Topology of DC energy dissipation device based on dual capacitor five-level sub-module and energy-power dual closed-loop control strategy

• A centralized DC energy dissipation device topology based on the Dual Capacitor Five Level Sub-module (DCFL-SM) is proposed. • The operating conditions and energy dissipation principles of the proposed topology are analyzed, and a mathematical model of the energy dissipation device is established. • An energy-power dual closed-loop control strategy is proposed. It enables precise dissipation power tracking and enhances DC voltage stability by dynamically matching surplus power. This effectively prevents protection maloperations during faults, offering a practical solution for real-world implementation. • A simulation model of an offshore wind farm connected through a VSC-HVDC transmission system was developed, with the proposed energy dissipation device integrated. The effectiveness of the proposed topology and control strategy was verified under various fault scenarios. • A comparative analysis of dissipation performance and cost was conducted between the proposed topology and existing conventional energy dissipation device topologies. Modular centralized DC energy dissipation devices hold broad application prospects in offshore wind power DC transmission systems. However, existing topologies face challenges such as a large number of power devices and high costs. To address these issues, this paper proposes a novel energy dissipation device topology based on a Dual-Capacitor Five-Level Submodule (DCFL-SM). Compared to the conventional half-bridge-based topology, the proposed structure reduces the number of IGBTs by 50%, significantly lowering manufacturing costs. Furthermore, an energy-power dual-loop control strategy is developed for this topology, enabling precise regulation of capacitor energy and dissipation power. In the following part, the operational principles of the proposed device are analyzed, a mathematical model is established, and the impact of modulation parameters on control performance is investigated. Finally, simulations conducted in MATLAB/Simulink validate the superiority of the proposed scheme in terms of dissipation effectiveness, operational performance, and economic efficiency.