A novel modular multilevel converter for medium voltage high power wind power generation system

Offshore wind power is an important component of clean energy, and the use of wind power can help achieve peak carbon and carbon neutrality goals. The combination of fractional frequency transmission system (FFTS) and direct-driven wind turbine will be beneficial to the development of offshore wind power industry. At the same time, the rated power of an individual offshore wind turbine has reached 16 MW and continues to rise in order to capture more wind energy at higher altitudes, thus reducing the unit cost of wind power generation. In order to adapt to the single wind turbine in the future with high voltage, large capacity and fractional frequency, a novel wind power converter based on cascaded H-bridge using insulated-gate bipolar transistor is proposed. The submodules of this converter consist of a rectifier, an inverter, a highfrequency transformer, and a pulse flip circuit. Power transmission is achieved through the H-bridge formed by the combination of the rectifier and inverter, while the highfrequency transformer provides electrical isolation. Finally, the pulse flip circuit reverses the high-frequency voltage to obtain the fractional frequency output. The feasibility of this proposed topology has been confirmed through simulation in Simulink.