Harmonic Loss Analysis of the Traction Transformer of High-Speed Trains Considering Pantograph-OCS Electrical Contact Properties

The traction transformer of the traction drive system of a high-speed train is one of the main equipments for energy conversion. The transformer loss will be increased by load harmonics and pantograph arcs at high speed. It is very important to predict losses for the improvement of traction transformer design. In this paper, a dynamic model of the pantograph-catenary system is established using the MSC.Marc software based on the finite element method to analyze disconnection events in different speeds. Then the pantograph arc, traction transformer and four-quadrant converter model is set up. Resistance variations with the change of harmonic frequency have been considered in the calculation formulae of harmonic losses. Traction transformer losses can be calculated based on the harmonic T-equivalent circuit and superposition principle. Considering the harmonic losses variations, the effects of arc voltage on harmonic copper loss and harmonic core loss are analyzed, respectively. The average loss at different disconnection ratios is also calculated. This method could be used to estimate the increment of transformer harmonic losses with poor current conditions at high speed.