A customized air-core transformer for a small power tapping station

In this paper, a specially designed air-core transformer, to be employed in a small power tapping scheme for HVDC transmission systems, is studied. First, the transformer is analyzed by classical electromagnetic theory. Next, a small prototype transformer is built and studied in the laboratory. Experimental results, confirm the validity and accuracy of the proposed method for calculating the self and mutual-inductances of the transformer. The results of the digital simulation of the transformer by the PSCAD/EMTDC software package, too, are in good agreement with the lab observations. Next, the transformer is incorporated into the proposed tapping scheme and the system performance is digitally analyzed. It is concluded that with this transformer, a load of 600 kW can be successfully tapped from the HVDC system. Finally, the field effects of the transformer are studied