Multi-architecture power distribution strategy for flexible DC interconnection system considering the capacity limitation

The flexible DC interconnection system, which cascades and unitedly controls several converter stations, can effectively improve the new energy consumption and significantly increase the power quality, thus has been widely used in the power grid. This interconnection system generally uses master–slave control strategy, where chooses one station as the master station to ensure the direct-side voltage’s stability and maintain the input and output power balance. However, in some emergency cases, the input or output power can increase to a huge value that even exceeds the capacity of the master station, which not only threatens the safety of the master station but also leads to power imbalance and abnormal fluctuation of the direct-side voltage. Therefore, to avoid the capacity exceedance of the master station, a multi-architecture power distribution strategy is proposed in this study, which sufficiently considers the capacity limitation in the system architecture and innovatively prioritizes the capacity factor in the control strategy of the master station. Furthermore, the proposed strategy also fully considers cases where the system contains different types of slave stations, such as the station with redundant power and the station that can support bidirectional power flow. The strategy then optimizes the power distribution and adjusts the power flow based on the system’s different architectures. The reliability and effectiveness of the proposed strategy are finally verified by simulation.