A software tool for the determination of dynamic equivalents of power systems

The dynamic equivalent is an important tool in power systems to deal with size and complexity since it provides a reduced representation of the system without compromising the transient behavior of the part of the system that is of interest. For instance, computational time and effort can be saved by employing dynamic equivalents in power systems simulation studies. The determination of dynamic equivalents, however, may also be a time consuming task, even if performed offline. Moreover, several dynamic equivalents may be required to represent different operating conditions of the same system. Therefore, it is important to have computational tools that automate the procedure to obtain the dynamic equivalent. This paper presents software applications that work integrated with the CEPEL software package to automate 3 steps of the procedure: (i) identification of power plants that present coherence, (ii) static reduction of the network and (iii) dynamic aggregation of the coherent generating unit models. The developed tools are applied to partially determine dynamic equivalent for the brazilian National Interconnected System for studies in the 765kV Itaipu transmission system. Results comparing the whole and equivalent models behavior are employed to validate the software applications developed.