A Multi-Objective Control Strategy for Power Quality Improvement with Enhanced LVRT Operation of a Grid-Interfaced Dual Voltage Source Inverter

With an increased penetration of renewable energy sources (RESs) into the grid, extracting maximum energy from them and also operating in grid supporting manner are the major challenges in a microgrid system. This paper focuses on the control technique implemented on utility connected dual voltage source inverter (DVSI) integrated with RES and hybrid energy storage unit to improve the power quality, reliability and low voltage ride through (LVRT) capability of the system. The microgrid system consists of two inverters, which supplies real power from RESs into the grid and compensates the harmonic, reactive and unbalance components of the load independently. The control scheme ensures that the DVSI stays connected to the grid under fault conditions, fulfilling the LVRT requirements according to grid code compliance. It enables the compensator to ride through voltage sags arising from grid side faults by providing maximum reactive power support which improves the point of common coupling (PC C) voltage and voltage recovery time, along with load compensation, to maintain balanced and sinusoidal grid current under various operating conditions. The DC link voltage is maintained constant throughout, and the photovoltaic (PV) system operates with maximum power point tracking (MPPT) under all conditions. The presented control strategy of DVSI is simulated and validated in MATLAB/Simulink under voltage sag, low irradiation (LiR) and high irradiation (HiR) conditions.