Conventional power transformers are very simple and reliable devices. Their efficiency, for large power rating, is well above 99 %. With such an excellent performance the improvement margin seems very strict. However, due to the large amount of power managed and the continuous service, also a small increase in the efficiency is desirable. As an example, consider that an efficiency increase of 0.5 % of a 25 MVA transformer leads to savings in the order of 100 k€/year. The use of superconducting materials opens the way to efficiency improvements on power transformers, and adds important advantages such as the reduction of size and weight, that are very attractive for strengthening of existing urban substations and transport applications. Moreover superconductors eliminate the need for refrigeration oil, thus avoiding the risk of fire hazard and reducing the environmental impact, in accordance with recent EU guidelines. In this paper first a design procedure for HTS power transformer is resumed. This procedure, that includes an analytical method for the calculation of the AC losses, is then used to design a 25 MVA – 154 kV / 20 kV transformer based on commercial BSCCO HTS conductors. The optimum solution is compared with a conventional transformer in terms of efficiency, size and leakage reactance. Different cooling solutions are examined and compared. Considerations on the use of 2nd generation YBCO coated conductors as well as future low AC losses MgB2 conductors are also reported.
A. Morandi, L. Trevisani, P.L. Ribani, M. Fabbri, L. Martini, M. Bocchi (2007). Superconducting Transformers: Key Design Aspects for Power Applications. BRUSSELS : s.n.
Superconducting Transformers: Key Design Aspects for Power Applications
MORANDI, ANTONIO;TREVISANI, LUCA;RIBANI, PIER LUIGI;FABBRI, MASSIMO;
2007
Abstract
Conventional power transformers are very simple and reliable devices. Their efficiency, for large power rating, is well above 99 %. With such an excellent performance the improvement margin seems very strict. However, due to the large amount of power managed and the continuous service, also a small increase in the efficiency is desirable. As an example, consider that an efficiency increase of 0.5 % of a 25 MVA transformer leads to savings in the order of 100 k€/year. The use of superconducting materials opens the way to efficiency improvements on power transformers, and adds important advantages such as the reduction of size and weight, that are very attractive for strengthening of existing urban substations and transport applications. Moreover superconductors eliminate the need for refrigeration oil, thus avoiding the risk of fire hazard and reducing the environmental impact, in accordance with recent EU guidelines. In this paper first a design procedure for HTS power transformer is resumed. This procedure, that includes an analytical method for the calculation of the AC losses, is then used to design a 25 MVA – 154 kV / 20 kV transformer based on commercial BSCCO HTS conductors. The optimum solution is compared with a conventional transformer in terms of efficiency, size and leakage reactance. Different cooling solutions are examined and compared. Considerations on the use of 2nd generation YBCO coated conductors as well as future low AC losses MgB2 conductors are also reported.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.