Electric railway power systems (ERPS) as one of the most critical and high-power end-user loads of utility grids are characterized by outlandish power quality (PQ) problems all over the world. The extension and evolution of different supply topologies for these systems has resulted in significant and various forms of distortions in network voltage and current in all ERPS, the connected power system, and adjacent consumers. During the last years, numerous studies have been offered to investigate various aspects of PQs in a specific supplying topology. Variation in the supply structure of the ERPS and different types of locomotives has propelled the observation of different PQ phenomena. This versatility and development have led to confront considerable types of two-way interactive interfaces as well as reliability and PQ problems in ERPS. In addition, the lack of standards explicitly dedicated to ERPS has added to the ambiguity and complexity of this issue. In this paper, an extensive review of PQ distortions and phenomena in different configurations of ERPS is proposed and a systematic classification is presented. More than 140 scientific papers and publications are studied and categorized which can provide a fast review and a perfect perspective on the status of PQ indexes for researchers and experts.
A significant amount of electric energy is produced applying regenerative braking in railway systems. The optimum use of this energy can improve the energy consumption efficiency in a railway Traction Power Supply Substation (TPSS). This paper presents a new method restoring the Regenerative Braking Energy (RBE) to the distribution grid and converting TPSS as a microgrid. In the proposed strategy, a Railway Power Quality Compensator (RPQC) exerted to feeding back RBE to the grid compliant with IEEE Power Quality (PQ) standards. Moreover, the proposed topology can supply other adjacent running trains. The intelligent control system used for RPQC can suppress harmonics, dominate Negative Sequence Current (NSC) and compensate Power Factor (PF). The simulation results have been provided to verify the effectiveness of the proposed strategy
Power quality (PQ) problems of AC railway systems have become a major obstacle so that over the years different compensation methods have been introduced to dominate them. Railway Power Quality Compensator (RPQC) is one of the effective strategies which had been presented with different structures and compensation methods. However, these conditioners basically have high capacity and also high potential to be exposed to destruction due to the shoot-through switching. In this paper a quasi Z-source based Railway Power Quality Compensator (qZRPQC) is proposed to improve mentioned problems. The proposed configuration is based on two-phase, three-wire converter composed of two step-down transformers connected to the two adjacent sections of the traction power substation. Despite having the all features of traditional RPQC, the proposed configuration can decrease the rating of the converter and increase the efficiency and reliability. In order to verify the performance and effectiveness of the proposed strategy the precise simulation results have been provided
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