Active power sharing and frequency regulation of islanded microgrids under communication islanding

• A hierarchical control framework resilient to communication link failures in microgrids. • Detects failures and seamlessly switches to a low-bandwidth NB-PLC supervisory layer. • Uses a recursive power estimation filter with enhanced delay and disturbance rejection. • Superior to conventional consensus in simulation, stability analysis, and experiment. This paper proposes a hierarchical fault-tolerant distributed control framework for islanded microgrids (MGs) composed of distributed generators (DGs). It addresses the critical issue of communication islanding, where the MG remains electrically connected but fragments into isolated communication islands (CIs) due to communication link failures. In such cases, conventional distributed control, relying on peer-to-peer neighbor interactions, fails to ensure global coordination, risking degraded power sharing and frequency stability. To resolve this, the paper introduces a four-layer control scheme that operates in two modes: under normal conditions, it uses local high-speed peer-to-peer communication for recursive power estimation (RPE); under communication faults, it switches to a low-bandwidth auxiliary supervisory layer leveraging narrowband power line communication (NB-PLC) to broadcast global average power references. A switched control mechanism enables seamless transitions between normal and faulted modes. The hybrid use of fast peer-to-peer links and slow NB-PLC ensures frequency synchronization and active power balance, even under persistent CIs. Extensive MATLAB/Simulink simulations on 6-node and 20-node MG test systems, coupled with small-signal stability analysis and experimental validation, demonstrate the effectiveness and resilience of the proposed strategy.