A predicted control scheme of single phase active power filter in electric traction system

Aiming at the performance of frequent and severe variation of electric traction load, a predicted control scheme of single phase active power filter (APF) based on the instantaneous reactive power theory and extrapolation algorithm is proposed in this paper. By predicting the fundamental component of traction load current pouring into the electric grid, to control the outage current of APF to compensate the harmonic currents produced by the traction load. The simulation to the proposed scheme by using the PSCAD/EMTDC simulation package is carried out, and the comparison to the conventional harmonic detecting methods under different conditions is presented. The simulation results show that the strategy proposed in the paper has little detecting errors, and the time delay of APF is greatly reduced.