Experimental and numerical analysis of fast transient phenomena in distribution transformers

Transformers can be damaged by transient overvoltages causing internal resonances in the windings. The study of these oscillations implies a total system approach, including transformer, distribution network, circuit breaker, etc. In this paper, the results of experimental investigations and numerical analysis are presented, explaining the possible occurrence of internal winding resonances. The experimental part consists of laboratory experiments and on-site measurements in a substation. The numerical analysis is carried out using a preprocessing programme that translates the geometrical transformer data into a duality-based model for use in ATP. This approach can be used to investigate different system designs.