Accurate transformer deep saturation model is the basis of the analysis of transient process of overvoltage in power grid.However

the current port test method can only get the parameters of the equivalent circuit model under rated operation

but can not get the parameters of the deep saturation area under overvoltage.In this paper

the numerical simulation methods are used to determine the parameters of three-phase transformer model.The numerical simulation methods are divided into two types

one is base on the port-based numerical experiment

and anther is the reluctance calculation method based on the electromagnetic field distribution.The former determine the equivalent circuit parameters by setting the open circuit or short circuit state in the transformer port

the latter calculate the reluctance based on the magnetic flux and energy distribution in the transformer.The numerical simulation method based on reluctance calculation is more suitable for the analysis of transformer equivalent circuit model parameters with complicated topology and deep saturation.