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Small Signal Analysis


Small signal stability is the study of the behaviour of the system subject to small fluctuations around an operating point.

The small fluctuations can be caused by light disturbances that occur at any time in a network (as a result of switching of loads, control actions…).


HERCULES  is a software for the analysis of the system stability for small perturbations.


The innovative algorithm permits the selection of only the eigenvalues of interest and the management of a very large system (more than 100.000 variables). The close link between EUROSTAG® and HERCULES, allowing the user to conserve the physical meaning of each variable, opens the door to advanced analysis such as:


  • Identification of unstable or badly damped modes;
  • Detection of the major machines involved in a particular mode through their participation factor;
  • Detection of inter-area oscillations using the mode shapes;
  • Detection of optimal PSS location through the controllability analysis;
  • Identification of the optimal positions of measurement devices through the observability analysis.