Reactive power and harmonic currents compensation in traction systems using active power filter with DFT-based current reference generator

This contribution deals with a shunt-type active power filter designed mainly for railway applications (50-Hz and 16.7-Hz electrification systems) which is able to compensate undesired harmonic currents as well as reactive power. Its control algorithm employs an optimized DFT-based fundamental current and voltage estimator generating an accurate control reference signal. The APF configuration, the current reference generator and the APF control algorithm are discussed in detail in this paper. Theoretical conclusions are verified beside simulations also by experiments on designed laboratory prototype of rated power of 5.75 kVA.