Demagnetization Detection, Misdiagnosis and Impact in Permanent Magnet Generators

Permanent magnet generators are key electrical machines in remote renewables power applications. Their ability to operate in direct-drive condition together with high efficiency and modularity are just some of the reasons. However, they may experience faults that if undetected will evolve. It is therefore crucial to detect faults reliably to avoid catastrophic failures. This paper deals with the detection of demagnetization in direct-drive permanent magnet generators. The paper focuses on the application of various diagnostic methods and compares their detection capabilities. Moreover, the authors will investigate cases of false negative diagnostic alarms that lead to misdiagnosis.