Study on the First Failure Rate of Transformer Based on Field Data

In order to guide the transformer maintenance planning and reliability analysis of the power grid, the critical or serious defect of transformer for the first time is defined as the first transformer failure, and the law of the transformer failure rate changing with time in a province of China is analyzed by using a statistical analysis method and failure rate modeling method in reliability theory. The transformer defect records of 20 years in the production management system(PMS) system of a provincial network are collected, 10 sample sets with different commissioning time are constructed, and the variation of the failure rate with the transformer operating years is analyzed. Three distribution functions with the best fitting effect are selected. The Weibull distribution model of failure rate for different sample sets is established, and the change rule of failure rate with the commissioning time and the operating years of transformer is analyzed. Moreover, the Weibull distribution model of failure rate of different parts and different transformer manufacturers is established, and the difference of fault rate of different components and different transformer manufacturers is analyzed. The results show that the random failure law of newly commissioned transformers is dominant, their mean time to failure is longer, there is no early failure law like the traditional bathing curve, and the failure rate in the random failure period is 0~0.2 times/(set•year). The shape of the Weibull distribution function of the failure rate is similar for different components and different manufacturers, but their mean time to failure is significantly different. The transformer failure law obtained in this paper can effectively guide the power supply unit to optimize and adjust the maintenance plan. © 2022, High Voltage Engineering Editorial Department of CEPRI. All right reserved.