Case Studies

Although doubly-fed induction generators are considered a relatively mature technology in the field, they possess an inherently low power density, low efficiency and relatively low reliability due to the use of brushes and slip-rings. Also, the presence of a gearbox in these wind power generation systems is problematic, as it further reduces system efficiency and increases the risk of failures. These problems can be overcome by employing directdrive permanent magnet generator technology. However, current permanent magnet counterparts, whilst providing significantly higher power-density and higher efficiency, are not usually designed with fault-tolerant capabilities, and can possess lower operational reliability and availability than present doubly-fed induction generators solutions. For offshore systems, therefore, a need exists to develop high-power-dense, efficient and faulttolerant permanent magnet generators and power converters to accommodate short- and open-circuit winding/converter faults and be robust to the effects of demagnetization stemming from exposure to elevated temperatures and overload fault currents.

The project aims to address key technological hurdles for the widespread adoption of reliable, power dense and efficient offshore wind-turbine generation systems, with a view to maximizing their full future exploitation potential. Specifically, the scope of the project includes the research and development of novel, fault-tolerant and faultaccommodating direct-drive permanent magnet generators and associated fault condition monitoring, detection and mitigation systems, in a unified framework.

The outcomes of the project will be the development of novel permanent magnet machines and converter systems that exhibit higher power density and efficiency compared to existing stateof- the-art doubly-fed induction generator solutions, and possesses significantly higher fault-tolerant capability compared to conventional surfacemounted permanent magnet machine counterparts, which will be demonstrated through the commissioning of scaled prototype units during the project.

The project will support the employment of 2 directly funded industrial engineers, 2 research associates and 1 technician. Siemens will actively seek to enhance its existing investment in the region for exploiting the research outcomes. Within 3 years of the start of the project, expected investment will create up to 15-20 further employment positions at the Sheffield-Siemens Wind Power Research Centre (S2WP) at Sheffield from additional and geared funding. Also, Siemens already has significant co-operation with UK manufacturing companies on offshore turbine components and the outcome of this research program will directly impact on the future content of local UK production of turbine components for both on- and off-shore installations.

Kurt Anderson
Head of Generator Department

Siemens Wind Power A/S
Borupvej 16, 7330 Brande
Denmark

Tel: +45 9942 8621
Email: kurt.andersen@siemens.com
Website: www.siemens.co.uk