Parallel wind turbine powertrains and their design for high availability

Conventional wind turbine powertrains tend to use single-input-single-output topologies (i.e. one gearbox coupled to a generator with a power converter). Here powertrains with single-input-multiple-output subsystems are analyzed with Markov state space models in order to quantify any improvements in availability. A baseline powertrain's availability and that of different parallel powertrains are evaluated using wind turbine powertrain failure and repair rate data. The results show that an increase in the number of parallel systems, N, does not automatically lead to a higher availability for a wind turbine powertrain; however when failure and repair rates scale with module power ratings then there is an improvement. The designer can further improve availability by over-rating each parallel module. The net benefit of parallel powertrains depends both on the turbine and the type of powertrain technology.