Study on Operation Mechanism and Strategy for DC Distributed Power-Collecting and Cascaded Voltage-Boosting Station With DEMS

In this article, an offshore DC distributed power-collecting and cascaded voltage-boosting (DPCB) system with distributed energy management system (DEMS) is presented for DC energy collection and DC-voltage boosting, which is differ from conventional centralized power-collecting and cascaded voltage-boosting structure applied in HVDC station. And the whole system includes multiple cascaded single active bridges (SABs) and distributed bidirectional DC/DC converters, which has advantages of powerful DC voltage-boosting capacity and system elasticity, and low design complexity, system failure-rate and cost. Three studied aspects are as follows. First, circuit equations and operational mechanism of DPCB are analyzed, and its performance is shown through Bode diagram under designed PI strategy according to small signal model; Second, power fluctuation suppression strategy is proposed to suppress power fluctuation, and designed FCS-MPC strategy for DC/DC converter makes DEMS have good system performance; Third, fault tolerance strategies are presented to protect DPCB system from breakdown when submodular, power difference or DC bus voltage drop faults occur. Finally, the system feasibility and effectiveness are verified by experiments.