Expanding the Capabilities of Electric Railway DC Systems Using the Modularized Bridge Rectifier

The greater reach of electrification has forced modernization in all modes of transportation. Electric railway systems have historically been at the forefront of electrification, currently being among the most efficient options. However, to fully embrace sustainability, further improvements and modernizations are necessary to diversify the energy supply and enhance grid functionality. This paper presents a modernization approach for DC electric railway systems (ERS) that minimizes intervention and adopts a modular design. This strategy is based on a cost-effective approach to deploying the concept of a Solid-State Transformer, specifically a modularized bridge rectifier. This unidirectional structure can utilize additional isolated stages to feed an auxiliary load, allowing its supply to be made in a manner that enhances power quality at the AC side. This paper applies this emerging concept to improve the performance of the passive front ends typically employed in the DC Railways substations, aiming to improve the power quality, reduce the peak power consumption during high-congestion scenarios and more importantly, evaluate a cost-effective, scalable, and modular approach to modernizing a system that cannot afford a green field approach for embracing a sustainable diversification of its energy sources. The concept is introduced and analyzed theoretically, and simulations are conducted in PLECS for various scenarios based on the Dutch ERS.