Simulation, Design, Analysis & Implementation of Three-Level Shunt Active Harmonic Filter using T-Type NPC (TNPC) Topology

Abstract

Power quality at the source side deteriorates due to current harmonics which are introduced in the power system by non-linear loads, originating a vital difficulty. Rectifiers, adjustable-speed inverter-driven water pumps, ac arc furnaces, switched mode power supply etc. are types of non-linear loads that create such harmonics. Conventional technique to eliminate such harmonics is the use of passive filters but this technique has the disadvantage of series and parallel resonance within the net- work impedance, overcompensation of reactive power at fundamental frequency and poor flexibility. Shunt Active Harmonic Filters (SAHF) are generally used to reduce current harmonics. The active harmonic filters introduce remunerating currents into the source to neutralize the harmonics possessed by the load current. The compensating/remunerating currents are derived by sensing three-phase voltages at the Point of Common Coupling (PCC) and Load currents. Efforts are made in this study to analyze Fast Fourier Transform (FFT) algorithm, Instantaneous Reactive Power (IRP) technique and Synchronous Reference Frame (SRF) technique used to derive the reference compensating currents. These compensating currents act as reference currents for the fixed switching frequency based current controllers which generate control signals for the SAHF employing three-level T-type Neutral Point Clamped (TNPC) topology for converter. For simulation study PSIM 7.0 software is used and for experimental purposes DSP TMS320F28377D controller is used. Efforts are made to compare experimental and simulation results at the end of this project.