Transformerless dual inverter based series injected shunt active power filter

The following paper proposes a topology for reactive power compensation and harmonic reduction for medium voltage three phase three wire systems during unbalanced load conditions. Main three phase inverter produces harmonic compensation. Three single phase inverters connected in series with the three phase inverter for separate compensation of reactive power in three different phases are present. The three phase inverter is a hybrid active power filter which is an HFI (High Frequency Inverter) and uses Hysteresis control. The three single phase inverters are LFIs (Low Frequency Inverters) which also operate using sinusoidal triangular PWM control. The DC bus voltages of the three single phase inverters are common. The topology specifically caters to the need of real-time load which is largely unbalanced and requires both a reduction in harmonic levels as well as reactive power and negative sequence compensation simultaneously. Simulation results are also provided to validate the claims made in this paper regarding the hybrid topology and associated control strategy.