Differentiated Topology Configuration and Operating Characteristics of a Multi-Energy DC Collection System for Offshore Wind Power Integration

To meet the demand for large-capacity and long-distance transmission of deep-sea offshore wind power and coordinated export of multiple energy sources in coastal clean-energy bases, this paper investigates the topology configuration and operating characteristics of a multi-energy DC collection system for offshore wind power integration. Based on the characteristics of offshore wind power, nuclear power, onshore photovoltaic generation and pumped storage, a source-type–converter-topology–control-function matching relationship is established. A ±800 kV true-bipolar DC large-bus system is then constructed, in which the four sources are configured as a lightweight offshore wind export branch, a stable power-export branch, a fast controllable renewable-energy branch and a system regulation resource, respectively. A polarity-interface conversion link is introduced to match the local offshore wind export structure with the main true-bipolar DC system, and the power-balance relationship among sending-end injection, receiving-end absorption and DC-bus voltage is formulated. PSCAD/EMTDC simulations are performed under steady-state operation, wind-speed step disturbance, a sending-end AC three-phase metallic grounding fault and a submarine-cable pole-to-ground fault. The results confirm that the proposed differentiated topology can support multi-energy collection, true-bipolar voltage coordination and continuous stable operation under typical disturbances.