AC distribution grid proposal to improve the power quality of the Line-B metro system of Mexico City

A power quality diagnosis campaign was done for the Line B of the Mexico City underground system to understand and improve its behaviour. A comparative analysis of the results obtained during the campaign is presented describing a method to improve the power quality. The AC distribution of this underground system consists of a set of transformers and multipulse rectifiers; however, the harmonic content is highly dominant by the 6k±1 harmonic order and the harmonic distribution is poorly mitigated by the load-balanced arrangement. The field measurement work, the practical issues at the power quality campaign and a proposal to improve the harmonic performance are explained together with the field and estimated results obtained with measurements realized to the AC medium voltage grid of the Mexico City Line B.