46. Lifetime Assessment and Optimized Maintenance System of Transformers Based on the HST Model

Currently, the maintenance mode of the power transformers is regular maintenance, which has been widely used. It is key to correctly evaluate the reliability level of the transformer in operation condition because it is directly related to the success of maintenance; on this basis, the lifetime evaluation and optimized maintenance model based on hot spot temperature (HST) in terms of the power transformer is developed in this chapter. In this model, the reaction speed theory of Arrhenius and Weibull distribution is considered as the fundamental theories, which are used to describe the aging process of the transformer and get the transformer failure rate \(\lambda \) ; and then the equations with exponential form are adopted to compute HST, namely, to calculate the top oil temperature relative to the environmental temperature \(\Delta {{\Theta }_{TO}}()\) the increment of top oil temperature \(\Delta {{\Theta }_{H}}\)and the hysteretic temperature \({{\Theta }_{Ae}}()\)so as to get HST (equals to the sum of the aforementioned three variables). Meanwhile, based on the model, the software analysis system based on Java language and Mysql database has also been developed, in which the transformer maintenance process was optimized and the statistical analysis was made for the hot spot area. Finally, the diagnosis results were obtained correspondingly, indicating that the designed model and system can effectively reduce the maintenance frequency, improve the utilization coefficient of the transformer, and thus improve the equipment’s reliability.