دانلود رایگان مقاله انگلیسی مدل مارکوف برای نگهداری ترانسفورماتور قدرت - الزویر 2018

ABSTRACT

The condition of the insulation paper is one of the key determinants of the lifetime of a power transformer. The winding insulation paper may deteriorate aggressively and result in the unexpected failure of power transformers, especially under the presence of high moisture, oxygen, and metal contaminants. Such types of scenarios can be prevented if the deterioration is detected on time. Various types of condition monitoring techniques have been developed to detect transformer condition such as dissolved gas analysis (DGA) and frequency response analysis (FRA). They are non-intrusive and provide early warning of accelerated deterioration both chemically and mechanically. However, the accuracy of those techniques is imperfect, which means periodic inspection is still indispensable. In this paper, we discuss the value of continuous condition monitoring for power transformers and present a way to estimate this value. Towards this, a continuous-time Markov decision model is presented to optimize periodic inspections, so that the cost is minimized and the availability is maximized. We then analyze the performance based on the information from both discrete inspection and continuous condition monitoring using DGA and FRA. The result shows the dissolved gas analysis can improve the availability and operation cost, while frequency response analysis can only improve the availability of power transformers.

Conclusion

In this paper, we first analyzed the malfunctions that may accelerate the deterioration of winding insulation paper. Then, we applied the information to refine the deterioration model of power transformers. We considered multiple types of failure rates of power transformers, such as infant mortality, sudden failure, and deterioration failures, so that the overall failure rate of power transformer follows a bathtub curve with multiple wear-out tails. We developed analytical models for power transformer maintenance in the distribution network and transmission network using CTMC. A condition-based maintenance is designed for power transformers in the transmission network. The designed condition-based maintenance model opens up a successful way to optimize the maintenance of power transformers according to the information from both periodic inspection and online monitoring devices. The value of DGA and FRA analysis were studied in a numerical case. The result shows that by applying DGA, both the availability and the operation cost of the power transformer can be improved. However, FRA can improve only the availability of the power transformer.