Voltage collapse precipitated by the immediate change in stability when generator reactive power limits are encountered

When a generator of a heavily loaded electric power system reaches a reactive power limit, the system can become immediately unstable and a dynamic voltage collapse leading to blackout may follow. The statics and dynamics of this mechanism for voltage collapse are studied by example and by the generic theory of saddle node and transcritical bifurcations. It is shown that load power margin calculations can be misleading if the immediate instability phenomenon is neglected.<
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