Shielding failure analysis of a hybrid transmission line with AC and DC systems on the same tower

Hybrid AC/DC transmission lines have different systems on the same tower and combine HVDC transmission over long distances with common HVAC transmission. Evaluation of the risk of lightning stroke outage of high power transmission lines is very important because lightning strokes cause mainly outages. The present paper illustrates how to combine efficiently different methods to support insulation coordination studies. Maximum lightning current amplitude that does not cause flashover across insulator string is estimated in response to first and subsequent lightning strokes with three different flashover models using several electrogeometric models and simulations in EMTP-ATP. Characteristic quantities like Shielding Failure Rate (SFR) and Shielding Failure Flashover Rate (SFFOR) are calculated for different shielding configurations.