Decoupled Power and Frequency Control of Offshore Wind Farms Connected With DR-HVDC Based on Consensus Algorithm

In the offshore wind farms connected to diode-rectifier-based high-voltage dc (HVDC), conventional distributed grid-forming control suffers from inherent coupling between active power, reactive power, and grid frequency, leading to large oscillations in reactive power and grid frequency during transient states. This work proposes a consensus-based distributed control to decouple power and frequency control. Firstly, a sparse communication network-based consensus algorithm is employed in each wind turbine controller, which enables local observation of the global average reactive power. On this basis, a dynamic virtual capacitance control and a droop-free frequency control are proposed, eliminating reactive power and frequency oscillations. The effectiveness of the proposed method is validated by comprehensive simulation and Controller Hardware-in-the-Loop (C-HiL) results.