AC cables strengthening low frequency AC railway with purely active power loads

Abstract

Converter-fed railway power systems traditionally use high voltage AC overhead transmission lines in the railway grid for increased loadability. An increased resistance to overhead high voltage AC transmission lines, may motivate cables as one alternative for the future.The focus of this paper is to compare a nonstrengthened system with two cable solutions for comparing loadability, voltages, and reactive powers for different levels of load scaling. The studies confirmed that the obstacle of reactive power produced in lowly utilized cables is, even if less significant for low frequency AC, still present.A simplified load model is used representing trains with VSC-converters and three-phase motors as purely active loads regardless of motoring or regenerating. A previous study has been done on thyristor-based trains. The voltage levels while regenerating are higher than in the thyristor-train case study. Besides that the loadability for motoring and regenerating is higher with modern VSC-trains.