Dielectric response characteristics of transformer oil-paper insulation system can be described using extended equivalent circuit of the Debye model. Study on extended Debye model equivalent circuit parameter identification method of oil-paper insulation system is of great significance. This paper proposes a method using polarization current curve to identify extended Debye equivalent circuit parameters of oil-paper insulation transformer. Because the terminal of polarization current curve depends on the large time constant exponential

so firstly

it can take the points at the end of the curve to calculate estimated values of the parameters

to modify the calculation based on estimated values to get accurate values

then check the calculation to obtain more accurate values. One branch respectively

all polarization branch parameters can be obtained. Using this method

the equivalent circuit parameters of several transformers are identified. The calculated equivalent circuit parameters are accurate and polarization current curves fitting good

the feasibility of this method is verified.