Active Harmonic Filter (AHF) / Static VAR Generator (SVG)

Under normal conditions, power system generators produce a clean sinusoidal voltage waveform. However, modern electronic equipment such as VFDs, UPSs, LEDs, battery chargers, and other devices powered by Switched-Mode Power Supplies (SMPS) inject non-sinusoidal currents into the power system. This results in electrical harmonic pollution, reduced power quality, and system inefficiencies.

An Active Harmonic Filter (AHF) is connected to the power system in parallel and continuously monitors system parameters through external Current Transformers (CTs). Using a high-speed DSP with an intelligent FFT algorithm, the system calculates the exact compensation current required and controls the IGBT inverter in real time.

The IGBT dynamically adjusts its switching frequency to generate a reverse current of equal magnitude, effectively canceling harmonic currents. This process reduces harmonic distortion at each order and achieves a Total Harmonic Distortion (THD) below 5% in compliance with IEEE 519 standards.