Three-phase instantaneous reactive and harmonic power compensation using three level inverters at constant switching frequency

Three single-phase wye-connected three level voltage source inverter is used for compensating reactive and harmonic power instantaneously for a three-phase system. A controlled rectifier load is considered to create harmonics and phase displacement for the source current. The compensation is achieved operating the inverter at constant switching frequency. The three level inverter configuration offers better voltage and current control capability than the three level neutral point clamped (NPC) inverter with a simple modulation strategy. The modulation strategy permits the use of a lower interfacing inductance than that possible with other schemes. This results in improved current response and makes the compensator compact. The topology is well suited for compensation of unbalanced loads.