Phasing Connection Of Electrified Railway Power Supply System And Study On Its Effect

The traction supply system loads for its single phase independence inject much negative sequence current into the power system, and the negative sequence current of public connection points in the system can generate the negative sequence voltage because of the power system negative-order impedance, which makes the three-phase voltage unbalance in the power system, and it will destroy the power equipments. Phasing connection of electrified railway power supply system changes the voltage phases in the power system in order to inhibit the negative sequence level from the traction loads. Through this way, there is not any additional equipment itself, which is a reliable measures for the negative sequence problem at a lower cost. But the phasing connection needs neutral sections in the catenary which limit the speed and the reliability of the electrified railway. If make sure the effect on the negative sequence control with the phasing rotation, it will be significant for the railway and power department.Purposing to definite the single traction station situation of negative phase-sequence features and based on the method of the negative sequence vector, the general characteristic and expressions of negative phase-sequence from different kinds of traction transformers are summarized, The phasing connection of different connections of traction transformers is analyzed one by one, which is formulated by the analytical method and proved that the way of phasing connection can restrain the negative sequence level. The way of stationary phase of different traction transformers is proposed, furthermore the electrified railway connections which change phases as less as possible in the same power system can be realized by the programming, with the traversal algorithm of phasing states basing on the depth first search and branch-and-bound method. At last, using the measured data of the electrified railway and the three-phase power flow program renewed, the distribution of negative sequence of the regional sub-grid is simulated and analyzed, which is proved of the feasibility of the stationary phase connection for cutting down the traction load negative sequence level.