An Adaptive Auto-Reclosing Scheme to Preserve Transient Stability of Microgrids

Conventional auto-reclosing algorithm (CRA) jeopardizes the transient stability of synchronous generator based distributed energy resource (SGBDER) and, accordingly, the transient stability of entire microgrid (μG). The fixed dead time associated with CRA is the origin of this deficiency. In this paper, an adaptive auto-reclosing algorithm is devised to overcome the transient stability problem in SGBDER-integrated μGs. The proposed method aims at reclosing the interrupted feeder in the least possible time while preserving the transient stability of μG even during permanent faults. To do so, the most appropriate reclosing instant (MARI) is determined based on the SGBDER potential energy assessment. MARI is an instant where the potential energy associated with SGBDER is minimum. Two indices are introduced to specify MARI. The indices are forecasted to determine the time to MARI for readiness purposes. To realize this, the least square error approach is deployed to elicit the temporal characteristics of the indices and their future behavior. The evaluation of proposed indices necessitates the availability of rotor angle of SGBDER as well as the associated rotor angular velocity deviation and its first order derivative. These signals are provided using the dynamic equations of the SGBDER which are fed to the algorithm.