Design of Backstepping Controller for a Three-phase Shunt Active Filter Interfacing Solar Photovoltaic System to Distribution Grid

This paper presents a controller for a three-phase four-leg shunt active power filter (SAPF), interfacing solar photovoltaic system to distribution grid. The controller consists of a non-linear, robust dc-link voltage control loop based on backstepping algorithm. It also consists of a current harmonic mitigation loop based on dual self tuning filter instantaneous power theory (DSTF-pq theory). The limitations of conventional pq theory based current harmonic mitigation controller are addressed in this paper by employing self tuning filters (STF) to extract the fundamental components of load currents and grid voltages. The effectiveness of the algorithm under steady state and dynamic conditions are comprehensively studied and evaluated in MATLAB/Simulink. The proposed controller is implemented in XC7a35t-cpg236-1 FPGA. The performance of the controller is tested and verified on a laboratory prototype of shunt active power filter.