DSP/FPGA Control for Variable-Speed Wind Turbines

This paper proposes an advanced control of three-phase three-level neutral point clamped (3L-NPC) PWM converter connecting a parallel connected generators to a grid. Control scheme is mainly based on active and reactive power loops and contains following additional blocks: virtual flux and filter-capacitor voltage estimators for sensorless operation, active damping (AD) of possible resonances in LCL filter connecting converter to the grid, PWM modulator with DC link voltage balancing and minimization of switching losses. It is shown that the proposed control method exhibits several features as: sensorless operation, robust algorithm, minimization of switching losses as well as simple tuning procedure of AD. Simulation and experimental results have proven an excellent performance and verified the validity of the proposed system