LVRT Operation with Power Management Strategy for Dual Voltage Source Inverter in Grid-Interfaced Systems

With increased proliferation of renewable energy sources (RESs), maximizing energy extraction while sustaining power quality of the grid is a major challenge in microgrids. This paper presents a novel application of dual voltage source inverter (DVSI) topology to facilitate low voltage ride-through (LVRT) under varying grid voltage conditions. It consists of two inverters that individually deliver active power from RESs to the grid and provide reactive and harmonic load current compensation. A modified dual second order generalized integrator (DSOGI) based quasi type-1 phase-locked loop (QTI-PLL) is introduced to enhance inverter control under grid disturbances such as harmonic distortion, unbalance, and DC offset. A power management strategy is proposed for the DVSI scheme, integrating RES and energy storage system to ensure power balance and frequency stability at the point of common coupling (PCC) during grid disturbances and fluctuating renewable and load conditions. A LVRT scheme is proposed for the system to ride through grid voltage sags by providing maximum reactive power support, simultaneously reducing voltage unbalance and power oscillations at the PCC, and enhancing the overall power quality of the system. The presented control strategy of DVSI is verified through simulation and experimental studies on the developed hardware prototype.