Hybrid MDSOGIROGI Control Strategy for Mitigating Harmonics and Unbalance in SEIG Based Standalone Systems

The self-excited induction generator (SEIG) is a promising machine for standalone, off-grid systems. However, this machine experiences multiple power quality issues (PQIs) when subjected to varying loads, particularly degradation in terminal voltage and frequency as the load increases. This paper presents a PQI mitigation technique using a shunt active power filter (SAPF) to regulate the terminal voltage of the SEIG and reduce the total harmonic distortion (THD) of the system, while maintaining power factor (PF) close to unity. A modified dual second-order generalised integrator (MDSOGI) is combined with a reduced-order generalised integrator (ROGI) to generate the reference current for controlling the SAPF. The terminal voltage of SEIG is regulated under dynamic load changes. Total harmonics distortion (THD) is reduced below 5% according to the IEEE 519-2022 standard. Furthermore, under an unbalanced load condition, the system becomes balanced after compensation with the SAPF. The experiment is conducted on a real-time platform using Opal-RT (OP4510), and the results of dynamic load changes are presented.