DC Wind Turbine Circuit with Series‐Resonant DC/DC Converter
Author
Zaja, Mario
Term
4. term
Education
Publication year
2015
Submitted on
2015-06-03
Pages
80
Abstract
Offshore wind farms often transmit power to shore via high-voltage direct current (HVDC) links, using voltage-source converters (VSCs) at both ends to convert between alternating current (AC) and direct current (DC). Today, each turbine’s output is collected as medium-voltage AC, so every turbine needs an AC-DC-AC converter. A promising alternative is to let each turbine deliver medium-voltage DC, which can then be collected and stepped up to HVDC on an offshore platform. In this approach, the turbine’s DC-AC stage is replaced by a series-resonant DC-DC converter with a medium-frequency transformer to raise the voltage. Operating at higher frequency makes the power conversion equipment smaller and lighter. However, the converter has a relatively narrow operating range, and its components experience high voltage and current stress. This thesis presents a theoretical analysis of the circuit, selection of key components, control system design, and validation through simulations and a scaled-down hardware setup.
Havvindmølleparker sender ofte strøm i land via højspændings-jævnstrøm (HVDC), hvor spændingskildeomformere (VSC) i begge ender omformer mellem vekselstrøm (AC) og jævnstrøm (DC). I dag samles effekten fra hver mølle som AC på mellemspænding, hvilket betyder, at hver mølle skal have en AC-DC-AC-omformer. Et lovende alternativ er at lade hver mølle levere DC på mellemspænding, som kan samles og transformeres op til HVDC på en platform til havs. I denne løsning erstattes møllens DC-AC-trin af en serieresonant DC-DC-omformer med en mellemfrekvent transformator til at hæve spændingen. Drift ved højere frekvens gør effektelektronikken mindre og lettere. Til gengæld er driftsområdet relativt snævert, og komponenterne udsættes for høje spændings- og strømbelastninger. Afhandlingen præsenterer en teoretisk analyse af kredsløbet, valg af nøglekomponenter, design af styringssystem samt validering gennem simuleringer og en nedskaleret hardwareopstilling.
[This apstract has been rewritten with the help of AI based on the project's original abstract]