Photovoltaic system operation as DSTATCOM for power quality improvement employing active current control

Abstract

This paper presents photovoltaic (PV) system control as distributed static compensator (DSTATCOM), termed as PV-DSTATCOM, operated with active current control (ACC) and feed-forward control loop (FFCL). Besides active power injection into the utility grid, the proposed PV system autonomously transforms into a DSTATCOM to provide various ancillary services including source current harmonic suppression, load reactive current compensation, zero sequences component mitigation, and power factor correction. Since PV-DSTATCOM operates with ACC, it precisely extracts the fundamental in-phase and quadrature components of current. It introduces high-gain at the third-order harmonic and thereby alleviates stationary errors in the current control loop of PV inverter. The proposed ACC+FFCL structure is computationally efficient and unconditionally stable. Practically, FFCL addresses the challenges emerged due to nonlinearity introduced by the PV unit and ensure a rapid power balance between the PV unit and electric grid. Further, a simplified perturb and observe based maximum power point tracker has been employed to evacuate the maximum power from the PV array. The proficiency of the developed ACC+FFCL structure is investigated through a comprehensive set of transient studies using MATLAB/Simulink software. Finally, a laboratory setup has been developed using the dSPACE-1104 platform and experimental results are recorded with detailed comparative evaluation.