Topology and Matching Capacity of Direct-Connected Converter for Co-phase Traction Power Supply Substation

To optimize the topology, improve the compensation capacity and decrease the space occupied by the equipment for co-phase power supply substations, universal transformation method about electrical parameters from three phase to single phase was adopted and three types of direct-connected converters are investigated including full power converter, active power compensation converter and reactive power compensation converter. Based on active integrated compensation characteristics and power sub-module cha-racteristics, the topologies of three types of direct-connected converters were designed respectively. The matching relation between transformer connection mode and compensation capacity of direct-connected converters was also established. And, the capacity utilization ratio of power electronic device was determined in the end. The research results show that the associated compensation capacity is closely related to the connection modes of traction substation, as well as the connection port of the traction load and the type of load. For the converter with active power compensation, when the load power factor is greater than 0.961, it is better to choose the 90connection traction transformer; when the load power factor is less than 0.961, it is better to choose the 120connection traction transformer. For the converter with reactive power compensation, if the load is AC-DC-AC type, 90connection mode is preferable; if it is the inductive load, the connection mode of 120 is better than 90. Under the conditions of the same AC-DC-AC traction load and the modulation index is 0.8, the converter with active power compensation has the highest utilization ratio of 11.34% in device power capacity.