Modernization of Power-Transformer Cooling Systems

Abstract

The absence of power reserve of transformers at substations has an acute effect upon failure of one of them. In addition, operation of the transformers within the hot season is often accompanied by their overheating and failure in the work of the cooling systems. The article describes a possibility of upgrading the cooling systems of the oil transformers. A device for additional cooling of the oil transformer with thermoelectric converters is considered, the principle of operation of which is based on the fact that, at night at the minimum ambient temperature, the cold is accumulated in the container due to formation of the ice layer on the extended surface of the thermoelectric converter fins, melting of which is used within the warm time of the day for additional cooling of the transformer oil in the transformer cooling systems. The mathematical description of the ice formation process on the fins with a constant thickness in the water is given. Results of investigations of assessment of the dependence of the ice thickness on different parameters are analyzed. It is shown that the ice layer thickness is distributed along the fin length as a parabola. In addition, the ratio of the maximum thickness and length of the frosting zone does not depend on the thermal mode, but depends almost only on the thermal conductivity of the fin. With an increase of the fin thickness, the ice layer along its length becomes more uniform at the same time interval of icing. It is necessary to increase the thermal conductivity of the fin due to its thickness, as well as the higher thermal conductivity coefficient of the fin material.