Coordination control and start-up strategy in flexible DC urban distribution networks for smart cities

Research on the Flexible DC Urban Distribution System (FDCUDS) is in the ascendant. Due to the lack of some key technologies, operating experience and relevant standards, the application of the FDCUDS has been limited. A multi-terminal FDCUDS topology, which contains photovoltaic cell and wind turbines, was first determined for further analysis. Secondly, key equipment was analyzed and the coordination control strategy of each terminal was verified. Subsequently, a new start-up control strategy of the FDCUDS was proposed and a hand-in-hand FDCUDS model with six terminals was built in PSCAD/EMTDC. The start-up control strategy, the normal operation, and the control-mode switch strategy with regard to the fault occurrence were analyzed. The results indicate the validity of both the start-up control strategy and the operation-mode switch method.