Abstract:The loop equation is established respctively from the Y/△ connection mode,and then the circulation current of triangle side and public magnetic chain of both sides is eliminated. The result shows the less need to change the TA configuration of the triangle side. The resistance and induction of transformer's winding parameter identification algorithm can be directly constructed from the line current of the triangle side and the current of the other side. The“data saturation”, got from the least square method (LSM) algorithm,can be eliminated by using the LSM with dynamic forgetting factor. EMTP simulation results show that the parameter identification algorithm is stable,not affected by the load fluctuation's and power factor's changes. This identification result has higher precision.