High-Power-Density Power Conversion Systems for HVDC-Connected Offshore Wind Farms

Abstract

Offshore wind farms are rapidly growing owing to their comparatively more stable wind conditions than onshore and land-based wind farms. The power capacity of offshore wind turbines has been increased to 5MW in order to capture a larger amount of wind energy, which results in an increase of each component's size. Furthermore, the weight of the marine turbine components installed in the nacelle directly influences the total mechanical design, as well as the operation and maintenance (O&M) costs. A reduction in the weight of the nacelle allows for cost-effective tower and foundation structures. On the other hand, longer transmission distances from an offshore wind turbine to the load leads to higher energy losses. In this regard, DC transmission is more useful than AC transmission in terms of efficiency because no reactive power is generated/consumed by DC transmission cables. This paper describes some of the challenges and difficulties faced in designing high-power-density power conversion systems (HPDPCSs) for offshore wind turbines. A new approach for high gain/high voltage systems is introduced using transformerless power conversion technologies. Finally, the proposed converter is evaluated in terms of step-up conversion ratio, device number, modulation, and costs.

Improved variable speed control of series‐connected DC wind turbines for offshore wind power collection to high‐voltage direct current system

“…To better integrate the HVDC technology to large offshore wind farm, advanced DC-DC power conversion concepts can be extended to the wind farm design [3][4][5][6][7], by which the different schemes of DC wind farm (DCWF) are thus proposed [8]. In the future DCWF, large-size power transformers can be replaced by power converters, and AC cables can be replaced by DC cables with lower losses and less materials [9][10][11][12].…”

“…High‐voltage direct current (HVDC) technology, is proved to be a promising solution for delivering large‐scale offshore wind power with long transmission distance, due to its reduced power losses and very low reactive power requirements [1, 2]. To better integrate the HVDC technology to large offshore wind farm, advanced DC–DC power conversion concepts can be extended to the wind farm design [3–7], by which the different schemes of DC wind farm (DCWF) are thus proposed [8]. In the future DCWF, large‐size power transformers can be replaced by power converters, and AC cables can be replaced by DC cables with lower losses and less materials [9–12].…”

High power step-up modular resonant DC/DC converter for offshore wind energy systems

“…The reasonable economics of offshore wind farms are driving toward the development of larger wind turbines but high installation costs and maintenance difficulties are critical issues for minimizing the operating and maintenance (O&M) costs [3], [4]. With increasing distances from the shore, the wind turbine industry faces new challenges, such as long distance electrical transmission on high-voltage submarine cables and the reliability of turbine equipment.…”

“…With increasing distances from the shore, the wind turbine industry faces new challenges, such as long distance electrical transmission on high-voltage submarine cables and the reliability of turbine equipment. Therefore, an optimized design is needed to reduce the size and weight of the components, O&M costs, and power losses of offshore wind turbines [3], [4].…”

Analysis of the Jeju Island Power System with an Offshore Wind Farm Applied to a Diode Rectifier HVDC

“…According to advanced research about HVDC with wind farm, voltage sourced HVDC can suitably deliver output power from wind farms to a weak grid such as the Jeju Island power system [2][3][4][5][6][7].…”