AUSZUG | eb - Elektrische Bahnen INT 2/2015

20 113 (2015) INT 2 Rail Power Supply Traction power converters 50Hz / 50Hz Axel Brandt; Christoph Saniter; Jörg Janning; Ivan Mikes, Berlin (DE) For electrical power supply of a heavy freight line in Queensland (Australia) two static frequency converters (SFC) are used and in operation since December 2014. These are voltage source convert- ers based on IGBT technology. This is the first time that power electronic converters are employed to feed a 50Hz electric railway. In this case, they couple a three-phase 132 kV 50Hz grid with a  sin- gle-phase ±25kV 50Hz railway line network. BAHNENERGIEUMRICHTER 50Hz /50Hz Für die elektrische Versorgung einer Eisenbahnstrecke mit schwerem Güterverkehr in Zentral- Queensland (Australien) werden zwei statische Umrichter eingesetzt, die seit Dezember 2014 in Betrieb sind. Dabei handelt es sich um Spannungszwischenkreisumrichter in IGBT-Technik. Erstmals wird damit die Leistungselektronik dafür benutzt, ein Drehstromnetz 132kV 50Hz mit einem Einpha- senbahnnetz ±25kV 50Hz zu koppeln. CONVERTISSEURS 50Hz / 50Hz POUR LA TRACTION ÉLECTRIQUE Pour l’alimentation électrique d’une ligne ferroviaire de trafic marchandises pondéreuses en Queensland/ Australie ont été mis en service en Décembre 2014 deux convertisseurs statiques. Il y s’agit de convertis- seurs de source de tension réalisés en technique IGBT. C’est la première fois que l’électronique de puissance est utilisée pour coupler un réseau triphasé 132kV 50Hz à un réseau monophasé ferroviair ±25kV 50Hz. 1 Introduction The first traction power converter in regular service was supplied by AEG for the Wiesentalbahn near Ba- sel in Germany. That converter supplied the  single- phase railway grid at a frequency of 15Hz out of a 50Hz three-phase grid and went on stream in 1936 [1]. At that time, the converter ensured sufficient voltage quality (Figure 1). Converter technology could not yet reached maturity, and for many decades the single-phase catenary voltage was either generated by rotating machines or, in countries with identical grid frequen- cies, by section-wise supply from the three-phase grid. In case of new 16,7Hz installations, power elec- tronic converters have replaced rotating converters completely. Key factors are the significantly higher efficiency, lower maintenance costs and, above all, lower investments. Today, power electronics have become an alterna- tive for 50Hz traction power supply as well. The advan- tages of the static frequency converter (SFC) solution become obvious in the overall system design despite the higher investment costs of the converter installa- tion when compared with the standard transformer solution. In 2014, General Electric (GE) commissioned the first static frequency converter station for a 50Hz rail system fed from a 50Hz three-phase utility grid. 2 Advantages of the converter solution Main advantage of the SFC solution is the almost com- plete decoupling of the two grids, the railway grid and the three-phase distribution network. This allows for the three-phase grid to be loaded symmetrically and provided with any reactive power independently of the reactive power in the single-phase rail grid. The effect of the harmonics distortions of the single-phase current (highly variable train load) is also limited owing to a DC link coupling in SFC. In that way, large filters or static VAR compensators are not required. Symmetrical loading also enables supply from a high-voltage grid with low short-circuit power, or from a distribution grid with lower voltage level (even medium voltage networks are possible). Con- Figure 1: Output voltage of the seven-anode converter of the Wiesenthalbahn.