Grid-voltage Synchronization Algorithms Based on Different Phase-Locked Loop for Power converter under Balanced and Unbalanced conditions

Abstract: In this article different types of Phased locked loop technique are studied and after comparing all circuits we found that the Voltage Reforming Synchronous Reference Frame PLL (VRSRF-PLL) shows better and quicker performance than the other PLL techniques. The control design depends on quick 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 voltage in a precise manner during distorted grid conditions. There are many PLL techniques introduced in the past decades. Some of the techniques only give good results in normal grid voltage, and some techniques give good results in both normal and abnormal grid voltage conditions. This paper deals with performance and investigation of different grid interactive PLL techniques in the unbalanced supply voltage conditions.

Keywords: Grid Synchronisation, Band pass filter, Low pass filter, Phase locked loop (PLL), total harmonic distortion, PI regulator.