COPSE-a new high performance controller for drying and oil filling of distribution power transformers

The drying process of distribution transformers in the manufacturing process is traditionally made by indirect heating of the windings of the transformer within an oven. This drying method causes low efficiency, high drying time, and associated lower quality for voltage isolation than the new method implemented by the authors and presented in this paper. The heating process has become a direct heating process, supplying the transformer in manufacturing with a low-frequency inverter and nominal power losses. The direct heating method requires a framework involving a control system for the heating current and winding temperature, handling highly nonlinear regimens in the output range of high temperature. Static operation points of temperature cause a drop of transformer input power down to 1% of the nominal power. The mean winding temperature is measured and controlled during all the process. This paper shows the design, implementation and results with a high performance controller for this process