Dual-supply Electrical Locomotives Traction System And Calculation On Corresponding Impedance Parameters

With the rapid development of high-speed railway techniques in China,the electrical locomotives manufactured by our nation have completely met the requirements of national traction railway transportation.To extend China’s high-speed railway techniques around the world,it is imperative to develop locomotives operating under multiple supply systems,because the mono-supply system based locomotives cannot satisfy the international market requirements due to the coexistence of various traction power systems in Europe and Africa.In the meantime,as the coexisting transport constructions of high-speed railway,interstate railway and city railway have been developed in China,it is needed to manufacture the electrical locomotives which can be supplied by both the 25kV/50 Hz AC systems and 1.5kV DC systems used by city metro and light rails.Attempting to achieve this goal,the researches performed in this thesis are as follows.(1)In this thesis the traction system of is described and topologies under two sorts of power supply systems are presented.The operating principle of the two-level inverter as well as the two-level rectifier is studied and the corresponding mathematical models are also established.Moreover,the traction system simulation model of the dual-supply electric locomotives is established in traction and regenerative braking conditions,and the feasibility and effectiveness of the employed control strategy is verified by the simulated results.To overcome the limitations of occupancy space and weights of traction units in dual-supply locomotives,the conception of traction windings of the traction transformers used as DC filter inductors is proposed,for realization of facility reuse of the transformers.Moreover,different connection schemes for traction windings used as DC filter inductors are discussed,and taking the electromagnetic and structural parameters into account,a Maxwell 3D simulation model of the traction transformer is established.(2)With regard to the multi-winding traction transformers with characteristics of multiple windings,high capacity and numerous electrical ports,the calculation of composite short-circuit impedance and circulating current is one of the key works in design and manufacture of the dual-supply locomotives.Due to the complicated and burdensome modeling of multi-winding transformers,a new field-circuit coupling method with inductance matrix as an intermediate variable is applied to compute the composite short-circuit impedance and circulating current of multi-winding traction transformers,which are also made comparisons with experimental results.And it is validates that the new method holds for accurate calculation of composite short-circuit impedance and short-circuit circulating current under various short-circuit conditions.(3)To address the problems of nonlinearity and complication of inductance calculation model as the traction windings are used as DC filter inductors,this thesis,combining with the port voltage equations of multi-winding traction transformers,proposes a new method for inductance calculation of DC filter inductors based on order-reduced inductance matrix.According to different connection schemes of traction windings used as DC filter inductors and combining with different boundary conditions of the traction transformers,the inductance of DC filter inductors corresponding to the schemes are calculated.And the calculated results are compared with the experimental ones,by which the validity and practical feasibility of the proposed method are confirmed and this method is verified as a reliable support for facility reuse of traction transformers.