A new Approach for DC-link Stability Analyses of a Grid Connected Inverter, DC/DC-Converters and a Hybrid Storage System

Abstract:
This paper presents a new approach for DC-link stability analysis of a grid connected inverter and a hybrid storage system, consisting of several power electronic based switching converters, a redox flow battery and a flywheel. The impedance method is used and the stability is analyzed with major stability criteria like Nyquist, Middlebrook or the Energy Source Analysis Consortium. The presented method can be used for any desired amount of storages at a single DC-link. It also includes control parameters of the converters and the parameters of their filter devices. A state space average model for a DC/DC-converter has been developed and implemented to determine the input and output impedances correctly. The presented method can also be used for varying power flow directions and different infeed and load situations of the storage system. Matlab is used for calculations and the results show a stable behavior of the used hybrid storage system.