Power Quality Improvement of Irradiance-Dependent Photovoltaic Microgrid by Three-Level Space Vector Modulation

Grid-tied inverters to implement a community-led distributed energy resource enriched microgrid has a dependency on solar irradiance making it prone to inject much higher harmonic current into the grid when irradiance is low. This upstream-caused power quality is addressed by using multilevel inverter driven by three-level Space Vector Modulation (SVM). The proposed method has significantly reduced the grid current harmonics distortion compared to the conventional single-level inverter driven by pulse width modulation (PWM). In 500 W/m²-low Irradiance, the proposed controller has reduced THD from 6.42 percent to 3.83 percent, where in 800 W/m²-high Irradiance it is from 3.84 percent to 2.04 percent. By pulling down the grid current harmonics satisfying IEEE 519.2 standard, the control level innovation has eliminated high-cost, bulk size constraints of filter in grid-tied inverter design, nevertheless the neutral point balancing offered better balance and DC bus stability. The OpalRT-based real time simulation results has verified the effectiveness of the proposed controller in improving the power quality of the PV-based hybrid grid.