TY - GEN
T1 - Optimisation and comparison of generators with different magnet materials for a 6MW offshore direct drive wind turbine
AU - Bhuiyan, Nurul Azim
AU - McDonald, Alasdair
N1 - This paper is a postprint of a paper submitted to and accepted for publication in 8th IET International Conference on Power Electronics, Machines and Drives and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at IET Digital Library
PY - 2016/4/19
Y1 - 2016/4/19
N2 - In the past few years interest in the use of low speed permanent magnet generators for direct-drive wind turbine generator applications has increased significantly. The significant fluctuations in NdFeB magnet prices has encouraged designers to optimise magnet utilisation and to look at alternative magnet materials for wind turbine electrical generators. In this paper an analytical design model is developed for 6 MW offshore direct-drive wind turbine generators using different magnet materials (one with surface mounted NdFeB and another with flux concentrating ferrite magnet). Finite element method models are used to check key dependent variables calculated by the analytical models. The generator designs are optimised using a hybrid optimisation method incorporating a Genetic Algorithm and Pattern Search approaches. This is applied for four different objective functions, the first two which concentrate on maximising rated torque per unit magnet mass or unit of generator active material cost. They are simple and quick to execute but prioritise cost reduction and ignore lower efficiencies leading to lower turbine energy yields and hence poor cost of energy. A third objective function which seeks to minimise the sum of the generator active material cost and the costs of lost revenue over a finite number of operational years. This gives similar results to a fourth objective function which is an explicit turbine cost of energy calculation. The cost of NdFeB magnets affect the cost of energy of the surface mounted generator which tested with different cost €40/kg, €60/kg and €80/kg. The ferrite magnet generator being better when the NdFeB magnet price rises to €80/kg.
AB - In the past few years interest in the use of low speed permanent magnet generators for direct-drive wind turbine generator applications has increased significantly. The significant fluctuations in NdFeB magnet prices has encouraged designers to optimise magnet utilisation and to look at alternative magnet materials for wind turbine electrical generators. In this paper an analytical design model is developed for 6 MW offshore direct-drive wind turbine generators using different magnet materials (one with surface mounted NdFeB and another with flux concentrating ferrite magnet). Finite element method models are used to check key dependent variables calculated by the analytical models. The generator designs are optimised using a hybrid optimisation method incorporating a Genetic Algorithm and Pattern Search approaches. This is applied for four different objective functions, the first two which concentrate on maximising rated torque per unit magnet mass or unit of generator active material cost. They are simple and quick to execute but prioritise cost reduction and ignore lower efficiencies leading to lower turbine energy yields and hence poor cost of energy. A third objective function which seeks to minimise the sum of the generator active material cost and the costs of lost revenue over a finite number of operational years. This gives similar results to a fourth objective function which is an explicit turbine cost of energy calculation. The cost of NdFeB magnets affect the cost of energy of the surface mounted generator which tested with different cost €40/kg, €60/kg and €80/kg. The ferrite magnet generator being better when the NdFeB magnet price rises to €80/kg.
KW - optimisation
KW - permanent magnet machine
KW - wind turbine generator
KW - tower and foundation cost
KW - hybrid algorithms
KW - pattern search algorithm
KW - genetic algorithm
KW - ferrite magnet machine
UR - http://digital-library.theiet.org/content/conferences/10.1049/cp.2016.0300
U2 - 10.1049/cp.2016.0300
DO - 10.1049/cp.2016.0300
M3 - Conference contribution book
SN - 978-1-78561-188-9
BT - 8th IET International Conference on Power Electronics, Machines and Drives (PEMD 2016)
T2 - 8th IET International Conference on Power Electronics, Machines and Drives
Y2 - 19 April 2016 through 21 April 2016
ER -