Power quality optimization framework for three phase microgrids with grid tied solar PV and battery storage under nonlinear loads

Worsening power quality driven by non-linear and converter dominated loads poses a significant challenge in renewable integrated microgrids. This paper develops and evaluates a coordinated source-filter control framework that (i) determines the optimal pairing of sources (PV, BESS, or grid) with either a Shunt Active Power Filter (SAPF) or a hybrid filter (SAPF + passive LC) employing load current based inverter referencing, and (ii) optimizes power quality via hourly selection of the lowest THD source. The study models a 100 kW three-phase grid-tied solar PV array, a 60 kWh BESS (bi-directional DC-DC interfaced), a three-phase H-bridge inverter, utility grid connection, and PQ devices (SAPF and hybrid filter). Linear (10-60 kW) and non-linear (0-50 kW) loads are applied across four modes: grid-tied PV (no BESS), grid-tied PV + BESS charging, BESS discharge (islanded), and grid only supply. An hourly Genetic Algorithm first selects the lowest THD source without filtering, then escalates only non-compliant hours to SAPF or hybrid filtering, ensuring IEEE 519-2014 THD compliance with minimal intervention. Results show BESS + SAPF maintains sub 5% THD even under heavy non-linear loads; PV requires SAPF + load-current referencing at moderate distortion levels; and the grid under ≥ 50% non-linear loading demands hybrid filtering to reduce THD from over 24% to below 3%. This optimization framework secures full hourly THD compliance, enhances microgrid power quality, and supports reliable renewable integration, thus advancing UN SDG-7.