Analysis of Temperature Change in a Permanent Magnet Synchronous Generator under Load due to Stator Winding Inter-Turn Short Circuit

Abstract

The permanent magnet synchronous generator (PMSG) finds application in wind and tidal-stream generation. The reasons for its deployment may be summed up as its efficiency and the fact that it is self-sustaining, that is, it does not require external rotor electrical power. Because of the high installation and maintenance costs of both tidal and wind energy systems on-going condition monitoring (CM) is advisable. In CM many parameters are monitored, one of those being temperature. However, absolute temperature values may provide limited information about the equipment being monitored. The temperature of a PMSG under full load will be higher than an unloaded one which, of itself, is not relevant. The proposal here, explores the relative temperatures values over time for the purpose of detecting stator inter-turn short circuits. For this, an enhanced experimental setup is proposed. A previous work proposed a methodology to detect inter-turn short circuits in an unloaded generator by temperature analysis. This work is an extension of that with, in this case, a generator under different load conditions. A range of experiments verified a detectable temperature rise, in a short time, above that which would be expected in a healthy generator under load to one with a faulted stator winding. Further, this proposal automatically allows for a generator starting from cold or restarting with an elevated temperature. This proposed system, while still at the laboratory stage, has been successful in capturing temperature change over time and robust in detecting stator inter-turn short circuits within a short period of start-up. Further, while in this work a programmable controller (PLC) is used as the CM platform the methodology proposed here may be integrated into existing monitoring systems utilizing existing temperature sensors by modifying the monitoring software program.