Insulation coordination process for HVDC converter stations: preliminary and final designs

The authors provide step-by-step procedures for determining the appropriate surge arrester characteristics and insulation levels for both transmission and back-to-back HVDC (high-voltage direct current) systems. Information is included on insulation coordination practices in existing HVDC systems, such as typical system voltage and insulation withstand levels. Two different design procedures with specific design objectives are presented: preliminary insulation coordination and final insulation coordination. The proposed procedures concentrate on the use of gapless metal oxide arresters for insulation protection