Grid synchronization technology for distributed power generation system

Grid synchronization is one of the key issues for distributed power generation system. In recent years, an increasing number of new energy generation systems are connected to the grid. This greatly affects stability of the grid, which brings difficults for inverters to be connecterd to the grid. So accurate detection of voltage frequency, positive and negative sequence components under complex and unbalanced grid faults becomes one of the key issues of control of grid-connected inverters. In this paper, three grid synchronization methods are introduced and simulation was done to see their performance under complex and unbalanced grid condition. Simulation results showed their availability. Advantages and disadvantages of them are compared in order to be applied to different situations.