This study addresses the problem of transient inrush current (IC) during the energization of a power transformer. Moreover, this research examines Partial Phase Switching (PPS), in contrast to traditional three-phase inrush investigations that concentrate on synchronous pole shutting. This situation occurs when one or two phases are powered on while the others are not. This is common during single-pole maintenance or clearing of an asymmetrical fault. This study is novel in that it examines the dynamic magnetic coupling between the energized and stationary phases, which causes unpredictable residual flux distributions. The proposed strategies, residual flux estimation and Vm synchronization, are specifically optimized to handle these asymmetric magnetic states, providing a robust solution in which standard balanced mitigation methods fail. The first is residual flux estimation, which integrates the primary voltage to estimate the residual magnetic flux and determine the optimal switching instant to eliminate it. The second is synchronized switching at the voltage peak ( Vm method), which forces the circuit breaker to open and close at the same point in the voltage waveform, typically at its peak, ensuring a zero initial flux. The entire system was modeled and validated on a real-time platform using a dSPACE card, enabling accurate synchronization between the simulation and measurements. The experimental results show that in all tested scenarios, the inrush current peaks are eliminated, regardless of the switching configuration or timing. Only the steady-state magnetizing current remains, confirming the efficiency, robustness, and practical relevance of the proposed strategies, even under asymmetric phase-switching conditions. |
