Failures of transformers in subtransmission systems not only reduce reliability of power system but also have significant effect on power system performance since one of the important components of any system quality is reliability of that system. To enhance utility reliability, failure analysis and rates, failure origin and physical damage causes must be study. This paper describes a case study of the reliability of subtransmission transformers (63/20 kV) installed in Mazandaran province, operated in subtransmission system. The information obtained from Mazandaran Regional Electric Company. The results of study and analysis on 60 substation including more than 110 transformers installed in subtransmission system show that the failure modes of transformers can be represented by Weibull distribution. Weibull statistics have been widely used and accepted as a successful mathematical method to predict the remaining life time of any equipment. Useful conclusions are presented both for power systems operators and manufactures for improving the reliability of transformers.
M.Mirzaie, A.Gholami, F.Aminifar, R.Saeedfar
(Iran University of Science & Technology (IUST
Sharif University of Technology