Investigation of PLL performance for utility connected systems under abnormal grid conditions

The operation of grid side converters (GSC) is significant in its robust control design. Phase locked loop (PLL) algorithm is introduced to acquire synchronization and perfect operation of GSC. The control design depends on rapid and exact tracking of phase angle of grid voltage. The task of PLL is crucial condition, since grid connected system is to operate the power system under grid fault conditions. The main objective of the PLL is to extract positive and negative fundamental voltages in a precise manner during distorted grid conditions. In the past decades several PLL techniques have shown better results in their accuracy. This paper deals with investigations of different grid interactive PLL techniques in the unbalanced supply voltage conditions. Decoupled double synchronous reference frame (DDSRF) shows better and quicker performance than the other PLL techniques. The analysis of different PLL techniques is compared and the results are shown in Matlab\Simulink.