Inspec keywords: power grids; flexible AC transmission systems; HVDC power transmission; power transmission lines; power transmission protection; power transmission faults; relay protection

Other keywords: protection schemes; double circuit transmission network; intermediate sources; grading strategy; DIgSILENT PowerFactory software package; National Grid transmission network; intermediate infeed; transmission line distance protection

Subjects: Power transmission lines and cables; Power system protection; d.c. transmission; a.c. transmission