A new modular multilevel converter for HVDC applications

In the coming years, due to an increasing shift towards electric mobility and further industrialisation, a rapid growth in the demand for electricity is expected. At the same time, this energy demand must be met in a clean and sustainable manner, to reduce climate change as well as to ensure securit...

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Main Author: Hassan, Zain
Format: Thesis (University of Nottingham only)
Language:English
Published: 2021
Subjects:
Online Access:https://eprints.nottingham.ac.uk/64832/
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author Hassan, Zain
author_facet Hassan, Zain
author_sort Hassan, Zain
building Nottingham Research Data Repository
collection Online Access
description In the coming years, due to an increasing shift towards electric mobility and further industrialisation, a rapid growth in the demand for electricity is expected. At the same time, this energy demand must be met in a clean and sustainable manner, to reduce climate change as well as to ensure security of supply. It is predicted that the High Voltage Direct Current (HVDC) transmission technology will play a key role in the future power systems which are expected to feature higher levels of interconnection and more renewable-based generation. HVDC transmission is preferred over AC transmission in applications such as power transmission over long distances and from offshore wind sources, and interconnection of asynchronous systems. The main elements of an HVDC system are the AC/DC converters that take up the majority of the initial set up cost, and therefore, there has been a huge focus lately on improving these converters in terms of functionality, cost and efficiency. Today, the state-of-the-art converter topology for Voltage Source Converters (VSC) based HVDC transmission is the Modular Multilevel Converter (MMC), which replaced the earlier two- and three-level VSC topologies. Recently, a new breed of VSC converters, known as the `hybrid VSCs' are introduced, that combine the aspects of two- and three-level VSCs with the modular multilevel structure of the MMC. In this work, a new hybrid VSC, the Switched Mid-Point Converter (SMPC), has been proposed. While maintaining the same efficiency as the MMC, the energy storage requirement of the SMPC is shown to be less than half of that of the MMC. The operating principle and the particular voltage waveshaping of the chainlinks of the submodules is investigated. For effective operation of the SMPC, suitable control strategies are proposed. The converter concept and the developed control schemes are verified both using computer simulations and a lab-scaled experimental prototype.
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language English
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publishDate 2021
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spelling nottingham-648322023-10-02T08:58:52Z https://eprints.nottingham.ac.uk/64832/ A new modular multilevel converter for HVDC applications Hassan, Zain In the coming years, due to an increasing shift towards electric mobility and further industrialisation, a rapid growth in the demand for electricity is expected. At the same time, this energy demand must be met in a clean and sustainable manner, to reduce climate change as well as to ensure security of supply. It is predicted that the High Voltage Direct Current (HVDC) transmission technology will play a key role in the future power systems which are expected to feature higher levels of interconnection and more renewable-based generation. HVDC transmission is preferred over AC transmission in applications such as power transmission over long distances and from offshore wind sources, and interconnection of asynchronous systems. The main elements of an HVDC system are the AC/DC converters that take up the majority of the initial set up cost, and therefore, there has been a huge focus lately on improving these converters in terms of functionality, cost and efficiency. Today, the state-of-the-art converter topology for Voltage Source Converters (VSC) based HVDC transmission is the Modular Multilevel Converter (MMC), which replaced the earlier two- and three-level VSC topologies. Recently, a new breed of VSC converters, known as the `hybrid VSCs' are introduced, that combine the aspects of two- and three-level VSCs with the modular multilevel structure of the MMC. In this work, a new hybrid VSC, the Switched Mid-Point Converter (SMPC), has been proposed. While maintaining the same efficiency as the MMC, the energy storage requirement of the SMPC is shown to be less than half of that of the MMC. The operating principle and the particular voltage waveshaping of the chainlinks of the submodules is investigated. For effective operation of the SMPC, suitable control strategies are proposed. The converter concept and the developed control schemes are verified both using computer simulations and a lab-scaled experimental prototype. 2021-08-04 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en cc_by https://eprints.nottingham.ac.uk/64832/1/14266614_Zain_Hassan_PhDthesis%20%28corrected%29.pdf Hassan, Zain (2021) A new modular multilevel converter for HVDC applications. PhD thesis, University of Nottingham. High Voltage DC Power Converters Modular Multilevel Converter Hybrid VSCs
spellingShingle High Voltage DC
Power Converters
Modular Multilevel Converter
Hybrid VSCs
Hassan, Zain
A new modular multilevel converter for HVDC applications
title A new modular multilevel converter for HVDC applications
title_full A new modular multilevel converter for HVDC applications
title_fullStr A new modular multilevel converter for HVDC applications
title_full_unstemmed A new modular multilevel converter for HVDC applications
title_short A new modular multilevel converter for HVDC applications
title_sort new modular multilevel converter for hvdc applications
topic High Voltage DC
Power Converters
Modular Multilevel Converter
Hybrid VSCs
url https://eprints.nottingham.ac.uk/64832/