Experiment on wind power integration grid via fractional frequency transmission system: Realization of the variable-speed variable-frequency power wind

Fractional Frequency Transmission System (FFTS) provides a novel approach to integrating the remote wind farm into grid. This approach can overcome the great challenges caused by the randomicity and the intermittence of the wind power. In 2005, the FFTS has been realized for the first time under the conditions of active inversion of phased-controlled cycloconverter, the result of it proves its effectiveness and feasibility. But this system can not fit the wind power well because the Total Harmonic Distortion (THD) of 6-pulse cycloconverter is very large. In this paper, the experimental FFTS is illustrated firstly, then the power circuit and the control circuit of the 12-pulse cycloconverter are designed, which is the key equipment of FFTS. In this experimental system, a synchronizing generator is used to simulate the Permanent Magnet Synchronous Generators (PMSG) in wind farm. Furthermore, the operation mode of cycloconverter is discussed in this paper. Finally, the open-loop active power regulations method is also introduced. Experiment results show that this system is capable of transmitting 20kW electric power into grid, and the feasibility of the system, which can be used to integrate wind power into grid via FFTS, is verified.