A Hybrid Front-end for Multi-Generator Power System Harmonic Elimination

A front-end for multi-generator power system was recently proposed, which utilizes a single wye-delta (Y-Δ) transformer to shunt between the two 30° phase-shifted generator outputs. The shunt type phase-shift transformer front-end provides comparable 5th and 7th harmonic elimination performance to the conventional 12-pulse rectifier with more than 75% transformer size reduction. In this paper, a hybrid front end, which consists of the shunt Y-Δ transformer and an active power filter is proposed to further improve the power quality. In this configuration, 11th and 13th harmonics from nonlinear load are actively compensated by the active power filter and 5th and 7th harmonics are trapped by Y-Δ transformer. Theoretically, the performance of the proposed front end is equivalent to a traditional 24-pulse rectifier with a significant reduction in the overall size and weight, which makes it attractive to large-scale industrial and shipboard applications. The harmonic cancellation principle of the proposed front end is derived and verified by simulation and experimental results.