Research Of Effects On Transformer Protection By Harmonics And Negative Sequence Of Electric Railway

With the rapid development of electrified railways,the adverse effects on the public power grid brought by traction power-supply system have been increasingly taken into account by railway and electricity department.In order to analyse the harmonics and negative sequence influence caused by traction power-supply system,the models based on PSCAD/EMTDC of typical traction power-supply system,public power grid and protective devices of transformer have been established.The sympathetic inrush may occur in the system transformer when no-load electric locomotive or traction transformer is switched,so the protection may be affected.The mechanism of the sympathetic inrush and the propagation in system are analyzed.The sympathetic inrush is assessed in different entering-phase using different traction transformer.The characteristic of differential protection are studied.The effects of differential protection are verified using the experimental platform based on RTDS.The effects of transformer back-up protection are evaluated in the typical traction power-supply system region.