Discrete SOGI based control of solar photovoltaic integrated unified power quality conditioner

A discrete second order generalized integrator (DSOGI) based control is presented in this work for control of solar photovoltaic integrated unified power quality conditioner (SPV-UPQC). Two DSOGI based band-pass filters are used to extract fundamental positive sequence component (FPSC) of unbalanced grid voltages. The shunt compensator of SPV-UPQC is controlled based on philosophy of drawing balanced positive sequence currents (BPSC) from the point of common coupling (PCC). The shunt compensator has the dual function of compensating for load power quality issues along with injecting power from solar photovoltaic (SPV) array. Sensitive loads are protected against grid voltage fluctuations such as voltage sags/swells etc with the help of the series compensator of SPV-UPQC. A step-up DC-DC converter is used for coupling SPV array to the DC-bus of SPV-UPQC. A Maximum power point tracking (MPPT) algorithm generates appropriate duty cycle for the dc-dc converter so that the SPV array is operated at its peak power. The performance of DSOGI based SPV-UPQC is simulated in Matlab-Simulink environment and tested under dynamic conditions of grid voltage disturbances, load disturbances and solar irradiation variation.