Analysis of SOGI-ROGI for synchronization and shunt active filtering under distorted grid condition

This paper presents an interesting application of two different generalized integrators connected in a cascade configuration. A Second-Order Generalized Integrator (SOGI) and a Reduced-Order Generalized Integrator (ROGI) controller have been considered to cascade. The designed controller is applied to filter distortions in the grid voltage to generate a synchronizing signal as well as estimate the fundamental component of load current. Thus, their combination can achieve synchronization as well as find application in the improvement of the power quality of the distribution grid. In addition, the performance of SOGI-ROGI with the frequency locked loop (FLL) under frequency variations has been improved. Extensive simulation and hardware results are presented to illustrate the actions of designed controller under normal and distorted grid conditions. Results under highly distorted grid and non-linear loading conditions are presented vis-à-vis simple generalized integrators considered independently.