Transformer residual magnetism determination method based on small signal measurement excitation inductance

The invention provides a transformer residual magnetism determination method based on small signal measurement excitation inductance. The transformer residual magnetism determination method comprisesthe following steps of: firstly, carrying out demagnetization operation on a transformer, then pre-charging a certain amount of magnetic flux as residual magnetism on the transformer, applying an alternating current excitation small signal which does not influence the original residual magnetism to the primary side of the transformer under a no-load condition, and measuring an excitation inductance value under the residual magnetism condition; secondly, changing the magnetic flux, repeatedly measuring excitation inductance values under different residual magnetism conditions, and acquiring a relation curve of the residual magnetism and the excitation inductance of the transformer; thirdly, after the transformer normally quits operation or a test and before reclosing, adopting an alternating current excitation smal