A Review Paper on Active and Reactive Power Control during Unbalanced Grid Voltage in Pv Systems

Abstract

     Single-stage grid-connected PV systems provide many advantages such as simple topology, high efficiency, high power density, and lower cost. The active power reference is obtained from a Maximum Power Point Tracking (MPPT) algorithm. However, achieving MPPT, while conditioning the output power and synchronizing with the power grid, is a big challenge in such systems. The inverter is an essential element in a photovoltaic system. This review-paper focuses on different technologies for connecting photovoltaic (PV) modules to a three-phase-grid. Several grid-fault control schemes are nowadays available for operating under unbalanced grid voltage. Several grid-fault control schemes are nowadays available for operating under unbalanced grid voltage. These control schemes usually have extreme power quality characteristics. Some of them have been conceived to completely avoid power ripple during unbalanced voltage sags, but at an expense of high current harmonic distortion. With other schemes, the harmonic distortion is totally eliminated but at an expense of high ripple in the injected power. The aim of this paper is to highlight the important theory that are employed in simulation, while at the same time making awareness of some of the interesting challenges that remain to be solved.