Abstract
Aim/Background:
Maintaining power quality in grid-connected systems with renewable energy sources, particularly solar, is a significant challenge due to stringent requirements for harmonic mitigation. Voltage source inverters serve as critical interfaces between the grid and renewable energy sources but require robust control strategies to ensure power quality.


Methods:
This study integrates renewable energy resources and DC micro-grids on the same bus and designs a shunt active power filter (SAPF) based on synchronous reference frame theory. The SAPF is compared with an instantaneous power theory-based controller. MATLAB simulations are conducted to test the performance under different nonlinear load conditions.


Results:
The synchronous reference frame theory-based controller demonstrated superior performance, with high efficiency, simplicity, and fast response. It reduced total harmonic distortion (THD) in the grid to 1.59% and 0.19% when connecting two nonlinear loads, compared to 1.66% and 1.62% for the instantaneous power theory-based controller. The SAPF effectively detected abnormal behavior, removed harmonics caused by non-linear loads, and improved the power factor.


Conclusion:
The synchronous reference frame theory-based SAPF is a reliable solution for enhancing grid power quality by mitigating harmonics and maintaining the desired compensation. Its superior performance highlights its suitability for applications involving renewable energy integration with the grid.