On speed stability

Distributed energy resources, such as wind turbine generators, often employ induction generators. When such a generator is subjected to a nearby fault, its rotor may accelerate and reach high steady-state speed far from that corresponding to the frequency of the system. This is the generator counterpart to induction motor stalling, which is classified as voltage stability. The phenomenon is a matter of stability, but it is not covered by current definitions of power system stability. We denote this type of stability as speed stability and propose a definition, which also includes induction motor stalling.