Fault tolerant generator systems for wind turbines

The objective of this paper is to review the possibilities of applying fault tolerance in generator systems for wind turbines based on what has been presented in the literature. In order to make generator systems fault tolerant in a suitable way, it is necessary to gain insight into the probability of different failures, so that suitable measures can be taken. Therefore, a literature survey of reliability of wind turbines, electrical machines and power electronic converters is given. Five different ways of achieving fault tolerance identified in the literature are discussed together with their applicability for wind turbines: (1) converters with redundant semiconductors, (2) fault tolerant converter topologies, (3) fault tolerance by increasing the number of phases, (4) fault tolerance of switched reluctance machines, and (5) design for fault tolerance of PM machines and converters. Because converters fail more often than machines, it makes sense to use of fault tolerant converter topologies. Increasing the number of phases is a useful form of fault tolerance because it can be achieved without increasing the cost significantly.