Abstract
Electric locomotives in AC traction power systems represent a huge single-phase non-linear load and, detrimentally, affect the power quality and the efficiency of the three-phase power grid. Nevertheless, along the last decades, power electronics are being used to mitigate power quality problems in the three-phase power grid. In particular, Rail Power Conditioner (RPC) helps to increase the loading capacity of traction substations and improve the power quality of three-phase power grids. As the main characteristics, an RPC can supply reactive power, suppress current harmonics and overcome currents imbalance of the three-phase power grid. On the other hand, the traction substations may be constituted by different types of power transformers. For instance, single-phase power transformers and open-delta (V/V) power transformers are widely used, while Scott power transformers are less frequently used, since they are more complex and expensive. In this framework, this work presents a review study of RPC topologies, including their operation modes, and a comprehensive comparison between the characteristics of the RPC topologies when using different types of AC traction substations and power transformers. This helps to ensure the correct selection of the RPC topology for a specific application, according to the main structure of the traction substation. Consequently, and based on the established review, it is possible to sort and allocate each RPC topology for limited or wider applications.
Highlights
In recent years, high-speed electrified railway has reached a rapid development and has been considered as one of the economic booster indicators, granting the most secure land transportation mode in terms of freight and passenger transport [1]
The following Rail Power Conditioner (RPC) schemes are based on the split of the traction power grid into two traction feeders separated by isolators known as catenary neutral sections
RPC Based on Two-Phase Three-Wire Converter (TW-RPC). This RPC system consists of two-phase three-wire converter (TW-RPC), which is fed by single-phase step-down coupling transformers (CTs) connected to the traction feeders of the traction power grid
Summary
High-speed electrified railway has reached a rapid development and has been considered as one of the economic booster indicators, granting the most secure land transportation mode in terms of freight and passenger transport [1]. RPC based on indirect AC/DC/AC Modular Multilevel Converter (MMC) and half-bridge submodule (SM) topologies has recently been proposed due to the MMC advantages, such as scalability, lower harmonics production, lower voltage stress, and lower switching losses [13] In this context, RPC based on two full-bridge B2B single-phase indirect MMC (HB-MMC4 RPC) and a V/V power transformer is presented in [29]. Other studies discuss the RPC based on two-phase three-wire indirect MMC (HB-MMC3 RPC) as a prominent solution in a V/V traction power system due to the lower costs and the high compensation capacity. In this framework, a combination of a hybrid HB-MMC3 RPC and a.
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