Control strategies of variable-speed wind system under new grid code requirement — A survey

The rate at which large variable speed wind farms are being developed had increased rapidly as the demand for green energy has grown. With this increase in distributed energy penetration into power networks, the main focus must be on power quality (Voltage Quality and Supply Reliability). However, new grid codes require wind energy generating systems to ride through grid faults, and at the same time inject reactive current into the grid. This paper presents a comprehensive survey of the control strategies for doubly-fed induction generator wind systems, including grid synchronization, maximum power point tracking (MPPT), active and reactive power regulation, and fault ride-through. From the assessment of these control techniques, conclusions about the trend of wind power generation technologies are drawn.