Pollution performance of HVDC insulator strings under normal and faulted conditions

HVDC transmission is becoming increasingly viable to EHVAC transmission system, since it can carry huge amount of power compared to same voltage levels as of HVAC. HVDC transmission is more economical when the power is to be transferred over the long distances, but the major problem is the failure of overhead transmission line insulator due to the pollution/contaminated conditions. This failure rate is observed to be higher as compared to the AC systems. This paper presents the simulation and experimental studies which are carried out on different types of newly developed HVDC insulators (± 500 kV and ± 800 kV system voltage) under different conditions such as normal, string containing faulty discs at arbitrary locations and under polluted/ contaminated conditions of different severity (medium and high pollution conductivity respectively). The results of the present investigation are analyzed and presented.