Fractional order pole fixed second order generalized integrator based control for grid connected solar photovoltaic system

In this article, the development of multi-functional grid connected solar photovoltaic (PV) system using improved Fractional order Control theory-based Pole fixed Second Order Generalized Integrator (FO-PFSOGI) is proposed. The fractional order (FO) control technique offers an advantage to adjust the fixed structure of the integer order and provide additional degree of freedom to achieve accurate response during the system operation. The FO-PFSOGI control technique is used to extricate fundamental constituent of the non-sinusoidal load current. The PV system is competent of feeding the local load requisite and may also inject surplus power into the grid. The voltage source converter (VSC) utilized in the grid-connected system can also be operated as power quality compensator, taking care of harmonics, unbalancing and excess reactive power demand of the local load. The feasibility of multifunctional operations of the converter is established in this article, thus achieving maximum utilization of the power electronics used in the system and reducing the overall cost. A performance comparison of the developed control technique is presented with the conventional techniques in terms of harmonic compensation, weight convergence and computational complexity. The implementation of the controller is modest and extracts fundamental quantities without any phase delay under different loading conditions. The developed system is validated using both simulation and experimental study. A scaled down experimental setup of grid-connected PV system is implemented in the laboratory and real time performance of the FO-PFSOGI is demonstrated using variations in system load and PV irradiance.