Offshore Wind Turbine DC-DC Converter For Direct Interface to HVDC Grid
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Authors
Basu, Shibaji
Date
2025-02-04
Type
thesis
Language
eng
Keyword
Offshore Wind Turbine , Resonant Converter , Modular Multilevel Converter , Adder Transformer
Alternative Title
Abstract
Among the renewable energy resources, the growth of wind energy is remarkable. It is becoming main stream at a steady pace and competitive with conventional sources of energy. The cumulative installed wind power capacity grew from 6100 MW in 1996 to 282.6 GW in 2012, with a predicted increase over 800 GW by end of this decade. Advances in power electronics in the last few decades has enabled this vast pool of energy to be available to mankind. Power Electronics is also playing a major role in bulk electrical power transmission, specifically in implementation of High Voltage Direct Current (HVDC) systems. HVDC Systems provide the advantage of connecting asynchronous systems and transmitting energy over large distances. The later aspect is a key feature, especially for renewable energy sources such as wind and hydro since these resources are seldom located near the population centers that need them.~\par
This thesis, proposes a novel high frequency resonant DC-DC Converter architecture based on the unique adder transformer configuration intended to be utilized for off-shore wind turbine applications. The rectified variable speed offshore wind turbine output voltage is typically in the range of 450V - 1100V corresponding to a input power variation of 1.5MW to 10MW. The proposed converter would step-up the relative low, variable output voltage to transmission level voltage of 160 kV at the off-shore wind-turbine site, thereby avoiding the use of intermediate off-shore platform stations. The use of high frequency power conversion techniques along with measures for obtaining soft-switching transition of all the switches in the converter is likely to facilitate high operating efficiency at significantly reduced volume, thereby strengthening the feasibility of the proposition.~\par
The adder transformer is a toroid core transformer consisting of multiple primaries and a single common secondary turn that traverses through all the primaries. The 'n' number primaries are conceived to be individually fed by high frequency resonant inverters and the resultant 'added' output voltage of all the inverters at the common secondary are fed to an active rectifier bridge. The active rectifier bridge is based on Modular Multilevel Converter (MMC) topology operating in Quasi three level mode (Q3L). Detailed mathematical analysis of the converter is performed for component design and operating condition specifications. The mathematical analysis of the proposed transformer, including its loss analysis, is presented. A scaled down experimental set up and simulation results are presented to demonstrate the efficacy of the proposed converter for off-shore wind turbine applications.
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Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivatives 4.0 International
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivatives 4.0 International