A novel strategy for fault location, isolation, and service restoration in active distribution networks

Abstract When a fault arises in an active distribution network, both the grid upstream of the fault point and the distributed generation (DG) downstream of the fault point contribute short-circuit currents, posing challenges for existing centralized feeder automation (FA) technologies in accurately locating and isolating the fault. Moreover, the radial network structure of the distribution network can lead to power outages for downstream loads when the DG downstream of the fault point ceases operation due to islanding effects. To tackle this issue, this paper introduces a communication-based distributed FA strategy that employs interlocking signals between adjacent switches to pinpoint and isolate faults in active distribution networks, effectively minimizing the scope of fault-induced power outages. Furthermore, to guarantee uninterrupted power supply to the non-fault zones located downstream of the fault point, an inverter control strategy integrating voltage negative feedback control, reactive power negative feedback control, and quasi-synchronization grid-connection control is proposed. This strategy allows for seamless switching between grid-following and grid-forming inverter control modes, enabling adaptive grid-connection/islanding control of DGs. Consequently, non-fault areas downstream of the fault point maintain uninterrupted power supply, significantly enhancing the reliability of power supply in distribution networks. Simulation models have been constructed using MATLAB/Simulink to validate the efficacy of the proposed approach.