Inspec keywords: power transmission lines; air gaps; substations; power transformers; HVDC power transmission; HVDC power convertors

Other keywords: northwest region; UHV converter station; Northwest Energy Base; high altitude areas; AC side; voltage 500.0 kV; clearance optimisation; converter transformer; UHVDC converter transformer; highest altitude; voltage 800.0 kV; phase–phase discharge characteristics test; backbone voltage; gap discharge voltage; AC system; size 3000.0 m; ultra-high-voltage direct current project; voltage level; phase-to-ground clearance; voltage 750.0 kV; converter station access

Subjects: Protection apparatus; Transformers and reactors; Power convertors and power supplies to apparatus; d.c. transmission; Substations