Modelling and analysis of fault ride through capability of grid connected wind systems using multilevel dynamic voltage restorer

In conventional dynamic voltage restorer (DVR) tied wind systems, traditional controller schemes provide only low-voltage ride through capability due to voltage dips. In order to improve the capabilities of DVR systems, multifunctional controller algorithm is designed and analyzed theoretically in multilevel DVR to compensate both voltage dips for low-voltage ride through (LVRT), voltage swells for high voltage ride through (HVRT) and voltage harmonics, simultaneously. For this purpose, different reference generation methods are performed for multifunctional compensation and compared in order to obtain better results. In addition, DVR topologies which use battery called as Topology I and share dc-link capacitors of back-back converter in doubly fed induction generator (DFIG) called as Topology II are performed. The controller methods are firstly tested in Topology I in order to obtain detection speeds for voltage dips and harmonic compensation capabilities. Following, different case studies are performed in grid connected DFIG based wind system for Topology I and II. Performance results verify the effectiveness of the multifunctional controller scheme to enhance uninterruptible voltage stability and harmonics compensation in grid connected wind systems.