Thermal stress monitoring and pre-fault detection system in power transformers using fibre optic technology

As a major and most efficient equipment in electrical power system, power transformers requires more concentration on its fault monitoring and protection. The main cause of faults in power transformers are the stress due to both thermal and mechanical effects. The monitoring of the thermal stress/temperature of transformer oil and other parts can be used as a prime step to identify fault. Not only the temperature measurement, but identifying the measuring locations is also of greater importance. In this paper, a pre-fault detection system using optical fibre sensing technology has been proposed. Phosphorescence of the material has been used for the temperature sensing. Temperature of the selected hotspots of the transformers will be monitored continuously and fed back to the protection system including cooling systems. The protection equipments of the transformer can be activated well before the circuit breaker operates and the reliability of the system can be maintained. The proposed method of thermal stress monitoring and fault detection has been tested and validated on a 16 MVA transformer.