Compensating Unbalances in Synchronous Railway Traction Systems with Railway Power Conditioners

Sammanfattning: The electrified railway presents significant challenges for the electrical grid. This is due to the characteristics of the constructed railway system. Trains are single-phase loads, fed by two adjacent phases from the grid. Feeding phases will change continuously at every substation. This load characteristic will lead to unbalances and poor power quality in the grid. The poor power quality is caused by the unbalance in currents, voltage drops along the line, and induced harmonics from power electronic devices used in traction.   To decrease the impact of the railway traction system in the public grid, Static Var Compensators (SVCs) and Static Synchronous Compensators (STATCOMs) have been implemented. These installations offer voltage control, maintain balance and mitigate harmonics. This thesis investigates other power electronic technologies to improve the power quality in the grid for the 50 Hz railway traction system.