Coordinated synchronism check settings for optimal use of critical transmission network corridors

The paper presents an efficient methodology for establishing synchrocheck relay settings for transmission lines of high power transit corridors, optimized for maximum use of the design capacity without jeopardizing equipment safety. It details the criteria used for limiting the generation units shaft mechanical surges to non-cumulative fatigue values and for keeping the electromagnetic stresses of generators and switching equipment within the withstand ratings. The main recommendation is that synchrocheck relay settings of critical lines shall be based on dynamic simulations of the switching particulars in a large number of relevant system configurations. Typical setting values as often applied in the practice may not be on the safe side, especially for lines in the vicinity of major power plants.