Residual Magnetic Flux of Transformer at Power System Accident

Abstract

When a transformer is being energized, a large magnetizing inrush current flows depending upon the closing phase of circuit breakers and the residual magnetic flux in the iron core. One of the suppressing the magnetizing inrush current method is controlling closing phase of the circuit breaker. For the controlled switching, to grasp condition of residual magnetic flux in the iron core is essential. Ample studies demonstrate that residual magnetic flux for no-load transformers. The residual magnetic flux for three-phase three-leg transformer had been investigated. However, little is known about residual magnetic flux after fault current interruption.In this paper, the residual magnetic fluxes after interruption at one line ground (1LG) and two lines short-circuited (2LS) faults in isolated neutral system were investigated with experiments and calculations.