An interconnected 60-Hz power system consisting of one area has two turbinegenerator units, rated 500 and 750 MVA, with regulation constants of 0.04 and 0.05 per unit, respectively, based on their respective ratings.
When each unit carries a 300-MVA steady-state load, let the area load suddenly increase by 250 MVA.
(a) Compute the area frequency response characteristic β on a 1000-MVA base.
(b) Calculate Df in per-unit on a 60-Hz base and in Hz.