Parallel control of generator-side converters for permanent magnet direct-drive wind power generation systems

We presents an easy-to-implement and robust Sliding Mode Observer (SMO) for rotor position sensing for a direct-drive wind power generation system. Without any position sensor, the generator torque and flux responses retain high performance both in the steady state and during transients. The problems on the shaft encoder installation difficulty, reliability and disturbance in encoder cable are remedied and the reliability of the PMSG generating system is increased. High power direct-drive wind power generation system needs full power converter compared to doubly fed induction generator. The parallel back-to-back PWM converters are used in megawatt-level high-power generation system. The generator-side converter and grid-side converter can be controlled separately. Two control strategies of the generator-side converters are compared. The test platform is designed and the experimental results prove the effectiveness of control strategy.