Analysis on the Setting Calculation of Line Relay Protection with V/V Wiring Traction Transformer

With the development of electrified railway,a large number of v/v wiring traction transformers are applied to power grid,which has great impact on the setting calculation of relay protection for power grid.In this paper,phase components method is used to analyze the short-circuit current when short circuit fault occur at low-voltage side of v/v wiring traction transformers.Through calculating the minimum measuring impedances of phase-to-phase and grounding impedance components on lines of source side and the maximum short-circuit current flowing in the protection,it is needed to modify the setting values of distance protection and zero-sequence current protection.And the quantitative modified strategy is given,which can effectively prevent the protection range of distance protection and zero-sequence current protection from over reaching the low voltage side of traction transformer,and guarantee their selectivity.