Research On The Control Of Permanent Magnet Straight Flooding Wind Generators Under Low Voltage Conditions

Recent years, wind power has been developing rapidly. It is more and more widespread concern that wind power is off-grid unplanned from power system. When power grid failure, the transient problems occur to wind turbine, as over current and increased Speed, etc. The delays make wind turbine off-grid. But a lot of wind turbines are off-grid, the recovery will be difficult for power system. Deterioration of operating status will occur.In the world, advanced countries have been released different quantitative criteria to low voltage ride through of wind turbine. That is, when power grid failure, the wind turbine keeps running in the power grid, and provides reactive power to the power grid until the fault is cleared.This dissertation gives theoretical study mainly the control of permanent magnet straight flooding wind generators under low voltage conditions in power grid. In the paper, a D-PMSG model comprising of a host AC power grid with two back-to-back PWM voltage source converters (VSCs) and a common DC link was established. The active and reactive powers of the two VSCs were independently controlled by the P I current controllers with feed forward decoupling. The control strategy with storage unloading based on the ratio of actual and rated grid voltage was proposed. The control method is put forward, and simulation analysis and physical model experiments were carried out. The results show that the control strategy based this paper can be better achieved through the low voltage generator.