three-phase transformer. The control technique is carried out by the consideration of the residual flux value when de-energizing the transformer as well as respecting the three-phase shifting. Moreover, an experimental setup to measure the inrush current will be presented. Furthermore, a technique for controlling the circuit breaker to energize a 2 kVA three-phase transformer which allows the sympathetic inrush current to be attenuated was also applied and tested in the experimental. The contribution of this paper is that this technique is applied in measurements with an in-depth estimation of the residual flux. The proposed technique made it possible to completely eliminate the sympathetic inrush current.