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Abstract
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The low inertia of renewable-based distributed energy resources (DERs) renders hybrid
networked microgrids (NµGs) dynamically susceptible to transients. Such fragility makes it very difficult
for NµGs operators to maintain a reasonable margin for the resilient operation during extreme condition
contingencies. This paper presents a three-stage emergency approach to improve resilience of NµGs through
maintaining dynamic security. The proposed approach targets preserving the resilient operation of NµGs by
preventing unnecessary tripping of the DERs after unintentional islanding incident. To do so, a resilient
operation zone (ROZ) is introduced which determines the secure operating zone for NµGs and the limits
for implementing the corrective countermeasures for resilience augmentation. The proposed approach is
outlined in three stages: First, offline analysis is carried out to model and calculate the ROZ. Second, hybrid
NµGs operating point is monitored at the pre-event stage and the calculated ROZ at offline stage is adapted
to the operating conditions. The third stage is responsible for real-time evaluation of hybrid NµGs security
using the ROZ and implementation of the countermeasures. Comprehensive simulation studies presented in
this paper demonstrate effectiveness of the proposed scheme for enhancing resilience of hybrid NµGs.
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