Simulation as-well-as experimental investigations on T-type NPC topology based three-level shunt active power filter

Conventional technique of eliminating current harmonics by use of passive filters suffers from drawback of series and parallel resonance within the network impedance, overcompensation of reactive power at fundamental frequency and poor flexibility. Shunt active power filters (SAPFs) are conventionally used to reduce current harmonics. The active harmonic filters introduce compensating currents into the source to mitigate the harmonics injected by the load current. The compensating currents will be derived by sensing three-phase voltages at the Point of Common Coupling (PCC) and load currents. This paper analyzes fast Fourier transform algorithm, instantaneous reactive power technique, and synchronous reference frame technique, to derive the reference compensating currents. The generated reference compensating currents act as reference for actual compensating currents for the fixed switching frequency based current controller which generates switching signals for the SAPF employing three-level T-Type Neutral Point Clamped (TNPC) topology of converter. Simulation studies for the presented SAPF is carried out using PSIM software. Hardware set-up of the presented SAPF is implemented using DSP TMS320F28377D.