A novel FFAC multi-turbine control scheme based on stator voltage orientation

A novel fractional frequency multi-turbine (FFMT) control scheme was proposed for improving the economy of wind energy transmission of medium distance. In this system, an AC-AC converter was used to control the operation of clusters of synchronous wind generators and transmit the power to the grid. The stator voltage orientation was adopted because all the generators have the same stator voltage vector while rotor filed orientations of them are various. In addition, an improved multi-turbine frequency optimization and an instantaneous reactive power based digital phase-locked loop(PLL) were adopted. The former raised the wind energy capture and improved the stability of the system, while the latter addressed the difficulty of stator voltage orientation. Finally, the proposed scheme was validated by simulations on a wind farm composed of four wind generators.