Railway loads are highly fluctuating, since acceleration and retardation lead to variation in voltage. FACTS controllers can keep the voltage levels stable. Stabilizing the voltage can bring about benefits as follows to grid owners as well as railway owners and operators:
- Dynamic mitigation of voltage fluctuations in feeding grids caused by heavy fluctuations of railway loads, thereby fulfilling Grid Codes as far as voltage fluctuations are concerned;
- Dynamic voltage support of catenaries feeding high power locomotives, thereby maintaining traction capability despite weak feeding, and without harmful voltage drops along the catenary; furthermore enabling adequate power into locomotives during outages of feeding points, or, alternatively, with fewer feeding points required in the system. (Money to be saved in infrastructure construction!);
- Dynamic voltage control of AC supply systems for DC converter fed traction (typically underground and suburban trains).