Abstract:
The offshore wind power low-frequency AC transmission system based on uncontrollable rectifier units(DRU) lacks the capability of power feedback, necessitating the use of grid-forming converters to enable self-networking of offshore wind farms. At the same time, considering the positive impact of the fast power response capability inherent in traditional grid-following converters on offshore wind power generation, this study uses a wind turbine unit composed of a six-phase permanent magnet synchronous generator as the research object. It elucidates the topological structure and operational characteristics of using parallel converters with two control strategies in the wind turbine unit, transmitting power through the DRU low-frequency AC system. The grid-forming control strategy and grid-following control strategy for the wind turbine’s grid-side converter are respectively designed. On this basis, the issue of power imbalance between the two grid-side converters is discussed, and a circulation suppression strategy is further developed to enable the transmission of wind power through the DRU. The feasibility of the proposed scheme is verified by constructing a Simulink simulation model and RT-LAB hardware-in-the-loop simulation system.