Study on the reliability of new kind of ±1 100 Kv DC voltage divider under the action of impulse voltage

To meet the special insulation demand of the DC transmission system with the highest voltage in the world, a new kind of ±1 100 kV DC voltage divider is designed. The reliability of the new structure voltage divider under the action of lightning impulse is studied. To achieve the voltage and electric field strength distribution of the voltage divider, a 3D transient electric field calculation model is established and a lightning impulse test for the prototype is carried out. The results reveal that (1)The voltage and electric field strength distributing on the voltage divider changing with time show a cumulative effect. (2)The maximum electric field strength occurs at the junction where the first grading ring connecting to the internal bushing. (3)The maximum current of resistance occurs at the peak voltage of lightning impulse with the corresponding time is 1.2 µs. (4)The voltage distributing on the capacitance imply that the capacitance really does play the role of equalisation voltage when the voltage divider suffering lightning impulse. (5)The prototype of HVDC voltage divider passing through the lightning impulse test successfully strongly demonstrates the correctness and reliability of the new structure ±1 100 kV voltage divider voltage.