Power transformers health index calculation using reliability methods for the case study of the Dez Dam and Karkheh Dam hydro power plants

Transformers in power plants act as intermediaries between the power plant and the power grid, which are affected by electrical stresses such as switching, thermal stresses such as overload and arc, and chemical reactions in the dielectric oil. Acid and moisture components cause deterioration of transformer oil and paper insulation. Condition assessment of transformers is a method to predict and prevent spreading of faults in power transformers. The purpose of this paper is to evaluate the health condition of sample transformers of Dez and Karkheh dam hydro power plants using the proposed probabilistic method. The voltage levels of these transformers are 410 and 230 kV and the possible first-order and second-order reliability methods used to determine failure in materials or structures are based on the data of the transformers of Dez and Karkheh dam power plants to determine the reliability assessment. The results are compared and the efficiency of the proposed methods is demonstrated.