Estimating first swing stability of synchronous machines as affected by saturation and controls

The first-swing transient stability of synchronous machines connected to a power system is studied when short-circuit faults occur. The selective influence on transient stability limits of several factors including prefault conditions, generator modelling, regulating devices, and transmission system characteristics is explored. Improvements deriving from saturation description and benefits offered by a static exciter with high initial response, static Var systems for reactive power compensation, and turbine energy control through fast-valving actuation are evaluated and compared. The stability analysis is based on numerical integration of the system´s dynamic equations, and the critical fault-clearing time is assumed as the reference parameter for the discussion of results