Due to the advantages of high insulation strength and accurate power frequency measurement of capacitor voltage transformer (CVT)

it is widely used in power system. As lightning overvoltage

switching overvoltage and other transient signals often occur in power system

CVT can only accurately transmit power frequency signals

and non-power frequency signals will produce varying degrees of distortion

so it is necessary to model CVT in broadband transient. A black box model based on port parameters of CVT is used to build the model

then with network analyzer measuring the scattering parameters of the CVT

and vector fitting method and Forster equivalent circuit theory are used to transform the model to π type of equivalent circuit. Finally

the high-voltage lightning input waveform of CVT is obtained by lightning impulse test

and the output waveform of secondary side is obtained by using Bergeron model and computing branch current equation

which is similar to the measurement results

so the correctness of the proposed model is verified.