Fractional frequency transmission system (FFTS), which is also known as low frequency AC transmission (LFAC), is a very promising transmission scheme for offshore wind farm integration. This paper proposed a droop-based control method for communication-free coordination of converters in FFTS. Firstly, the concept and topology of Multi-terminal FFTS (MT-FFTS) for offshore wind farm integration is introduced. Secondly, the droop control of parallel converters in MT-FFTS is designed. Finally, the droop control is implemented in a MT-FFTS case study in MATLAB/Simulink and the results shows that the proposed droop control performs well.

Fractional frequency transmission system (FFTS),droop control,offshore wind farm