Modified GIO-FLL for UPQC Based SEIG with Double Stage Solar PV Battery System

This paper presents improvement of power quality (PQ) in three-phase standalone system using generalized integrator observer (GIO) frequency locked loop (FLL) control algorithm, for three-phase self-excited induction generator (SEIG) driven by hydro turbine as a three-phase source feeding the sensitive/nonlinear/linear loads along a double stage solar PV-battery is integrated at the DC link, connected via a unified power quality conditioner (UPQC). The UPQC consists of two voltage source converters (VSCs) connected back to back at common DC bus. The series VSC of the UPQC is used for compensating voltage power quality and to maintain the harmonic free and constant amplitude voltage at load terminals, irrespective of any variation in the system. Moreover, the power qualities such as reactive power compensation, harmonics elimination, unity power factor corrections are provided by the shunt VSC of the UPQC, simultaneously while voltage power quality is improved. It significantly enhances the power quality at the generator terminals and ensures to adhere the mandate the IEEE-519 and the IEC-61727 standards even with either balanced or unbalanced loads. Moreover, by operating the SEIG below its rated voltage and maintaining the voltage across loads at its desired value, one can minimized the excitation current and hence the core losses.