Detection and switching control scheme of unintentional islanding for 'hand-in-hand' DC distribution network

With the large-scale access to distributed generation and energy storage (ES), the rapid growth of DC loads, and the development of power electronics technology, the DC distribution network is becoming a new type of high-reliability power supply. Detection and switching control of islanding is important to ensure the stability and robustness of the DC distribution network. In this study, first, for a 'hand-in-hand' DC distribution network, an unintentional islanding detection method, which is a combination of the main criterion based on switch status and an auxiliary criterion based on no-current and difference-voltage criteria, is proposed. Second, an unintentional islanding control strategy based on the coordination of the switching strategy of ES controller and DC solid-state transformer is proposed. Finally, the proposed detection and switching control scheme is validated through simulations using the real-time digital simulator platform. Simulation results indicate that the proposed scheme for the DC distribution network can accurately identify an island, and effectively switch control mode to achieve stable islanding control.