Method for restraining no-load closing magnetizing inrush current of transformer

The invention provides a method for restraining no-load closing magnetizing inrush current of a transformer. A power-factor angle of the transformer at the opening moment is measured and used as a basis for selecting the optimal closing phase angle, and mechanical properties of a disconnector are considered to determine the optimal target phase angle and to carry out no-load closing operation on the transformer. According to the method for restraining the no-load closing magnetizing inrush current of the transformer, an arc quenching property of the disconnector is considered, the voltage phase angle at the opening moment is determined according to the power-factor angle so that residual magnetism can be estimated, and key parameters are acquired in a simple, convenient and effective way; meanwhile, the method is combined with the controlled switching technology, the optimal target phase angle is selected to conduct switching on the transformer, supersaturation of an iron core of the transformer is prevented, and the magnetizing inrush current is restrained fundamentally.