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Solar-powered rail transportation in China: Potential, scenario, and case

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Abstract

China's railway has been experiencing rapid growth recently. The achievement of solar energy for the increasing electricity consumption in the rail sector attracts significant attentions. In this paper, the available solar energy on the covered land and trackside land in the rail itself is assessed for further utilization. The development of the railway electrifications is briefly presented. In the split- and co-phase AC electrifications, AC and DC microgrids are introduced to constitute the solar-powered rail transportation. This approach offers both the on-site access and the local consumption of the available solar energy alongside railways. Focused on the solar power regulation, an individual phase current control (IPCC) strategy is developed without extractions between sequences. This strategy can achieve a flexible current provision for both powering single-phase locomotives and feeding back to the three-phase grid. Finally, the solar-powered rail transportation contributes to a sustainable future of both the rail and solar energy sector and a win-win situation in both the economy and environment in China.

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Due to the dynamic characteristics of traction load and unevenly train dispatch schedule, the unbalances currents are generally presented at point of common coupling (PCC). To suppress the degree of unbalance, a specially connected transformer or/and reactive power compensation device can be applied. Traditionally, a phase-shifted Scott transformer type SVC was installed in front of Scott connection transformer to improve the voltage fluctuation which is caused by high speed railway (HSR) systems. However, this solution is the most effective only in case that the power factor angle of each phase load equals pi/6 lagging; otherwise, a quite severe negative sequence current still presented at PCC. In this investigation, a new hybrid SVC scheme is proposed to improve this disadvantage. The results show that the proposed scheme can effectively restrict the negative sequence current to zero no matter what power factor of traction load
Conference Paper
This paper proposes a static power conditioner (SPC) using self-commutated inverters in order to solve the problems of an AC electric railway. For compensating the voltage unbalance of a three-phase electric power system, the SPC controls the electric power in railway substations. Besides, for compensating the voltage drop in the feeding circuit, the SPC controls the reactive power in sectioning post. Further, it can also control the harmonic currents, so the SPC can be expected to be an ideal compensator. This paper gives an outline of the SPC, the theoretical studies of compensation using an SPC and the results of simulation of its performance.< >
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