Detection of internal faults in transformers using nonlinear observers

The developments in transformer construction made the basic principle of the classical differential protection not practicable, when some kind of faults are present in the transformer. Internal faults could not be detected by using differential protection. In this work an approach based on analytical redundancy is applied to the problem of detection of internal faults in the transformer. Using a nonlinear model of the transformer it is shown how faults could be effectively detected.