Harmonic Current And Negative Sequence Power Management Research Of New VV Traction Power Supply System

The load of electrified railway traction system has frequent fluctuations and greatimpact to the grid, which produces a lot of harmonic current, negative sequencecurrent, harmonic power and negative sequence power. Electric locomotive hasbecome the most important harmonic source and negative sequence source to powersystem, which brings serious threat to security and reliable operation of powersystem.The thesis has a detailed analysis of electrified railway traction transformer、harmonic control and negative sequence control. The thesis puts forward and does aresearch on a new Vv wiring transformer and railway power conditioner to effectivelyreduce the harmonic and negative influence sequence from the traction power supplysystem to the grid.Firstly, the thesis analyses electrified railway’s development and operationcharacteristics, meaning and properties,of harmonic and negative sequence producedby electrified railway traction’s load and traditional harmonic and negative sequenceadministration measures.Secondly, the thesis summarizes detailed analysis of the single-phase transformer,Vv wiring transformer, three-phase YN/d11wiring transformer, woodbridge wiringtransformer, cross wiring transformer, scott wiring transformer, impedance matchingbalance wiring transformer,many traction transformers in basic structure、powertransformation relationship、material utilization,、capacity utilization etc,and analysesthe development history of traction transformer. On the basis of high speed trend ofprospective railway, the thesis points out that the Vv wiring the transformer is thefuture trend of application of railway traction transformer.Thirdly, combined with traction transformer and induction filtering technique，the thesis puts forward and studies a new Vv transformer.and focuses research on itsthe equivalent circuit, harmonic model, the technology features and advantages ofthe induction filter. What is more, harmonic wave suppression principle of new Vvwiring traction transformer are also discussed. Traction power supply system withnonlinear load respectively simulation model is Established in Simulink. Thesimulation results show that the new Vv wiring transformer can effectively restrainthe harmonic current and harmonic power of high voltage grid side. Finally, combined with the characteristics of the traction power supply system,according to the symmetric component method, the thesis analyses negative sequencevoltage, sequence current and negative sequence power of the traction power supplysystem.On this basis, The thesis puts forward and does the key research on negativesequence power transmission device used to control the negative sequence powertransmission device, and analyzes the negative power transfer device compensatingprinciple and control methods. The new Vv traction transformer with a railway powerconditioner dragging nonlinear load respectively simulation model is established inPSIM6.0software.The simulation results show that the railway power transmission rdevice can restrain negative sequence current and negative sequence power of thehigh-voltage grid.