Power converter control for offshore wind energy generation and transmission
This thesis discusses the control of different power converters that will have a key role in future offshore wind power systems, enabling the integration of the power generated by the wind turbines into the mainland grid. First, an overview of the evolution of wind turbines is presented, from the fi...
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| Format: | doctoral thesis |
| Status: | Published version |
| Publication Date: | 2016 |
| Country: | España |
| Institution: | CBUC, CESCA |
| Repository: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/396110 |
| Online Access: | http://hdl.handle.net/10803/396110 https://dx.doi.org/10.5821/dissertation-2117-96360 |
| Access Level: | Open access |
| Keyword: | Àrees temàtiques de la UPC::Energies 620 621.3 |
| Summary: | This thesis discusses the control of different power converters that will have a key role in future offshore wind power systems, enabling the integration of the power generated by the wind turbines into the mainland grid. First, an overview of the evolution of wind turbines is presented, from the first prototypes to the latest topologies in use. Then, a new decentralized control strategy of a triple three-phase permanent magnet synchronous generator, a machine topology specifically designed for offshore wind, is presented. The proposed controller is tested on a wind turbine emulator with a scaled down 30 kW nine-phase generator. It has been suggested that future wind power plants could use medium voltage DC collection networks. These would require DC/DC converters to adapt the voltages between the turbine output and the DC collection grid. Based on this idea, the control design of a DC/DC Dual Bridge Series Resonant Converter (DBSRC) unit is developed and tested in a scaled 50 kW converter prototype. The availability of significant energy resources far from the coast favors the idea of creating offshore wind farms. This poses important technical and economical challenges. To this end, Voltage Source Converter-based High Voltage Direct Current (VSC-HVDC) technology enables high power transmission across distances where High Voltage Alternating Current (HVAC) is impractical. The Modular Multilevel Converter (MMC) is the preferred topology to reach high AC and DC voltages. In this work, the control design of a half-bridge based MMC to enable the converter operation under both normal and unbalanced AC voltage conditions, is addressed. Finally, considering that many offshore wind power plants will be installed in the North Sea in the coming years, a multi-terminal HVDC grid interconnecting several production plants and different points of the mainland grid is envisaged. To deal with DC multi-terminal grid voltage stability, a methodology to address the grid primary voltage control design is proposed based on multivariable frequency methods which are able to evaluate the dynamic behavior of the system. |
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