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Stability analysis of electrical network is divided in the classical theory in two types. The first type is so-called transient stability analysis, where the dynamic behavior of the network is analyzed during large disturbances (such as, for instance, short-circuits). Typical outcome of the transient stability analysis is the Critical Clearing Times (CCTs). The CCTs are the short-circuit times for which the system still finds itself on the border of stability. Larger short-circuit times result in out of step operation of synchronous machines, transient voltage instability phenomena, etc. CCTs can be determined in Vision using Dynamic Analysis module.

 

The second type of stability analysis considers behavior of the system during relatively small changes (like, for example, the reference step of the active power of a generator or normal changes of load powers). For this type of stability analysis the dynamic model of the network is linearized first, and after that the eigenvalues of the linearized system are computed. Based on the real parts of the eigenvalues it is concluded whether the system is stable or not. These second type of stability analysis can be performed with Stability Analysis module.