Multifunctional VSC Controlled Solar Photovoltaic System with Active Power Sharing and Power Quality (PQ) Improvement Features

This paper presents a multifunctional voltage sourced-converter (VSC) controlled solar photovoltaic (SPV) system with a generalized ‘dq’ and adaptive PLL-based approach to extract the dual features. These include enhanced active power sharing feature based on the availability of active power at DC-side collector bus while also serving as an active harmonic filter (AHF). The presented control is computationally less intensive and easy to formulate compared to its conventional counterpart like synchronous reference frame theory (SRFT). The objective of this work is to effectively extract the various ancillary services offered by multifunctional VSC in the power distribution system. The primary function of any grid-connected inverter (GCI) is to serve the active power demand of the load connected at the point of interconnection (PoI) in the power distribution network. However, the multifunctional VSC with presented control approach can also be utilized as AHF to attenuate the rich harmonic content present in source current, to mitigate the load reactive current demand, and to adequately supply the zero sequences harmonic component requirement of the unbalanced and nonlinear load by the fourth leg of the multifunctional VSC. Additionally, the proposed system typically ensures the unity power factor (UPF) operation. An incremental conductance (IC) based control technique is employed to optimize and continuously track the maximum power point (MPP) during solar intermittency. The usefulness of the proposed multifunctional VSC is demonstrated through transient test cases, conducted in the MATLAB/Simulink software environment. Additionally, its practicality is validated through a comprehensive set of experimental studies investigated on a laboratory developed prototype.