Study Of Comprehensive Assessment Method For The Reliability Of Power Transformer

A power transformer is one of the most important energy transmission devices in power system. Its safe and reliable operation is vital to the continuous and well run of power grid. So, accurately evaluating the reliability of power transformer and guiding the operating and maintaining of power transformer is good for improving the reliability level of power system. Based on the operation parameter and detection parameter, two different reliability models of power transformer are built. And these two models are combined to build comprehensive assessment method at the end of the paper. Main contents are as below:1. The principle and reliability influence factors of transformer are introduced and analyzed. Indicate that the reason of decline of reliability level of transformer is the weakening of dielectric strength.2. Based on hot-spot-temperature model, reliability assessment of transformer is built. A simple and useful roll computing method is put forward to tracking the reliability of power transformer.3. Evaluation indexes of transformer’s health status are introduced, and gas content of the oil is chose to be the evaluation index. A method of evaluating the health status of transformer was built by using grey relational analysis. And analytic hierarchy process(AHP) was used to determine the weight of different gases.4. The framework and flow of transformer reliability prediction is built. An optimal initial value based GM(1,1,?) method is proposed to solve the prediction problem. The example case shows that the proposed method can well predict the reliability of transformer.5. Based on the two models above, the concept of degradation is put forward and the two models were combined by using the confidence coefficient factor, which is to the benefit of guiding the operation and maintenance of transformer.