The Initial Temperature Rise in a Permanent Magnet Synchronous Generator as a Tool in the Detection of Stator Inter-Turn Short-Circuits

The permanent magnet synchronous generator (PMSG) has many of the characteristics required for wind and tidal-stream generators. It is however, prone to stator winding inter-turn short-circuits, which can progress to catastrophic failure. This paper explores the possibility of detecting inter-turn short-circuits by analysis of the generator’s temperature rise under stator open-circuit conditions. The platform for detecting and flagging temperature rise is the programmable controller (PLC). The effects of, and the detection of inter-turn short-circuits from the literature are examined. A series of experiments to capture generator temperature at 5-minute intervals at different output frequencies and at different starting temperatures is carried out. From those experimental results it was evident that there was detectable temperature difference between a normal and a faulted stator winding in the first 5 minutes of operation. A methodology to detect, and within the 5-minute time scale, flag this abnormal temperature rise is proposed. The novelty of this approach is that it focusses on the rate of change of the PMSG temperature rise rather than absolute values. This is relevant as PMSG initial temperatures can vary due to operational and environmental factors. The methodology proposed was found to be robust. Further work will explore temperature rise under generator load conditions.