Modeling of distributed energy resources for simulating fault-initiated islanding of microgrids

To increase the reliability of distribution networks, novel network operation concepts including fault-initiated islanding of microgrids may be integrated in the future. During fault-initiated islanding a sequence of fault, islanding and control-mode switching transients take place. In the literature, simplified distributed energy resource models are often used for simulations, however stability assessment for this complicated switching transient requires dedicated models. Different distributed energy resource models are developed in this paper and compared to a reference model to analyze the impact of switching harmonics, DC-link dynamics and PLL dynamics on fault-initiated islanding simulations. Additionally, the impact of several distributed energy resource and load parameters on the modeling accuracy is determined. The results indicate that the switching harmonics and DC-link dynamics can be neglected is some cases, while the PLL dynamics should be modeled when PLLs have different bandwidth or structure.