The use of static frequency converter feeder stations and a new control strategy enabling mesh feeding for 50 Hz AC railways

Sharifi, Delaram (2020). The use of static frequency converter feeder stations and a new control strategy enabling mesh feeding for 50 Hz AC railways. University of Birmingham. Ph.D.

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Railways around the globe are rapidly growing as the passenger numbers surge due to the increasing requirements for connectivity and cleaner methods for transport. To accommodate the current and future demand, new and existing lines are being built and updated. Electrification has been identified as key to achieve sustainable railways, yet solutions have remained unchanged for decades. Although efficient, conventional electrification systems are inflexible and limit the application of multi-source power solutions.

Static Frequency Converters (SFCs) are an alternative to conventional transformer-based electrification systems which provide a more highly interconnected electrification solution, due to their controllability, which potentially allows increased operational flexibility and robustness. Early static converter deployments for 16.7 Hz supplies the potential for dual-end feeding, however, due to the novelty of the SFC technology and its application to railways, a full mesh-feeding solution has not yet been explored.

In this thesis, the author considers the deployment of SFC technologies within the 50 Hz, 25 kV, railway and the application of smart control strategies in deploying the mesh feeding concept. Comparative studies using mathematical models and computational simulations representing the electrification infrastructure and the moving trains have been carried out, in considerable detail, using code written in MATLAB Script.
The mathematical modelling of the traction system is based on a lumped parameter modelling approach. These studies show that the application of SFCs requires lower rated feeder stations and provides increased operational flexibility and fault tolerance, while not suffering from the power quality issues associated with conventional transformer-based systems. In optimised deployments, SFC feeder station ratings and transmission losses can be reduced even further. Additionally, it has been shown that the use of a smart control system for mesh feeding increases flexibility in the locations available for efficient deployment of the feeder stations.

An economic evaluation has demonstrated that SFCs are financially beneficial over a 50-year lifespan, with the novel control system introduced in this thesis proving beneficial, both economically and technically. As the technology is evolving, it is anticipated that economic and operational benefits will increase, and the flexibility associated with SFC solutions is expected to support advances in wider railway electrification, including the deployment of railway smart grids. A roadmap anticipating the wider technology development is therefore also presented.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Licence: All rights reserved
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Engineering, Department of Electronic, Electrical and Systems Engineering
Funders: Other
Other Funders: Department of Electronic, Electrical and Systems Engineering, University of Birmingham
Subjects: T Technology > TF Railroad engineering and operation
T Technology > TK Electrical engineering. Electronics Nuclear engineering


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