Improved Grid Synchronization Technique Under Adverse Grid Condition

Abstract

The identification and extraction of positive sequence fundamental component from an unbalanced and polluted grid signal have a vital role in controlling the grid integrated electrical power converters. The mostly used synchronous reference frame phase lock loop (SRF-PLL) fails in executing this task for an unbalanced and harmonically distorted grid voltage. In this paper, the SRF-PLL along with a low pass filter (fourth order Butterworth filter) is utilized to extract the positive sequence fundamental signal from a distorted grid voltage. The detailed study of the proposed low pass filter with second order generalized integrator (SOGI) and SRF-PLL is presented to exhibit its adaptability to adverse grid conditions and power quality issues. The proposed synchronization structure will provide fast and robust performance under voltage sag, harmonics, and sudden phase jump without compromising the dynamic performance and stability of the overall synchronization structure. To validate the performance of the proposed technique, a detailed dynamic analysis and harmonic analysis are carried out in MATLAB/Simulink environment.