Estudo do sincronismo de múltiplos osciladores acoplados: aplicação ao paralelismo de UPS

Abstract

In this work stability analysis techniques were developed to investigate synchronization of interconnected and isolated multiple uninterruptible power supplies - UPS. The UPS systems were considered as nonlinear oscillators that should attain a special synchronization condition, namely the equal sharing of active power demanded by the load, while keeping as sinusoidal as possible the voltage on the load. Various factors were considered in the above mentioned analysis, such as parameter uncertainties and maximum number of interconnected UPS systems. Among the contributions of the present thesis, it is possible to highlight: (i) the poposition of a new implementation for the synchronization strategy based on frequency and amplitude variation according to the estimated active power delivered by each UPS, without explicitly estimating the corresponding reactive power; (ii) the use of Floquet Theory to analyse the stability of periodic solutions exhibited by the system comprised by multiple isolated UPS systems, which has led naturally to the investigation of superior limits for the number of interconnected UPS synchronized using the technique based on estiamted delivered active and reactive power.