Adaptive notch filter: An alternative synchronizer for effective performance of active power filter under challenging grid conditions

Harmonic distortion issues on modern power systems are becoming highly 
significant due to the increasing integration of renewable energy sources, 
electric vehicles, and smart technologies. These distortions, mainly caused by 
the operation of power electronics devices, potentially degrade overall system 
quality, increase losses, and shorten equipment lifespan if they are not 
properly mitigated. Shunt active power filters (SAPFs) are found to be most 
effective against current harmonics issues, but their performance strictly 
depends on accurate grid synchronization. In this paper, an alternative method 
developed based on the adaptive notch filter (ANF) concept is proposed for 
reliable grid synchronization under challenging conditions. The proposed 
ANF-based synchronizer is modelled in MATLAB/Simulink and 
benchmarked against the existing self-tuning filter (STF) method under four 
cases involving sinusoidal, distorted, noisy, and distortion-with-noise grid 
conditions. Simulation findings demonstrate that the proposed method enables 
the connected SAPF to effectively mitigate harmonics by providing low total 
harmonic distortions (2.71% to 2.82%) and minimal phase deviation (0.2° to 
0.5°), while maintaining the accuracy of fundamental current between 94.48% 
to 97.21%. As a result, the overall power factor of the system is raised to near 
unity, confirming the ability of the proposed ANF-based method to serve as a 
better alternative for SAPF synchronization.