Lightning protection of 1 MV HVDC test power supply

Eskom is establishing an HVDC outdoor test facility for HVDC corona performance and field effects research. A stringent lightning protection system with high interception efficiency is required. A particular challenge is that the test facility must be corona discharge free and the ultra-high DC voltages generated by the power supply will readily cause electrostatically induced corona from nearby air terminations or shield-wires. Preliminary electrostatic simulations are presented indicating that the LPS will require careful selection and electric field grading measures to ensure that the high lightning protection efficiency, as ensured by proximity to the UHVDC equipment, is corona free. Lightning masts with moderately blunt air terminals are recommended in favour of shield wires which are shown to be unsuitable.