A transient stability approach for the analysis of droop-controlled islanded microgrids

Abstract Microgrids (MGs) control is one of the most important and challenging topics in nowadays power system engineering research. The most common and well-known primary control logic is the droop one, since it allows MG sources to share the power request and to participate to the frequency and voltage regulation without a dedicated communication network. Therefore, the stability of a droop-controlled MG working point is a crucial issue that is typically assessed resorting to the small-signal stability theory. However, such approach does not allow to understand whether an equilibrium point can be reached starting from a specified initial condition. In this paper, this problem is faced proposing a stability condition that relies on some simplifying assumptions. The proposed solution does not need any numerical methods or software simulators (often highly CPU demanding). The developed methodology is validated with simulations performed in the PSCAD-EMTDC environment representing the MG components with a high level of detail.