Resonance Analysis on Inverter-Populated Power Grids

Inherently, power grids with multiple inverters have interactions that may lead to resonant phenomena, which is undesirable. Thus, this paper exploits the interaction between grid-following converters and the power grid. Generally, the idea is to use the representation of the electrical grid populated by converters to determine the resonant modes using a frequency- domain impedance-modeling approach and eigenvalue analysis. This knowledge will enable planners to predict the oscillatory phenomena caused by inverters and prevent them by proposing modifications to the control systems of the inverters. The paper presents a step-by-step discussion of how to organize the impedance models into a multibus power grid and how to conduct eigenvalue analysis in this aggregated model. For testing the models, it was considered a 10-bus grid in different scenarios, one stable and another unstable. Simulations were also carried out to validate the results of the analysis.