Improving the flow and thermal uniformities of transformer disc-type windings using a self-blocking oil circuit

Abstract

The design of winding oil circuits is of great significance for improving the reliability, lifetime and loading capability of power transformers. Given the limited cooling capacity and local hot spot problems of the traditional oil circuits, a self-blocking oil circuit was introduced in this work. This study focused on exploring the potential advantages of this self-blocking oil circuit over the traditional ones in terms of the flow and thermal performance. To this end, the winding heat losses, flow and temperature were first calculated using a multi-physics coupling numerical model. Subsequently, the flow and heat transfer mechanisms of the winding were studied. Then, the flow and heat transfer performance of the winding with the self-blocking and traditional oil circuits were evaluated and compared. Furthermore, the effects of blocking degrees and oil flow rates on the winding flow and thermal performance were investigated. The results showed that compared with the traditional oil circuits, the self-blocking oil circuit exhibited a significant potential to improve the flow uniformity of transformer disc-type windings. It owned a larger cooling potential and the ability to lower winding hot spot temperature.