A Novel Dynamic Aggregation Modeling Method of Grid-Connected Inverters: Application in Small-Signal Analysis

Converter-control-based generators exhibit different dynamic characteristics compared with traditional synchronous generators, and thus affect the oscillation modes and small-signal stability of power systems in a different manner. Simplified representation of a great number of grid-connected inverters is indispensable for efficient and accurate dynamic analysis of power systems integrated with large-scale renewable energy generation. This paper proposes a novel dynamic aggregation modeling method of grid-connected inverters using coherency-based equivalence, and validates the applicability of the aggregated model for small-signal stability analysis. Modal analysis and dynamic simulation are conducted on the detailed model and aggregated models of the test system. The frequency-domain results and the time-domain results from PSCAD/EMTDC both verify the adequacy of the coherent equivalence practice in the small-signal rotor angle stability analysis.