A review on synchronization methods for grid-connected three-phase VSC under unbalanced and distorted conditions

The requirements for grid-connected voltage source converters (VSC) are increasing with the evolution towards smartgrids. In this context, synchronization methods for VSC have become a key feature for a fast and reliable control. The first synchronization methods, which were originally dedicated for communication applications have been gradually adapted to power systems applications and, today, an extensive collection of techniques exist. Although partial reviews and comparisons exist, a comprehensive classification of these approaches is needed. This paper presents an all-embracing survey of synchronization methods for grid-connected series and shunt VSC applications.