Notch filter based modified CSOGI-PLL to improve dynamics of single phase grid connected solar PV array

Abstract The phase-locked loops (PLLs) are one of the frequently employed algorithms to precisely estimate amplitude of voltage, frequency and phase of single phase grid connected Solar PV (GCSPV) array based system. However, there is deviation in PLL’s output during extraction of fundamental voltage component being hampered by presence of grid side harmonics, DC Offset and other disturbances occurred. Therefore, for the first time Notch Filter (NF) based modified cascaded second order generalized integrators (MCSOGI)-PLL with progressive control over frequency is designed for removing the error present in phase undisturbing its response which must be dynamic in nature. The proposed method systematically embeds the notch filtering mechanism within the multi-cascaded SOGI framework itself. Also, this work limelight’s the effect of proposed algorithm on DC Offset and harmonics through transfer function modeling via stability analysis (bode, polar & root locus plots) while selecting appropriate value of damping factor. The effectiveness of proposed technique is confirmed by thorough analysis through various cases of grid disturbances via Matlab/Simulink simulations. Results revealed that the proposed method has been effectively enhancing the power quality by complying with the IEEE 519 standards (THD grid side 10.96% & load end 2.65%). Hence, the proposed work approaches to significant improvement in stability and providing dynamic response via better filtering abilities.