The current in a saturable reactor of HVDC converter valve will change suddenly at switching moment

inducing microsecond-grade pulsed high voltage the winding. Therefore

the inter-turn insulation of the saturable reactor has to suffer frequent periodic pulsed voltage stress. Unfortunately

it is difficult to directly measure the pulsed high voltage

hence discussions about the distributions of the pulsed voltage and the electric field in the winding insulation material still cannot arrive to final conclusion. In this study

the inter-turn voltage distribution was analyzed based on the measured voltage waveforms of the HVDC Jinping-Sunan ±800 kV/4 750 A transmission project

and finite element analysis was employed to simulate the distribution of the transient electric field. The results show that the microsecond-grade pulsed high voltages among turns are not uniform

and the voltage on first turn gets the maximum

which is 1.14 times higher than that on last turn. The highest electric field of each turn appears on its surface

and the transient peak of electric field on the first turn surface reaches to 2.08 kV/mm

which is also higher than those on other turns.