As the core material and technology optimization

the ferroresonance overvoltage caused by commissioning 500 kV auto-transformer gradually reduced. But in the thinner terminal station of the power grid structure

due to the improper way of debugging

the main transformer was still likely to inspire ferroresonance. To solve the above problems

the author take the terminal 500 kV Han-Ta stations of North China power grid as an example

on the research of the auto-transformer ferroresonance excitation characteristics

developed the BPA-PSCAD equivalent interface program

it modeled and calculated the possible ferroresonance overvoltage

natural resonant frequency

operating overvoltage and excitation inrush current in the starting mode of the long line and commissioning main transformer with no-load

to avoid the resonance failure occurs

it puts forward the right way to start debugging

the studyings for the debugging plans provides the feasible theory basis

it is significance for the terminal station of the main transformer to cut and run.