Control of a three-level converter for power quality improvement in wind power plants

High penetration of wind energy into the grid may introduce stability and power quality problems due to the fluctuating nature of the wind and the increasing complexity of the power system. By implementing advanced functionalities in power converters, it is possible to improve the performance of the wind farm and also to provide grid support, as it is required by the grid codes. The main compliance difficulties that can be found in such power plants are related to reactive power compensation and to keep the harmonics content between the allowed limits, even if the power of the wind power plant converters is increasing. The proposed system is based on a three-level NPC converter performing STATCOM and Active Filter functionalities which is used in compensating reactive power and harmonic voltages. Experimental results of the proposed control strategy are analyzed in order to validate the performance of the entire system.