Harmonic suppression with passive-active hybrid filters for electrified railways

Harmonic suppression schemes for electrified railway with hybrid filter consisting of passive filter network and active filter in series- or parallel-connected configuration are discussed in this paper. A new hybrid filter topology and its capacity design method about APF, taking some traction substation as an example, are presented in the paper. The analysis and calculation results show that in the proposed hybrid filter, the converter in active filter, required to produce harmonic currents for compensation, has a rating of only 15.3% when compared with the converter rating in an active filter, and 65.4% of that in a series-hybrid filter. The proposed topology enables practical implement of active harmonic suppression for harmonic comprehensive compensation on electrified railways.