A Coherency Recognition Based on Structural Decomposition Procedure

The aim of this paper is to present an algorithm for coherency recognition. In the proposed decomposition model, the system structure is explored by analyzing and quantifying the strength of connection among generating units by means of suitable coupling factors. These factors take into account interconnection constraints among dynamic components of the system. In particular, coherency indicators are based on the influence that state variables of generators have on the voltages of all other generators. Test results demonstrated that the coherency recognition obtained with this procedure is independent of fault location and of size of disturbance, since it is based on the very structural characteristics of coupling factors. The practicality of the proposed procedure is demonstrated by numerical examples involving the IEEE 118-bus test system.