Simulation analysis of inrush current in no load closing of transformer in Hydropower Station

Abstract

When the transformer is switched on without load, the magnetizing inrush current will be caused due to the saturation of the iron core, which may lead to the misoperation of the relay protection device, cause overvoltage and damage the insulation of the equipment. To solve this problem, EMTP/ATP software is used to simulate the no-load closing of three-phase transformer, the applicability and accuracy of BCTRAN model in the simulation of no-load closing of transformer are studied, and the inrush current waveform under different closing angles and residual magnetism is analyzed. The results show that the BCTRAN model can simulate the hysteresis characteristics of the core by adding external nonlinear elements, and the calculation results are more accurate.